Vegetation Changes of Communities Containing Medusahead (Taeniatherum Asperum (Sim

AN ABSTRACT OF THE THESIS OF

ROBERT BRUCE TURNER for the DOCTOR OF PHILOSOPHY (Name) (Degree) in RANGE MANAGEMENT presented on 1A\ Title: VEGETATION CHANGES OF COMMUNITIES CONTAINING

MEDUSAHEAD (TAENIATHERUM ASPERUM (SIM. ) NEVSKI)

FOLLOWING HERBICIDE, GRAZING, AND MOWING TREAT-

MENTS Abstract approved: Redacted for Privacy Cha s E. ou-iton

Studies were conducted from 1962 to 1966 to investigate the effectiveness of several practices in manipulating medusahead (Taeniatherum asperum (Sim. ) Nevski) infested and/or dominated ecosystems by releasing competition in favor of perennial grasses. Several herbicide treatments were evaluated for selective control of medusahead and cheatgrass (Bromus tectorum L.) and the subsequent release from competition of perennial grasses on deteriorated sagebrush (Artemisia tridentata Nutt. ) /bluebunch wheatgrass (Agropyron spicatum (Pursh) Scribn. andSmith) range in the Snake River hills of eastern Oregon. On foothill range in western Oregon, sheep grazing and mowing treatments were applied in attempt to selectively control medusahead dominance in favor of suppressed perennial grasses, primarily California oatgrass (Danthonia californica Boland). Effectiveness of all treatments, including control, was evaluated by measuring vegetative changes in species density, reproductive vigor, and plant bulk, and interpreting these in terms of plant succession. Herbicides were applied in spring and fall, 1962 and spring,

1963.Annual vegetation and the small, tufted perennial Sandberg's bluegrass (Poa secunda Presl. ) were measured for frequency of occurrence in 50 nested plots of22-inchand12-footquadrat sizes, randomized in 8 by 50-foot macroplots (8 by 25 feet at one site) four times for each treatment at each of three experimental sites.For perennials, frequency was measured in12-footquadrats only, and in addition, percent canopy cover was determined.Frequency measurements were taken from 1963 to 1966 at one site and 1964 to 1966 at two other sites.Canopy cover measurements were excluded in 1966 due to extreme drought-and foraging by grasshoppers. Much variation occurred for annual species due to climatic conditions and herbicide treatments.Cheatgrass was dense and vigorous only in 1963.Medusahead was more sparse and patchy but made vigorous growth in 1963, 1964, and 1965.Being about three weeks later in phenology than cheatgrass, medusahead was able to benefit from late spring precipitation in 1964 and 1965.Both were practically absent in 1966 from drought.Fiddleneck (Amsinckia intermedia Fisch. and Mey) and sunflower (Helianthus annuus L. ) were the dominant annuals in 1964 and 1965, except where medusahead was co-dominant in patches. Frequencies of Sandberg's bluegrass were higher in 1963 but lower and static the remaining years.Herbicides isocil and atrazine at rates of 1 and 2 lb/acre reduced Sandberg's bluegrass to low frequencies.Under different environmental conditions, atrazine, at rates of 1/2 and 3/4 lb/acre, harmed bluegrass to only a small degree. Sandberg's bluegrass was resistant to bromacil at a rate of 1/2 lb/acre, whereas the closely related herbicide, isocil, was quite harmful. Atrazine increased vigor, height, and number of reproductive stems of bluebunch wheatgrass for three consecutive years following application.Wheatgrass plants responded to atrazine as if they had received a nitrogen fertilizer treatment.This was manifested by darker green, denser, and leafier clumps than those observed in other treatments. Atrazine, at rates of 1/2 to 2 lb/acre, caused no apparent injury to bluebunch wheatgrass.Since atrazine is most harmful at the seedling stage, young seedlings perhaps were killed from residual atrazine. Other factors such as grasshoppers, poor seed crops, and inadequate climatic conditions could have contributed in part, or solely, to static wheatgrass frequencies during the period of study. In western Oregon, sheep grazing treatments in mid April, mid April - followed by late May, and late May; and mowing treatments in mid April and mid April - followed by late May were applied from 1963 to 1965 on randomized 1/20-acre paddocks, replicated three times.Frequency of all species were measured following treatment each year and in 1966 in 50 nested plots of22-inch, 62-inch, and12-footquadrat sizes.Basal area of California oatgrass, yields of medusahead, oatgrass, other herbage, and total herbage were measured in 1966 for all treatments. From relationships of vegetation data and habitat factors of soil, degree of slope, and exposure, two distinct ecological sites were noted at the main study area at the Hill Pasture.These were referred to as the mesic site and xeric site.Frequencies of medusahead and California oatgrass were higher on the xeric and mesic site, respectively. The early-late grazing was highly effective on both the xeric and mesic site for utilizing medusahead.The late grazing was effective on the mesic site but extremely poor on the xeric, even with heavier grazing pressure applied.Medusahead had a high density in 1966 on paddocks where both treatments had been applied, and was again dominant. The early-late mowing effectively reduced medusahead to near absence, improved California oatgrass vegetative and reproductive vigor markedly, and shifted dominance to California oatgrass. Low frequencies of medusaheadwere recorded in 1966. The early grazing and early mowingwere both ineffective for reducing medusahead frequencies eachyear. Medusahead was readily consumed when grazed early.This reduced the buildup of litter to some extent.

Vegetation-habitat relationshipswere investigated at 12 other hill range sites along the westernedge of the Willamette Valley and were related to the mesic and xeric sites at the HillPasture. Under conditions of the treatments applied,results of the Hill Pasture study could be extrapolated to all buttwo of the 12 sites as ameans of gaining rapid range improvement. Vegetation Changes of Communities Containing Medusahead (Taeniatherum asperum (Sim. ) Nevski.) Following Herbicide, Grazing, and Mowing Treatments

by Robert Bruce Turner

A THESIS submitted to Oregon State University

in partial fulfillment of the requirements for the degree of Doctor of Philosophy June 1969 APPROVED: Redacted for Privacy

in charge of major

Redacted for Privacy

Heacifo the ljepartment of Farm Crops

Redacted for Privacy

Dean of Gaduate School

Date thesis is presented

Typed by Gwendolyn Hansen for Robert Bruce Turner ACKNOWLEDGMENTS

The author is deeply indebted to his Major Professor, Dr. Charles E. Poulton, whose inspiration and guidance attributed a large measure toward the completion of this dissertation and fulfillment of a graduate program in Range Management at Oregon State University. Special thanks is due to Dr. Donald W. Hedrick, who so ably filled in as Acting Major Professor during Dr. Poulton's term of absence.The numerous wise and technical suggestions and criti- cisms furnished by Dr. Hedrick is greatly appreciated. Kind regards are also extended to Dr. William R. Furtick for his many valuable suggestions, interest, and stimulating optimism provided during the course of the investigations. For their critical review of the manuscript by the above per- sons, I am most grateful. Sincere appreciation is extended to the remainder of those who served on my graduate committee, including: Dr. William W. Chilcote, Botany Department; Dr. Chester T. Youngberg, Soils Department; and Dr. Ernest M. Dickinson, who represented the Graduate School. The writer is grateful to Professor W. H. C. Schallig for the many thought-provoking ideas and technical assistance which he gave with such unbounding patience and unselfishness. Thanks are also due to Dr. Gerald H. Simonson, Soils Depart- ment, and Mr. Clarence Knezevich, Soil Conservation Service, for their professional assistance in checking soil profile descriptions and tentative soil series. Gratitude is extended to the Oregon State University Animal Science Department and the numerous Willamette Valley landowners who provided experimental animals and study sites during the course of the investigations.Mr. Lloyd Westcott, Animal Science Depart- ment Sheep Herdsman, is due thanks for his assistance in handling animals during experimentation. Several Agricultural Chemical companies share in my gratitude, by providing herbicides used in the study. The author is much indebted to the Bureau of Land Management, United States Department of the Interior, for the support provided through their cooperation with the Oregon Agricultural Experiment Station Project 486 -- "The Control of Medusahead on Oregon Ranges," of which I was Project Leader. Lastly, I am deeply grateful to my wife, Eleanor, who has been a constant source of understanding and encouragement during my graduate program at Oregon State University. TABLE OF CONTENTS

Page

INTRODUCTION 1

Statement of the Problem 1 Purpose of Study 2

DESCRIPTION OF STUDY AREAS 5

Eastern Oregon 5 Geography and Physiography 5 Geology and Soils 6 Climate 6 General Climatic Conditions 6 Climatic Conditions During the Study 7 Vegetation 11 Western Oregon 14 Geography and Physiography 14 Geology and Soils 15 Climate 16 General Climatic Conditions 16 Climatic Conditions During the Study 16 Vegetation 17

REVIEW OF LITERATURE 22

Aute cological Considerations 22 Selective Herbicides 29 Grazing and Mowing Influences 38

METHODS AND PROCEDURE 42

Eastern Oregon 42 Selection of Study Sites 42 Experimental Design 42 Treatment Schedule 43 Vegetation Measurements 43 Soil Des criptions 49 Western Oregon 49 Selection of Study Sites 49 Experimental Design 50 Page Treatment Schedule 50 Vegetation MeasurementsHill Pasture Site 52 Macroplots 52 Frequency 54 Clipping Yields 54 Basal Area 55 Vegetation Measurements - Other Foothill Sites 55 Soil Descriptions 55

RESULTS AND DISCUSSION- EASTERN OREGON 56

Stripe Mountain West Site 56 Vegetation Response to Treatments and Climate CONTROL Treatment 56 Frequency 5 6 Canopy Cover 68 Height and Vigor Measurements of Bluebunch Wheatgrass 70 Vegetation Response to Treatments and Climate HERBICIDE Treatments 70 Frequency 70 Canopy Cover 76 Height and Vigor Measurements of Wheatgrass 80 Germination Tests of Bluebunch Wheatgrass Seed 82 Stripe Mountain East Site 82 Vegetation Response to Treatments and Climate 1964 to 1966 82 Frequency 82 Canopy Cover 88 District Boundary Site 88 Vegetation Response to Treatments and Climate - 1964 to 1966 88 Frequency 88 Canopy Cover 93

CONCLUSIONS AND IMPLICATIONS TOWARD MANAGEMENT 95

RESULTS AND DISCUSSION - WESTERN OREGON 102

Hill Pasture Site 102 Vegetation Response to Treatments and Climate - 1963 to 1966 102 Frequency 102 Basal Area of California Oatgrass 117 Page Clipping Yields of Medusahead, California Oatgrass, Other Herbage and Total Herbage 120 Climatic Influences 127 Edaphic Influences 128 Discussion of Ecosystem Dynamics 128 Other Foothill Sites 133 Purpose of Investigations 133 Vegetation Measurements 134 Soil Des criptions 134 Vegetation - Habitat Relationships 136

CONCLUSIONS AND IMPLICATIONS TOWARD MANAGEMENT 143

SUMMARY 151

BIBLIOGRAPHY 160

APPENDICES 171 LIST OF TABLES

Table Page 1.Dates of application and rates of herbicide treatments at the Stripe Mountain West, Stripe Mountain East, and District Boundary sites. 44 Dates sampled for frequency and canopy cover at the Stripe Mountain West, Stripe Mountain East, and District Boundary sites. 48

3.Dates of mowing and grazing with numbers of sheep days grazed for treatments at the Hill Pasture site. 53

4.Mean frequency and standard errors of annual species within 22-inch and 12-foot quadrats at the Stripe Mountain West site (percent). 57

5.Mean canopy cover, frequency and standard errors of perennial species within 12-foot quadrats at the Stripe Mountain West site (percent). 58

6.Mean leaf and inflorescence heights, percent of reproductive clumps, and maximum number of heads per clump of bluebunch wheatgrass at the Stripe Mountain West site. 71

7.Mean germination percentages and standard errors of bluebunch wheatgrass seed collected from macroplots at the Stripe Mountain West and Stripe Mountain East sites and tested under laboratory conditions. 83

8.Mean frequency and standard errors of annual species within 22-inch and 12-foot quadrats at the Stripe Mountain East site (percent). 84

9.Mean canopy cover, frequency and standard errors of perennial species within 12-foot quadrats at the Stripe Mountain East site (percent). 85

10.Mean frequency and standard errors of annual species within 22-inch and 12-foot quadrats at the District Boundary site (percent). 90 Table Page 11.Mean canopy cover, frequency and standard errors of perennial species within 12-foot quadrats at the District Boundary site (percent). 91

12.Freqyncies of species sampled within22-inch, 62-inch and 1-foot quadrats in the CONTROL TREATMENT at the Hill Pasture site. 103 2 13.Frequencies of species sampled within 2-inch,62-inch, and 12-foot quadrats in the EARLY GRAZED TREAT- MENT at the Hill Pasture site. 104 14.Frequencies of species sampled within22-inch, 62-inch, and 1-foot quadrats in the EARLY - LATE GRAZED TREATMENT at the Hill Pasture site. 105

15.Frequencies of speciessampled within22-inch,62-inch, and 12-foot quadrats inthe LATE GRAZED TREATMENT at the Hill Pasture site. 106 16.Frequencies of speciessampled within22-inch, 62-inch, and 12-foot quadrats inthe EARLY MOWED TREATMENT at the Hill Pasture site. 107

17.Frequencies of species sampled within22-inch, 62-inch, and 12-foot quadrats in the EARLY-LATE MOWED TREATMENT at the Hill Pasture site. 108

18.Mean basal area and standard errors of California oatgrass measured after clipping in 19 66 at the Hill Pasture site. 118

19.Mean yields in lbs /acre and standard errors of medusahead, California oatgrass, Other Herbage, and Total Herbage clipped at the Hill Pasture site in late May, 1966. 121 20.Frequencies of species sampled in 1966 within22-inch and 12-foot quadrats in 12 stands at Other Foothill sites along the western edge of the Willamette Valley. 135

21.Percent slope, exposure, soil depth, and elevation at each of the 12 stands at Other Foothill sites studied in 1966. 139 LIST OF FIGURES

Figure Page 1.Mean monthly temperatures at Huntington during the period of study and departures from long-time averages. 8 2.Mean monthly precipitation received at Huntington during the period of study and departures from long- time averages. 9

3.Mean monthly temperatures at Corvallis during the period of study and departures from long-time averages. 18 4.Mean monthly precipitation received at Corvallis during the period of study and departures from long- time averages. 19 5.The hand-pushed, one-wheel plot sprayer which was used for all herbicide applications. 45

6.Experimental design and layout of treatment paddocks at the Hill Pasture site. 51 7.Mean frequencies of important species sampled in the CONTROL treatment within 22-inch (solid) and 12- foot (hatched) quadrats at the Stripe Mountain West site. 60 8.Mean frequencies of important species sampled in the ATZ-2-S treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 61

9.Mean frequencies of important species sampled in the ATZ-1 1/2-F treatment within 24-inch (solid) and 12- foot (hatched) quadrats at the Stripe Mountain West site. 62 10.Mean frequencies of important species sampled in the ISO-1-S treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 63 11.Mean frequencies of important species sampled in the ISO-1-F treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 64 Figure Page 12.Mean frequencies of important species sampled in the DAL-2-S treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 65

13.Mean canopy cover (solid) and adjusted canopy cover (hatched) of bluebunch wheatgrass measured at the Stripe Mountain West site among all treatments. 69

14.The contrast in fiddleneck density and vigor on an ATZ-1 1/2-F macroplot where bluebunch wheatgrass was dense and vigorous (upper photograph) versus sparce to absent (lower photograph). 74

15.The contrast of bluebunch wheatgrass vigor in an ATZ-2-S macroplot and an adjacent cheatgrass- dominated strip in 1963. 77

16.An illustration of the same photopoints as was seen in Figure 15 in 1964 (upper photograph) and in 1965 (lower photograph).Note the increase in reproductive stems on the treated plot in 1965 compared with the non-treated adjacent strip. 78

17.The contrast in vigor of bluebunch wheatgrass on an ATZ-1 1/2-F macroplot in 1964 (lower photograph) in comparison with that of a CONTROL macroplot (upper photograph). 79

18.Excellent control of medusahead on an ATZ-3/4-F macroplot and the subsequent increase in vigor of bluebunch wheatgrass.Note the poor vigor of wheatgrass growing in competition with dense medusahead in left foreground. 89 19. A comparison of mean frequencies of medusahead for all years and all treatments within 22-inch quadrats between Block 1 (solid) and Block 3 (hatched) at the Hill Pasture site.No grazing or mowing treatments were made in 1966. 109 Figure Page 20.Complete utilization (upper photograph) of medusahead, California oatgrass, and other herbage in an EARLY- LATE GRAZED paddock in 1964. A comparative EARLY-LATE MOWED paddock (lower photograph) prior to the late mowing.Note the vigor of oatgrass and very little medusahead. 112 21. A comparison of the same paddocks shown in Figure 20 as they appeared in 1966.Note the dense medusahead dominance in the EARLY-LATE GRAZED treatment (upper photograph) versus the dominance by vigorous California oatgrass in the EARLY-LATE MOWED treatment (lower photograph). 113 22. A comparison of mean frequencies of California oatgrass for all years and all treatments within 22-inch quadrats between Block 1 (solid) and Block 3 (hatched) at the Hill Pasture site. 115

23.Mean yields of medusahead and California oatgrass sampled among all treatments in Blocks 1 and 3 at the Hill Pasture site in late May, 1966. 122

24.Mean yields of Other Herbage sampled among all treatments in Blocks 1 and 3 at the Hill Pasture site in late May, 1966. 123

25.Mean yields of Total Herbage sampled among all treatments in Blocks 1 and 3 at the Hill Pature site in late May, 19 66. 124 26. A comparison of an EARLY-LATE GRAZED paddock (upper photograph) and an adjacent LATE GRAZED paddock (lower photograph) in 1965.Note the large amount of exposed mineral soil in the latter but very little in the former. 131 Vegetation Changes of Communities Containing Medusahead (Taeniatherum asperum (Sim. ) Nevski) Following Herbicide, Grazing, and Mowing Treatments

INTRODUC TION Statement of the Problem

Medusahead) (Taeniatherum asperum), a winter-annual grass native to the Mediterranean Region, iscurrently one of the primary range weed problems inOregon, California, Washington, and Idaho (Murphy and Turner, 1959; Torell, Erickson, andHaas, 1961; Sharp and Tisdale, 1952; and Turner, Poulton, andGould, 1963).Medusa- head is an aggressive competitor and of low foragevalue, which makes it a serious threat to the range livestockindustry.Once this menacing weed invades and gains a foothold on deteriorated range,productivity is drastically impaired.Medusahead has spread extensively since it was first collected in theUmpqua Valley in southwestern Oregon in

1884. Ecologically, medusahead is well adapted forsurvival on foothill ranges dominated by annual grasses inwestern Oregon and California, and on deteriorated range withinthe big sagebrush (Artemisia tridentata)/bluebunch wheatgrass(Agropyron spicatum) climatic zone of the lower Columbia andSnake River Basins.As a

1A complete lisling of generic and commonnomenclature and authorship is presented in AppendixA.After first reference, common names are employedfor important species; generic names are used for all other species. 2 result of recurring wild-fires and overgrazing of perennial grasses by herbivores, much of this area now-supports cheatgrass (Bromus tectorum) as the main forage plant. Many of these areas, in turn, are being invaded by medusahead.Hironaka (1961) has estimated 50 to 80 percent reductions in grazing capacities in some areas within a period of only a few years.Higgins and Torell (1960) have estimated that the monetary loss on Idaho ranges infested with medusahead amounts to about $3, 500,000 annually.Since medusahead occurs in Oregon throughout an area in excess of two million acres, as reported by Turner, Poulton, and Gould (1963), losses of potential forage here, too, are exceedingly high! As a means of combating the medusahead problem, the Oregon Agricultural Experiment Station and the Bureau of Land Management, United States Department of the Interior initiated a cooperative research project in 1961.The over-all objective was entitled "The Control of Medusahead on Oregon Ranges. " When this writer was assigned as project leader, it was agreed that a portion of the research could be used in the dissertation reported herein.

Purpose of Study

The manipulation of vegetation to enhance a more desirable production, both in quantity and quality, is commonplace in today's agriculture.Factors within ecosystems can be altered to effect 3 changes toward improvement. With advanced agricultural technology, man has an array of tools available for manipulating range ecosystems. Some of these are quite new such as use of specialized machinery, fertilization programs, biological pest control, and selective herbicides.Others, such as mowing and using animals as tools for removing herbage have been practiced for years. Some of these techniques are thought to have an important place in a medusahead control program. The primary purpose of this study was to investigate the effectiveness of several practices in manipulating medusahead infested and/or dominated ecosystems by releasing competition in favor of more desirable perennial grasses.The experimental plans followed two main approaches: first, to evaluate the use of herbicides for selective control of medusahead and cheatgrass and the subsequent release from competition of perennial grasses on deteriorated big sagebrush-bluebunch wheatgrass range in eastern Oregon; secondly, to use and compare sheep grazing and mowing treatments to selectively control and manipulate medusahead on a foothill range in western Oregon.Effectiveness of all treatments in the respective ecosystems was evaluated by measuring vegetation changes and interpreting them in terms of natural plant succession. A secondary objective of the study was to document and evaluate 4 the dynamic nature of medusahead in eastern Oregon as a subordinate invader of range ecosystems. 5

DESCRIPTION OF STUDY AREAS

Eastern Oregon

Geography and Physiography

The study area is located in northern Malheur County, five miles south and one mile west of Huntington, Oregon,2and comprises two sites which are about one mile apart.These are referred to as the "Stripe Mountain site" and the "District Boundary site. "Although both sites have but little slope, the general topography of the area is that of dissected hills and shallow canyons, typical of the Snake River watersheds of the Willow Creek and Birch Creek tributaries. A few of the higher points of elevation in the region have been historically referred to as "mountains. "Stripe Mountain rises to 3355 feet just to the west of the study area. According to Baldwin's physiographic provinces of Oregon (1964), the study area is in the transition zone of the Blue Mountains to the north and the Owyhee Upland to the south.

2Names of specific sites and their location by legal description and elevation and slope are indicated in Appendix B. 6

Geology and Soils

The predominant rock formations in the study area are basalts and basaltic andesites of late Tertiary age (Baldwin, 1964).Variably metamorphosed shales, sandstones, limestones, greenstones, and tuffs of Pre-Tertiary formations are also described for the region. Soil parent material at both the Stripe Mountain site and District Boundary site is from residual basic rocks and some amount of loess, particularly at the latter site.The soil association for the area, as indicated in the U. S. Dept. of Agric. Yearbook of Agriculture Soils and Men (1938), is McCammon- Deschutes.This association includes lithosols and shallow soils of arid-subhumid regions.

Lovell et al.,(1967) have made a generalized soil survey of the northern Malheur area. From this the soil at the Stripe Mountain site is mapped as the Lookout Series and that at the District Boundary site as the Virtue Series.Descriptions of these are presented in Appendix

Climate

General Climatic Conditions

The Huntington vicinity has a semi-arid, continental climate with a high percentage of sunshine. Summers are hot and dry; 7 winters are cold with moderate snowfall.According to the U. S. Dept. of Agric. Yearbook of Agriculture Climate and Man (1941), 37 percent of the yearly precipitation comes in winter, 27 percent in spring, 12 percent in summer, and 24 percent in fall.The average first killing frost in fall is about October 10 and the average last killing frost in spring is about April 20.The long-time average monthly temperatures and precipitation over a 52-year period at Huntington, as recorded by the U. S. Weather Bureau, are shown in Figures 1 and 2 (Climatological Data, 1966). Summer electrical storms occur infrequently, but ecologically, are important from the standpoint of igniting range fires.Frequent droughts are normal, not the exception, in this arid portion of the Snake River Basin.

Climatic Conditions During the Study

Monthly averages of maximum, minimum, and mean temperatures; average monthly amounts of precipitation; and departures from the long-term average are shown for Huntington in Figures 1 and 2 (Climatological Data, 1962-1966). Temperature and precipitation relationships considered as having been ecologically significant during the course of study are summarized for each year as follows:

1962 - Cool, dry February and March; warm, moist April; cold 90

80 Average Maximum

N a) 50 40 30 20 Average Minimum 10

JFMAMJJASONDIJFMAMJJAS ONDIJFMAMJ J ASOND 1962 1963 1964

Figure 1.Mean monthly temperatures (circle) received at Huntington during the period of study and departures from long-time averages (bar).

00 JFMAMJJASONDJFMAMJ 1965 1966

Figure 1.(Continued) 3 0

Q T

6 jFMAM; jASOND JFMAMj J ASOND JFMAMJ J ASOND 1962 1963 1964

J F MAMj JAS 0 NDJ FMAMJ 1965 1966

Figure 2.Mean monthly precipitation (circle) at Huntington during the period of study and departures from long-time averages (bar).

0 11 May; warm September; cool, moist October; and warm, dry November. 1963 -Extremely warm, dry February; warm, dry March; cold, moist April; warm May; warm, moderately moist September. 1964 - Cold, dry February and March; cool, moderately moist April; cool, moderately dry May; cool, moist June; cool, dry fall; extremely moist December. 1965 -Extremely moist January; warm, dry February; cool, dry March; warm April; cool, moderately dry May; moist June; cold, moderately dry September; and warm, dry October. 1966 - Dry January, February, March, April, May; warm April and extremely warm May.

Vegetation

As evidenced by the prevailing climate, soils, and seral vegetation, the ecological unit comprising the study area is representative of the Artemis is tridentata/Agropyron spicatum/Poa secunda habitat type.3In pristine condition, the plant association characterized by the foregoing generic trinomial is thought to have been the climatic climax for the local region.Hence, according to the plant

3Ahabitat type was defined by Daubenmire (1952) as, "The collective area which one association occupies, or will come to occupy as succession advances. " 1:2 geographical scheme of Daubenmire (1942), this seral vegetation further serves to indicate that the study area lies within the Artemisia tridentata/Agropyron spicatum climatic zone.The Artemisia tridentata/Agropyron spicatum habitat type has been described by Poulton (1955), who worked in the Deschutes-Umatilla province in northern Oregon, and by Eckert (1957) in the High Lava Plains province in south central Oregon.Tueller (1962) determined successional relationships of this habitat type in the same province.Culver (1964) described the Artemisia tridentata/Agropyron spicatum habitat type in southern Malheur County, which is the nearest known detailed synecological data to the study area. The study area had been grazed by cattle, occassionally by horses in recent years, and likely by sheep prior to the Taylor Grazing Act in 1934.Present grazing use permitted by the Bureau of Land Management has generally been from early April until early October each year.Use by horses has been less restricted as to season than the controlled cattle grazing. Stoddart and Smith (1955) have indicated that too intensive grazing is marked by a disappearance of the preferred plants or of those physiologically less resistant to grazing.Moreover, Daubenmire (1940) recognized that heavy grazing reduced bluebunch wheatgrass plants and therefore, used "abundance" and "stature" of these to be an indicator of the relative severity of grazing, when recordsof actual 13 kinds and numbers of animals and periods of use were lacking.Later, Daubenmire (1942) reported that repeated fires have been influential in eliminating big sagebrush where it was originally a component of the climax. Range fires, often caused by lightning, have likely occurred at rather frequent intervals since the advent of cheatgrass dominance in the region, with a consequent reduction in big sagebrush.Bluebunch wheatgrass varied from widely scattered clumps to rather continuous patches in which it was the stand dominant.Sandberg's bluegrass (Poa secunda) was ubiquitous over the study area, except where extrinsic causes of variation such as rodent mounds had occurred. In years of favorable growing conditions, cheatgrass was the dominant species in the absence of wheatgrass, except for widely scattered, small patches of medusahead at the Stripe Mountain site.Medusahead was present only as isolated individual plants at the District Boundary site. Based on the present vegetative composition, the Stripe Mountain site had considerably greater past-grazing pressure than the District Boundary site.The latter was completely burned by a wildfire during the summer of 1963, but with no apparent residual damage to the perennial grasses. 14 Western Oregon

Geography and Physiography

The main study area in Benton County, one mile west and one mile north of Corvallis is referred to as the "Hill Pasture site. "The site is on a tract of pastureland owned by Oregon State University. Grass-dominated south exposures on which the treatments were applied occupy positions between the flat bottomlands and the continuous Quercus garryana and Pseudotsuga menziesii forests of higher elevations and predominantly on other than southerly exposures. These are often referred to as "grassy balds" and commonly occur in the transitional zone of the Willamette Valley and Coast Range physiographic provinces. A few isolated balds occur on hills throughout the Willamette Valley and at higher elevations. In addition to the main study area, vegetation-soil relationships were analyzed at seven other locations in Benton County.This was done to determine representativeness of the Hill Pasture site to other foothill sites.These included: "Adair location, " three miles southwest of Camp Adair; "Frye location," three miles southeast of Air lie; "Burgett location," 1 1/2 miles east of King's Valley; "Grange Hill location, " one mile north of Wren; "Bald Hill location," two miles west of Corvallis; "Gray location," three miles southwest of Philomath; and "Noble location," two miles northwest of Philomath. 15 Geology and Soils

The oldest strata exposed along the western edge of the Willamette Valley is the Siletz River Basaltic Volcanics of early Tertiary formations (Snavely and Baldwin, 1948).These volcanics are composed predominantly of submarine pillow lava flows and breccias with intercalated sedimentary rock.The Tyee sandstone is usually present above the basaltic rock.Baldwin (1964) states that the Siletz River Volcanics crop out by Camp Adair and south- ward in the hills to the west of Corvallis and Philomath.Moreover, the Tyee formation in this area contains an appreciable amount of silt.Bedded micaceous sandstone and siltstone is also found to the south toward Eugene along the foothills of the Coast Range. According to Carpenter and Torgerson (1924) in their soil survey of Benton County, soils at each of the study sites were mapped as follows: Hill Pasture, Bald Hill, and Noble sites - Olympic clay, shallow phase; Burgett, Grange, Hill and Gray sites - Olympic clay loam; Adair and Frye sites - Aiken silty clay loam.Characteristics of these soils as they were described by Carpenter and Torgerson are presented in Appendix D. 16

Climate

General Climatic Conditions

The climate of the Willamette Valley is characterized by mild, moist seasons from early fall through late spring. Summers are moderately cool and dry.These conditions prevail from a predominant oceanic influence.Infrequent cold weather in winter and hot weather in summer result from continental air masses extending to western Oregon.According to Climate and Man (1941), 44 percent of the yearly precipitation comes in winter, 24 percent in spring, 5 percent in summer, and 27 percent in fall. The average precipitation at Corvallis, as recorded by the U. S. Weather Bureau over a 70-year period is 39 inches (Climatological Data, 1966).The extreme range over this period was a high of 58.06 inches in 1937 and a low of 22.99 inches in 1944.Extremes in temperature recorded were 107 degrees F. on July 20, 1946 and minus 14 degrees F. on December 13, 1919.The average date of the last killing spring frost is April 12 and the first killing fall frost is about October 25 (Powers, 1950).

Climatic Conditions During the Study

Monthly averages of maximum, minimum, and mean temperatures; average monthly amounts of precipitation; and departures from 17 the long-term average are shown for Corvallis in Figures 3 and4 (Climatological Data, 1963 - 1966). The months considered to be ecologically important for plant growth and development at the study sites included February, March, April, and May. Except for a warm February, 1963 was characterized by a cool and moist spring.February was dry in 1964; March was near normal, and late spring was dry.The entire spring period was exceptionally cool.February and March were dry in 1965; April was normal, and May was moderately dry.Temperatures were near normal for all four months.February was dry in 1966; March was much above normal, and late spring was dry.February and March were cool; late spring was near normal.

Vegetation

The Hill Pasture site has been grazed by sheep for the past 16 years.Cattle were also grazed at least one year in the late fifties. The pattern of grazing has been by ewes and lambs in early spring, dry ewes in the summer, and by breeding groups in fall.Prior to this schedule, the area was grazed by sheep and goats. The vegetation of the Hill Pasture site is quite variable and represents a seral stage of succession.Remnants of an old seeding were noted on a small portion ofthe site.At the initiation of the study medusahead and other annual grasses dominated the site.At the 80

75 Mean Maximum 70

a s0

Mean Minimum 35

30 IJFMAMJJASONDIJFMAMJJASONDIJFMAMJJASONDIJFMAMJ 1963 1964 1965 1966

Figure 3.Mean monthly temperatures (circle) at Corvallis during the period of study and departures from long-time averages (bar). 13 Q 0 11 0 10

9 0

8 0 0 0 Vs7 d6U

2 0 0 1 0 0 0 0

I I t 1 1 1 1 1 I i 1 _ 1 IL 1111111 I I JFMAM JJASONDIJF M A M J JASON DIJ FMAMJ J AS ONDIJ F MA MJ 1963 1964 1965 1966 Figure 4.Mean monthly precipitation (circle) received at Corvallis during the period of study and departures from long-time averages (bar). 20 uppermost, less exposed portion a greater mixture of annual grasses, forbs, and perennial grasses occurred.California oatgrass (Danthonia californica) was ubiquitous throughout the study site, except in a few, small "seepy" micro-habitats containing Carex spp. and other more mesic species.The vigor of oatgrass was notably reduced, apparently from competition of the annual grasses and the sheep grazing which had occurred. Evidence strongly suggests that the vegetation, with its large component of weedy annual grasses and forbs, is markedly similar to portions of the "California annual-type" grassland. From the literature, evidence suggests that Stipa spp. and California oatgrass were the dominant species on habitats where the "bunchgrass growth-form" of the sward prevailed.In an early report, Davy (1902) considered that oatgrass was probably the most important component of the climax grass cover in northwestern California, with other bunchgrasses such as Stipa, Melica, Elymus, Poa, and Festuca also represented.Clements (1934) noted in 1917-1918 fragments of Stipa pulchra in relict areas over "many hundred miles" of California. Beetle (1947) considered the California grassland to have been originally as "nearly a climax type of grassland as the more extensive prairies of the interior of North America. " Bentley and Talbot (1948) indicated that although perennial species made up less than five percent of the cover over most of the 21 California annual type, "Stipa and Danthonia bunchgrass remnants occur over all of the foothill area. " They state further,"there are many residual stands that can be increased to make up animportant portion of the forage on large areas. " Heady (1956) substantiated this by noting an increase in Stipa pulchra from none to 612 plants within an exclosure for an exceptionally short successional period from 1952 to 1955.Huffaker and Kennett (1959) have indicated that oatgrass had greatly increased after Hypericum control in areas of Humboldt County where it was initially present, but sparingly. Since California oatgrass has been observed mainly on southerly exposed sites in the Willamette Valley, it seems appropriate to speculate that it would be the dominant at the culmination of succession, and would represent a topographic climax in this region. Due to the lack of ecological documentation for the non-forested hill range in Oregon, the writer has drawn heavily and extrapolated from similar type topographies and flora of California. 22

REVIEW OF LITERATURE

Autecological Considerations

According to Piemeisel (1951), the annual species that ranks high in seed production, earliness of germination, earliness of maximum growth and maturity, and ability to withstand crowding possesses a decided advantage in occupying and holding a particular habitat. These characteristics are important for consideration in the competitive nature of medusahead and related annual and perennial species on eastern and western Oregon ranges. In 1907, as quoted by Clements, Weaver, and Hanson (1929), F. E. Clements wrote: Competition is purely a physical process. With few exceptions, such as the crowing up of tuberous plants when grown too closely, an actual struggle between competing plants never occurs.Competition arises from the reaction of one plant upon the physical factors about it and the effect of the modified factors upon its competitors.In the exact sense, two plants, no matter how close, do not compete with each other so long as the water content, the nutrient material, the light and the heat are in excess of the needs of both. When the immediate supply of a single necessary factor falls below the combined demands of the plants, competition begins. Chippindale (1932) demonstrated that grass seedlings may persist for long periods under conditions rendered unfavorable for their growth by competition of other plants, yet recover rapidly upon release from this competition.In southern Idaho a natural conversion 23 from an annual forb stage to cheatgrass to Sitanion hystrix dominance had occurred in 1961 on abandoned land within the big sagebrushzone which had been protected from grazing by domestic livestock and rabbits since 1938 (Hironaka and Tisdale, 1963).Moreover, these investigators reported that comparable increases of Sitanion hystrix have been occurring on a medusahead-infested area protected from grazing since 1952, with corresponding decreases in medusahead and other annual species. Medusahead grows over a rather wide range of climatic conditions where winter frosts occur, but where extended periods of cold are lacking (Major, 1959).The species occurs where annual precipitation is distributed over fall, winter, and spring (Major, McKell, and Berry, 1960).Medusahead occurs from a minimum of 10 inches of mean annual precipitation to an upper limit of 50 inches.According to Major, McKell, and Berry (1960), the upper limit is influenced largely by factors such as temperature and competition from plants which utilize moisture more effectively. The ecological amplitude of cheatgrass is greater than medusahead, as indicated by a more extensive distribution in North America where cheatgrass occurs mostly in precipitation zones of six to 22 inches (Hull and Pechanic, 1947; Platt and Jackman, 1946).According to Klemmedson and Smith (1964), cheatgrass was introduced from Europe about the middle of the nineteenth century and now is widely 24 distributed throughout Canada, Mexico, and the United States except in Alabama, Georgia, South Carolina, and Florida.Cheatgrass normally invades areas where the natural cover has been disturbedor lost through cultivation, grazing, or fire (Piemeisel, 1938). Daubenmire (1942) observed, however, that cheatgrass occurred in Washington as a thoroughly naturalized alien in a climax bluebunch wheatgrass community protected for 30 years.He recorded a 14/14 constancy of the species in climax stands of the wheatgrass communities analyzed. Being winter annuals, medusahead and cheatgrass normally germinate in the fall providing sufficient moisture is available, but germination may occur in spring if fall germination has not occurred. Harris (1965b) compared rootgrowth of cheatgrass and bluebunch wheatgrass under eastern Washington conditions and found that cheatgrass roots grew throughout the winter, reaching an average depth of 34 inches by early March.Roots of fall germinated wheatgrass seedlings remained essentially dormant, reaching only 5. 5 inches depth at the same date.Harris further indicated that cheatgrass matures four to six weeks earlier than bluebunch wheatgrass, thereby placing critical stress on soil moisture required for seedling rootgrowth of wheatgrass under crowded conditions. Hironaka (1961) compared rootgrowth of medusahead and cheatgrass in Idaho and found that the root system of the two grasses 25 consisted primarily of a single main root with short laterals prior to April.Much ramification and lateral development of the root systems were observed about the time the aerial portion of the plants began to add conspicuous growth.Both species made considerable root growth during the winter months and no significant difference in root length was found during any period of their life cycles.

LA- Hironaka (1961) further reported that 411 emergence of the inflorescence of cheatgrass occurred during the third week in May, whereas medusahead reached full flowering during the second week in June.The later phenology of medusahead of two to three weeks from that of cheatgrass is well established in the literature (Harris, 1965a; Sharp, Tisdale, and Hironaka, 1957; Turner, Poulton, and Gould, 1963).On the basis of the earlier phenology of cheatgrass, Hironaka (1961) predicted: It appears likely that a stand of cheatgrass would be able to resist invasion by medusahead in situations where soil moisture was sufficiently limiting that cheatgrass was able to utilize nearly all of the available moisture for its development, leaving an insufficient amount of medusahead to complete its life cycle. In areas having a surplus of soil moisture after cheatgrass reaches maturity, medusahead would be able to complete its life cycle in spite of the presence of cheatgrass. Observations in eastern Oregon after the droughty spring of 1966 supported the above statement to the extent that on some habitats cheatgrass made moderately favorable growth, whereas medusahead 26 failed to complete its life cycle (produce seed)after germinating.In contrast, narrow, shallow waterways inthe same area were character- ize'd by sharp ecotones where medusaheadflowered abundantly. Harris (1965b) postulated that because of itsearlier phenology, cheatgrass should be able to deplete the stored soil watersupply before medusahead could reach maturity.However, since medusahead plants are able to compete with andreplace cheatgrass on many sites, Harris offered the following explanation: Even though cheatgrass roots normally reachdepths of four feet, only the surface two feet of soil moistureis depleted by the time cheatgrass matures.Cheatgrass roots are so constructed that they cannot efficiently translocatedeep soil moisture through dry surface horizons.On the other hand, medusahead roots are protected by aheavily suberized endodermis layer, and can apparently continuegrowth in competition with cheatgrass after the latterspecies had matured.This relationship may explain why medusahead is often reported to compete best onnorth exposures or heavy soils where late-season moisture stressmight be expected to be ameliorated. Autecological characteristics of bluebunch wheatgrassand cheatgrass seedlings growing together underfield conditions were also investigated by Harris (1965b).Wheatgrass seedling survival was found to be 39, 69, and86 percent under dense, moderate, and sparse cheatgrass,respectively.Moreover, wheatgrass seedlings growing in sparse cheatgrass averaged7. 5 times as heavy (dry weight weight basis) as wheatgrass seedlings growingin dense cheatgrass. Roots of the larger wheatgrass plantsextended to depths of 136 27 centimeters, whereas the smaller plants in dense cheatgrass were rooted to 50 to 60-centimeter depths. Harris (1965a) found bluebunch wheatgrass to have a heavily suberized endodermis similar to medusahead, which he considered an adaptation to withstand moisture stress.Cheatgrass roots were found to lack such a mechanism, but were more diverse and made fuller contact with the soil than wheatgrass roots.Hironaka (1961) indicated that cheatgrass developed a more fragile and fibrous root system than medusahead. Under greenhouse conditions, Evans (1961) reported that cheatgrass densities of 64 and 256 plants per square foot severely cur- tailed shoot and root growth and greatly increased mortality of Agropyron cristatum.At four and 16 plants per square foot, cheatgrass moderately decreased growth and survival of Agropyron cristatum.The permanent wilting point of the soil was reached first by the higher densities of cheatgrass, next with the lower densities, and last with Agropyron alone. Also from greenhouse studies, Rummell (1946) reported highly significant reductions in number of seedlings, number of tillers, weight of tops, and weight of roots of Agropyron cristatum and Agropyron smithii from cheatgrass competitionVigor of Agropyron smithii transplants was materially lowered by competition from cheatgrass but Agropyron cristatum vigor was less affected.The reduction 28 in vigor of Agropyron smithii was evidenced by highly significant differences in weight of tops, weight of roots, number of tillers, height of tops, and length of roots found in the competition plots compared with those in the controls. A number of workers report soil conditions favorable for growth of medusahead as being quite variable (Sharp, Tisdale, and Hironaka, 1957; Tore 11, Erickson, and Haas, 1961; Major, Mc Kell, and Berry, 1960; Turner, Poulton, and Gould, 1963).More intensive studies reported by Dahl, Hironaka, and Tisdale (1964) on 43 paired medusahead and cheatgrass-dominated sites indicated that soil differences were the major environmental factor favoring growth and site dominance of one or the other species.Soils on the medusahead plots were well developed with a heavy clay B horizon less than 18 inches from the surface.On cheatgrass sites, this clay horizon was either lacking or found at greater depth.Medusahead soils had higher water-holding capacities, were more slowly permeable, and had less air capacity than cheatgrass soils. Medusahead and cheatgrass are prolific seed producers under favorable growing conditions (Sharp, Tisdale, and Hironaka, 1957; Stewart and Hull, 1949).Both species require an after-ripening, summer-dormancy period before germination occurs (Murphy and Turner, 1959).Murphy and Turner (1959) and Hulbert (1955) demonstrated by germination tests that seeds of both species are 29 viable under optimal conditions of the environment.According to Major (1958), medusahead requires a cold treatment and possibly a light stimulus after germination in order for seed formation to occur. Hulbert concluded that nearly all seeds of cheatgrass germinate the first season that external conditions are favorable.In a seed burial study he found, however, that a few seeds remained viable the summer following a fall planting.Most of these germinated and died at burial depths of 11 and 100 centimeters. Sharp, Tisdale, and Hironaka (1957) found that ten percent of the medusahead seed buried for a year remained viable.They considered this small percentage to be of importance owing to the large amount of seed produced. A later study by Hironaka, Tisdale, and Dahl (1965) indicated that medusahead seed can retain viability in the soil for at least three years, at which time germination was three percent. From studies in California, Kay (1964) found that medusahead continued to germinate for at least two years on 250 square feet of sod moved to Davis in winter, 19 61 and clipped to prevent formation of seeds. An average of 7. 5 seedheads per square foot were measured in 19 63.

Selective Herbicides

The value of selective herbicides in range and pasture renovation was appraised by Davies and Jones (1964); 30 A grassland sward consists of a mixture of plant species in dynamic equilibrium, governed by environment and management.Change of management will depress one species and favour another, so shifting the balance; similarly, a herbicide can suppress a selected component, but with greater speed and precision, and therefore must be regarded as an additional tool of grassland management. They indicated that the optimum way of utilizing the new tool falls into three main categories; selective control of one or more species, temporary suppression of some species to allow an increase in others, and control of all species as a pretreatment to seeding. Ennis (1964) has aptly warned that herbicides should be selective for not only killing certain weeds without harm to others, but also selective so as not to injure man, domestic animals, wildlife, fish, and other beneficial forms of life.Ennis broadly classed principles for using herbicides to achieve selective control of weeds under physical selectivity and biochemical selectivity.Factors affecting physical selectivity are herbicide placement and morphological characteristics such as plant form and shape, leaf position, density, surface, and margins.These factors greatly influence the foliar distribution, retention, and uptake of herbicides, whereas differences in shape, size, distribution, and density of the roots of crop plants and weeds also partly determine the effectiveness of soil-applied herbicides.As a consequence, plants with different types of root systems growing in close association may respond quite differently to soil-applied herbicides. 31 Biochemical selectivity results from factors such as differential absorption, translocation, and accumulation; metabolic alterations of organic compounds; activation of non-phytotoxic chemicals to toxic; and detoxification whereby many herbicides are metabolized differen- tially within plants. According to Wain (1965), the selective action of any herbicide depends upon a complex of factors, some of which are related to the physical properties of the substance and others to its chemical behavior within the plant or in the soil. Control of undesirable plants by specific selective herbicides offer outstanding promise as aids for improving forage production and quality on vast areas of agricultural lands now largely unimproved

(Ennis et al., 1963).Numerous investigators reported substantial yield increases of forage released from competition of brush species by using selective herbicides of the chlorinated phenoxyacetic acid group (Hyder and Sneva, 1956; Alley and Bohmont, 1958; Crawford, 1960; Cable and Ts chirley, 1961; Pond, 1964; Schmutz and Whitman,

1962).Hyder and Sneva (1956) reported increased grass yields of 882 pounds per acre on sprayed big sagebrush-bluebunch wheatgrass range in central Oregon.They recommended that such sites in fair condition, with deep-rooted bunchgrasses yielding about 150 pounds per acre, are suited to profitable improvement by chemical control of big sagebrush. 32 Results of chemical control of big sagebrush in Wyoming by Alley and Bohmont (1958) indicated that yields of native grasses such as fescues, bluegrasses, and wheatgrass were increased from 100 to 150 percent the first year following treatment.Over a five-year period percentage composition of all forbs was not measureably changed, but production from native grasses increased fourfold. Areas on which control of big sagebrush was 75 percent or more produced 2,075 pounds per acre of air-dry herbage compared with 526 on unsprayed areas. Long-term ecological responses following mechanical and chemical removal of big sagebrush in central Oregon were investigated by Hedrick et al.(1966).Herbage yield was doubled on fair-condition range, mostly from increaser-type species Koeleria cristata and Sitanion hystrix.Herbage response on poor-condition ranges was primarily for annuals, with a marked increase of cheatgrass on treated plots. Laude (1958) applied a dinitro compound to selectively remove broad-leaved plants from a California annual grass range.The grasses increased from 25 percent to 90 percent of the weight of herbaceous cover on the treated plots.Moreover, the grasses on the sprayed plots were taller and had more plants in the larger size classes.The increase in grass was attributable in part to the greater development of seedlings previously suppressed by competition from 33 other species. Examples of selectively removing undesirable grasses from various species of legumes are indicated in the literature.In Great Britain Jones (1962c) reported that paraquat at four ounces per acre was effective in eliminating Poa trivialis, resulting in a significant increase in alfalfa yield.Kay (1964) reported in California that medusahead was selectively removed from stands of rose clover (Trifolium hirtum) and subterranean clover (Trifoliumsubterraneum) when sprayed with paraquat during winter months. As yet there are few instances of selective chemical removal of weedy grass species from desirable ones in the arid and semi-arid range regions of the world.Investigations by Turner (1965) in north- central Oregon indicated that atrazine at 1.5 pounds per acre was effective for selectively removing medusahead from an Agropyron trichophorum stand.Average yield of Agropyron increased from 840 (control) to 1400 pounds per acre the second growing season following treatment.Medusahead meanwhile decreased from 470 (control) to 14 pounds per acre. In more mesic grasslands, Jones (1962b) in Great Britain found that paraquat at 1.8 pounds per acre applied in spring to a mixed-grass sward substantially reduced the yield of Agrostis stolonifera and Poa trivalis, with resulting increase in the yield of Dactylis glomerata and Lolium perenne.Also in Great Britain, 34 Elliot (1962) reported that dense stands of Deschampsia caespitosa were replaced after treatments with dalapon and amitrole by Agrostis spp. and Agropyron repens, which represented a useful improvement to the grazing value of the sward.Jones (1962a) has suggested the feasibility of using dalapon to selectively remove Nardus and thereby release competition in favor of Festuca/Agrostis swards.According to Thompson (1958) in New Zealand, dalapon at 1. 25 pounds per acre resulted in a 31 percent increase in yield of perennial ryegrass at the expense of other grasses. In California, Kay and Mc Kell (1963) found that simazine, EPTC, and atrazine aided in the establishment of Trifolium hirtum and Phalaris tuberosa by reducing competition from resident annual plants, primarily medusahead.Further work by Kay (1963) showed that dalapon as low as two pounds per acre gave excellent kill of medusahead and left a favorable balance of species among the remaining forage plants. Under Nebraska conditions, Wicks, Fester, and Burnside (1965) found that atrazine was the most successful herbicide for control of cheatgrass in grassland.Agropyron intermedium, Agropyron cristatum, Agropyron smithii, Bouteloua gracilis, and Carex spp. were noted by them to be more sensitive to atrazine than Stipa comata and Sporobolus cryptandrus. The persistence of herbicide toxicity in soil has both beneficial 35 and detrimental effects.Reduced competition from weeds may be prolonged by herbicide residue, but desirable seedlings, too, are selectively killed.Paraquat has excited weed researchers throughout the world because of its shortlived residual effect.According to Boon (1964), paraquat, a salt of an extremely strong base, undergoes ionic exchange with clay minerals and other ion-exchange systems and thereby is virtually inactivated immediately in contact with most soils, especially the heavier ones. Thiegs (1955) reported that dalapon disappeared most rapidly from warm, moist soils.This was further indicated by Holstun and Loomis (1956) who found that dalapon decomposition was adversely affected by low soil moisture, low pH, temperature below 20 to 25 degrees C. ,and large additions of organic matter.They concluded, therefore, that the decomposition of dalapon is a function of micro- biological activity.In California, Day, Jordan, and Russell (1963) studied the persistence of dalapon in 43 soils and observed that the capacity of the soil to decompose dalapon was essentially random with respect to soil series, texture, cation exchange capacity, total organic matter, and geographical source.They suggested that differences in populations of soil microorganisms capable of decomposing dalapon may account for the variability observed between soils. Microbial degradation of dalapon was investigated by Kaufman (1964) under greenhouse and laboratory conditions.His analyses, based on 36 oat-plant bioassays at 28 degrees centigrade, revealed that dalapon persisted 4 to 8 days in muck soils, 8 to 16 days in loam and silty clay loam, 16 to 32 days in sandy loam and 32 to 64 days in silty clay. Moreover, dalapon degradation by effective organisms was affected by organic matter level, pH, cation exchange capacity, and aeration. A review of the s-triazines by Ashby (1962) indicated that atrazine acts by blocking photosynthesis and dependent reactions and does not inhibit seed germination.Atrazine is most effective against young seedlings.Its characteristics of adsorption, persistence, movement and penetration, and breakdown are important in relation to crop selectivity, and with respect to undesirable persistence and potential accumulation in the soil. In Canada, Birk and Roadhouse (1964) applied atrazine in June to a loam soil at rates of two to 20 pounds per acre.Ninety percent of the applied atrazine was present in the zero to two-inch depth layer at the end of the first sampling period as long as one year after treatment.They attributed the lack of breakdown of atrazine to inactivity of microorganisms under generally dry soil conditions. Wilson and Cole (1964) indicated that the rate of application, formulation, and moisture level had an effect on persistence of atrazine in the soil.Sheets and Shaw (1963) attributed destruction of atrazine, in part at least, to microbial activity, whereby decomposition of atrazine doubled with each ten degree rise in temperature from 10 to 37 30 degrees centigrade, thus paralleling the response of soil organic matter decomposition.Opposing evidence was reported, however, by MacRae and Alexander (1965) who found thatC1402was not released microbiologically from soil receiving taggedatrazine. McGlamery and Slife (1966) reported that adsorption ofatrazine on a clay loam soil increased as pHdecreased, but it was affected only slightly by temperature and concentration.Desorption of atrazine, however, was greater with increasing temperatureand pH. Increased temperature and pH also decreased adsorptionof atrazine in studies reported by Talbert and Fletchall(1965).Moreover, increased amounts of organic matterand/or montrnorillonite clay in a soil generally were associated with increasedadsorption of atrazine. Considerably less work has been reported for theuracil herbicides, isocil and bromacil, than the s-triazines.Studies by Hilton et al.(1964) indicated that the uracil herbicides act in higher plants as inhibitors of photosynthesis. Working in Wisconsin, Swann and Buchholtz(1966) found that oats were virtually eliminated by anapplication of isocil at two pounds per acre made 12 to18 months prior to seeding.At one and two pounds per acre, bromacil was distinctly lessdamaging than was isocil.They concluded, however, that soil residuesfrom both 38 herbicides are a serious hazard for corn or oats for 18 months after treatment.

Grazing and Mowing Influences

In wildland management animals are an important tool in controlling undesirable plants (Heady, 1964).Ellison (1960), in his review of the influence of grazing on plant succession of rangelands, has stated: Generally speaking, the effect of grazing certain species in a community is to handicap those species and encourage others. This fundamental principle is the basis for using selective grazing (or clipping), or selectively-timed grazing, as a tool in applied range and pasture ecology.The selective grazing and subsequent trends in plant succession, according to Ellison, are brought about by differences in palatability, growth form, and phenology.According to Laude, Kadish, and Love (1957), herbage removal, timed with regard to the growth characteristics of individual species, offers a means for manipulation of vegetation. Johnston and Peake (1960) reported that selective grazing by sheep in Canada was an effective method for use in controlling Euphorbia esula.Four years of grazing, however, was required for control to be attained. 39 Workers in Australia found that a change in botanical composition of annual-perennial range of subterranean clover and Lolium perenne resulted from differing stocking rates of sheep(Sharkey, Davis, and Kenny, 1964).The effects of stocking rates on vegetation trends are abundantly reported in range and pasture publications in the United States and Canada. An excellent review on mainly physiological and morphological responses on individual plants to harvesting was contributed by Jameson (1963). Jones and Love (1945) described a grazing system for the seral California annual type.Heavy grazing in early spring (prior to May 15 for northern California) followed by late deferment was observed to result in a higher proportion of taller grasses and lower proportion of early maturing small weeds and grasses.According to Cooper (1960), California oatgrass and Bromus mollis can be favored by appropriate grazing management systems. California oatgrass is considered by Heady et al. (1963) to be the most important perennial grass in both preference and abundance of the California annual type rangelands of Humboldt County innorth- western California.These investigators compared the forage values of oatgrass and Bromus mollis and concluded that the formeris a better forage species and that a management system should be designed to favor oatgrass over Bromus mollis.According to Biswell (1956), perennial grasses in the forage cover of the California annual 40 type often increase by grazing management that retards the growth and reproduction of annuals but favors perennials.This management system requires that the annuals are grazed fairly close up to the time of maturity, followed by complete protection to permit the perennials to develop flower stalks and mature seed.Oatgrass was shown to increase under this system of grazing from three to 15 percent cover in three years. Livingston (1953) recognized the possible value of heavy grazing early in the season on western Oregon unimproved foothill range. This type of management was thought to be helpful in removing part of the competition between the annual and perennial species in late spring.This investigator recommended that early heavy grazing should be followed by complete protection after about May 1 in order to allow the perennials to set seed and store adequate food reserves. A portion of Livingston's study area comprised the same general landscape as the Hill Pasture site reported herein by the writer. Bogart and Hedrick (1955) reported that considerable improvement of native hill pastures in Oregon resulted from a sheep grazing management in which periods of heavy use were employed in the spring when annuals were at peak production.This was followed by complete protection during late spring and early summer.The improvement was manifested especially in the late proportion of desirable perennials, such as California oatgrass. 41 Stechman and Laude (1962) compared the response of four of the common annual grasses of the California annual type to early, late, and season-long clipping in the greenhouse and sheep grazing on the range.These included Bromus mollis, Bromus rigidus, Hordeum hystrix, and Avena fatua.In the nursery and on the range, late and season-long use reduced head height and number of spikelets produced. In California, Lusk et al.(1961) indicated that medusahead may be eaten by sheep at all of its vegetative stages, particularly before the formation of seedheads.The animals generally avoided areas where old litter was heavy and grazed where litter had been burned, clipped, or previously grazed.Under forced-grazing conditions these workers reported that sheep consumed some medusahead after seedheads had formed and the plants had dried. 42

METHODS AND PROCEDURE

Eastern Oregon

Selection of Study Sites

A reconnaissance was made in February, 1962 for the selection of study sites.Criteria for evaluating suitable locations were as follows:(1) the site showed some degree of retrogression from big sagebrush/bluebunch wheatgrass climax, (2) itwas considered as representative of this habitat type, (3) it contained both cheatgrass and medusahead, but not dominated by the latter,(4) it was relatively homogeneous as to soil and microrelief, and (5) the site was on land administered by the Bureau of Land Management. The Vale District of the Bureau of Land Management constructed fences around the 300-foot square study sites for the exclusion of livestock in June, 1962.

Experimental Design

The experimental design of the treatments at each site was a randomized block with four replications.The Stripe Mountain site was further divided into two separate experimental areas.These are differentiated as Stripe Mountain West and Stripe Mountain East.Plot 43 sizes were 10 by 60 feet at Stripe Mountain and 10 by 30 feet at the District Boundary site.

Treatment Schedule

Herbicide treatments were applied according to the schedule shown in Table 1.Method of application was by a hand-pushed, one- wheeled plot sprayer shown in Figure 5.Water was used as the carrier at a volume of 40 gallon per acre.Rates of herbicides as indicated in pounds per acre are based on active ingredient rather than the amount of commercial product, all of which contained a certain amount of inert material. The spring herbicide treatments were applied when medusahead and cheatgrass were at the two to three leaf stage and 1 1/2 inches in height.These annuals were at the one to two leaf stage and about 3/4 of an inch in height for those which had germinated at the time of the fall application.Many plants were emerging out of the coleoptile while it was obvious that many seeds had not yet germinated.

Vegetation Measurements

One permanent transect line 50 feet in length was randomly selected for each replicated experimental plot at the Stripe Mountain West and Stripe Mountain East sites.Two, 25-foot lines were Table 1.Dates of application and rates of herbicide treatments at the Stripe Mountain West, Stripe Mountain East, and District Boundary sites. Rate a Date of Treatment lbs/acre Site Application

Atrazine (ATZ-2-5) 2 SMW April 4, 1962 Isocil (ISO-1-S) 1 SMW April 4, 1962 Dalapon (DAL-2-S) 2 SMW April 4, 1962 Atrazine (ATZ-1 1/2-F) 1 1/2 SMW October 24, 1962 Isocil (I50-1-F) 1 SMW October 24, 1962 Bromacil (BRO-1/2-S) 1/2 SME April 4, 1963 Is ocil (ISO-1/2-S) 1/2 SME April 4, 1963 Atrazine (ATZ-3/4-F) 3/4 SME November 13, 1963 Bromacil (BRO-1/2-F) 1/2 SME November 13, 1963 IPC (IPC-4-F) 4 SME November 13, 1963 Atrazine (AT Z - 1 /2 -S) 1/2 DB April 4, 1963 Atrazine (ATZ-3/4-S 3/4 DB April 4, 1963 Atrazine (ATZ-1 1/2-S) 1 1/2 DB April 4, 1963 Bromacil (BRO-1/2-S) 1/2 DB April 4, 1963 Isocil (ISO-1/2-S) 1/2 DB April 4, 1963

aChemical formulas of the herbicides used in this studyare as follows: Atrazine - 2-chloro-4- ethylamino- 6- is opropylamino- s -triazine; Bromacil - 5-bromo- 3- sec-butyl- 6-methyl uracil; Isocil - 3-isopropyl -5-bromo-6-methyl uracil; Dalapon - Sodium 2, 2-dichloropropionate; IPC - Isopropyl N-phenylcarbamate. 45

Figure 5.The hand-pushed, one-wheel plot sprayer which was used for all herbicide applications. 46 established in each plot at the District Boundary site.Side and end effects were eliminated by restricting the sampling area to a macroplot size of 8 by 50 feet within the 10 by 60-foot experimental plot, and 8 by 25 feet within the 30-foot plots. Fifty, contiguous quadrats 12foot in size were sampled within each transect,For annuals and Sandberg's bluegrass, frequency of occurrence was determined within the 12-footquadrat and also within a22-inchquadrat in the lower, left-hand corner of the plot frame. For perennials other than bluegrass, frequency was recorded only within the 12-footquadrat size. Hyder et al. (1963) have indicated that frequency of occurrence of a species represents an abstraction or blend of density4and dis- persion.In a later report, Hyder et al. (1965) reported that an appropriate quadrat size for frequency sampling is one that allowsa frequency of 63 to 86 percent for a most frequent species.These investigators further stated, "a primary objective in frequency sampling is to obtain mean frequencies larger than 5 percent but smaller than 95 percent for all species of interest because low and high mean frequencies can result from badly skewed distributions." Because of variation in growth form, density, and distribution of the species present at the eastern Oregon study sites, it was

4Density as used here means number of individuals per unit area. 47 considered necessary to use the small quadrat size as well as the larger size for sampling the annuals and Sandberg's bluegrass.5 The small quadrat size enabled a better comparison of frequency values of high-density populations of small plants.The larger quadrat size was considered the best, however, when frequency of small plants was sparce. For perennials excluding bluegrass, canopy cover was determined in addition to frequency in a manner modified after Daubenmire (1959). Canopy cover serves as a two-dimensional measure of bulk and vigor of a taxon. A ranking of seven cover classes was used. These were set at class intervals according to the following scale: Class Percent Cover

1 0. 0to 6. 25 2 6. 25 to12. 5 3 12.5to 25 4 25 to 50 5 50 to75 6 75 to93.75 7 93.75 to100 The class number was recorded on the field data sheets and these in turn were later converted by their mid-point values to percent cover for each class.Sampling schedules for frequency and cover determinations for all sites are presented in Table 2.

5Although Sandberg's bluegrass is a small, tufted perennial, it was samples for frequency in the same manner as were the annuals because of its growth form, ubiquity, and relatively high density. 48 Table 2.Dates sampled for frequency and canopy cover at the Stripe Mountain West, Stripe Mountain East, and District Boundary sites.

Site Year Dates Sampled

SMW 1963 June 11, 12, 13 SMW 1964 June 24, 25 SMW 1965 June 22, 23 SMW 1966 June 16, 17 SME 1964 June 25, 26, 30 SME 1965 June 24, 29, 30 SME 1966 June 17, 18 DB 1964 July 1,2 DB 1965 June 30, July 1 DB 1966 June 20

Vegetative and reproductive stem heights of bluebunch wheatgrass were recorded at the Stripe Mountain West site on 20 plants, where available, within each macroplot for the years 1963 through

1965.Vigor and canopy cover were omitted during the 1966 sampling because of extreme influences by grasshoppers and drought. Among a number of criteria employed to appraise vigor, Hanson (1957) indicated that one of these was the number and condition of flower stalks.Hence, a method was employed in 1965 of counting the fertile flower stalks in the largest clumps within each treatment of replications one and two at the Stripe Mountain site. Estimated numbers were then made in replications three and four. 49 In July, 1965 wheatgrass seed was collected from plants in all macroplots of the Stripe Mountain West and East experimental areas. Germination tests of these were later made at Corvallis.

Soil Descriptions

Soil profiles were analyzed within each enclosure according to the procedure presented in the U. S. Dept. of Agric. Soil Survey Manual (1951).Moisture tension points at 1/3 (approximate field capacity) and 15 atmospheres of pressure (approximate permanent wilting point) were made for selected horizons by the "pressure membrane" technique of analysis.Soil descriptions are presented in Appendix C.

Western Oregon

Selection of Study Sites

The main study site on the Hill Pasture near Corvallis was selected as being fairly representative of medusahead-infested, southerly exposed foothill range of the western edge of the Willamette Valley. Fifteen paddocks 1/20 of an acre in size were constructed at the site in March, 1963 to facilitate control of experimental sheep grazing.These were arranged in three tiers of five contiguous 50 paddocks. The sites selected for comparing vegetation-soil relationships at other locations with the Hill Pasture were considered as representative of the normal variation of medusahead-infested foothill range in the Willamette Valley.In order to better evaluate the variation of a local landscape, groups of stands were sampled at two locations. These included stands 1,6, 7, and 10 at the Bald Hill location and stands 3,4, and 9 at the Noble location.

Experimental Design

A randomized block with three replications was used to'compare sheep grazing, mowing, and control treatments at the Hill Pasture site.The mowing treatments were further divided into a split plot.The arrangement of the randomized treatments, block (replication) numbers, and paddock numbers are illustrated in Figure

Treatment Schedule

The experimental treatments included the following:(1) CON- TROL; (2) early spring grazed (EARLY GRAZED); (3) early spring, followed by late spring grazed (EARLY-LATE GRAZED); (4) late spring grazed (LATE GRAZED); (5) early spring mowed (EARLY MOWED); and (6) early spring mowed, followed by late spring mowed Block 1 Block2 Block3

11 21 31 17%Slope 27%Slope 32% Slope LATE GRAZED EARLY GRAZED CONTROL

12 22 3 2 17%Slope 25%Slope 32%Slope EARLY GRAZED CONTROL LATE GRAZED

13 23 21%Slope 33 17%Slope EARLY-LATE MOWED 31%Slope EARLY-LATE GRAZED EARLY-LATE GRAZED EARLY MOWED

14 24 34 27%Slope 17% Slope 21%Slope EARLY MOWED CONTROL LATE GRAZED EAR LY-LATE MOWED 17%Slope 1 5_ 25 EAR LY- LATE MOWED 19% Slope 35 25% Slope EARLY-LATE GRAZED EARLY GRAZED EARLY MOWED

Figure 6.Experimental design and layout of treatment paddocks at the Hill Pasture site. 52 (EARLY-LATE MOWED).

The treatments were applied in 1963, 1964, and 1965.The number of sheep-days grazed and dates of grazing and mowing treatments are indicated in Table 3.The sheep were made available from the Animal Science Department. Rams were employed in 1963 and 1964, whereas dry ewes were the only animals available for the 1965 grazing. It was purposely attempted to obtain complete utilization of herbage, if possible, in all grazing treatments.Therefore, intensity of grazing in terms of sheep-days per unit area was not held constant among treatments.The animals were usually gaunt and hungry when removed from the paddocks, but had not deteriorated in general condition.

A power, rotary-type lawnmower was used to mow at a three- inch stubble height.Litter was removed following the mowing treatments by means of raking in 1963 and 1964, but not in 1965.

Vegetation Measurements - Hill Pasture Site

Macroplots

Macroplots 10 by 70 feet in size were established for evaluation within all replications of treatments.Five transect lines ten feet in Table 3.Dates of mowing and grazing with numbers of sheep days grazed for treatments at the Hill Pasture site.

1963 1964 19 65 Treatment Block Date Number Date Number Date Number CONTROL 1, 2, 3 EARLY April April April GRAZED 1, 2, 3 12 -17 15 14-19 15 17-21 15 EARLY- LATE Maya a May May GRAZED 1 22- 25 27 28-31 27 12 -16 30 EARLY- LATE Maya May May GRAZED 2, 3 22- 25 27 28-31 27 1 2-1 5 27 LATE May May May GRAZED 1 22-30 27 22- 28 29 12 -16 27 LATE May 22- May May GRAZED 2 June 3 39 22-31 42 12 -17 39 LATE May 22- May May GRAZED 3 June 3 39 22-31 42 12 -17 42 EARLY April April April MOWED 1, 2, 3 18 23 22 EARLY- LATE May June June b MOWED 27 lb lb aAll values for the EARLY-LATE GRAZED treatment include the date and number for the EARLY- GRAZED listed above. bDate of EARLY MOWED is indicated above. 54 length were randomly selected across the narrow width of the macroplot within each 14-foot sector.

Frequency

Frequency of occurrence was measured for all species in nested-plot sizes of22inches,62inches, and12foot in ten contiguous quadrats along the transect lines.Measurements were made in early July of 1963, 1964, and 1965, and late May, 1966.The latter was a measurement of residual effects, since treatments were not applied after 1965.

Clipping Yields

Following frequency sampling in 1966, two circular plots 2. 4 square feet in area were randomly selected on each of the five transect lines of the 18 macroplots.All herbage was clipped from these plots and frozen for later hand separation.The species were separated into three groups; medusahead, California oatgrass, and Other Herbage.Litter was removed and discarded.Following separation, the bags were oven-dried at 1000 C for 24 hours prior to weighing. 55 Basal Area

Following clipping in 1966, the basal area of all California oatgrass plants within each plot was cumulatively measured as a percent area of the 2.4 square-foot area.

Vegetation Measurements - Other Foothill Sites

Macroplots of 10 by 70 feet in size were established in twelve homogeneous stands at the Other Foothill sites.Frequency of occurrence was measured, in the same manner as previously described for the Hill Pasture, in July and August, 1966 with exception that the62-inchquadrat size was excluded in sampling.

Soil Descriptions

Soil profiles were analyzed at each site according to the procedure of the Soil Survey Manual (1951).Two profiles were analyzed and described at the Hill Pasture site within blocks 1 and

3.Moisture tension points were also determined for selected horizons at 1/3 and 15 atmospheres for all of the western Oregon profiles. Soil descriptions are presented in Appendix E. 56

RESULTS AND DISCUSSION- EASTERN OREGON

Stripe Mountain West Site

Vegetation Response to Treatments and Climate - CONTROL Treatment

Frequency

Frequencies of occurrence of all species sampled among all treatments at the Stripe Mountain West site from 1963 to 1966 are presented in Tables 4 and 5 as mean percentages of the four replications of each treatment.The relative variation among replications is shown by an estimation of standard error of themeans6for all frequency values between 10 and 90 percent. A calculation of this statistic was thought to have but little significance below and above these values. The species which exhibited ecologically important responses to treatment and climatic effects in the communities studied included perennial grasses, bluebunch wheatgrass and Sandberg's bluegrass;

6Theestimation of standard error of the means was calculated by the following formula where N number of means was less than ten: highest replication mean minus lowest replication mean divided by N number of means.The symbol used for designation of standard error of the means is S_. Where N number of means was greater than ten, in other sections Of this dissertation, the standard formula S/NrN = S was used in the calculations. 2 2 Table 4,Mean frequency and standard errors of annual speciesspecies within 2 -inch and 1 -foot quadrats at the Stripe Mountain West site (percent).

Treatment CONTROL ATZ-2-S ATZ-1 1/2-F ISO-1-S ISO-1-F DAL-2-S '63 '64 '65 '66 '63 '64 '65 '66 '63 '64 '65 '66 '63 '64 '65 '66 '63 '64 '65 '66 '63 '64 '65 '66 Species b POSE 56/99 39/9232/9432/99 17/697/36T/153/242/15 T 1 14/76 5/32 2/28 4/292/21 1 T 1 31/8417/8420/8819/85 5 9 4 7/20 15 13 12 11 19 15 13 7 Sx 7/y 4/ 8 9/12 7/ 75/ 76/ 7 BRTE 95/10039/84 1/29 6/342/20 2/191/12 1 2/192/221/7 5/31T/ 8 2 2 4 1 12 1 80/10048/92 4/42 7 STc 5 17 5 10 12 14 11 16 4 5 7 10 TAAS 6/45 11/55 8/58 T/ S 15 11 T 2 7 1/ 6 T/T 7 T/ 8 9 T T/ 6 T/29 4/68 1/58 3 5 6 7 Sx 5 8 10 AMIN 46/99 x/9822/81 T 13/84x/8012/44 13/78 x/80 32/68 1233/100x/9624/64 4 31/99x/10058/97 1 42/100x/10021/84 8 12/10 1/ 2 11 8/16 4/ 7 12 13/16 2/ 2 9/22 12 Sx 7 8 8/12 HEAN T 24/98 4/32 3 27/100T/17 T 20/83 2/33 2/3941/99 1/28 T/436/941/24 127/98 2/32 5 4 11 3 7 7/ 6 5 4 13 8 8 4 13 FEOC T 2 1 T 3 4 1/ 2 T/ 3 1 BLSC 4 T T T/3 3/24 12 5 13 15 1 2 T S.5c- 8 4 5 9 DEPI 3 EPPA 1/18 4/55 T T/ 2T/12 1 T/2 2/34 6 2T/21 3 T/19 T/5 4 2/33 6/58T/ 8

S. Tc 4 8 4 14 10 8 16 16 LARA 1 T/ 6T/11 2 T T 1 3 1 T/ 4 1/12T/18 5 Sx 5 8 10' LASE T T/10 1 T 1 T T 2 T/12 1 S 6 2 LPE T T SIAL T a Sandberg's bluegrass (POSE) is a small perennial but was sampled as an annual. bSee Appendix A for interpretation of abbreviated symbols. x = Not recorded for the year indicated; T = Trace, less than 0. 5 percent;y = Standard errors were not determined for frequency values less than 10 or more than 90. Table 5.Mean canopy cover, frequency and standard errors of perennial species within12-foot quadratsat the Stripe Mountain West site (percent).

Treatment CONTROL ATZ-2-S ATZ-1 1/2-F ISO-1-S ISO-1-F DAL-2-S '63 '64 '65 '66 '63 '64 '65 '66 '63 '64 '65 '66 '63 '64 '65 '66 '63 '64 '65 '66 '63 '64 '65 '66 SpeciesCF CF CFCFCFCF CFCFCFCF CFCF CFCF CFCFCFCF CFCFCFCF CFCF a AGSP4/156/15 12/20x/18 17/3024/3140/34x/398/20 14/2123/21x/23 10/2111/2217/23x/206/15 6/13 12/13x/12 12/114/108/15 10/10 12 5 Sx 1/ 62/ 5 4/ 7 5 3/ 85/ 7 9/8 8 4/10 7/10 1/ 62/ 67/ 7 2/ 33/ 4 7/ 4 6 1/ 52/ 23/ 2 POBU T/ 1T/ 1T/2 SIHY T/T T/T T/Tx/T T/ 1T/1 T/2x/ 2T/T T/ 2T/ 1x T/ 1T/ 2T/2 x/T T/T T/2 ASPU T/T T/T T/Tx/T CALsp T/T T T/T T/T T/T T/tT/2 T T CIUN CROC T/T T T LIRU T/T LOMA T/ 1 T/ 1T/2 T/T T/T T T/T S-i LOTR T/ 2 T/1 T/T LUSE T/ 41/ 3 T/ 2T/2 T/1 1/ 4 1/3 1/ 2x/ 1 T/ 2T/ 2T/ 2 T/ 31/ 2 1/ 3 T/ 42/-6 1/ 2 Sx 1 1 1 1 1 1 2 MITR x/T x/2 x/T x/ 2 x/ 2x/ 1 x/ 2x/ 3x/ 2 x/T x/T x/Tx/ 4x/T PENsp T/T PHLO T/T T/ 1T/ 2x/T T/ 2T/2 T/T T/ 3 T/3 T/2x/ 2 T/ 2T/ 3T/2x/1 T/ 1T/T T/ 1x/T TRDU T 1

a See Appendixfor interpretation of abbreviated symbols. bC = Cover; F = Frequency x Not recorded for the year indicated T - Trace = less than 0. 5 percent. y - Standard errors were not determined for frequency values less than 10. 59 annual grasses, cheatgrass and medusahead; and annual forbs, fiddleneck (Amsinckia intermedia) and sunflower(Helianthus annuus). The mean frequencies of these species which occurred in the22-inch quadrat size and12-footquadrat size are presented as histograms for all treatments for the years 1963 to 1966 in Figures 7, 8, 9, 10, 11, and 12.The annual and perennial grasses and forbs not shown graphically were encountered at low frequencies and were ecologically subordinate in all macroplots.These will be mentioned only where they have special significance. The pattern of growth and development of annual vegetation varied greatly among years at the Stripe Mountain West site.Since this site was studied for a longer duration than the Stripe Mountain East site and District Boundary sites, more detail is indicated. Community dynamics among years for the Stripe Mountain West site are best indicated by the CONTROL treatment. Cheatgrass made dense and vigorous growth in 1963 with well developed panicles throughout all of the eastern Oregon study area. By scrutinizing the climatic data in Figures 1 and 2 it can be seen that the success of growth and development of cheatgrass in 1963 may be attributable to a moist October, 1962; a warm late winter-early spring period of 1963, which favored root development; and above normal precipitation in April, which favored vegetative and reproductive development.Growth of cheatgrass was impoverished in 1964, 100 90

50 a. 40 30-

6 66 6 66 6 6 666 6 666 6 6 66 6 6 6 6 6 3 4 5 6 34 5 6 3 4 5 6 34 5 6 3 4 5 6 3 4 5 6 BLUE- CHEAT - MEDUSA- FIDDLE- SUN- WHEAT - GRASS GRAS S HEAD NECK FLOWER GRASS Figure 7.Mean frequencies of important species sampled in the CONTROL treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 5 6 BLUE- CHEAT - MEDUSA- FIDDLE- SUN- WHEAT- GRASS GRASS HEAD NECK FLOWER GRASS Figure 8.Mean frequencies of important species sampled in the ATZ-2-S treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 100

V 50 a.40

6 6 6 6 6 6 6 6 6 6 6 6 6 66 6 6 66 6 6 6 6 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 56 3 45 6 3 4 5 6 BLUE- CHEAT - MEDUSA- FIDDLE- SUN- WHEAT - GRASS GRASS HEAD NECK FLOWER GRASS

Figure 9.Mean frequencies of important species sampled in the ATZ- 1 1/2-F treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 5 6 BLUE- CHEAT - MEDUSA - FIDDLE- SUN- WHEAT - GRASS GRASS HEAD NECK FLOWER GRASS

Figure 10.Mean frequencies of important species sampled in the ISO-1-S treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 66 6 6 6 6 6 6 6 66 6 6 66 6 6 6 6 6 6 6 66 3 45 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 5 6 3 4 5 6 BLUE- CHEAT - MEDUSA- FIDDLE- SUN- WHEAT - GRASS GRASS HEAD NECK FLOWER GRASS

Figure 11.Mean frequencies of important species sampled in the ISO- 1-F treatment within 22-inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 6 666 6 6 6 6 6 6 6 6 66 6 6 6 66 6 6 66 6 3 4 5 6 3 4 5 6 3 4 5 6 3 45 6 3 4 5 6 3 4 5 6 BLUE- CHEAT- MEDUSA- FIDDLE- SUN- WHEAT - GRASS GRASS HEAD NECK FLOWER GRASS Figure 12.Mean frequencies of important species sampled in the DAL-2-S treatment within 22 -inch (solid) and 12-foot (hatched) quadrats at the Stripe Mountain West site. 66 whereby the plants flowered from a poorly developed inflorescence which contained only one or a few spikelets.Under stress of the adverse environment, flowering occurred when the plants were but a few inches in height.Climatic conditions were extremely unfavor = - able for cheatgrass development in 1965 and 1966.The sharply declining frequencies among years is indicated in Figure 7. Medusa- head responded quite differently than did cheatgrass to the prevailing climatic conditions in 1964 and 1965.by capitalizing on late spring precipitation which came too late for cheatgrass.Medusahead grew tall and developed large, normal heads.Although medusahead was dispersed in dense patches and a few sparsely scattered individual plants, frequency increased slightly from 1963 to 1965.The severe climatic conditions prevailing for the 1966 spring growing period resulted in an almost negligible frequency of medusahead and cheatgrass. The response of Sandberg's bluegrass from 1963 to 1966 is best represented by frequency in the22-inch quadrat size.The highest frequency of over 55 percent coincided with the excellent cheatgrass year of 1963 and declined in 1965 and 1966.General vigor and development of bluegrass seed culms were better in 1963 than in subsequent years. Relative density of fiddleneck and sunflower exhibited a high degree of variation from 1963 to 1966. When cheatgrass was dense 67 and vigorous in 1963, fiddleneck wasn't recorded in any of the quadrats and sunflower was negligible.The absence of fiddleneck and sunflower in the control macroplots in 1963 is indicative of the competitive advantage of annual grasses over these forbs. Growing conditions were ideal for fiddleneck in 1964, as indicated by the high frequencies shown in Figure 7.The cold spring temperatures were not detrimental to its ultimate development because of a lack of competition from cheatgrass and the ample supply of stored soil moisture. Where medusahead was abundant, however, fiddleneck was poorly developed. Sunflower, which is phenologically later than fiddleneck, also made favorable growth in 1964 (Figure 7).This species was likely benefited by late spring precipitation. In 1965 it was difficult to observe which plants of fiddleneck were rooted in the22-inchquadrats because of litter from the previous year.Frequency data were taken for fiddleneck only in the12-foot quadrat size in 1965, and it is ecologically significant that this was the only annual species which made any development in 1966 (Figure

7). Frequency of bluebunch wheatgrass remained the same between 1963 and 1964 but increased from 15 to 20 percent from 1964 to 1965. A small decline resulted again in 1966. 68

Canopy Cover

Canopy cover percentages and standard errors of meansof perennial species excluding bluegrass and Microseristroximoides are presented for all treatmentand years in Table 5.The latter species was excluded because it was too deterioratedto sample in mid June. Bluebunch wheatgrass was the only perennial specieswhich had an average canopy cover amongall treatments of one percent or greater.Mean canopy cover percentages for wheatgrass amongall treatments for the years 1963, 1964, and1965 are presented graphically in Figure 13. Percent canopy cover values were adjusted forwheatgrass by averaging only quadrats on the 50-foot transectwhich had some degree of cover.Gaps and extensive spaces in which quadratshad zero values for cover, therefore, wereomitted from the denominator when adjusted macroplot means were calculated.The summation value of cover class midpoints in the numerator .remained unchanged in the calculation.These adjusted canopy cover percentages are also shown as histogramsin Figure 13.Adjusted percent cover of wheatgrass increasedfrom 18. 5 percent in 1963 to 29. 6 percent in 1964, and to37.9 percent in 1965 in the CONTROL treatment. 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 3 4 5 3 4 5 3 4 5 3 4 5 3 4 5 3 45 CONTROL ATZ-2-S ATZ-1 1/2-F ISO-1-S ISO-1-F DAL-2-S

Figure 13.Mean canopy cover (solid) and adjusted canopy cover (hatched) of bluebunch wheatgrass measured at the Stripe Mountain West site among all treatments. 70 Height and Vigor Measurements of Bluebunch Wheatgrass

Leaf and reproductive stem heights of bluebunch wheatgrass measured from 1963 to 1965 are presented in Table 6 with their respective standard errors.Also included in Table 6 are the percent of clumps of wheatgrass containing at least one or more reproductive stems and the maximum number of flowering stems counted in 1965 in samples from all treatments in replications one and two. Leaf height of wheatgrass increased slightly in the CONTROL treatment from 9. 9 inches in 1963 to 11.8 inches in 1964 to 13.2 inches in 1965.Inflorescence height of wheatgrass was essentially the same in 1963 and 1964 at about 19 inches and increased to 27.1 inches in 1965.The mean percent of wheatgrass clumps which had one or more flowering stalks was nearly the same in 1963 and 1964 but increased markedly to 100 percent in 1965.The maximum number of flowering stalks counted in the largest observed clumps in 1965 was 166.

Vegetation Response to Treatments and Climate - HERBICIDE Treatments

Frequency

Frequencies of Sandberg's bluegrass declined markedly in the Table 6. Mean leaf and inflorescence heights, percent of reproductive clumps, and maximum number of headsper clump of bluebunch wheatgrass at the Stripe Mountain West site.

T reatment

CONTROL ATZ-2-S ATZ-1 1/2-F ISO-1-S ISO-1-F DAL-2-S '63 '64 '65 '63 '64 '65 '63 '64 '65 '63 '64 '65 '63 '64 '65 '63 '64 '65

Leaf height, 9.9 11.8 13.2 17.3 18. 2 a 14.7 16.2 a 14. 1 14.8 a 13.9 15. 5 a 9.011.5 13.0 inches .6 .2 .3 .5 .8 1.8 x .8 - .4 .5 .3 1.2 .5 .5 1.3

Inflorescence 19. 4 18.8 27. 1 25. 9 30. 5 33.3 24, 2 30.0 31. 3 22. 7 26.0 29. 4 20. 3 23. 8 27. 7 20. 822.026.6 height, inches S- .8 1.8 .6 1.0 x .4 .6 .7 1.01.0 .5 1.2 .7 .2 1.0 1.3 2.71.0 1.1

Reproductive 23 21 100 65 80 100 38 70 100 68 50 100 49 82 100 11 3 100 clumps, %

S- .04 .08 0 .05 .03 0 x .09 .15 0 .08 OS 0 .06 .05 0 .05.01 0

Maximum number- 166 332 314 257 258 160 heads/ clumpb a Essentially all stems were reproductive b Mean of replications 1 and 2.

-4 72 ATZ-2-57and ISO-1-S treatments in 1963, as can be seen by corn- paring Figures 8 and 10 with the CONTROL treatment.Reduction of bluegrass in subsequent years suggests that most of the individual plants succumbed following the weakened condition noted in 1963.The low recording of cheatgrass of 6 percent in the22-inchquadrat size in 1963, a good cheatgrass year, is a result of herbicide residue in the soil.Moreover, all annuals were notably sparse where wheatgrass clumps were vigorous and closely spaced. The similar pattern of decline of cheatgrass and medusahead in 1963 in the ATZ-2-S and ISO-1-S treatments is illustrated in Figures 8 and 10.The further decline of cheatgrass in subsequent years reflects the adverse environmental conditions for this species, and probably some suppression from herbicide residue. Since weather conditions weren't adverse for medusahead in 1964 and 1965, the low frequencies might be due to herbicide residue or to a short seed supply from 1963. Control of annual grasses by the ATZ-1 1/2-F and ISO-1-F treatments was essentially complete in 1963, as can be seen in Figures 9 and 11.The increase in cheatgrass in 1964 in the ATZ- 1 1/2-F treatment, and its comparatively small amount in the ISO-1-F

7An interpretation of abbreviated symbols for treatment descriptions is presented in Table 1. 73 treatment serves to indicate that herbicide residue inimicable to the development of annual grasses is persisting in the latter. Control of fiddleneck and sunflower was almost complete in 1963 for both atrazine treatments and the ISO-1-F treatment.In other investigations by the writer, it was demonstrated that sunflower is much more resistant to isocil than it is to atrazine.The high frequency of fiddleneck and sunflower in 1964 indicates a low level of residues from atrazine and isocil treatments.The decline of sunflower frequencies in 1965 and 1966 reflects the droughty conditions. Where wheatgrass clumps were closely spaced and vigorous in the atrazine treatments, competition was too great for fiddleneck and the species was practically absent.This relationship is exemplified in Figure 14 showing the contrast of a macroplot of the ATZ-1 1/2- F treatment. No kill of annuals occurred in 1963 from dalapon applied in spring, 1962.From Figure 12 it can be seen, however, that a bluegrass frequency of 31 percent in the22-inch quadrat size in 1963 was significantly lower than its frequency in the CONTROL.This reduction is indicative that some bluegrass plants were killed by the herbicide.The comparative patterns of medusahead and cheatgrass frequencies in the large quadrat size between the CONTROL and DAL- 2-S treatments suggests that medusahead was selectively reduced in numbers in 1963.Other herbicide investigations by the 74

Figure 14. The contrast in fiddleneck density and vigor on an ATZ- 11 /2-F macroplot where bluebunch wheatgrass was dense and vigorous (upper photograph) versus sparse to absent (lower photograph). 75 writer have revealed that dalapon is selective for killing medusahead out of cheatgrass rather effectively at rates of about two pounds per acre.The pattern of medusahead frequency between 1963 and 1964 for theCONTROLandDAL-2-Streatments is indicative that medusahead was selectively reduced in 1963, whereas cheatgrass was not. The patterns of frequencies of all other species were essentially the same as theCONTROLexcept for wheatgrass which were somewhat lower.It has been observed by the writer in other studies that dalapon can be injurious to wheatgrass under certain environmental conditions.Whether or not the low frequency of wheatgrass (11 percent) in 1963 was partially a result of some degree of kill by dalapon can only be a conjecture.There was no evidence of injury to live plants observed in 1963. Acomparison of the variation of frequency of wheatgrass among treatments is invalid because of bias in the experimental design. It was obvious from field observations prior to evaluating the data that the macroplots of theATZ-2-Streatment contained a higher initial density of wheatgrass plants than did any of the other treatments. The variation of wheatgrass frequencies among years for all treatments was nearly stable.Aslight increase can be noted for several treatments between 1964 and 1965, such as in theATZ-2-S,

DAL-2-S,andCONTROLtreatments.This change may reflect the increased vigor of the wheatgrass plants when annual competition was 76 low.If such is the case, the frequency-sampling technique measured plant bulk to some degree in addition to relative density and ubiquity, particularly in the small plot size.

Canopy Cover

Vigor of wheatgrass increased markedly in 1963 from the reduction in annual plant competition by their selective removal with the ATZ-2-S treatment.Figure 15 illustrates the contrast of wheatgrass in an ATZ-2-S macroplot and a cheatgrass-dominated strip at the west edge of the exclosure.The photos in Figure 16 show the subsequent increase in vigor of wheatgrass in 1964 and 1965 at the same photo-point.The increase in vigor of wheatgrass on an ATZ- 1 1/2-F macroplot in 1964 is shown in comparison with that of a CONTROL in Figure 17. The adjusted canopy cover of wheatgrass for the ATZ-2-S treatment increased from 42. 4 percent in 1963 to 53.9 percent in 1964 and to 60.0 percent in 1965.These values represented increases over the CONTROL by 56, 45, and 37 percent, respectively.Adjusted cover of wheatgrass in the ISO-1-S treatment increased about ten percent over the CONTROL the first year in which annual competition was reduced, but was of little difference in subsequent years.Although the increase over the CONTROL was less for wheatgrass in the ATZ-1 1/2-F treatment than that of 77

Figure 15.The contrast of bluebunch wheatgrass vigor in an ATZ-2-S macroplot and an adjacent cheatgrass-dominated strip in 1963. 78

Figure 16.An illustration of the same photopoints as was seen in Figure 15 in 1964 (upper photograph) and in 1965 (lower photograph).Note the increase in reproductive stems on the treated plot in 1965 compared with the non-treated adjacent strip. 79

Figure 17.The contrast in vigor of bluebunch wheatgrass on an ATZ-1 1/2-F macroplot in 1964 (lower photograph) in comparison with that of a CONTROL macroplot (upper photograph). 80 ISO-1-S in 1963, large increases were recorded in 1964 and 1965. Wheatgrass plants were noticeably injured in 1963 by the ISO- 1-F treatment.This condition was manifested by a withering of the terminal portions of the leaf blades which occurred after the leaves had made their growth.The lack of an increase in cover of wheatgrass from 1963 to 1964 (5. 5 and 5.6 percent, respectively) was inconsistent with all treatments.This serves as further evidence that a few plants were perhaps killed by the ISO-1-F treatment.The increase in cover in 1965 is in accord with the other treatments and a result of the excellent growing conditions for wheatgrass. Adjusted canopy cover of wheatgrass in the DAL-2-S treatment varied but little from that of the CONTROL.

Height and Vigor Measurements of Wheatgrass

Leaf and inflorescence heights of wheatgrass in the atrazine treatments were significantly greater at the one percent level of probability8than those of the CONTROL treatment (Table 6) in 1963, 1964, and 1965.Sixty-five percent of the ATZ-2-S clumps contained one or more flowering stalks in 1963 compared with 23 percent in the CONTROL. The disparity was even greater in 1964 with values

8The probability that differences noted were due to chance alone will be abbreviated henceforth as P = .01, meaning one chance out of 100; and P = . 05,meaning five chances out of 100. 81 of 80 and 21 percent, respectively.All treatements reached 100 percent in 1965.The maximum number of heads counted in the largest clumps of the ATZ-2-S treatment contained over double those of the CONTROL in 1965, 332 compared with 166.The number counted in the ATZ-1 1/2-F treatment were almost as great, and considerably more than both isocil treatments.The numbers in the DAL-2-S treatments were about the same as those of the CONTROL. The measurements of wheatgrass leaf heights were not significantly greater (P = .05) for the ATZ-1 1/2-F treatment than both isocil treatments in 1963 and 1964.Inflorescence heights of the latter were significantly lower (P = .01) than the atrazine treatments in 1964 and 1965. Measurements taken in the DAL-2-S treatment closely resem- bled those of the CONTROL. Leaf heights were not significantly different (P.05) in 1963 and 1964 between the DAL-2-S and CON- TROL treatments.Inflorescence heights were not significantly different in 1965.The low vigor of wheatgrass plants in 1963 reflects the competition from the dense stand of annual grasses.Only three percent of the clumps of the DAL-2-S treatment contained reproductive culms in 1964, a reduction of 18 percent from that of the CON- TROL treatment. 82 Germination Tests of Bluebunch Wheatgrass Seed

Results of germination tests of wheatgrass seed collected in 1965 from all treatments at the Stripe Mountain West and Stripe Mountain East sites are shown in Table 7.Seed viability was high and the variation was relatively low for all treatments at both sites. From this it can be concluded that a large number of viable seeds were disseminated in 1965.The extreme droughty conditions in the fall of 1965 and spring of 1966 was thought to preclude the possibility of any germination of wheatgrass at these times.

Stripe Mountain East Site

Vegetation Response to Treatments and Climate - 1964 to 1966

Frequency

Frequencies of occurrence and standard errors of the means sampled among treatments at the Stripe Mountain East site from 1964 to 1966 are presented in Tables 8 and 9.Although the Stripe Mountain East site was the same ecological site as the Stripe Mountain West site, there was notably less wheatgrass and much more medusahead present.The latter is shown to have a frequency in the12-footquadrat size of 89 percent in 1964 in the CONTROL treatment, which compares with less than 60 percent in the Stripe Table 7.Mean germination percentages and standarderrors of bluebunch wheatgrass seed collected from macroplots at the Stripe Mountain West and Stripe Mountain East sitesand tested under laboratory conditions.

Stripe Mountain West Stripe Mountain East Percent Percent Treatment Germination 5--x Germination 5 Control 83 4. 2 ATZ- 2-S 82 6. 2 ATZ-1 1/2-F 85 3.0 ISO-1-S 85 6. 2 -- ISO-1-F 84 0.7 -- DAL-2-S 90 1. 8 - Control 86 5. 2 ATZ-3/4-F 82 2.8 ISO -1 /2 -S 80 1. 5 BRO-1/2-S 80 4.0 BRO-1/2-F - 83 4.8 IPC-4-F - 86 3.5 a Table 8. Mean frequency and standard errors of annualspecies within 22-inch and 12-foot quadrats at the Stripe Mountain East site (percent).

Treatment CONTROL ISO-1/2-S BRO-1/2-S BRO-1/2-F ATZ-3/4-F IPC-4-F Species '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 b POSE 30/91 34/94 24/96 6/51 7/604/6021/8522/8613/8232/9125/9118/9011/7012/646/66 16/81 18/8611/85 S-x 2/y 3 5 10 8 7 2/ 35/ 8 3/18 3 4 3 4/ 93/ 8 6 5/ 7 6/ 53/ 4 BRTE53/96 2/50 1/106/39 2/38 6 5/372/36 2/20 1/13 2/30 7 3/152/26 7 4 4/41 10 57 6 6 4 10 8 7 8 8 5 1 9 6 TAAS13/89 10/75 8 3/35 1/23 3/36T/38 TT/13 17 1 14 2/30 4/32 3/36 S)-c. 7/ 5 4/10 16 11 16 14 11 15 15 15 AMIN36/100 x/10015/8356/99 x/10030/9620/70 x/8823/8416/67 x/88 8/53 4/33 x/624/36 44/97 x/10014/82 S-; 4 8 4 7 8/16 11 12/12 7/12 7 20 5 15 11 8 6/ 8 HEAN23/94 2/20 40/94 3/48 16/702/30 6/53 2/42 5/43 5/69 32/93 4/46 S-x 7 10 4 7 5/ 6 8 2 2 8 6 7 5 BLSC 1 2 DEPI T 3 EPPA 1 1/11 1/24 4 T/10 1 T/10 1/34 2 T/ 8T/ 6 51/ 8 T/14 T/36 1 sTc 5 5 5 5 5 4 4 LARA 3 5 T 1 2 2 2 1 T 5 1/10 2 S7 6 LASE 6 3 T/ 6 T 2 2 2 2 2 T /18 ST-, 12 LEPE T 2 SIAL T T 2 a Sandberg's bluegrass (POSE) is a small perennial but was sampled as an annual. b See Appendix A for interpretation of abbreviated symbols x = Not recorded for the year indicated. T = Trace; less than 0,5 percent.y = Standard error were not determined for frequency values less than 10 or more than 90. Table 9.Mean canopy cover, frequency and standard errors of perennial species within 12-foot quadrats at the Stripe Mountain East site (percent).

Treatment CONTROL ISO-1/2-S BRO-1/2-S BRO-1/2-F ATZ-3/4-F IPC-4-F '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 SpeciesCbF CF CF CFCF CF CE CF CF CF CF CF CF CF CF CFCF CF

AGSPa4/8 7/11 x/9 1/4 4/6 x/ 67/1611/16 x/153/6 5/8 x/6 10/1817/23 x/22 5/16 8/16 x/17 Sa. 3/y 4/4 1 1 ")( 7 4/ 7 7 2 2 4/ 74/ 4 4 2/ 6 3/ 6 7 SIHY T/T T/T T/T x/T ALLsp x/T x/ 2 ASPU T/T CALsp T/T T/T 1/3 T/T T/T T/1 T/T Sx 1 CROC T/T T/T T T T LIRU T LOMA T LOTRT/2 T T/2 T/1 T/1 T/T x/T T/1 LUSE 2/2 T/T 2/8 1/4 x/1 T/2 T/1 x 3/7 T/2 T 1/3 2 1/4 1/ 2 Sx 1 1 1 2 1 1 1 MITR x/2 x/4 x/T x/2 x/1 x/2 x/2 x/1 PHLO T/1 T/1 T/T T/TT/2 TRDU T T/T T T/1 T/1 T T/T T/2 T/4 a See Appendix A for interpretation of abbreviated symbols. bC = Cover; F = Frequency x = Not recorded for the year indicated. T = Trace; less than 0.5 percent.y = Standard errors were not determined for frequency values less than 10. 86

Mountain West site.The response of all the species to climatic conditions was essentially the same for both sites.Medusahead, however, decreased 14 percent in frequency in the12-footquadrat size at the Stripe Mountain East site between 1964 and 1965, whereas it increased slightly at the other.Medusahead developed vigorous plants in 1964 and 1965, whereas cheatgrass plants were depauperate for the same period. Atrazine, applied in the fall of 1963 at 3/4 of a pound per acre and bromacil at 1/2 of a pound per acre, were equally effective for reducing cheatgrass and medusahead to rather low frequencies in

1964.Frequency of bluegrass(12-footquadrat size) in the ATZ-3/4- F treatment was reduced about 20 percent from that of the CONTROL. The plants not killed were obviously more vigorous vegetatively than those of the CONTROL treatment, but were slightly burned at the tips of leaves.It is of significance to note that bluegrass frequency did not drop appreciably in subsequent years as it did on atrazine treatments of higher rates at the Stripe Mountain West site. From observations in the field, it was apparent that Sandberg's bluegrass exhibited a rather high resistance to injury from bromacil at the rates and dates at which the herbicide was applied but was injured by isocil, a closely related herbicide in structure, under the same rate and date of application.As in the atrazine treatment, there was no drop in frequency of bluegrass in subsequent years. 87 The spring applied bromacil was about as effective as the isocil treatment for residual control of the annual grasses.Both bromacil treatments, however, were more toxic to fiddleneck and sunflower than was the isocil treatment.The ATZ-3/4-F treatment was better than any of the uracils for reduction of the annual forbs. From other investigations by the writer, IPC applied in the fall at four pounds per acre has been quite variable in its effectiveness for control of annual grasses.Under the climatic conditions which prevailed, the herbicide gave excellent control of cheatgrass in 1964. Control of medusahead was quite effective but less so than cheatgrass. It is presumed that the herbicide residue diminished early enough in the spring to enable some medusahead to germinate and complete its life cycle. Sandberg's bluegrass frequencies in the smaller quadrat size tends to suggest that IPC was lethal to a small degree to this short- rooted perennial species.IPC is characteristically non-lethal toward broad-leaved plants. There was a slight increase in frequency of wheatgrass for most of the treatments in 1965; otherwise these frequencies were relatively constant.There was no indication of injury to the wheatgrass from any of the herbicides. 88 Canopy Cover

The relatively low density and variability inoccurrence of wheatgrass make these cover data unreliable for treatment comparisons over such a short period of time.It was clearly observed, however, that the vegetative vigor of wheatgrass plants in the atrazine treatment was improved in 1964.This improvement in 1964 appeared to contribute much toward increased vigor which was furtheraug- mented by excellent climatic conditions for wheatgrass.Figure 18 shows the control of medusahead in an ATZ-3/4-F macroplot treated in November, 1963 and the subsequent increase in vigor of wheatgrass, both reproductively and vegetatively, in 1964.

District Boundary Site

Vegetation Response to Treatments and Climate- 1964 to 1966

Frequency

Frequencies of occurrence and standard errors of the means of all species sampled at the District Boundary site from 1964 to 1966 are presented in Tables 10 and 11. The flora of the District Boundary site was practically the same as at Stripe Mountain,Phlox longifolia was recorded rather frequently at the District Boundary site, whereas Lupinus sericeus Figure 18.Excellent control of medusahead on an ATZ-3/4-F macroplot and the subsequent increase in vigor of bluebunch wheatgrass.Note the poor vigor of wheatgrass growing in competition with dense medusahead in left foreground. Table 10. Mean frequency and standard errors of annual a species within 22-inchand 12-foot quadrats at the District Boundary site (percent).

Treatment CONTROL ATZ-1/2-S ATZ-3/4-S ATZ-1 1/2-S BRO-1/2-S IS0-1/2-8 Species '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 '64 '65 '66 b POSE 42/90 25/96 20/9332/84 22/9415/8420/8212/71 8/7110/76 4/49 4/5330/9824/9711/9015/81 3/48 4/56 9/ 7 5/y 7 Sx 9/ 9 5 6/ 53/ 95/ 6 7 1/ 8 9 12 4 7 4/ 22/ 8 6 9 BRTE38/86 40/78 8/5416/54 30/648/53 4/4220/7812/58 T/ 36/34 2/26 4/30 5/304/28 3 1/18 10 SI- 14 11/ 8 15/12 8/19 15/23 24 1514/20 9/22 18 15 12 21 13 10 6 TAAS T T T/ 1 AMIN 8/54 x/80 4/3711/45 x/792/21 9/42 x/87 3/19T/12x/48T/126/47 x/82 1/2216/74 x/904/26 13 8 11 Sx 10/23 11 11 15 5 8 6 13 5 11 6 9 6/12 7 8 HEAN 28/92 T/16 14/70 2 28/78 3/30 6/452/48 13/74 14 17/85 18 Si 7 5 9/11 11/ 9 17 15 16 7/ 6 9 7/ 6 13 EPPA T T/22 8 T T/ 7 2 1/13 6 8 4 10 6 14T/22 & 10 7c. 8 2 4 16 FEOC T T/ 1 T 2 1 T 3 2 T/T T T/ 1 3 2 LASE T 1 2 T/ 5 2 2 LARA T/T 6 T T T 2 2 LEPE T 2 12 S 9 3 4 SIAL T/10 4 2 1/12 2 T/11T/11 4/30T/13 4/29 2 T/5 T/10 T T 6 S-Tc 6 5 7 6 19 8 23 8 a Sandberg's bluegrass (POSE) is a small perennial but was sampled asan annual. beeAppendix A for interpretation of abbreviated symbols. x = Not recorded for the year indicated.T = Trace; less than 0.5-percent.y = Standard errors were not determined for frequency values less than 10 or more than 90. Table 11. Mean canopy cover, frequency and standard errors of perennial species within 12-foot quadrats at the District Boundary site (percent).

Treatment CONTROL ATZ-1/2 S ATZ-3/4-S ATZ-1 1/2-S BRO-1/2-S ISO -1/2-S '64 '65 '66 '64 '6S '66 '64 '65 '66 '64 '65 '66 '64 '6S '66 '64 '65 '66 SpeciesCbF CF CFCF CFCFCFCF CFCF CF CFCF CF CFCF CFCF a AGSP 4/10 7/12 x/106/10 9/12 x/12 4/6 6/9 x/7 8/1210/10x/12 8/1310/13 x/11 9/12 11/14x/13 87, 2/ 3 2/ 4 3 3/ 4 3/ 5 5 2/y 3 3/ 43/ 4 3 4/ 65/ 6 4 2/ 3 2/ 2 3 SIHY T/ 2 T/ 2 x/ 2T/ 4T/ 4x/ 2T/T T/T 2/ 52/ 6x/ 62/ 41/ 4x/ 4T/ 2 T/ 2 S-x- 1 2 1 1 ANDI T/ 3 T/ 2 x/ 4T/ 4 T/ 4x/ 4 T/ 1T/T x/T T/ 2T/ 2 2 ASPU T/ 1 T/T T/T T/ 1T/T T/T LOMA T/2 x/1 T/ 6T/T x/ 4T/ 2 x/ 1 LOTR T/ 2 T/T T T/T T/ 2 T/ 2 T/ 2 MITR x/1 x/T x/T PHLO 1/15 2/15 x/ 9 1/13 3/18x/14T/9 T/9 x/6 3/20 3/18x/152/19 3/23x/12 3/20 4/20 x/21 S.; 1 1/10 8 1/ 8 1/10 8 1 /10 1/ 9 7 1/10 1/12 11 2/ 9 2/ 7 8 TRDUT a See Appendix A for interpretation of abbreviated symbols. bC = Cover; F = Frequency x = Not recorded for the year indicated. T = Trace; less than 0.5 percent.y = Standard errors were not determined for frequency values less than 10. 92 was absent. The frequency data for Sandberg's bluegrass indicated that the ATZ-1/2-S treatment damaged bluegrassto only a slight degree. The next higher rate appears to have killed a few of the bluegrass plants.The decrease of bluegrass in 1965 tends to further sub- stantiate some detrimental effect.The ATZ-1 1/2-S treatment reduced bluegrass substantially in 1964, as many of the plants appeared to retain only a thread of life.The data show that many of these succumed in 1965. The ISO-1/2-S treatment effected bluegrass essentially the same as did the high rate of atrazine.Bromacil, at the 1/2-pound per acre rate injured bluegrass but little, and the frequencies are quite comparable to those of the ATZ-1/2-S treatment. Control of cheatgrass by atrazine in 1964 was progressively better from the lower to the higher rates.The latter gave practically complete control.The ISO-1/2-S treatment also gave complete control in 1964.The frequency data for cheatgrass indicate that herbicide residue was still remaining two years after application in 1965 from the ATZ-1 1/2-S, BRO-1/2-S, and ISO-1/2-S treatments, and possibly to a lesser degree from the lower atrazine rates. The high standard errors for many of the cheatgrass frequencies among treatments indicate the wide variation of relative density and ubiquitity of its presence over the study area.The east side of the 93 experimental area contained dense patches of cheatgrass, while it was practically absent in much of the two west replications. The ATZ-1 1/2-S treatment gave the best control of sunflower and fiddleneck in 1964, but frequency was still 45 percent in the 12- foot quadrat size for sunflower. Fiddleneck had a much lower relative density at the District Boundary site in 1964 than was present at the Stripe Mountain sites. The low frequencies of fiddleneck in the CONTROL treatment in 1964 show that it was not present in many of the quadrats.Competition from bluegrass and wheatgrass appeared to be too strong for the development of fiddleneck.It was stated earlier that the absence of fiddleneck was noted at the Stripe Mountain West site onlyon atrazine treated macroplots where wheatgrass clumps were close together and where bluegrass competition was removed by the herbicide. Frequency of wheatgrass remained quite constant from 1964 to 1966 for all treatments.Phlox longifolia decreased in 1966 in all treatments except for ISO-1/2-S.

Canopy Cover

Canopy cover of bluebunch wheatgrass was consistently higher among all treatments in 1965 than in 1964, as shown in Table 11. These increases appeared to result from the favorable climatic 94 conditions.Because of the inherent variability of the stand of wheatgrass and low cover values, comparisons among treatments are not interpretable for suggesting that plant vigor might have increased as a result of the residual effect of herbicides. 95

CONCLUSIONS AND IMPLICATIONS TOWARD MANAGEMENT

The most effective herbicide treatments evaluatedfor the selective control of medusahead and cheatgrass ondeteriorated bluebunch wheatgrass range were atrazine and bromacilapplied in fall at rates of 3/4- and 1/2-pounds per acre,respectively.Higher rates gave somewhat better control ofthe annual grasses but sustained serious injury to Sandberg's bluegrass.The damaging effects of isocil on bluegrass precludes its desirability forselective use where bluegrass is an important component of the plant cover.The resistance of fiddleneck and sunflower to isocil wasconsiderably lower than for the atrazine and bromacil treatments. There was no indication from field observations orfrom the frequency data that atrazine or bromacil injuredwheatgrass at the prescribed rates listed above.Under the climatic conditions and resulting soil moisture relationships which prevailed,it can be assumed that no injury occurred to wheatgrassplants which were well established in the communities.The question of injury to very young wheatgrass plants, ortheir death from residue of these herbicides shortly after germination, is amatter of speculation.The wheatgrass frequency data for the herbicidetreatments revealed that there was little or no increase in plantnumbers during the period of the study.Small plants encountered in the sampling wereessentially 96 absent.Several factors or interactions could have resulted in the static nature of wheatgrass density in addition to the possibility of seedling mortality from soil residues.Seed production of wheatgrass was poor in 1963 and 1964, which perhaps resulted in an inadequate dispersal of seed.In addition, many of the seeds lacked a well- developed caryopsis.Should there have been some wheatgrass germination in 1964, competition from fiddleneck would have been intense during the early spring period.Grasshoppers were noted to be foraging wheatgrass each year of the study, and these could have killed wheatgrass seedlings.In 1963 it was observed in a near- by range seeding that grasshoppers removed all aerial parts of seedlings of other Agropyron species. It was obvious from field observations at the study sites and also in other investigations by the writer that atrazine hasa nitrogen- like fertilizer effect on wheatgrass.The clumps were dark green, dense, and leafy.Sandberg's bluegrass also increased in vigor where the rate of atrazine was lower.At the higher rates, however, bluegrass was injured or killed. Mason and Miltimore (1963), working in Canada reported results from fertilization studies on big sagebrush/bluebunch wheatgrass/Sandberg's bluegrassrange which serves as an interesting parallel to the response from atrazine being discussed herein.They applied ammonium nitrate at rates varying from zero to 60 pounds 97 per acre.Wheatgrass yield increased from 640 to 10 60 pounds per acre.in. 1957 and from 678 to 17 25 pounds per acre in 1958.Sub- stantial increases in numbers of reproductive culms were also indicated.These workers optimistically stated,an increase in ground cover from 6. 6 to 9. 4 percent has been achieved after only two years of nitrogen application.In addition, the selective action of nitrogen in its effect on Agropyron spicatum and Poa secunda is noteworthy and suggests that an upgrading of the distribution of species will take place.The tremendous increase in culm production with its potential increase in seed production also suggests a long-term increase in the population of Agropyron spicatum. " Working under Washington conditions, Patterson and Youngman (1960) reported that additions of nitrogen up to 40 pounds per acre doubled bluebunch wheatgrass yields; but these increased rates of nitrogen aided cheatgrass at the expense of native grasses.They indicated that wheatgrass was greatly reduced by cheatgrass competition subsequent to fertilization but that Sandberg's bluegrass was not greatly affected. When herbicides such as atrazine and bromacil are applied at effective rates which are not harmful to wheatgrass but which selectively remove competing annuals, the physiological response of the wheatgrass is in effect a result of improved fertility and water economy. Assuming that nitrogen might be the mostlimiting mineral 98 nutrient in the ecosystems studied, wheatgrass could be benefited in the atrazine and bromacil treatments simply because competition for nitrogen would be reduced.The same reasoning could be applied to water economy, resulting in a "summer-fallow effect. " Since clumps of wheatgrass in the bromacil treatment did not exhibit the dark green appearance as did those of the atrazine treatments, a peculiar nitrogen economy and metabolism appears to be in effect for the atrazine-treated wheatgrass plants. Studies by Ries and Gast (1965) indicated that the addition of 0. 5 ppm simazine (a triazine herbicide closely related chemically to atrazine) increased the nitrogen content and shoot/root ratio ofcorn as much as 570 additional milligrams of nitrogen.Their hypothesis was that low levels of simizine may increase the rate of respiration and nitrogen absorption and/or metabolism during periods of unfavorable environment for corn growth.Gramlich and Davis (1967) reported that corn plants treated with 2 lb/acre of atrazine were larger and contained considerably more total nitrogen than untreated plants. Atrazine and bromacil, as selective herbicides on deteriorated range lands dominated by medusahead and cheatgrass, both fulfilled the objective of improving wheatgrass seed production as well as forage production.Three major problems are associated with the use of selective herbicides, however, for accelerating the rate of 99 secondary succession.First, what is the significance of herbicide residue on wheatgrass seedling establishment? As reported earlier, Ashbey (1962) found that atrazine does not inhibit seed germination, but injures young seedlings.Secondly, to what degree do the broad- leaved annual plants restrict wheatgrass establishment when these annuals are selectively released of competition from annual grasses? Thirdly, what combination of suitable climatic conditions are essential for wheatgrass establishment? The problem of soil residue is best solved by substituting selective herbicides of short residual activity.The problem of broad-leaved annuals would require properly timed application of a non-residual herbicide effective for controlling broad-leaved weeds. The fortuitous nature of climatic conditions in the semi -arid regions is the most serious peril of the three, and the one for which man has little control.Successful timing of an effective herbicide schedule with favorable climatic conditions (other than by chance) essential for establishment of wheatgrass is probably impractical in a range rehabilitation program. Schwendiman (1966), an authority on wheatgrasses in the Pacific Northwest, stated at a range management symposium that bluebunch wheatgrass produces a supply of seeds about once in five years.He generalized further that the combination of an adequate supply of viable seeds and climatic conditions favorable for germination occurs only about once in 25 years! 100 It may be economically sound and desirable to apply a soil sterilant such as atrazine or bromacil to enable a release from competition with subsequent improvement in the physiological vigor and seed production of wheatgrass as an adjunct to a range improvement program. When followed by prudent grazing management, the initial increase of wheatgrass vigor might lead to an improved range condition at a more rapid rate than without treatment.In time there should be no residue problem.The investigations presented herein were of too short a duration for an evaluation of such long-term range improvement.In the opinion of the writer, at least ten years would be a minimum period of time to evaluate effective results. Animal use would of course be integrated with the improvement program. Some scheme of deferred grazing would be necessary, particularly the first growing season or two.Perhaps only late summer, fall, or early spring grazing would insure a better opportunity of seed production and dispersal. At the onset of the investigations, a major objective was to follow the spread of medusahead during a short period of years on deteriorated range where it only had a foothold.Since medusahead was distributed only in patches and a few widely spaced plants at the Stripe Mountain location and only rarely present at the District Boundary site, there was an opportunity to scrutinize the dynamics of the weed during the period of study.Even though medusahead 101 made favorable growth in 1963, 1964, and 1965, the populations did not expand appreciably in numbers or spacial distribution.During droughty climatic conditions of 1966 medusahead was virtually absent at the study sites. 102

RESULTS AND DISCUSSION - WESTERN OREGON

Hill Pasture Site

Vegetation Response to Treatments and Climate - 1963 to 1966

Frequency

Frequencies of occurrence for all species sampled among treatments at the Hill Pasture site from 1963 to 1966 are presented in Tables 12, 13, 14, 15, 16, and 17.Variation in medusahead frequencies among blocks, treatments, and years for the 22-inch, 62- inch, and12-footquadrat sizes is indicated by analysis of variance presented in Appendix F. Because of site difference between blocks, mean frequencies of species within each block are indicated rather than an average of the three blocks.Only frequencies of the dominant species medusahead and California oatgrass will be emphasized in detail for treatments and blocks.Other species with an ecological significance or particular response to treatment effects will also be mentioned. The contrast of frequency patterns for medusahead are illustrated graphically in Figure 19 among all treatments and years in Blocks 1 and 3.It can be seen that medusahead had higher frequencies in all instances in Block 3. aiqr Jo - pu-e -2I zi salouanbaaa saioads paidures upppn `gout -Z9 `[put loo; smprnb ut atp TOLIINTOD ,LNIUIALINall.L re IP IIIH a,m3s'eci alts

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ea% xTpuaddv v aoj uognaadaaauT Jo papoo saturu jo svpads 6 6 66 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 66 66 3 45 6 3 45 6 3 4 5 6 3 4 5 6 3 4 5 6 3 45 6 CONTROL EARLY LATE EARLY-LATE EARLY LATE GRAZED GRAZED GRAZED MOWED MOWED Figure 19.A comparison of mean frequencies of medusahead for allyears and all treatments within 2-inch quadrats between Block 1 (solid) and Block 3 (hatched) at the Hill Pasture site.No grazing or mowing treatments were made in 1966. 110 Differences among treatment means, block means, and year means for medusahead were significant (P =.01) for the three quadrat sizes22-inch, 62-inch,and12-foot,as determined from an analysis of variance.Since there was much variation in medusahead frequencies due to site, treatments, and years, the graph serves as the best means of interpreting the results. The decline in frequency of medusahead in the CONTROL treatment in 1965 was apparently the result of an accumulation of its own litter.Since this litter is slow to decompose, when ungrazed, medusahead commonly "chokes" itself out of a community by the presence of its own litter. The EARLY GRAZED treatment had higher medusahead frequencies than that of the CONTROL, particularly in 1965 and 1966. Early grazing utilized some of the litter along with the young green forage but was ineffective for reducing subsequent medusahead density. By the second year frequencies in the22-inchquadrat size were about four times higher than that of the CONTROL treatment in Block 1. In Block 1 with low medusahead frequencies, the pattern among years in the EARLY MOWED treatment was similar to that of the EARLY GRAZED treatment.In Block 3 where frequencies were higher, the two treatments exhibited the same response pattern. The EARLY-LATE GRAZED and LATE GRAZED treatments both reduced medusahead frequencies to low levels in 1963 through 111 1965.This comparison is misleading, however, because the grazing intensity applied for theLATE GRAZEDtreatment was much higher, particularly in Blocks 2 and 3.Many of the medusahead plants were not grazed in theLATE GRAZEDtreatment, but rather were killed by trampling.There was little evidence of this for theEARLY-LATE GRAZEDtreatment.Figure 20 shows the utilization of medusahead,

California oatgrass, and other herbage inanEARLY-LATE GRAZED macroplot in 1964.The lower photograph shows a comparative EARLY-LATE MOWEDmacroplot in an adjacent paddock in Block 3 prior to the late mowing. In 1966 when grazing was not applied, frequencies of medusahead were again high for both theEARLY-LATE GRAZEDandLATE

GRAZEDtreatment. When theEARLY-LATE GRAZEDandLATE GRAZEDtreatments are compared with theEARLY-LATE MOWED treatment, it is evident that the mowing was the most effective treatment for reducing medusahead in 1963, 1964, and 1965.Mowing removed essentially all of the medusahead stems at the reproductive stage, thereby reducing seed production.Without mowing in 1966, medusahead frequencies were very low in:theEARLY-LATE MOWED treatment and California oatgrass was distinctly, dominant.The contrast in relative density of medusahead between theEARLY-LATE GRAZEDandEARLY-LATE MOWEDtreatments in 1966 is shown in Figure 21.The plot frame employed for frequency sampling can be 112

Figure 20.Complete utilization (upper photograph) of medusahead, California oatgrass, and other herbage in an EARLY- LATE GRAZED paddock in 1964. A comparative EARLY-LATE MOWED paddock (lower photograph) prior to the late mowing. Note the vigor of oatgrass and very little medusahead. 113

Figure 21.Acomparison of the same paddocks shown in Figure 20 as they appeared in 1966.Note the dense medusahead dominance in theEARLY-LATE GRAZEDtreatment (upper photograph) versus the dominance by vigorous California oatgrass in theEARLY-LATE MOWED treatment (lower photograph). 114 seen in the lower photo. Variation in oatgrass frequencies among blocks, treatments, 2- and years for the22-inch,6 in ch, and12-footquadrat sizes is indicated by an analysis of variance presented in Appendix G. Since medusahead was predominant over the entire Hill Pasture site at the initiation of the study, it was surprising to find such large frequency values for oatgrass during the first year of sampling in 1963.Most of these plants were weakened by competition from medusahead and other annuals in the CONTROL, EARLY GRAZED, and EARLY MOWED treatments.Oatgrass plants were closely grazed in the EARLY-LATE GRAZED and LATE GRAZED treatments. In comparing California oatgrass frequencies between Block 1 and Block 3,it can be seen from Figure 22 that frequencies in the 22- inch quadrat size are higher for all treatments in Block 1.The relative density of oatgrass was inversely proportional to that of medusahead between Blocks 1 and 3 (compare Figures 19 and 22).Frequencies of California oatgrass in the 22 -inch quadrat size were much less variable between years than were those of medusahead, where treatment effects were exerting a pronounced influence.Variable oatgrass frequencies between treatments within blocks limits, however, an interpretation of probable treatment effects. In addition to the relative densities of medusahead and oatgrass which serve to distinguish habitat differences between Block 1 and 6 6 6 6 66 6 6 6 6 6 6 6 6 6 6 6 66 6 6 6 66 3 4 5 6 3 4 5 6 3 45 6 3 4 5 6 3 45 6 3 4 5 6 CONTROL EARLY EARLY-LATE LATE EARLY EARLY-LATE GRAZED GRAZED GRAZED MOWED MOWED

Figure 22.A comparison of mean frequencies of California oatgrass for all years and all treatments within 22-inch quadrats between Block 1 (solid) and Block 3 (hatched) at the Hill Pasture site. 116 Block 3, several species appear to be good "site indicator" species over the Hill Pasture area.Their presence and relative density serve as ecological "phytometers" of the habitat.Their phytometric value provides further evidence that Blocks 1 and 3 are ecologically different habitats.By scrutinizing the list of species for the CONTROL treatment in Table 15, the following species are thought to have affinities to block 1 under the prevailing conditions of competition: Festuca rubra, Poa pratensis, Cynosurus echinatus, Erodium cicutarium, Lactuca serriola, Lathyrus sphaericus, Ranunculus occidentalis, and Sherardia arvensis.Of these, the perennials Festuca rubra and Poa pratensis are considered to be the most important biological indicators of the group.Both were present in a couple of microsites in Block 3 where seepage resulted in higher effective soil moisture.Except for these irregularities, neither species was present in the remainder of Block 3 nor the drier paddocks 21 or 22 of Block 2. It can be seen from the species lists for all paddocks that Erodium cicutarium exhibited the same frequency pattern as Festuca rubra and Poa pratensis over the study area.However, Erodium cicutarium could not be used as an indicator, since it was removed by grazing and mowing.

No plants of reliable indicator value appeared in Block 3.In summary, paddocks 21 and 22 of Block 2 and all of Block 3 could then 117 be arbitrarily referred to as the XERIC site and paddocks 23, 24, and 25 and all of Block 1 as the MESIC site. The removal of vegetation in the EARLY-LATE GRAZED, LATE GRAZED, and EARLY-LATE MOWED treatments resulted in an increase in forbs.This change was most pronounced in the EARLY- LATE MOWED treatment because the mower didn't remove as much of the plants as did the animals.The residual effect of these treatments was evident by the large numbers of small-sized forbs sampled in 1966.Lactuca serriolla exhibited the largest increase in frequency of any of the forbs.

Basal Area of California Oatgrass

Mean basal area percentages and standard errors for California oatgrass measured in 1966 are presented in Table 18.By "t" test analysis, means between blocks were not significantly different (P = .05) for the CONTROL treatment.The high standard error in Block 1 reflects, however, variation of oatgrass basal area between transects in the block.

Basal area was significantly higher (P =.01) in Block 1 of the EARLY GRAZED treatment than Block 3, but not between Block 1 and

2.In the EARLY-LATE GRAZED treatment, basal area was significantly higher in Block 1 (P =.05) than Block 3.In the LATE GRAZED treatment, means of Block 1 and 2 were significantly higher Table 18.Mean basal area and standard errors of California oatgrass measured after clipping in 1966 at the Hill Pasture site. Treatment EARLY EARLY-LATE LATE EARLY EARLY-LATE CONTROL GRAZED GRAZED GRAZED MOWED MOWED Block 1 Mean 12.9 9. 9 13. 5 13.4 8. 0 15. 1 S- 3.1 1.4 1.6 2.0 .8 1.4 Block 2 Mean 6. 3 7. 6 12.7 9. 9 9.0 18. 4

S- 1. 1 1. 1 4. 2 1. 2 1. 7 1. 8 Block 3 Mean 7. 6 3. 4 8. 1 2. 2 5. 3 14. 8

S- 1. 1 1. 3 1. 6 1. 2 1. 0 1. 0 119

(P =.01) than Block 3, but of no significance between Blocks 1 and 2. There was no significant difference in means between blocks for either of the mowing treatments. The means of oatgrass basal area in Block 3 of the EARLY- LATE MOWED treatment was significantly higher (P = .01) than all other treatments in Block 3.In Block 1 the mean basal area in the

EARLY-LATE MOWED was significantly higher (P =.01) than the EARLY MOWED treatment and significantly higher (P = 0. 5) than the EARLY GRAZED treatment. Mean differences in Block 1 were not significant (P = .05) between the EARLY-LATE MOWED, CONTROL, EARLY-LATE GRAZED, and LATE GRAZED treatments. The increase of oatgrass basal area in the EARLY-LATE MOWED treatment was about double that of the CONTROL treatment in Blocks 2 and 3.Considering again that Block 2 is transitional between Blocks 1 and 3, emphasis for discussion will be on the latter two.Under low oatgrass densities, the increase in basal area was proportionately greater where medusahead competition was markedly reduced.Oatgrass was the sole perennial dominant in Block 3 but was under competitive stress from Festuca rubra and other species in Block 1.From a life-form standpoint, oatgrass was of a "bunchgrass" form on the xeric site of Block 3, whereas it was more of a caespitose sod in Block 1. 120

Clipping Yields of Medusahead, California Oatgrass, Other Herbage and Total Herbage

Mean yields and standard errors of MEDUSAHEAD,OATGRASS, OTHER HERBAGE, and TOTAL HERBAGE for all treatments and blocks are shown in Table 19.By an analysis of variance it was found that yield differences between treatments, between blocks, and the interaction of treatments times blocks were all significantly different (P = .01) for medusahead, oatgrass, and Other Herbage.Total Herbage yield differences were also significantly different (P =.01) except between blocks where there was no significantdifference (P =

.05). Because of much variation over the experimental site, statistical differences in yield means were made by "t" tests betweenblocks within treatments and between treatments within the sameblocks for medusahead, oatgrass, Other Herbage, and Total Herbage.Graphic illustrations of yields of medusahead, oatgrass, Other Herbage,and Total Herbage for treatments within Blocks 1 and 3 areshown in Figures 23, 24, and 25.Yields of medusahead were significantly

higher (P =.01) in Block 3 than Block 1 for all treatments exceptthe

EARLY-LATE MOWED. In Block 1 medusahead yield in the CONTROL treatment was significantly lower (P = . 01) than the EARLY GRAZEDtreatment, and significantly lower (P = .05) than the EARLY-LATEGRAZED and Table 19.Mean yields in lbs/ acre and standard errors of medusahead, California oatgrass, Other Herbage, and Total Herbage clipped at the Hill Pasture site in late May, 1966.

California Other Total Treatment Block Medusahead S- Oatgrass S- Herbage S- Herbage S- x

1 101 17.2 603 72. 8 527 37.6 1231 80. 8 CONTROL 2 802 44.4 405 60.0 70 9.2 1277 64.0 3 492 56.4 441 52.8 261 58.0 1194 110.8

1 424 73.6 418 32. 0 532 101.6 1374 82. 4 EARLY 2 950 57.6 303 35.6 132 18.4 1385 94. 8 GRAZED 3 880 47.2 164 59. 2 140 21, 6 1184 35. 6

EARLY- 1 361 78.0 451 44.0 932 102.0 1744 83.2 LATE 2 573 112.0 256 68.0 372 38.8 1201 106.8 GRAZED 3 896 62.0 233 40.0 335 46.0 1464 80. 8

1 182 42. 0 348 27. 6 300 34. 4 830 58.0 LATE 2 426 92.4 563 74.0 323 36.0 1312 74.4 GRAZED 3 1044 142.0 66 35.2 540 66.0 1650 210.8

1 276 48.0 319 51. 6 502 40.0 1097 37.2 EARLY 2 581 54.4 285 29, 2 160 20.8 1026 58. 8 MOWED 3 578 72. 4 266 46.0 141 20.8 985 55.6

EARLY- 1 50 13.6 608 59.2 312 36.0 970 48.0 LATE 2 32 6. 0 691 34. 4 218 19. 2 941 43. 2 MOWED 3 47 14.4 845 100.0 246 30.0 1138 114, 4 Medus ahead 1000 California oatgrass 900 - fifil

800

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111 1111 B1 B3 B1 B3 B1 B3 B1 B3 B3 B1 B3 CONTROL EARLY EARLY-LATE LATE EARLY EARLY-LATE GRAZED GRAZED GRAZED MOWED MOWED Figure 23.Mean yields of medusahead and California oatgrass sampled among all treatments in Blocks 1 and 3 at the Hill Pasture site in late May, 1966. 900

800

700

600

P. 500

. 300

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100

Block 1 3 1 3 1 3 1 3 1 3 1 3 CONTROL EARLY EARLY -LATE LATE EARLY EARLY -LATE GRAZED GRAZE) GRAZED MOWED MO WED Figure 24.Mean yields of Other Herbage sampled among all treatments in Blocks 1 and 3 at the Hill Pasture site in late May, 1966. 1700

1600 -

1500 -

1400

1300

1200 j

1100 -1

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Block 1 3 1 3 1 3 1 3 1 3 1 3 CONTROL EARLY EARLY-LATE LATE EARLY EARLY -LATE GRAZED GRAZED GRAZED MOWED MOWED Figure 25.Mean yields of Total Herbage sampled among all treatments in Blocks 1 and 3 at the Hill Pasture site in late May, 1966. 125 EARLY MOWED treatments. No significant difference was noted between medusahead yield in Block 1 between the CONTROL treatment versus the LATE GRAZED and EARLY-LATE MOWED treatments.

In Block 3 medusahead yield was significantly less (P =.01) in the CONTROL treatment than the yields in the EARLY GRAZED and EARLY-LATE GRAZED treatments, and significantly less (P= .05) than the LATE GRAZED. Yields of medusahead ranging from 875 to 1000 pounds per acre were the highest in Block 3 for the three grazing treatments. Yields of oatgrass ranging from 400 to 600 pounds per acre among blocks in the CONTROL treatment were not significantly different (P = .05).Comparing treatment yields in Block 3 with the CONTROL, yields were significantly less (P = .01) in the EARLY GRAZED and LATE GRAZED treatment, and less (P = .05) in the EARLY-LATE GRAZED and EARLY MOWED treatments.There was no significant difference between yield of oatgrass in the CONTROL treatment and the EARLY-LATE MOWED treatment of Block 1, but yields were significantly higher (P = .01) in the EARLY-LATE MOWED treatment over those of the CONTROL in Block 3. Among the grazed treatments, yields of oatgrass were significantly less (P = .01) in Block 3 than yields in Block 1.No significant differences were noted between blocks in the EARLY MOWED treatment. 126 Inversely, in contrast with all other treatments, oatgrass yield was higher in Block 3 than Block 1 in the EARLY-LATE MOWED treatment.The difference was significant at P = .01.Moreover, yields were significantly higher (P = .01) in the EARLY-LATE MOWED treatment than all other treatments in Block 3.In Block 1 yields were significantly higher (P = .01) in the EARLY-LATE MOWED treatment than the LATE GRAZED and EARLY MOWED treatments, and significantly greater (P = .05) than the EARLY GRAZED treatment. Differences in yield in Block 1 between the EARLY-LATE MOWED and EARLY-LATE GRAZED treatments were non-significant (P = .05). Yields of Other Herbage were higher in Block 1 than Block 3, with exception of the LATE GRAZED treatment.Because of the large variation, however, there were no significant differences in yields of other herbage between Blocks 1 and 3 for any of the treatments. The Total Herbage yield was not significantly different (P = .05) among all treatments than the CONTROL in Block 3.The same was the case in Block 1 with the exception of the LATE GRAZED treatment in which the yield of 830 pounds per acre was significantly less

(P =.01) than 1230 pounds per acre in the CONTROL. The largest yield (Total Herbage) of all treatments of 1744 pounds per acre in the EARLY-LATE GRAZED treatment of Block 1 127 resulted partly from the large proportion of Other Herbage which contained a considerable amount of Cynosurus echinatus. The high total yield in Block 3 of the LATE GRAZED treatment consisted mainly of medusahead and Other Herbage.Here, oatgrass was the only perennial grass and it composed only 66 pounds per acre of the total weight of 1650 pounds per acre.Medusahead was noted to be more vigorous in this paddock compared with the adjacent paddocks of Block 3.It was concluded that the large size of medusahead plants was a fertilized effect from the high intensity of grazing employed. Although the analysis of variance indicated no significant difference (P =.05) between blocks, a "t" test indicated the total yield of the LATE GRAZED treatment in Block 3 to be significantly higher than Block 1 (P = .01).This difference was reversed among blocks in the EARLY GRAZED treatment and was significant (P =.05).

Climatic Influences

The period of rapid vegetation growth in April and May was somewhat later in 1963 and 1964 than 1965 and 1966, apparently the result of colder than normal temperatures the first two years of the study.The advanced phenology of medusahead in 1965 necessitated an earlier grazing schedule.The total amount of plant material produced appeared to be about the same each year regardless of contrast- ing temperatures.Other than the normal early summer drought which 1 28 prevailed each year at the study site, moisture conditions were similar in all years of the study.The only climatic influence of ecological significance was the variable phenological development of the vegetation brought about by different temperature regimes.

Edaphic Influences

Descriptions of soil profiles examined in Blocks 1 and 3 of the CONTROL paddocks are presented in Appendix E.Depth of these soils to massive, weathered bedrock was 30 inches in Block 1 and 28 inches in Block 3.The first was finer textured throughout all horizons and had a higher water holding capacity, based on higher moisture tension points at 1/3 and 15 atmospheres of pressure. Because of a higher soil moisture storage and less extreme exposure, the soil of Block 1 appeared to be the more favorable for plant growth than that in Block 3.No soil moisture tests were made but the earlier phenological development in Block 3 indicated that the soil in Block 3 dried to the wilting point earlier than in Block 1.

Discussion of Ecosystem Dynamics

From analysis of vegetation and soil-microclimatic conditions, the Hill Pasture site has been shown to represent two different ecosystems.The one with higher moisture effectiveness has been referred to as the mesic habitat, and the other, which is steeper and 1 29 exposed to more intense radiation, the xeric habitat.Vegetation response to the tools of sheep grazing and mowing was demonstrated to be markedly different among treatments and between the mesic and xeric habitats. The EARLY GRAZED and EARLY MOWED treatments were both ineffective as tools for reducing medusahead dominance. By evaluating frequencies of medusahead each year and yield in 1966, it was clearly demonstrated that these treatments were of negative benefit as management tools.The decrease in basal area and yield of California oatgrass in the xeric habitat further exemplified the deleterious response from these treatments. Practically complete utilization of medusahead was easily attained in the EARLY-LATE GRAZED treatment on both the mesic and xeric habitats.Some of the medusahead litter was consumed along with young, green forage and most of the remainder was trampled during the grazing in mid-April.Since there was essentially no old medusahead litter present and somewhat less total herbage available than had there been without early grazing, the sheep readily consumed medusahead and other herbage when grazed again in mid or late May, at which time medusahead was in the boot stage of development. In Table 3 it can be seen that 27 sheep-days were employed to graze the paddocks of the EARLY-LATE GRAZED treatment, with 130

exception of Block 1 in 1965 which supported 30 sheep-days.Of the 27 sheep-days of grazing, 15 of these were during the mid-April period and 12 were during the period of grazing in May. The utilization of medusahead was quite different between Block 1 and Block 3 of the LATE GRAZED treatment.In Block 1 where medusahead did not have such a high density the sheep consumed the plant readily along with other forage.Probably of much importance was the fact that medusahead litter had not accumulated to any appreciable extent.Essentially complete utilization of medusahead was also attained in Block 1 of the LATE GRAZED treatment by the same cumulative grazing intensity of 27 sheep-days, as was required for the EARLY-LATE GRAZED treatment. In Block 3 of the LATE GRAZED treatment, where medusahead was dense and litter accumulation was heavy, the sheep were selective in their grazing.By the time the more desirable forage (mainly oatgrass) was consumed, medusahead had headed out.The animals nibbled on the perennials so thoroughly that some of the smaller oatgrass plants were apparently killed the first year.The intensity of grazing employed in Block 3 in an attempt to obtain complete utilization of medusahead at about 40 sheep-days each year was exceedingly high.Figure 26 shows a comparison of an EARLY-LATE GRAZED paddock which had an intensity of 27 sheep-days and an adjacent LATE GRAZED paddock which had an intensity of 39, 42, and 39 for 1963, 131

Figure 26.A comparison of an EARLY-LATE GRAZED paddock (upper photograph) and an adjacent LATE GRAZED paddock (lower photograph) in 1965.Note the large amount of exposed mineral soil in the latter but very little in the former. 132 1964, and 1965, respectively.The increased amount of bare soil is evident in the photo of the late grazed treatment.In contrast, on the basis of vegetation measurements and field observations during the period of the study, no negative or retrogressive ecological effects appeared in any of the EARLY GRAZED and EARLY-LATE GRAZED paddocks. The data presented and the photographic record bare evidence that the EARLY-LATE MOWED treatment was excellent for reducing medusahead to an insignificant component in both the mesic and xeric habitats.With this reduction in competition oatgrass vigor increased markedly both vegetatively and reproductively.After two successive years of mowing, oatgrass plants had been released from other competition and hadessentially,closed the stands to medusahead.This

was clearly evident prior to the late mowing applied in 1965.The ecological dominance had been shifted from annual to perennial grass. More noticably in the xeric site, this shift was almost solely from medusahead dominance to that of California oatgrass.In California, Huffaker (1951) demonstrated that during the relatively short period of four years, California oatgrass, the climax bunchgrass, entered the space vacated by Hypericum perforatum following control of this weed by beetles of the genus Chrysolina.Oatgrass had returned as the sole dominant in one area which had been free of Hypericum for three years. 133 Early mowing was of practically no benefit for controlling medusahead as indicated by results of the EARLY MOWED treatment. Therefore, a late mowed application would have resulted in just as efficient control of medusahead and perhaps more benefit to the perennials. The EARLY-LATE GRAZED treatment of Block 3 resulted in effective control of medusahead when treatments were applied, but the residual control was essentially lacking.It was felt that oatgrass vigor was impaired somewhat from the grazing pressure but not from the EARLY-LATE MOWED treatment.

Other Foothill Sites

Purpose of Investigations

Synecological studies were made at Other Foothill sites infested with medusahead along the western edge of the Willamette Valley in an attempt to better understand the variations, similarities and differences in different areas and local landscapes.This additional information was needed in order to relate whereby the findings at the Hill Pasture study might be applicable, at least as to the nature of vegetation and habitat.It was conceivable that the pattern of soil- vegetation relationships found from the intensive research at the Hill Pasture site might be repeated over similar ecological sites.It was 134 further considered that much variation might be found, especially since the sites had been disturbed by various factors and to various degrees. The writer wishes to make clear that the studies of Other Foot- hill sites was limited in extent and depth of research.Therefore, no intention was made to "classify" the landscapes studied nor to attempt to "decipher" patterns or stages of plant succession and gradients. The purpose was mainly to obtain some relationships of these sites and compare with the Hill Pasture site, particularly the importance of key and/or dominant species as well as soil-slope relationships.

Vegetation Measurements

Frequencies of occurrence of plants measured within22-inch and12-footquadrat sizes in 12 stands of Other Foothill sites are presented in Table 20.Comparing the composite species list with the Hill Pasture, only four species were not present at the Hill Pasture site.These included Koeleria cristata, Fragaria spp. , Linum angustifolium, and Eriophylum lanatum.

Soil Descriptions

Descriptions of soil profiles analyzed at each of the 12 stands are presented in Appendix E.All of the soils were fine textured in the A and B horizons.Variations in texture were not very large among sites.Soil moisture percentages of water retained on a weight 135 Table 20.Frequencies of species sampled in 1966 within 22 -inch and 12-foot quadrats in 12 stands at Other Foothill sites along the western edge of the Willamette Valley. Percent Stand 1 Stand 2 Stand 3 Stand 4 Stand 5 Stand 6 Stand 7 Stand 8 Stand 9 Stand 10 Stand 11 Stand 12 Species BH-Ca FP NP-C NP-B AP BH-D BH-B GH NP-A BH-A BP GP MEDUSAHEAD 20 58/100 58/100 56/100 80/100 6/ 54 46/100 56/100 7 2/100 8 4/100 14/ 60 98/100 CALIF. OATGRASS 22/ 94 16/ 94 48/100 18/ 84 8/ 62 58/100 4 48/100 14/ 86 2/ 16 10/ 60 2/ 12 Agrostis hallii 12 Elymus glaucus 6/ 30 Pb 2/ 8 Festuca rubra 50/100 14/ 74 12/ 64 12/ 32 8/ 24 16 4/ 1 2 2/ 8 2/ 8 4 Koeleria cristata 54 2 P P 2 Lolium perenne 4 6 4/ 6 2/ 24 18/ 60 4 Poa pratensis 8 2/ 26 6 28 2/ 14 Sitanion hystrix 8 2/ 6 P 2 Stipa columbiana 8/ 72 2/ 6 Aira caryophyllea 2/ 10 4/ 26 18/ 58 10 2/ 24 4 30/ 86 2 8/ 46 14/ 7 2 Avena fatua 4/ 26 P Bromus commutatus 16/ 90 38/ 96 52/100 34/100 32/ 82 14/ 98 48/100 16/100 52/100 22/100 16/ 7 2 48 Bromus rigidus 4 6 4/ 18 8/ 20 Cynosurus echinatus 24 54/ 98 4/ 26 18/ 58 14/ 84 6/ 54 2/24 2/ 16 68/100 6 Festuca dertonensis 8/ 30 4/ 14 38/ 90 46/100 16/ 42 30/100 26/ 82 34/ 90 18/74 8/ 34 4 6 Gastridium ventricosum 2 4 2/ 22 8 Achillea lanulosa 16 8 2 4 10 Cerastium viscosum 12 2 2 2/16 Daucus carota 4 2 2 6 2 4 Epilobium paniculatum 2 6/ 50 2 16 2 14 4/20 2 Eriophyllum lanatum 34 14 16 14 2/ 46 14 2 4 Erodium cicutarium 2/ 14 2/ 18 2 4/ 20 Fragaria spp. P 4/ 6 24/ 76 Hypericum perforatum 6 P 2 Hypochaeris radicata 2 2/ 18 2/ 18 2 4 2 P 2/42 Lactuca serriola 4 10 2 10 2 Lathyrus sphaericus 14 4 2/ 14 12/ 32 Linum angustifolium 98 6 4 Lotus micranthus 2 6 4 4 8 Myosotis versicolor 2 18 4/3 2 2 Plantago lanceolata 28/100 26/ 9 6 4/ 18 2 20/ 98 3 2/ 98 38/100 18/ 66 12/94 Ranunculus occidentalis 38 2 22 42 6 26 4/ 28 2 2/24 2 Sanicula bipinnatifida 2 2 Sherardia arvensis 2/ 18 12/ 48 4/ 20 6 2/ 14 4/ 20 10 6/ 3 2 8 2/28 Torilis nodosa 4 6 2 2 4 Veronica peregrina 2 2 2 baSee Table 21 for interpretation of abbreviated symbols. P refers to "presence" within the macroplot. 136 basis under tensions of 1/3 and 15 atmospheres of pressure were all relatively high, ranging from 16 to 42 percent, respectively.These values are indicative of high clay content.Several of the soils contained a large amount of gravel and cobble or chert-sized fragments.

Vegetation - Habitat Relationships

All of the stands analyzed were at a seral stage of succession, varying from low to medium-high.The apparent retrogression was thought due primarily to past-biotic influences in the respective ecosystems.These included primarily cattle and/or sheep grazing, probably angora goats grazing, and rodent activity.Stands at the Noble location had been grazed by cattle for a number of years while stands at the Frye, Grange Hill, Burgett, and Gray locations had been grazed primarily by sheep.Stands at the Bald Hill and Adair locations have had no grazing in recent years. In order to evaluate the variation of local landscapes, groups of stands were selected at two of the seven locations.These included stands 1,6,7, and 10 at the Bald Hill location and stands 3, 4, and 9 at the Noble pasture location. It can be seen in Table 20 that medusahead was the dominant species in all of the communities studied except stands 1 and 6 at the Bald Hill location.These stands were the nearest to being stable communities (climax) of all those sampled.Recent rodent activity was 137 evident in stand 6, however, which afforded ideal micro-habitats for weedy annuals. The stands were arranged in Table 20 from left to right by the descending frequency of Festuca rubra. Where it was absent in stands 11 and 12, descending frequency of California oatgrass was considered as the criterion. On the basis of the detailed study at the Hill Pasture site, Festuca rubra was considered to be the best species for indicating more moist and cool environments of the ecosystems studied.This supposition was based on its restriction to these environmental conditions.Because of the seral nature of the stands, such an arbitrary ranking from mesic to xeric likely has descrepancies.The actual site potential may not be of such order, providing all of the stands were near climax.Moreover, Festuca rubra may not be the best indicator of a moist environment in some of the stands encountered. A case of question is exemplified in stand 8.Fragaria spp. is known to have rather high moisture requirements and in turn has a high frequency in stand 8, while Festuca rubra is of low abundance.In this stand, Fragaria would be the better phytometer of rather high moisture effectiveness. Because of the seral nature of the communities, other environmental conditions supplement the vegetation analysis in the understanding of the respective ecosystems.Hence,percent of slope, 138 direction of exposure to light intensity, elevation, and soil depth are presented in Table 21. Mainly because of the slight percent of slope, exposure toward the northwest, and moderately deep soil, stand 1 represents the highest moisture effectiveness of the habitats studied.All of the others had an exposure toward a southerly direction. The relatively high abundance of Koeleria cristata in stand 1 raises the question of whether the species is better adapted for this habitat or whether it is reduced in abundance in other stands because of the disturbance factor.

Variation of frequency of dominant species among stands 1,6, 7, and 10 sampled at the Bald Hill location was striking.California oatgrass was most abundant in stand 6 in which it had a frequency of 58 percent in the22-inchquadrat size.In stand 1 where oatgrass was competing strongly with Festuca rubra (50 percent frequency in the 22-inchquadrat size), vigor of oatgrass plants was much reduced from those in stand 6. The phytosociological contrast of stand 7 with stands 1,6, and 10 may be noted in Table 20.Oatgrass frequency in stand 7 was only four percent in the12-footquadrat size, but Stipa columbiana frequency was 72 percent. Exposure of 58°W was considerably more xeric than stand 1 although percent of slope of 14 percent was the same. Ecologically, however, the 14 percent slope toward the northwest Table 21 Percent slope, exposure, soil depth, and elevation at each of the 12 stands at Other Foothill sites studied in 1966.

Stand Percent Soil Number Habitat Slope Exposure Depth Elevation

1 Bald Hill-C 14 N15°W 23" 500' 2 Frye Pasture 16 S26°E 17" 500' 3 Noble-C 16 S67°W 28" 650' 4 Noble-B 29 S21°W 16" 650' 5 Adair Pasture 25 S50°E 15" 500' 6 Bald Hill-D 19 S19°E 28" 450' 7 Bald Hill-B 14 S 8°W 11" 500' 8 Grange Hill 15 S40°W 35" 550' 9 Noble-A 32 S 2°E 15" 650' 10 Bald Hill-A 36 S 2°E 20" 550' 11 Burgett Pasture 25 S46°E 19" 450' 12 Gray Pasture 25 S33°E 17" 350' 140 differs greatly from the 14 percent to the south.Comparing stand 7 with stand 6, on the other hand, reveals a difference of oatgrass frequency of four percent in the12-footquadrat size versus 100 percent, and no Stipa columbiana in the latter.Based on the net effect of slope and exposure, this portion of the habitat of stand 6 was slightly more xeric than that of the Stipa dominated stand 7.Soil depth, however, was only 11 inches to weathered bedrock, whereas depth was 28 inches in stand 6. The slope-exposure combination of 36 percent toward S2°E in stand 10 was the most xeric at the Bald Hill location (and of all stands sampled in western Oregon, including the Hill Pasture site).Soil depth in stand 10 was about double of stand 7, however.Disturbance was more noted in stand 10, but the succession appeared to betoward a California oatgrass/Stipa columbiana dominated community. The vegetation-habitat relations of the Bald Hill landscape which were sampled indicates that three discrete ecological units were present.In summary, these included:(1) a Festuca rubra dominant ecosystem in the more moist and cool habitat, (2) a California oatgrass dominant ecosystem under more xericconditions, and (3) a Stipa columbiana dominant ecosystem in the most extreme xeric habitat.The Festuca ecosystem at Bald Hill appeared to have a higher moisture effectiveness than the mesic ecosystem at the Hill Pasture site.Although dominated by oatgrass, stand 6 was comparable to the 141 mesic ecosystem at the Hill Pasture site because of moderate slope and mutual indicator species such as Festuca rubra, Lathyrus sphaericus, and Erodium cicutarium. The Stipa dominated ecosystem had no similar counterpart within the Hill Pasture study area. A few Stipa columbiana plants were present, however. The three stands at the Noble location also expressed variation of different habitat conditions.The percent slope, exposure, and soil depth of stand 3 resulted in the highest moisture effectiveness of the three stands.The species present and their relative densities served as a good phytometer as being comparable to the mesic ecosystems at the Hill Pasture.Considering that the percent slope was much greater, exposure more westerly, and soil depth greater in stand 3 than stand 4, the two were quite similar in their community structure and composition.Their differences were mainly in higher frequencies of the dominant perennials.Stand 4 would also be similar to the mesic site at the Hill Pasture. Stand 9 occupied the most xeric habitat at the Noble location. Although oatgrass frequency was as high as that of stand 3, the total flora expressed the lower moisture effectiveness of habitat factors at stand 9. The pattern of Plantago lanceolata frequency and presence was notably variable among the three stands at the Noble location, ranging 142 from 96 percent in stand 3 to 18 percent in stand 4 to none in stand 9. This apparent "site response" was not evident at the Bald Hill location where it had a high frequency in all stands.Its variation at the Noble location was probably accidental. In summary, there was found to be marked similarity in species composition, soils, exposures and elevations between most of the sites investigated and the Hill Pasture sites.The major differences were noted where moisture effectiveness was greater (Stand 1), apparent disturbances were greater (Stand 10 and Stand 12), and where depth of soil was shallow (Stand 7). It is likely that sites such as Stands 10 and 1 2 would benefit but little in the way of rapid improvement providing medusahead were to be removed, since there occurs such a paucity of perennial grasses. 143

CONCLUSIONS AND IMPLICATIONS TOWARD MANAGEMENT

Since eradication of medusahead is not practical, only control measures will be discussed here.Control implies elimination of a portion of the population in order to reduce competition and dominance in a plant community.Control of medusahead may be considered in yet another way.For example, control of medusahead litter may be necessary to change the species from an unplatable weedy grass to one that is utilized.Research by Lusk et al. (1961) cited earlier suggests this kind of "shift in palatability."It follows then that if utilization of medusahead is effectively accomplished by sheep grazing, it is no longer a problem.9 Except for ash, which in medusahead was much higher in silica content (11. 3 percent in medusahead compared to 4. 4 percent in cheatgrass), Bovey, LeTourneau, and Erickson (1961) found that medusahead was comparable to cheatgrass and many desirable grass species in all nutrients. When utilized, therefore, medusahead may be considered a nutritious forage. The problem of managing unimproved medusahead infested

9Areservation might be made here in that the high silica content of medusahead could possibly invoke a metabolic problem such as urinary calculi.This is purely speculative reasoning and the writer is not aware of any evidence or research which sheds light on this question regarding medusahead. 144 foothills is primarily one of utilizing medusahead- not of its eradication.The writer feels that it is unrealistic to imagine that medusahead can be eradicated by grazing alone, once it acquires dominance in an ecosystem. Under the conditions of the experiment, the EARLY-LATE GRAZED treatment by sheep accomplished the objective each year of utilizing medusahead effectively on both the mesic and xeric habitats. The critical biological factor in relation to the mechanics of grazing appeared to be the need for the close utilization prior to emergence of heads of medusahead.Although the utilization was accomplished effectively within the confinement of the paddocks, there remains the question of just how efficiently this could be accomplished on a larger and more practical scale.The "late" period of grazing in the EARLY-LATE GRAZED treatment was indicated to be 12 sheep days per 1/20 of an acre.This intensity was accomplished by grazing three sheep for four days duration, which is certainly of the order of "flash grazing. "The sheep-days intensity employed in mid-April was likewise of short duration.Timing was not a critical factor involved with the April grazing, since consumption of forage and obliteration of litter were the desired objectives. The start and termination of the grazing would have to be timed with the prevailing yearly phenology of plant development. Some degree of flexibility of sheep numbers would be required to assure heavy grazing pressure 145 particularly at the time when medusahead has reached the early-boot stage.It appears essential that most of the previous year's medusahead litter should not be present when grazing pressure is applied at the critical mid or late May period. The kind of sheep-grazing management necessary for implement- ing utilization of medusahead has been shown to be strongly affected by habitat and its vegetative composition.Here, the degree of density of medusahead and density of perennial cover is important.The LATE GRAZED treatment was biologically as effective for utilization of medusahead at the same intensity of 27 sheep days per 1/20 of an acre (540 sheep days per acre) as was the EARLY-LATE GRAZED treatment in the mesic site (Block 1).The effectiveness of the LATE GRAZED treatment was shown to be very poor for utilization of medusahead on the xeric habitat. In most unimproved hill pastures there normally would be variation of the landscape which would result in a mosaic of two or more ecologically different sites.Since these respond quite differently to sheep grazing management, as has been demonstrated in this investigation, the only grazing system which can be recommended, where other tools of management such as fire or mowing are not combined, is the EARLY-LATE GRAZING - or the continuous extension of grazing over the period from mid April to mid or late May.Defining time in phenological terms, this grazing period would be from which 146 time medusahead is about four inches in height to when it is in the boot stage. The flash grazing employed in mid April and late May in the EARLY-LATE GRAZED treatment is probably impractical for a hill pasture operation.Since animal performance was not actually determined in the study, the grazing intensity could have been too heavy for the welfare of the sheep, the effects of which were not noticeably detrimental during such short periods of grazing. A grazing schedule of lower intensity in terms of sheep days per acre, and for a duration which would draw together the April and May periods into one continuous period, would be practical from the standpoint of management providing the pastures were not too large. In order to facilitate the attainment of heavy grazing pressure in mid May, additional fencing should be considered so that grazing units are as small as possible and yet be practical. Among other factors considered important in the layout of the pastures, consideration should be given to placing unit fences and cross-divisional fences at or near ecotones which separate different ecological units.For example, where a steep south exposure and a rather flat bench form an expanse of the landscape, the best location for the fence would be at the base of the slope.Such divisions of ecological units would facilitate better grazing control which is essential for utilization of medusahead. 147 The effectiveness for using a rotary-type mower for eradication of medusahead just after head emergence has been amply docu- mented in this investigation. Where the landscape is not too steep, nor too stony, mowing has much potential as a tool to combine with grazing in a hill pasture sheep and/or cattle operation, where management is geared to utilize and reduce populations of medusahead. Weedy brush species such as Rosa spp. could also be controlled in the same operation. Where there is a good perennial cover, primarily of California oatgrass which is suppressed by medusahead, perhaps it would be advantageous to rest a pasture from grazing for two years in May and apply mowing in order to shift dominance and restore vegetative and reproductive vigor to the perennials.Although the EARLY GRAZED treatment was ineffective for controlling medusahead, it could possibly be used effectively in combination with late mowing without the need for a complete seasonal rest of a pasture.Grazing up to the first of May should have no physiological ill effects on subsequent vigor of perennial grasses.The early grazing would serve to relieve the effects of medusahead litter accumulation and would furnish a fair supply of nutritious green forage.Mowing at the last of May would follow at a clipping height sufficient to remove most of the heads of medusahead. Such a schedule should benefit the perennials considerably. 148 Further research is needed to test the effectiveness of sheep grazing for the control of medusahead in larger pastures and under more practical grazing schedules than those employed in the small paddocks.In the present study, the primary objective was to evaluate the response of the vegetation and the effectiveness for its manipulation by the mechanics of sheep grazing and mowing. Under more practical conditions, animal performance needs to be evaluated in relation with intensities and durations of grazing schedules.Further investigations are needed, too, for evaluating the effectiveness of medusahead utilization and comparative community response and productivity between different ecological sites where these form a mosaic of plant communities within a pasture.The behavorial pattern of animals in their preference of foraging might well be an area of worthwhile study between mesic and xeric habitats within the same pasture, in which medusahead is a problem. As stated earlier, sites such as Stands 10 and 12 of the Other Foothill sites have little opportunity for rapid improvement should medusahead be removed by grazing management or mowing, since there is such a low frequency of perennial grasses at these sites.

Conversely, sites such as Stands 2,3, 4,5,6,7, 8, 9, and 11 have the potential for quick response for recovery and increased forage production, based on the high frequency of perennials growing in competition with dense medusahead.The positive results obtained 149 from the Hill Pasture study should apply as well and be extrapolated to these potentially favorable Other Foothill sites. It is recommended that detailed vegetation composition be obtained in the way of some form of vegetation sampling technique (such as the "toe point" method or some more refined method for obtaining frequency) prior to planning or initiating a medusahead control program whereby perennials are released from medusahead competition.The sampling is desirable because dense medusahead plants and litter mask and hide the depauperate perennials, chiefly California oatgrass, to a marked degree. While schemes of grazing and mowing might be used to advantage on many ranges, the most effective approach for the control of medusahead (its utilization and suppression) on non-forested hill range of western Oregon is by implementation of facilitating improvements which raise the fertility of the site.The practice which appears to have the greatestpracticability,on most hill range sites, where moisture effectiveness is sufficiently high, is the introduction of subterranean clover.This species provides nutritious forage and raises the nitrogen level of the soil. Fortunately, the needs for adequate subclover management complement very well the requirements for medusahead utilization. Field demonstrations have shown that medusahead palatability is improved when the plants are growing under a more favorable nitrogen 150 balance.Timing and intensity of grazing for the maximum stresson medusahead in May would also be at optimum for the benefit of subclover utilization and the trampling of its seed.Providing that a few ungrazed medusahead plants were present after grazing in late May, a mowing for the purpose of destroying soft heads of medusahead could be made without detrimental effects upon the subclover. 151

SUMMARY

Species which exhibited ecologically important response to treatment and climatic effects in communities studied in eastern Oregon included perennial grasses bluebunch wheatgrass and Sandberg's bluegrass, annual grasses medusahead and cheatgrass, and annual forbs fiddleneck and sunflower. The pattern of growth and development of annual vegetation varied greatly from 1963 through 1966 in the CONTROL treatment at the Stripe Mountain West site.Cheatgrass made dense and vigorous growth in 1963 with well developed panicles, apparently the result of excellent climatic conditions.Condi- tions were less favorable in 1964 for cheatgrass and frequency of occurrence declined.These plants were small in stature and set seed on depauperate panicles.Frequency of cheatgrass dropped sharply in 1965 and was practically absent in 1966, an extremely droughty year.The highest frequencies recorded for Sandberg's bluegrass also coincided with the excellent cheatgrass year of 1963. Medusahead responded quite differently than did cheatgrass in 1964 and 1965.Being about three weeks later in phenology, medusahead benefited from late spring moisture. Medusahead grew tall and developed large, normal heads. 152 Although medusahead was restricted to patches and considerably more sparse than cheatgrass, frequency values increased slightly from 1963 to 1965.Like cheatgrass, medusahead was almost negligible in 1966. Fiddleneck and sunflower exhibited a high degree of variation in frequency from 1963 to 1966. When cheatgrass was dense and vigorous in 1963, fiddleneck was not recorded and sunflower was negligible.Growing conditions were ideal for fiddleneck in 1964.Frequency increased to 46 percent in the 22-inchquadrat size.Frequency of sunflower also increased sharply.

3. High variation resulted among herbicide treatmentsin effecting densities of the annuals and Sandberg's bluegrass. The latter declined markedly in 1963 at the Stripe Mountain West site following spring, 1962 applications of atrazine (2lb/ acre) and isocil (1 lb/acre). Many of the weakened plants succumbed in subsequent years.Frequencies of cheatgrass and medusahead were also sharply reduced in 1963.Further decline of cheatgrass in subsequent years reflected the adverse growing conditions. Control of annual grasses and kill of Sandberg's bluegrass was almost complete from residual atrazine(1 1/2 lb/acre) and isocil (1 lb/acre) applied in fall, 1962, based on 1963 153 frequency data.Frequencies of fiddleneck and sunflower in 1963 were extremely low in both spring and fall atrazine and isocil treatments.The high frequencies of fiddleneck and sunflower in 1964 was indicative of no remaining herbicide residue, at least in amounts detrimental to these forbs. Where wheatgrass clumps were closely spaced and vigorous in the atrazine treatments, competition was too great for fiddleneck and the species was practically absent. There was no apparent residue from the dalapon treatment in 1963 and the annual grasses flourished.Frequency data suggested that some plants of Sandberg's bluegrass were killed by spring applied dalapon (2 lb/acre).

4. No injury was evident to bluebunch wheatgrass plants from the atrazine treatments at the Stripe Mountain West site.Small seedlings may have succumbed without being noticed. Variation of wheatgrass frequencies among all years for all treatments was nearly stable.

5. Vigor of bluebunch wheatgrass increased markedly in 1963 from the reduction in annual plant competition resulting from their selective removal by the spring, 1962 atrazine treatment.Adjusted canopy cover of wheatgrass increased from 42 to 54 to 60 percent from 1963 through 1965.These values represented increases over the CONTROL treatment by 56, 154 45, and 37 percent, respectively.Large increases over the CONTROL were also recorded for the fall, 1962 atrazine treatment but only slight increases by the isocil treatments, both of which burned wheatgrass to a slight degree.

6. Increases of leaf and inflorescence heights and percent of clumps containing reproductive culms of bluebunch wheatgrass in the spring, 1962 atrazine treatments were markedly greater than those of the CONTROL in 1963 and 1964 at the Stripe Mountain West site.The maximum number of heads counted in 1965 in the largest clumps contained 332 heads in the atrazine treatment compared with 166 in the CONTROL.

7. Atrazine, applied in fall, 1963 at 3/4 lb/acre and bromacil at 1/2 lb/acre were equally effective for reducing cheatgrass and medusahead to low frequencies at the Stripe Mountain East site in 1964.Frequency data suggested slight injury to Sandberg's bluegrass from the atrazine treatment but none from the bromacil.It was apparent that Sandberg's bluegrass exhibited a much higher resistance to injury from bromacil at equivalent rates and dates of application than from closely related isocil.

8. At the District Boundary site Sandberg's bluegrass was injured to a slight degree from spring, 1963 applied atrazine at 1/2 lb/acre.The next higher rate of 3/4 lb/acre killed a 155 few plants, while the highest rate of 1 1/2 lb/acre reduced bluegrass frequency substantially.

9. Frequency data for bluebunch wheatgrass among all treatments revealed that there was little or no increase in plant numbers.Small plants encountered in the sampling were essentially absent.Several factors or interactions may have been inimical to wheatgrass seedling establishment. Among these include possible herbicide residue, competition from annuals, grass- hopper foraging, poor seed production in 1963 and 1964, and unsuitable climatic conditions.Wheatgrass seed collected from all treatments in 1965 at the Stripe Mountain sites all were highly viable under laboratory germination tests.

10. Bluebunch wheatgrass exhibited a nitrogen-like fertilizer response on atrazine treated macroplots.This was manifested by darker green, denser, and leafier clumps than those observed in other treatments.Aside from this response, when atrazine and bromacil are applied at rates non-injurious to wheatgrass, the removal of competing annuals is in effect an improvement in fertility and water economy to the wheatgrass.

11. Even though medusahead made favorable growth in 1963, 1964, and 1965 at all of the eastern Oregon sites studied, the populations did not expand appreciably in numbers or spacial distribution of patches.Population dynamics appeared to be 156 fairly well stabilized under the conditions which prevailed. It was essentially absent in 1966. 12. From interpretation of species presence and frequency of occurrence in relationship with degree of slope,exposure

and soil conditions, it was found that the Hill Pasture sitecon- tained two distinct ecological units.Block 1 was representative of the more mesic site, and Block 3 the more xeric. Block 2 was ecotonal to both.Frequencies of medusahead were higher in all instances in Block 3.California oatgrass, the other dominant species throughout the Hill Pasture site, had

higher frequencies in Block1. Anumber of species had much higher frequencies in Block 1.Festuca rubra and Poa pratensis were considered to be key "phytometric" species and their presence and relatively high abundance was restricted to the more mesic Block 1. 13. A large degree of variation was found among treatments

within blocks, due to treatment effects.TheEARLY GRAZED andEARLY MOWEDtreatments were ineffective for reducing

medusahead frequency.TheEARLY-LATE GRAZEDand LATE GRAZEDtreatments both reduced medusahead frequencies to low levels in 1963 through 1965.The grazing pressure which was applied in Blocks 2 and 3 in attempt to utilize medusahead was considerably higher in the latter, however, and much 157 medusahead was killed by trampling rather than consumed. 14. Complete utilization of medusahead, as well as California oatgrass and other herbage, was easily attained in the EARLY-LATE GRAZED treatment among all blocks by sheep confined in the 1/20 of an acre paddocks.Complete utilization of medusahead was as readily attained by the same grazing intensity in the LATE GRAZED on the mesic Block 1, but highly ineffective even with more sheep days grazed on the xeric Block 3.The response by sheep to the two ecological sites was clearly evident.

15. In 1966, when treatments were not applied, frequencies of medusahead were again high for both the EARLY-LATE GRAZED and LATE GRAZED treatments.

16. The EARLY-LATE MOWED treatment was highly effective for reducing medusahead frequencies each year of the study.Without mowing in 1966, medusahead frequencies were extremely low, and California oatgrass was distinctly dominant.At the initiation of the study California oatgrass plants were weakened considerably by competition from medusahead.Marked increase in vigor resulted for this perennial grass in the EARLY-LATE MOWED treatment.Basal area of California oatgrass increased much more in the EARLY-LATE MOWED treatment in xeric Block 3.Here, percent basal area 158 was significantly higher (P = . 01) than all other treatments. Mean differences in Block 1 were not significant (P = .05) between the EARLY-LATE MOWED, CONTROL, EARLY-LATE GRAZED, and LATE GRAZED treatments.The increase of oatgrass basal area in the EARLY-LATE MOWED treatment was about double that of the CONTROL in Blocks2 and 3.Oat- grass basal area increased proportionately greater where its density was lower and when medusahead competition was markedly reduced.

17. Yields of medusahead ranging from 875 to 1000 lbs /acre were the highest in Block 3 in the three grazing treatments. Yields of oatgrass ranging from 400 to 600 pounds per acre among blocks in the CONTROL treatment were notsignificantly different at P = .01.There was no significant difference between yield of oatgrass in the CONTROL treatment and the EARLY-LATE MOWED treatment in Block 1, but yields were significantly higher ( P = .01) for the latter in Block 3. Among the grazed treatments, yields of oatgrass were significantly less ( P = . 01) in Block 3 than yields in Block 1. No significant differences were noted between blocks in the EARLY MOWED treatment. Inversely, in contrast with all other treatments, oatgrass yield was significantly higher in Block 3 than Block 1 in the 159 EARLY-LATE MOWED treatment (P = .01).Moreover, yields were significantly higher (P = .01) in the EARLY-LATE MOWED treatment than all other treatments in Block 3.

18. There was found to be marked similarity in species composition, soils, exposures, and elevations between most of the Other Foothill sites investigated and the Hill Pasture mesic and xeric sites.The major differences were noted where moisture effectiveness was greater, apparent disturbances were greater, and where depth of soil was shallow. It was concluded that rapid improvement should be possible providing medusahead was removed by grazing management and late mowing on all but two of the stands studied at Other Foothill sites.Perennial grasses were much too sparce at the two exceptions mentioned in the way of "shifting dominance" quickly. 160

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Appendix A. Generic, symbolized, and common nomenclature with life form indicated for all a plants encountered in the eastern and western Oregon studies. Eastern Oregon Plants b Genus - species Symbol Name Common Name Life Form' Artemisia tridentata Nutt. ARTR big sagebrush PS

Agropyron spicatum (Pursh) Scr. & Sm. AGSP bluebunch wheatgrass PG

Poa bulbosa L. POBV PG

Poa secunda Presl. POSE Sandberg's bluegrass PG

Sitanion hystrix (Nutt.) J. G. Sm. SIHY PG

Allium sp. ALLsp PF

Antennaria dimorpha (Nutt.) T. & G. ANDI PF

Astragalus purshii Dougl. ASPU PF

Calochortus sp. CALsp PF

Cirsium undulatum Nutt. CIUN PF

Crepis occidentalis Nutt. CROC PF

Lithospermum ruderale Dougl. LIRU PF

Lomatium macrocarpum (Nutt.) C. & R. LOMA PF

Lomatium triternatum (Pursh) C. & R. LOTR PF

Lupinus sericeus Pursh LUSE PF

Microseris troximoides gray MITR PF

Penstemon sp. PENsp PF

Phlox longifolia Nutt. PHLO PF

Tragopogon dubius Scop. TRDU PF

Bromus tectorum L. BRTE cheatgrass AG

Festuca octoflora Walt. FEOC AG

Taeniatherum asperum (sim.) Nevski TAAS medusahead AG Amsinckia intermedia Fisch. & Mey AMIN fiddleneck AF

Blepharipappus scaber Hook. BLSC AF Descurainia pinnata Walt. DEPI AF

Epilobium paniculatum Nutt. EPPA AF

Helianthus annuus L. HEAN sunflower AF

Lactuca serriola L. LASE AF

Lagophylla ramosissima Nutt. LARA AF

Lepidium perfoliatum L. LEPE AF

Sisymbrium altissimum L. SIAL AF 172

Appendix A (continued) Genus - species Symbol Name CommonNameb Life Forme

Western Oregon Plants

Agrostis halli Vassey AGHA PG

Arrhenatherum elatius Presl. AREL PG

Carex spp. CARspp PS

Danthonia californica Boland DACA California oatgrass PG

Elymus glaucus Buckl. ELGL PG

Festuca rubra L. FERU PG

Koeleria cristata Pers. KOCR PG

Lolium perenne L. LOPE PG

Poa pratensis L. POPR PG

Sitanion hystrix (Nutt.) J. G. Sm. SIHY PG

Stipa columbiana Macoun. ST CO PG

Aira caryophyllea L. AICA AG

Avena fatua L. AVFA AG

Briza minor L. BRMI AG

Bromus commutatus Shrod. BRCO AG

Bromus rigidus Roth BRRI AG

Cynosurus echinatus L. CYEC AG

Festuca dertonensis (All.) A. & G. FEDE AG

Gastridium ventricosum (Gouan) S. & T. GAVE AG

Taeniatherum asperum (Sim.) Nevski TAAS medusahead AG

Achillea lanulosa Nutt. A CLA PF

Agoseris grandiflora (Nutt. ) G. & P. AGGR PF

Brodiaea Douglasii (Lind). ) Wats. BRDO PF

Centarium umb ell atum Gilib. CEUM AF Cerastium viscosum L. CEVI AF

Cesium sp. CIRsp PF Daucus carota L. DACAR AF

Epilobium paniculatum Nutt. EPPA AF

Eryophyllum lanatum (Pursh) Forb. ERLA AF Erodium cicutarium L. ERCI AF

Fragaria sp. FRAsp PF 173 Appendix A (continued) b Genus - species Symbol Name Common Name Life Form'

Galium divaricatum Lam. GADI AF

Hypericum perforatum L. HYPE PF

Hypochaeris radicata L. HYRA PF

Lactuca serriola L. LASE ABF

Lathyrus sphaericus Retz. LASP PF

Linum angustifolium Huds. LIAN AF

Lotus micranthus Benth. LOMI AF

Myosotis versicolor (Pers.) J.F.Sm. MYVE AF

Penstemon sp. PENsp PF

Plantago lanceolata L. PLLA PF

Potentilla sp. POTsp PF

Ranunculus occidentalis Nutt. RAOC PF

Rumex acetosella L. RUA C PF

Sanicula bipinnatifida Dougl. SABI PF

Sherardia arvensis L. SHAR AF

Sonchus asper L. SOAS BF

Taraxicum officinale Web. TAOF PF

Tori lis nodosa L. TONO ABF

Trifolium bifidum Gray TRBI AF Trifolium subterraneum L. TRSU Subterranean clover AF

Veronia peregrina L. VEPE AF

Vicia americana Muhl. VIAM PF Vicia tetrasperma (L.) Moench. VITE AF Quercus garryana Dougl. QUGA T

Rhea diversiloba Tor. & Gray RHDI S

Rosa rubiginosa L. RORU S a Sources used for authorship of scientific nomenclature were Hitchcock's Manual of the Grasses of the United States, Peck's A Manual of the Higher Plants of Oregon, Hitchcock et al. Vascular Plants of the Pacific Northwest - Parts 2,3,4, and 5.For medusahead, the Weed Society of America's standardized terminology was used (Weeds 14:346-386). b Only the common names which were used in discussion of results are indicated. c Symbols used for Life Form are as follows: S = Shrub, PG = Perennial Grass, PF = Perennial Forb, AG = Annual Grass, AF = Annual Forb, PS = Sedge, ABF = Annual - Biennual Forb, T = Tree. Appendix B.Locations and elevations of study sites in eastern andwestern Oregon.

Feet Site Location Elevation

Stripe Mountain West NW 1/4Sec. 11,Twp,15S,R. 44 E 2850 Stripe Mountain East NW 1/4Sec. 11,Twp.15S,R. 44 E 2850 District Boundary SW 1/4Sec.1,Twp.15S,R. 44 E 2750 Hill Pasture SW 1/4Sec. 29,Twp.11S,R. 5 W 450 Adair Pasture SW 1/4Sec. 23,Twp,10S,R. 5 W 500 Frye Pasture NE 1/4Sec. 15,Twp.10S,R. 5 W 500 Burgett Pasture SE 1/4Sec. 15,Twp.10S,R. 6W 450 Grange Hill NE 1/4Sec. 21,Twp.115,R. 6W 550 Bald Hill SW 1/4Sec. 31,Twp.11S,R. 5W 500 Gray Pasture NW 1/4 Sec. 21,Twp.12S,R. 6W 350 Noble Pasture SW 1/4 Sec. 34,Twp.11S,R. 6W 650 175 Appendix C.Descriptions of typical profiles for tentative soil series at the eastern Oregon study sites.

Stripe Mountain - Tentative Series, Lookout

All 0-2" Light grayish brown (10YR 5/2) dry, grayish brown (10YR 5/2) moist; clay loam; moderate, fine platy structure breaking to moderate, very fine crumb; loose, friable, sticky, plastic; many, very fine to fine tubular and vesicularpores; abundant roots; pH 7. 2; abrupt, smooth boundary.

Al2 2-5" Grayish brown (10YR 5/2) dry, very dark grayish brown (10YR 3/2) moist; clay loam; moderate, medium platy structure breaking to moderate, fine platy; slightly hard, friable, sticky, plastic; many, very fine tubular and vesicularpores; abundant roots; pH 6. 9; abrupt, smooth boundary; moisture tension at 1/3 atm. 31. 68%, 15 atm. 19. 48%.

B21 5-14" Light brownish gray (10YR 6/2) dry, very dark grayish brown (10YR 3/2) moist; clay; moderate, coarse to medium prismatic structure breaking to moderately strong, fine to medium angular blocky; hard, firm, sticky, plastic; common, fine tubular and vesicular pores; occassional roots; pH 7. 1; abrupt, smooth boundary.

B22 14-22" Light gray (10YR 7/2) dry, dark grayish brown (10YR 4/2) moist; clay; moderate,coarse to medium angular blocky 176 structure breaking to moderately strong, medium to fine angular blocky; hard, firm, sticky, plastic; many, very fine tubular and vesicular pores; occassional roots; pH 7. 7; clear, smooth boundary; moisture tension at 1/3 atm. 38. 49%, 15 atm. 21.10 %.

C1 22-30" Light gray (10YR 7/2) dry, brown (10YR 4. 3) moist; clay loam; massive structure; slightly hard, friable, sticky, plastic; common, very fine tubular and vesicular pores; few roots; pH 7. 7; clear, smooth boundary.

Cca Below 30" Hardpan consisting of accumulations of calcium carbonate.

Remarks: Thick, continuous clay films on peds and in pores of the B21 and B22 horizons.Thin clay films in Cl.

District Boundary - Tentative Series, Virtue

All 0-2" Light brownish gray (10YR 6/2) dry, dark grayish brown (10YR 4/2) moist; loam; weak, fine platy structure breaking to dust; soft, friable, slightly sticky, slightly plastic, common, very fine to fine tubular and vesicular pores; abundant roots; pH 7. 4; abrupt, smooth boundary.

Al2 2-6" Light brownish gray (10YR. 6/2) dry, dark grayish brown (10YR 4/2) moist; loam; weak, medium platy structure 177 breaking to very fine platy; slightly hard, friable, sticky, plastic; few, very fine to fine tubular and vesicular pores; abundant roots; pH 6. 9; abrupt, smooth boundary.

B21 6-12" Dark grayish brown (10YR 4/2) dry, very dark grayish brown (10YR 3/2) moist; clay loam; moderate, medium to coarse subangular blocky structure breaking to moderate, fine subangular blocky; hard, firable, sticky, plastic; few medium, common, very fine to fine tubular and vesicular pores; occassional roots; pH 6. 2; clear, smooth boundary; moisture tension at 1/3 atm. 34. 72 %, 15 atm. 18. 57 %.

B22 12-21" Pale brown (10YR 6/3) dry, brown (10YR 5/3) moist; clay loam; moderate, medium to coarse subangular blocky structure breaking to fine subangular blocky; very hard, firm; sticky, plastic; few, fine to medium tubular and vesicular pores; occassional roots; pH 6. 3; clear, smooth boundary.

C 21-38" Light gray (10YR 7/2) dry, brown (10YR 5/3) moist; loam; weak to moderate, medium subangular blocky structure breaking to weak to moderate fine subangular blocky; hard, firable, sticky, plastic; few very fine to medium tubular and vesicular pores; very few roots; pH 7. 3; gradual, smooth boundary.

R Below 38" Weathered bedrock. 178 Appendix D.Descriptions of western Oregon soils and topography by Carpenter and Torgeson from their Soil Survey of Benton County.

Olympic Clay "The surface soil of the Olympic clay is a brown to dark- brown, heavy, plastic clay, extending to a depth of 8 to 10 inches.The type is generally shallow, the bedrock being reached at depths of 2 to 4 feet, though rarely outcropping. The topography is gently sloping or rolling, and the drainage is well developed. The Olympic clay is a residual soil derived from the weathering of the coarser grained basic igneous rocks. The Olympic clay, shallow phase, includes areas in which the bedrock, which is similar to that in more deeply weathered areas, is reached within 6 to 20 inches of the surface.The surface features vary from steeply sloping hillsides to the low rolling knolls of the lower foothills. "

Olympic Clay Loam "The surface soil of Olympic clay loam has a depth of 10 to 12 inches and consists typically of brown to dark reddish brown friable clay loam, relatively high in silt in places, and carrying appreciable quantities of organic matter and rusty-brown iron concretions or pellets.The subsoil is a brown compact silty clay loam, clay loam, or clay, underlain at depths varying from 2 to 6 feet by massive basalt.Angular fragments or rounded weathered boulders of the parent rock occur locally throughout the soil profile. Olympic clay loam is of residual origin, being derived from the weathering of basalt and associated igneous rocks. Olympic clay loam, shallow phase, is brown to dark brown in color, and rests upon the underlying bedrock at depths of 6 to 18 inches.Rock outcrop is common over the phase and scattering rock fragments are everywhere present. Drainage is excessive." 179 Aiken Silty Clay Loam The surface soil of the Aiken silty clay loam in its typical development consists of 10 to 12 inches of red to brownish-red silty clay loam.The subsoil is red in color, generally of about the same texture or slightly heavier than the soil, and compact.In places the soil contains angular fragments of basalt and the bedrock is found at shallow depths though it rarely outcrops. For the most part this soil is deeply weathered, bedrock being reached orinarily at from 4 to 6 feet from the surface. The type occupies gently rolling hilltops and some areas that are nearly level.The drainage is everywhere well developed. The Aiken silty clay loam is a residual soil derived from the weathering in place of basalt and to some exttnt from coarser grained basic igneous rocks. " 180 Appendix E.Descriptions of typical profiles for tentative soil series at the western Oregon study sites.

Hill Pasture, Block 1 - Tentative Series, Dixonville All 0-2" Very dark grayish brown (10YR 3/2) dry, very dark gray (10YR 3/1) moist; clay; moderate, medium to fine subangular blocky structure breaking to moderate, medium crumb; very hard, firm, very sticky, very plastic; few, very fine tubular and vesicular pores; abundant roots; pH 6.0; abrupt, smooth boundary; moisture tension at 1/3 atm. 37. 7 %, 15 atm. 22. 1 %.

Al2 2-6" Dark gray (10YR 4/1) dry, very dark gray (10YR 3/1) moist; clay; strong, coarse subangular blocks breaking to moderate, coarse subangular blocky; very hard, firm, very sticky, very plastic; few, very fine to fine tubular and vesicular pores; abundant roots; pH 5. 8; abrupt, smooth boundary.

A13 6-12" Dark gray (10YR 4/1) dry, very dark gray (10YR 3/1) moist; clay; strong, very coarse prismatic structure breaking to strong, coarse subangular blocky; very hard, firm, very sticky, very plastic; few, fine tubular and vesicular pores; occassional roots; pH 5.8; clear, smooth boundary.

B21 12-20" Dark reddish brown (5 YR 3/2) dry and moist; clay; 181 moderate, coarse subangular blocky structure breaking to moderate, fine subangular blocky, few, patchy clay skins; very hard, firm, very sticky, very plastic; few, fine to medium tubular and vesicular pores; few roots; pH 5. 9; abrupt, wavy boundary.

B22 20-30" Dark reddish brown (5YR 3/2) dry and moist; clay; strong, medium subangular blocky structure breaking to strong, fine subangular blocky, moderate patchy clay skins; very hard, firm, very sticky, very plastic; few, fine to medium tubular and vesicular pores; few roots; pH 5. 9; clear, smooth boundary; moisture tension at 1/3 atm. 40.51%, 15 atm. 24. 77%.

R Weathered, basic, igneous, intrusive-type bedrock; many veins.

Hill Pasture, Block 3 - Tentative Series, Dixonville All 0-2" Dark grayish brown (10YR 4/2) dry, very dark gray (10YR 3/1) moist; clay loam; moderate, medium to fine subangular blocky structure breaking to moderate, medium crumb; very hard, firm, very sticky, very plastic; common, very fine tubular and vesicular pores; abundant roots; pH 6. 0; abrupt, smooth boundary; moisture tension at 1/3 atm. 28. 10%, 15 atm. 14. 75%. 182 Al2 2-5" Dark grayish brown (10YR 4/2) dry, very dark brown (10YR 2/2) moist; clay loam; moderate, coarse subangular blocky structure breaking to strong, medium subangular blocky; very hard, firm, very sticky, very plastic; common, fine to medium tubular and vesicular pores; abundant roots; pH 6. 0; abrupt, smooth boundary.

A13 5-12" Dark gray (10YR 4/1) dry, very dark brown (10YR 2/2) moist; clay loam; moderate, coarse to medium prismatic structure breaking to moderate, medium angular blocky; very hard, firm, very sticky, very plastic; few, very fine to medium tubular and vesicular pores; occassional roots; pH 6. 1; clear and wavy boundary.

B 12-24/28" Dark brown (7. 5YR 3/2) dry and moist; clay loam; moderate, medium prismatic structure breaking to moderate, fine subangular blocky; very hard, firm, very sticky, very plastic; few, very fine tubular and vesicular pores; few roots; pH 6. 2; abrupt and wavy boundary; moisture tension at 1/3 atm. 29.36%, 15 atm. 16. 45%.

CR Below 28" Weathered basic, igneous, intrusive type bedrock; many veins 183 Adair Pasture - Tentative Series, Lithic Philomath All 0-2" Very dark grayish brown (10YR 3/2) dry, very dark brown (10YR 2/2) moist; clay; very weak, medium to fine subangular blocky breaking to moderate, very fine crumb; very hard, firm, very sticky, very plastic; few, very fine to medium tubular and vesicular pores; abundant roots; pH 5. 9; abrupt, wavy boundary; moisture tension at 1/3 atm. 38.52%, 15 atm. 23. 69%.

Al2 2-5" Very dark grayish brown (10YR 3/2) dry, very dark brown (10YR 2/2) moist, clay; weak, medium to fine subangular blocky breaking to moderate, very fine subangular blocky; very hard, firm, very sticky, very plastic; few, very fine to medium tubular and vesicular pores; abundant roots; pH 6. 0; clear, wavy boundary.

B 5-10" Very dark gray (10YR 3/1) dry, very dark brown (10YR 2/2) moist; clay; moderate, coarse to medium subangular blocky breaking to strong, fine subangular blocky; very hard, firm, very sticky, very plastic; common, very fine to medium tubular and vesicular pores; occassional roots; pH 6. 0; clear, wavy boundary; moisture tension at 1/3 atm. 29. 64%, 15 atm. 25. 23%. 184

C 10-15" Well weathered parent material containing some elluviated clay; few roots.

R Below 15" Weathered, basic igneous, intrusive-type bedrock.

Variation: Coarse fragments, gravel-size to angular cobblycomposed 20 to 40 percent of the soil profile.

Frye Pasture - Tentative Series, Nekia All 0-2" Dark brown to brown (7. 5YR4/4) dry, dark brown (7. 5YR 3/2) moist; silty clay loam; weak, medium to fine subangular blocky structure breaking to moderate, fine crumb; hard, firm, very sticky, plastic; common, very fine to fine, few, medium tubular and vesicular pores; abundant roots; pH 5. 8; abrupt, wavy boundary; moisture tension at1/3 atm. 41.49%, 15 atm. 23.75%.

M2 2-17" Dark brown to brown (7. 5YR4/4) dry, dark brown (7. 5YR 3/2) moist; silty clay loam; moderate, medium subangular blocky structure breaking to moderate, fine to very fine subangular blocky; very hard, firm, very sticky, very plastic; many, very fine to fine, few, medium tubular and vesicular pores; abundant roots; pH 5. 7; gradual, wavy

boundary.

B 17-22" Reddish brown (5YR 4/4) dry, dark reddish brown 185 (5YR 3/2) moist; silty clay loam; moderate,medium to fine subangular blocky structure breaking tomoderately strong, fine to very fine subangular blocky; veryhard, firm, sticky, very plastic; common,fine tubular and vesicular pores; few roots; pH 5. 8; clear, wavy boundary.

R Below 22" Weathered bedrock.

Remarks: Over 75 percent of the solidmaterial below 17 inches composed of gravel-sized fragments.

Burgett Pasture "- TentativeSeries, Philomath All 0-3" Brown to dark brown (10YR4/3) dry, very dark grayish brown (10YR 3/2) moist; clay loam;weak to moderate, fine subangular blocky structure breaking tomoderate, fine crumb; very hard, firm, very sticky,plastic; few, very fine to medium tubular and vesicular pores;abundant roots; pH 6. 5; clear, smooth boundary.

Al2 3-7" Brown to dark brown (10YR4/3) dry, very dark grayish brown (10YR 3/2) moist; clay;moderate, medium subangular blocky structure breaking to moderate veryfine subangular blocky; very hard, firm, very sticky, veryplastic; common, very fine to mediumtubular and vesicular pores;abundant roots; pH 6. 2; clear, wavyboundary. 186

B 7-19" Dark brown (7. 5YR 3/2) dry and moist; clay; moderate to strong, medium subangular blocky structure breaking to moderate to strong, fine to very fine subangular blocky; very hard, firm, very sticky, very plastic; common, fine to very fine tubular and vesicular pores; occassional roots; pH 6. 1; clear smooth boundary; moisture tension at 1/3 atm. 36. 19 %, at 15 atm. 24, 10%.

R Weathered bedrock.

Remarks: Frequent gravel-sized fragments in the A horizons. Gravel composed over 60 percent of the B horizon, increasing with depth.

Grange Hill - Tentative Series, Dixonville All 0-2" Dark brown (7. 5YR 3/4) dry, dark brown (7. 5YR3/2) moist; clay loam; weak to moderate, medium to fine subangular blocky structure breaking to moderate, fine crumb; very hard, firm, very sticky, very plastic; few, veryfine to medium tubular and vesicular pores; abundant roots; pH 5. 6; abrupt, smooth boundary.

Al2 2-9" Brown to dark brown (10YR 4/3) dry, dark brown (7.5YR 3/2) moist; clay loam; weak, medium to fine prismatic structure breaking to moderate, very fine subangular blocky; very hard, firm, very sticky, very plastic; common, very fine to 187 fine, few, medium tubular and vesicular pores; abundant roots; pH 5. 4; clear, smooth boundary; moisture tension at 1/3 atm. 29.72%, at 14 atm. 24. 49%.

B 9-35" Reddish brown (5YR 4/3) dry, dark reddish brown (5YR 3/2) moist; clay; strong, coarse to medium block structure breaking to strong, fine to very fine subangular blocky; very hard, firm, very sticky, very plastic; few, fine to medium tubular and vesicular pores; few roots; pH 5. 6; clear smooth boundary.

C 35-40" Brown (7. 5YR 4/4) dry, dark brown (7. 5YR 3/2) moist; clay loam; massive structure; very hard, firm, very sticky, very plastic; few, fine to medium tubular and vesicular pores; very few roots; pH 5. 6; gradual smooth boundary.

R Weathered basalt.

Remarks: Sparce gravel up to 1 1/2 inches in diameter found throughout the profile.

Bald Hill A - Tentative Series, Philomath All 0-3" Dark grayish brown (10YR 4/2) dry, very dark gray (10YR 3/1) moist; clay loam; moderate, fine subangular blocky structure breaking to moderate, medium crumb; very hard, firm, sticky, plastic; few, very fine to medium tubular and 188 vesicular pores; abundant roots; pH 5. 8; clear, wavy boundary.

Al2 3-10" Dark grayish brown (10YR 4/2) dry, very dark gray (10YR 3/1) moist; clay; moderate, medium subangular blocky structure breaking to moderately strong, fine subangular blocky structure; very hard, firm, very sticky, very plastic; common, very fine to fine, few, medium tubular and vesicular pores; abundant roots; pH 5. 9; clear, wavy boundary; moisture tension at 1/3 atm. 32. 38%, 15 atm. 18. 35%.

B 10-16" Dark brown (10YR 3/3) dry, very dark brown (10YR 2/2) moist; clay; moderate, medium subangular blocky structure breaking to strong, fine subangular blocky; very hard, firm, very sticky, very plastic; many, very fine to fine, few, medium tubular and vesicular pores; occassional roots; pH 6.2; gradual, wavy boundary.

B-C 16-20" Dark brown (7. 5YR 3/2) dry and moist; clay loam; moderate, medium to fine subangular blocky breaking to moderately strong, fine to very fine subangular blocky; very hard, firm, very sticky, very plastic; common, very fine to fine, few medium tubular and vesicular pores; few roots; pH 6. 2; diffuse, smooth boundary.

R Below 20" Weathered bedrock. 189 Remarks: Few gravel above 16 inches depth, over 50 percent

below.

Bald Hill B - Tentative Series, Lithic Philomath All 0-2" Dark brown (10YR 3/3) dry, very dark brown (10YR 2/2) moist; silty clay loam; moderate, fine, subangular block structure breaking to moderate, medium, brumb; very hard, firm, sticky, plastic; few, very fine, and fine tubular and vesicular pores; abundant roots; pH 6. 1; abrupt, wavy boundary.

Al2 2-5" Dark brown (10YR 3/3) dry, very dark brown (10YR 2/2) moist; silty clay loam; moderate, medium subangular blocky structure breaking to strong, fine subangular blocky, very hard, firm, sticky, plastic; common, very fine to fine, few, medium tubular and vesicular pores; abundant roots; pH 5. 8; abrupt, wavy boundary; moisture tension at 1/3 atm. 41.28%, 15 atm. 23.95%.

B 5-11" Dark brown (10YR 3/3) dry, very dark brown (10YR 2/2) moist; clay; weak, medium prismatic structure breaking to moderate, medium subangular blocky; very hard, firm, very sticky, very plastic; many, very fine to fine, few, medium tubular and vesicular pores; few roots; pH 5. 7; abrupt, wavy boundary.

R Wedthered bedrock. 190

Remarks: Narrow tongues of clay were channeled down into R.

Bald Hill C - Tentative Series, Philomath All 0-2" Dark grayish brown (10YR 4/2) dry, very dark gray (10YR 3/1) moist; silty clay; moderate, fine subangular blocky structure breaking to moderate, very fine crumb; very hard, firm, sticky, plastic; few, very fine to medium tubular and vesicular pores; abundant roots; pH 5.8; abrupt, smooth boundary.

Al2 2-5" Dark grayish brown (10YR 4/2) dry, very dark gray (10YR 3/1) moist; clay; strong, fine subangular blocky structure breaking to moderate, very fine subangular blocky; very hard, firm, sticky, plastic; few, very fine to fine tubular and vesicular pores; abundant roots; pH 5. 7; abrupt, wavy boundary; moisture tension at 1/3 atm. 39. 19 %, 15 atm. 23. 41 %.

B 5-15" Dark grayish brown (10YR 4/2) dry, very dark gray (10YR 3/1) moist; clay; moderate, medium prismatic structure, breaking to moderate, medium subangular blocky; very hard, firm, very sticky, very plastic; common, very fine to fine tubular and vesicular pores; occassional roots; pH 5.8; clear, wavy boundary.

B-C 15-23" Dark brown (10YR 3/3) dry, very dark brown (10YR 191 2/2) moist; clay; moderate, coarse prismatic structure breaking to moderate, medium subangular blocky; very hard, firm, very sticky, very plastic; common, fine tubular and vesicular pores; few roots; pH 6.0; abrupt, wavy boundary.

R Below 23" Weathered bedrock.

Remarks: Manganese dioxide staining on bedrock fragments. A few gravel three inches in size.

Bald Hill D - Tentative Series, Dixonville All 0-2" Brown to dark brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; clay loam; moderate, fine subangular blocky structure breaking to moderate, fine crumb; very hard, firm, sticky, plastic; few, very fine to medium tubular and vesicular pores; abundant roots; pH 5. 9; abrupt, smooth boundary.

Al2 2-4" Dark grayish brown (10YR 4/2) dry, very dark gray (10YR 3/1) moist, clay loam; moderate, medium prismatic structure breaking to moderate, fine to medium subangular blocky; very hard, firm, sticky, plastic; few, very fine to medium tubular and vesicular pores; occassional roots; pH 5. 6; clear, wavy boundary; moisture tension at 1/3 atm.

33. 66%, 15 atm. 15. 78 %. 192

B 4-15" Dark brown (10YR 3/3) dry, very dark brown (10YR 2/2) moist; clay loam; moderate, coarse prismatic structure breaking to moderate, fine to medium subangular blocky; very hard, firm, very sticky, very plastic; common, very fine to medium tubular and vesicular pores; few roots; pH 5. 7; clear, wavy boundary; moisture tension at 1/3 atm. 33. 92 %, 15 atm.

16. 45%.

B-C 15-21" Brown to dark brown (7. 5YR 4/2) dry, dark brown (7. 5YR 3/2) moist; clay loam; weak, medium prismatic structure breaking to moderate, medium subangular blocky; very hard, firm, very sticky, very plastic; common, very fine to medium tubular and vesicular pores; very few roots; pH 5.7; gradual, wavy boundary.

C 21-28" Dark grayish brown (10YR 4/2) dry, very dark grayish brown (10YR 3/2) moist; clay loam; moderate, medium subangular blocky structure breaking to moderate, fine subangular blocky; very hard, firm, sticky, plastic; many very fine to medium tubular and vesicular pores; very few roots; pH 5, 8; clear, smooth boundary.

R Below 28!' Weathered bedrock. 193

Gray PastureTentative Series, Philomath All 0-3" Brown to dark brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; clay loam; moderate fine to very fine subangular blocky structure breaking to moderate, fine crumb; very hard, firm, sticky, plastic; few, very fine to fine tubular and vesicular pores; abundant roots; pH 5. 9; abrupt, smooth boundary.

B 3-13" Brown to dark brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; clay; moderate, medium subangular blocky structure breaking to moderate, fine subangular blocky; very hard, firm, very sticky, very plastic; common, fine to very fine tubular and vesicular pores; abundant roots; pH 5. 9; gradual wavy boundary; moisture tension at 1/3 atm. 41. 60%, 15 atm. 25.71%.

C 13-17" Brown (7. 5YR 4/3) dry, dark brown (7. 5YR 3/2) moist; clay loam; weak, fine subangular blocky structure breaking to moderate, very fine subangular blocky; very hard, firm, very sticky, very plastic; many, very fine to fine tubular and vesicular pores; few roots; pH 6.0; gradual, smooth boundary.

R Below 17" Weathered bedrock.

Remarks: Numerous small to large gravel throughout profile.Over 194

75 percent gravel below 13 inches depth.

Noble Pasture A - Tentative Series, Philomath All 0-2" Dark yellowish brown (10YR 4/4) dry, very dark grayish brown (10YR 3/2) moist; silty clay loam; weak, medium to fine platy structure breaking to moderate, very fine subangular blocky; very hard, firm, sticky, plastic; few, very fine to medium tubular and vesicular pores; abundant roots; pH 5.7; abrupt, smooth boundary.

Al2 2-8" Brown to dark brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; silty clay loam; weak, medium prismatic structure breaking to moderate, fine subangular blocky; very hard, firm, very sticky, very plastic; few, very fine to fine tubular and vesicular pores; abundant roots; pH 5. 5; abrupt, wavy boundary; moisture tension at 1/3 atm. 40. 34 %, 15 atm. 24.35%.

B 8-22" Brown to dark brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; clay; moderately strong, medium subangular blocky structure breaking to strong, very fine subangular blocky; very hard, firm, very sticky, very plastic; many, very fine, few, fine to medium tubular and vesicular pores; occassional roots; pH 6. 0; clear,smooth boundary; moisture tension at 1/3 atm. 41.71%, 15 atm. 27.27%. 195

R Below 22" Weathered bedrock

Remarks: Three percent fine gravel below two inches. Gravel layer at one foot, increasing to about 50 percent composition of solid material at 20 inches depth.

Noble Pasture B - Tentative Series, Philomath

A 0-2" Brown to dark brown (10YR 4/3) dry, very dark grayish brown (10YR 3/2) moist; silty clay loam; moderately strong, medium subangular blocky structure breaking to moderate, medium crumb; very hard, firm, very sticky, very plastic; few, very fine to fine tubular and vesicular pores; abundant roots; pH 5.7; clear, smooth boundary.

B 2-16" Very dark grayish brown (10YR 3/2) dry and moist; silty clay; moderately strong, medium subangular blocky structure breaking to moderately strong, medium to fine subangular blocky; very hard, firm, very sticky, very plastic; common, very fine to fine tubular and vesicular pores; abundant roots; pH 5.7; diffuse, wavy boundary; moisture tension at 1/3 atm. 37.82%, 15 atm. 24. 91 %. 196

B-C 16-27" Dark brown (7. 5YR 3/2) dry and moist; silty clay loam; moderately strong, medium subangular blocky structure breaking to moderately strong, medium to fine subangular blocky; very hard, firm, very sticky, very plastic; few, fine to medium tubular and vesicular pores; few rootsr pH 6.0; diffuse, wavy boundary.

R Weathered bedrock.

Remarks: The profile is composed of over 50 percent gravel below two inches, increasing with depth.

Noble C - Tentative Series, Dixonville All 0-5" Dark grayish brown (10YR 4/2) dry, very dark gray (10YR 3/1) moist; clay loam; moderate, medium subangular blocky structure breaking to moderately strong, medium crumb; very hard, firm, very sticky, very plastic; few, fine to medium tubular and vesicular pores; abundant roots; pH 5. 4; clear, smooth boundary.

Alt 5-18" Dark brown (10YR 2/3) dry, very dark brown (10YR 2/2) moist; clay loam; moderate, medium to fine subangular blocky breaking to moderately strong, fine to very fine subangular blocky; very hard, firm, very sticky, very plastic; common, very fine to fine, few, medium tubular andvesicular 197

pores; abundant roots; pH 5.4; gradual, wavy boundary; moisture tension at 1/3 atm. 32.86%, 15 atm.21.59%.

B 18-28" Brown to dark brown (7. 5YR4/2) dry, dark brown (7. 5YR 3/2) moist; clay loam; moderate, mediumto fine subangular blocky structure breaking to moderate,fine to very fine subangular blocky; very hard, firm,sticky, plastic; few, very fine to fine tubular andvesicular pores; few roots; pH 5.7; gradual, smooth boundary.

B-C 28-30" Dark yellowish brown (10YR4/4) dry, dark brown (10YR 3/3) moist; clay loam; moderate, medium tofine subangular blocky structure breaking tomoderate, fine subangular blocky; very hard, firm, very sticky, veryplastic; few fine to medium tubular and vesicular pores;few roots; pH 5. 9; gradual, smooth boundary.

R Below 30" Weathered bedrock.

Remarks: About 20 percent of the profilevolume composed of gravel- sized fragments to a depth of 18inches. 198

Appendix F.Analysis of Variance for medusahead frequencies at the Hill Pasture site.

Plot Size Source of Variation 22-inch 62-inch 12-foot Blocks ** ** Treatments ** ** ** Blocks X Treatments ** ** ** Y ears ** ** ** Years X Treatments ** ** ** Years X Blocks NS NS Years X Treatments X Blocks

Significant difference at P = .05 **Significant difference at P = .01 NS No significant difference 199

Appendix G.Analysis of Variance for California oatgrass frequencies at the Hill Pasture site.

Plot Size Source of Variation 22- inch 62- inch 12-foot Blocks ** ** ** Treatments NS NS Blocks X Treatments NS NS NS Years ** ** Years X Treatments ** NS NS Years X Blocks NS NS NS Years X Treatments X Blocks ** **

Significant difference at P = .05 **Significant difference at P = .01 NS No significant difference