Environmental Cues in the Seasonal Development of the Southern California Annual Grassland

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6-1978

George E. Johnson

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Recommended Citation Johnson, George E., "Environmental Cues in the Seasonal Development of the Southern California Annual Grassland" (1978). Loma Linda University Electronic Theses, Dissertations & Projects. 634. https://scholarsrepository.llu.edu/etd/634

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ENVIRONMENTAL CUES IN THE SEASONAL DEVELOPMENT OF

THE SOUTHERN CALIFORNIA ANNUAL GRASSLAND

by George E. Johnston

Annual grasslands characteristically experience a succession of seasonal phases which provide for the coexistence of various species by allowing them to make their major demands upon environmental resources at different times. Thus, an ecosystem furnishing certain resources at a limited rate is enabled to support a larger total biomass.

The grasslands of southern California consist principally of annual grasses coexisting with the few remaining native perennial grasses.

Characteristic also is the inclusion of forbs which are distinctly either early spring or late summer plants. Many spring forbs, annual grasses, and summer forbs are observed to germinate in approximAte unison shortly after the first winter rains. In spring, however, differing individual responses to environmental opportunities and stresses segregate these species along a time gradient. The effect is that the grassland then passes successively through a spring phase dominated by filaree (Erodium spp., Geraniaceae), an intermediate phase dominated by annual grasses (e.g. Avena spp., Poaceae), and a summer phase characterized by tarweed (iloll4marpha spp., Hemizonia spp., Asteraceae).

A problem of intense interest to plant ecologists is the means by which this segregation into phases is accomplished. If segregation is achieved independently of environmental influences, then what are the mechanisms? If not, then which environmental factors serve as cues indicating to each species when its time for action has come?

To determine the value of specific environmental factors in segre-

gating annual grassland plants along a time gradient, representative

species were studied in field and controlled-environment conditions.

Growth of the plant species in field plots was observed over a three-

year period, and the individual and collective patterns characterized and quantitatively described. Climatic and microenvironmental factors were simultaneously monitored and then correlated with plant growth.

Effects of intra- and inter-specific competition were examined by sowing all possible combinations of the three species into sterilized soil of field plots, each combination repeated in three different densities.

Effects of temperature, daylength, and soil moisture tension were determined by analyzing development of the species grown in controlled environmental conditions.

The fundamental contributions of this study appear to fall naturally into two groupings. First, temporal phase segregation of representative species in the southern California grassland is quantitatively and graphically described. We believe this description is long overdue.

Second, controlled-environment laboratory experiments, examining hypotheses suggested by field correlation studies, indicate that filaree, slender oat, and tarweed are segregated along a temporal gradient by their differing individual responses to particular combinations of temperature, dayiength, and soil moisture tension.

Bearing in mind the fact that results obtained in controlled environments are not directly transposable to the field, where a multitude of possibly unrecognized factors may be effective, certain limited

2 conclusions appear to be warranted by the present study. Phenologic

advancement of filaree appears to be favored by lower temperatures,

shorter days and higher soil moisture tension. Slender oat is advanced

more rapidly by moderate temperatures and soil moisture tension, and

by long days. Tarweed shows marked advancement at higher temperatures

and longer days, when soil moisture tensions are moderate.

Statistical correlation of seasonal growth or phenological develop-

ment with local environmental factors, although intuitively appealing,

is of little use in determining causal relationships. One .reason is

that the dependent variable (plant growth or phenology) is an expression

of physiological processes that may not be the same from time to time

throughout the season. Also, the questionable assumption is made that

successive phenological events are independent. For these reasons,

correlative results obtained from limited ecological studies are most

profitably used only to suggest hypotheses for subsequent experimental testing.

Intra-specific and inter-specific competition, while slightly

affecting individual species' development, are not significantly

important in temporal phase segregation of southern California annual

grassland species. But if these factors are not gignificant, others

exist which definitely are. This study indicates that the time a

southern California grassland species spends in the vegetative stage is

not an inherent constant. Rather, it is determined by the individual

species' physiological and phenological responses to the quantitive

availability of water, heat and light. It is the synergy of individual

responses which accomplishes the temporal segregation described by this study. 3 T LOMA LINDA UNIVERSIY Graduate School

ENVIRONMENTAL CUES IN THE SEASONAL DEVELOPMENT OF THE SOUTHERN CALIFORNIA ANNUAL GRASSLAND by

George E. Johnston

A Dissertation in Partial Fulfillment of .the Requirements for the

Degree Doctor of Philosophy in.the Field of Biology

June 1978, · Each person whose signature appears below certifies' that. this. dissertation in his opinion is adequate,.. in scope and quality, -as. a diSsertat. ion for the .degree Doctor' of. Philosophy.

Si, 'NI ir '4117 4 ab , Chairman Earl W. Lathrop, AssocIlre Professor of Biology

Leonard R. Brand, Associate Professor Biology

Conrad D. Clausen, Assistant Professor o Biology

Norman L. Mitchell, sociate Professor of Biology

Paul Y. 'I Associate Professor of Biostatist cs/Epidemiology

ii ACKNOWLEDGEMENTS

The author takes this opportunity to express his sincere appreci-

ation for guidance, support and counsel received from many unselfish

individuals. A tremendous debt of gratitude is owed to Dr. Earl W.

Lathrop, major professor and chairman of the guidance committee. His

unflagging interest and continual support have been of inestimable

value. He has been, and remains, more than a counsellor. He is a

friend.

Special recognition is due also to the other members of the guidance

• committee, Drs. Leonard R. Brand, Conrad D. Clausen, Norman L. Mitchell

and Paul Y. Yahiku. They have contributed selflessly of their time,

talent and expertise. Arthur Chadwick, Berney Neufeld and Bill Hughes

have contributed valuable thoughts concerning philosophy, experimental

design and procedure. Elmer Widmer has offered many helpful suggestions

during preparation of the manuscript. John Rosario has furnished

encouragement, helpful discussion of technique, and hours of physical

assistance in the field.

Pat Johnston, the author's wife and continual joy, has supplied

constant confidence and support on the home front, and has endured many

frustrating hours in typing the manuscript.

The study was supported in part by Loma Linda University Graduate

Fellowships and Loma Linda University Graduate Research Grants #06-82-30

and #06-82-202. Computational support was provided by Loma Linda

University Scientific Computational Facility, supported in part by NIH

grant ffRR00276. Statistical consultation was provided by Dr. Paul Yahiku

and the Department of Biostatistics, School of Health, ,Loma Linda

University. Table of Contents

Page Introduction

The California Annual Grassland . • • • • • • • • • • • II •

Historical Background • • • • • • • • • • • • • • • • • • •

Ecological Importance • • • • • • • . • . • • . • • • • . . 17

Recent Approaches • . • . • • • . • • . • • • • • . 19

• Description of the Present Study • • • . . ••• •,.... . 22. The Study Area

Location and Topography . . . • . • • • • • • • . • • • • . . 24. Geology and Soils . • . • . • • • • ••• • ••• • • . . . . . 24

Climate .• . • • . • . • . • . • . • • • • • • • . • . . . . . 29

Vegetation .• . •• • • . • . . . . • . • • • . • • . • . . • • 31

• History . • •.* • • • • •..6 . • • • • • ...... 32 Methods and Materials

• Field Observations • • • • • • • • 0 • • • • 111. • • • • • 0 s. 33

The Manipulated-Association Experiments . . . . . • • • . . . 36

The Controlled-Environment Experiments • . • • • • • . • . . 37 Results and Discussion

Field Growth and Phenology . •. • . . . • . . • • • • . . . 56

Relation to Environmental Factors . .•.••• . .. • • . . 72

Rainfall . • • • • • . • • • • • • • • • • • • • • • 72.

Soil Moisture . . . • . . •0 ...... 76

- Temperature of Air and Soil • • • . • . • • • • ••• 77

Daylength • • • • • • • • • • . • • • • • . . 78

Page Manipulate&-Association Experiments . . • • • • • • • • • . . . 79

Effects of Species Combinations • . • • . • • • . 0 • . • Effects of Density ...... • • • • . • • • • • • •

Competition as a Cause of Phase Segregation • • • ...... 87009 Controlled-Environment Experiments . . . . • • • • . • • . . . 84

Filaree ••...••••••••.•••••••• •

Slender Oat . • • • • • • ...... • • • . • • • 0 . : ::

Tarweed . . . • • • • • • . • . • • . . . • • . • • . . 85

Environmental Stress and Phenological Development . . . . 90

Conclusions • • • . • • • • • • • • • • • • • . 91

Literature Cited • • • • . • • • • . • • • • . • • . 93

• W • • Appendixes . • • 4 O. • • 0 • • • • • 4 • • 4 • • • .100

Appendix I: Rainfall, Soil Moisture and Soil Temperature,

1974-1977 . . . • • • . • • . • • • • . . 101 Appendix II: Maximum, Minimum and Mean Daily Air

Temperatures, 1974-1977 •••••••. . . . 107 Appendix III: Daily Duration at High and Low Air Tempera-

tures and Relative Humidities, 1974-1977 . 113 Appendix IV: Daylength, Maximum and Minimum Daily

Relative Humidities, 1974-1977 . . . • . . . 119 Appendix V: Elongation of Filaree, Slender Oat and

Tarweed in the Field, 1974-1975 ...... 125 Appendix VI: Elongation of Filaree, Slender Oat and

Tarweed in the Field, 1975-1976 . 0 4 0 • • • 127 Page

Appendix VII: Phenologic Stage of Filaree Growing in

Eighteen Controlled-Environment Treatments . . 130

Appendix VIII: Phenologic Stage of Slender Oat Growing in

• Eighteen Controlled-Environment Treatments . . 136

Appendix IX: Phenologic Stage of Tarweed Growing in

Eighteen Controlled-Environment Treatments . . 143

Appendix X: Phenologic Stage of Filaree Growing in

Twelve Manipulated-Association Treatments . 147

Appendix XI: • Phenologic Stage of Slender Oat Growing in

Twelve Manipulated-Association Treatments . 152

Appendix XII: • Phenologic Stage of Tarweed Growing in Twelve

Manipulated-Association Treatments . . . . 156

v4. List of Figures

Page Figure 1 Distribution of the California Annual Type . . • • • • . 3

Figure 2 Herbage Production in the California Annual Grassland . . 8

Figure 3 Typical California Annual Grassland . . • • . . • . • . . 10

Figure 4 Plant Succession in the California Annual Grassland . . . 12

Figure 5 Comparison of Hythergraphs of the California Annual

Grassland and of Great Plains Grasslands . . • • . . . . 14

Figure 6 Location Map of the Santa Rosa Plateau . . . • • • . . . 26

Figure 7 A Mesa Typical of the Santa Rosa Plateau • • . • • • . . 28

Figure 8 The Study Site on Mesa de Colorado . • • . . • • . . . 41

Figure 9 Measuring Elongation of Plants at the Study Site • • . .43 Figure 10 Schematic Plot Plan of the Study Site . . . . • -• . • . . 45

Figure 11 Study Plots Tilled and Planted . . . • . • • • • • • . . 47 Figure 12 Spectral Distribution of Light at the Study Site and

in the Controlled-Environment Rooms . • . • . . . . . • • 49 Figure 13 Experimental Design of Manipulated-Association and

Controlled-Environment Experiments . • • . . • • • • . . 51

Figure 14 Schematic Representation of Soil Column Construction . . 53

Figure 15 Plants Growing at the Top of Soil Columns . . . • . . . . 55 Figure 16 Vegetative Elongation and Phenological Development of

Plants in the Field, 1975-1976 . • • • • . • . • • 59 Figure 17 Rainfall, Soil Moisture, Soil Temperature, Air

Temperature and Daylength Monitored during the 1975-1976

Season ..•. • ..••.•••.••. • • . • • . . 61 Figure 18 Ranges of Air Temperature and Relative Humidity

Monitored During the 1975-1976 Season . . . • • • . • . . 63

vii Page Figure 19 Accumulated Rainfall, 1974-1977 . S • . . . . 65 Figure 20 Variations in Soil Moisture, 1975-1977 . . • • • . 67

Figure 21 Soil Moisture Retention Characteristic of Soil . . . 69 Figure 22 Soil Moisture Block/Meter Calibration Curves . • • . 71 Figure 23 Phenological Response of FI,laree, Slender Oat and

Tarweed to Environmental Treatments . • • • . 87

viii List of Tables

Page

Table 1 Important Plant Species Commonly Present in the

California Annual Grassland . . •fr . • • • • • • • • . • • . 6

Table 2 Statistical Correlation of Mean Elongation Rate of

Species With Selected Environmental Factors, 1975-1976 . . 73

Table 3 Monthly Distribution of Rainfall, 1974-1977 .

Table 4 Analysis of Phenologic Stage at Given Date for Filaree

in Manipulated Associations • • • • . • • • . • . . . . . 81

Table 5 Analysis of Phenologic Stage at Given Date for Slender

Oat in Manipulated Associations . • • • • • • • . . 82

Table 6 Analysis of Phenologic Stage at Given Date for Tarweed

in Manipulated Associations . • • • • • • • • • • • • . . 83

Table 7 Statistical Correlation Between Phenologic Stage and Days Since Germination for Plants in Environmental

Treatments • . • . • . . • . ▪ • - ...... 88

Table 8 Number of Days to Anthesis for Plants in Environmental

Treatments • • • . • • • . . . • . ▪ • . . • . . 89

ix INTRODUCTION

THE CALIFORNIA ANNUAL GRASSLAND

The grassland ecosystem of California is an intriguingly complex plant community composed of wide expanses of treeless grassland in some areas, and forming the ground cover under open woodlands in others.

Currently termed the California grassland, and subdivided into the

Northern Coastal Prairie, the Great Central and Coast Range Valley

Grassland, and the Southern California Grassland (Thorne, 1976), this community has been variously referred to as Coastal Prairie and Valley

Grassland (Munz and Keck, 1959), California Prairie, .Central Valley

Prairie and North Coastal Prairie (Bul7clum, 1957), the California annual type (Talbot et al., 1939; Heady, 1958), and the California annual-grass type (Heady, 1956). These grasslands form a vegetation type unique in North America: a distinct and extensive community con- sisting largely of introduced and native annual species (Biswell, 1956).

L. T. Burcham (1975) points out that the essential unity of this ecosystem is attested by its distinctive climatic features and physiographic similarity throughout.; Wad by the dominantly herbaceous annual life form of its vegetation, as well as the physiological and phenological responses of the vegetation to factors of the environment.

Occupying most of the untilled plains of the Central Valley of

California and adjacent foothills of the Sierra Nevada and Coast Ranges, the California annual grassland extends into both the north and south

Coast Ranges (Talbot, et al., 1939) and covers disjunct areas south through the Peninsular Ranges (Fig. 1). It extends through about 8 1/2°

1 2

Figure 1 Distribution of the California annual type (From Talbot et al., 1939; Biswell, 1956; Heady, 1956; &Naughton, 1968). Included are the annual grassland proper, as well as areas of woodland and chaparral in which grassland species constitute the dominant ground story cover. Not • included are desert areas which may include many annual species, but which resemble more closely the vegetation of Great Basin areas. 3 of latitude north and south, and across 50 longitude from east to west

(Burcham, 1975), and has been estimated to cover as much as 10,000,000 hectares of California rangeland (Talbot et al., 1939). Occurring in a variety of physiographic situations, the California annual grassland is found on open plains, low, rolling hills, valley floors, plateaus and mesa tops and gentle slopes, usually below 1220 meters but extending up to 1830 meters elevation (Burcham, 1975; Thorne, 1976), (Fig. 3).

Certainly the distinguishing characteristic of the California grassland is the overwhelming dominance of native and introduced annual herbaceous species. Talbot, Biswell and Hormay (1939), in their classic study of fluctuation in the California annual type, point out that annuals comprise 94% of the herbaceous cover in grassland areas, 98% in the woodland, and 93% in the more open chaparral. They also bring out the impressive fact that introduced species, which are predominantly annuals, constitute 63% in the grassland, 66% in the woodland, and 54% in the chaparral. Robbins (1940, 1951) indicates that nearly 400 alien species now associate naturally in the California annual type.

In spite of the encroachment of alien annuals, native perennials are still present in association with the newcomers (Table 1). Most important among the perennial grasses are species of Stipa, Poa, Melica,

Elymus and Danthonia. Annual grasses include the native Pestuca megalura as well as alien species of Bromus Avena, Festuca, Hordeum and

Vulpia. Associated with the grasses are many forbs,- including natives such as the tarweeds (Nadia, Hemizonia, Holocarpha) and such aliens as

Erodium spp., Brassica and Nedicago (Talbot et al., 1939; Biswell, 1956;

Heady, 1956; Burcham, 1957, 1975; Thorne, 1976). To a casual observer, the vegetation of the California annual type may appear quite uniform.

It is, however, extremely diverse and exhibits severe fluctuations in

composition and dominance both through the growing season and from year

to year (Talbot et al., 1939; Heady, 1956, 1958; Biswell, 1956;

McNaughton, 1968).

Another characteristic of the California grassland is its distinctive pattern of annual development. Many annual species, including both grasses and forbs, are observed to germinate shortly after the first effective fall rains. After a period of moderate growth, development slaws, producing very little growth during the winter months (Fig. 2).

In early spring, growth resumes, with the effect that certain species elongate suddenly and seem to dominate for a short time, only to die and relinquish their place to other, later-maturing species (Burcham, 1957,

1975; Biswell, 1956; Heady, 1958; Duncan, 1975). Thus, from early spring through mid-summer a succession of phases predominate in turn, each produced as a physiological and phenological response to factors of the environment.

HISTORICAL BACKGROUND

The pristine condition of California's grassland is still debated.

Although most investigators believe that the prehistoric vegetation was perennial (gunz and Keck, 1949; Thorne, 1976; Burcham, 1957, 1975), historical evidence is not overwhelming. Biswell (1956) points out that there are hundreds of native annuals in the California grassland as well as numerous perennial grasses, with the obvious implication that both annuals and perennial grasses could have been displaced by the invaders in varying degrees in different areas. Perennial grasses may have been Table 1: Important plant species commonly present in the California annual grassland.

Annual Perennial Native Alien

Grasses

Purple needlegrass, Stipa pulchra Pine bluegrass, Poa scabrella Creeping wildrye, Elymus triticoides Mane grass, Melica californica California oatgrass, Danthonia californica Squirrel grass, Sitanion hystrix Soft chess, Bromis mollis Ripgut grass, Bromis riidus Foxtail brome, Bromis rubens Slender oat, Avena barbata Wild oat, Avena fatua Common foxtail, Horde= Ilystrix Foxtail fescue, Festuca meipalura Common ryegrass, Lolium multiflorum

Forbsl

Broadleaf filaree, Erodium botrys x x Red-stem filaree, Erodium cicutarium x x Bur clover, Medicago hispida x x Annual clovers, Trifolium spp x x Napa thistle, Centaurea melitensis x x Tarweed, Hemizonia spp. x x Spanish clover, Lotus americanus x x Annual lupines, Lupinus spp. x x

Shrubs and Trees

Blue oak, Quercus douglasii x x Interior live oak, Quercus wislizenii x x Valley oak, Quercus lobata x x Buckeye, Aesculus californica x x Digger pine, Pinus sabiniana x x Ceano thus, Ceano thus cuneatus x x Poison oak, Rhus diversiloba x x Buckthorn, Rhamnus crocea x x Manzanita, ArctostaPhVlos spp. Chamise, Adenostoma fasciculatum x - x

1/ Forbs: herbaceous plants other than grasses.

Figure 2 Production of aboveground herbage biomass at the San Joaquin experimental range in the California annual grassland. Data are values for ungrazed areas averaged for 1973 and 1974. From a preliminary report by Duncan (1975). 500,

100 as o 0.merosomsommemera.4e. w w

J A A

Figure 3 Typical California annual grassland bordering oak woodland and chaparral on rolling hills and mesa tops in southern California. 10

Figure 4 Four stages of plant succession in the California annual grassland as recognized and modeled by Burcham (1957, 1975). Indicated are some of the important species characteristic of each successional stage. wild barleys foxtail brome medusahead hare barley nit grass barb qoatgrass black mustard broad-leaf filaree virgate tdrweed dogtail grass 1 wild oat red-stem filaree purple falsebrome slender oat

I J 1800 1825 1850 1875 1900 1925 1950 1975 13

Figure 5 A comparison of the composite hythergraph for the California annual grassland with those of Great Plains grasslands (from Burcham, 1975). The disinctiveness of the climate prevailing over the California annual grassland is evident, with its higher winter temperatures and extremely rare summer rainfall. 14

301- summer

California

Short Grass

I g I S I I • • 1 4 6 8 10 12 14 16 18 20 Mean Monthly Rainfall (cm.) 15 the decreasers nearer the coast, where climatic conditions had favored

perennial col6tunities, while native annuals were being replaced on

the inland slopes. Biswell also points out that protection from burn-

ing actually favors the establishment of annuals while frequent burning

favors the maintainance of purple needlegrass (S_tipa pulchra), one

of the "indicators" remnant of perennial dominance in California. A

,Stip47dominated grassland in California, then, would' appear to require -

repeated burning, possibly by the prehistoric Indian inhabitants. White

(1966) found that 29 years of protection from grazing and fire in some

Central California grasslands resulted in no measurable reversion to

perennial dominance, but resulted rather. in a community still dominated

by Bx.omus, Avena, and Erp4um. McNaughton (1968) observes that the present annual grassland is probably more similar. than the Original prairies to the vegetation that would result from theelimination of

disturbance.

The historical development of the grassland in California has been

described in detail by L. T. Burcham (1957). This sane author also recognizes four distinct phases in this development from the first settlement by Europeans to. the present (Burcham, 1961, 1975). The first of these phases began with the establishment of the Spanish missions, starting in 1769 and eventually covering as much as one-sixth of the total area of the state with their associated ranch lands. It was during this mission period, 1769-1824, that such important alien species as wild oats (Altana), bur clover (Medicago) and Napa thistle (Cent aurea) were

.introduced (Robbins,. 1940). Examinations of plant remains in the adobe of the earliest mission walls have indicated that three species-- 16 red-stem filaree (Emit= cicutarium), curly dock (Rumex crispus) and

prickly sow thistle (Slanchus asper) -- probably preceded the arrival of

the permanent colonists (Hendry and Bellue, 1925), possibly arriving in

the baggage or on the animals accompanying the first explorers. By 1833

large tracts of valley grassland were already covered by dense stands of

wild oats (Leonard, 1834) a condition reminiscent of the almost

immediate establishment of wild oats (Avena fatua and A. barbata) across

large expanses of North America (Baum, 1968) after its introduction by European explorers and colonists.

The second phase consisted of the ranching activities of the

Mexican ranchos, which succeeded the mission ranches after Mexican

independence from Spain and the secularization of the mission lands.

Lasting from the mid-1830's until about 1850, this phase then graded

into the third--the early American ranches. The sudden great demand for

livestock products created by the discovery of gold and the accompanying

rapid development of commercial centers in Central and Northern Calif-

ornia led to explosive expansion of ranching throughout the state. It

was during this period, which lasted until about 1865, that overgrazing

and drought devastated the plant community, allowing the permanent

establishment of the majority of alien opportunist species (Burcham, 1975).

The fourth stage, the process and effects of which are still evident

today, is the period of adjustment to the tiansition from open range ranching to organized agriculture. As the level valley areas of the

grassland came under the plow and the reaper, open range land disappeared and the ranching operations moved toward the upper margins of the 17 grasslands. There they have stabilized, with grazing concentrated in

the foothill and plateau grasslands and the adjacent woodlands.

It has been repeatedly pointed out that the impact of grazing,

agriculture, and urban development pushes the grassland along a directed

course of plant succession (Burcham, 1975; Talbot, et al., 1939; Biswell,

1956; Thorne, 1976; Heady, 1956). Burcham's studies (1957) have even

led him to suggest a succession of dominant plant communities running

in series from 1800 to the present (Fig. 4).

ECOLOGICAL IMPORTANCE

Of abiding interest to ecologists is the way in which native perennial and annual species, and alien annual species from widely separated parts of the world, thrawn together in the California grassland, have established a unified ecosystem' of their own within such a short time. Talbot, Biswell and Hormay (1939) noted that this

"delicately balanced" vegetation is susceptible to rapid change in response to variations in the environment. Guerrero and Williams (1975) point out more recently that a proper balance of various annual species serves as a buffer against disastrous production losses in years of extreme environmental effects. Thoro.ugh tudies of the fluctuation characteristic of this annual vegetation have shown I that changes through the year and from year to year in the California grassland are as contrasting as successional stages in many other vegetation types (Heady, 1958).

S. J. McNaughton (1968), in his study of structure and function in the grassland of the San Francisco peninsula, found that dominance and diversity are inversely related, and that increased dominance generates 18 increased productivity. MhNaughton also compared this grassland ecosystem to the general ecological model proposed by Margalef (1958). This model holds that diversity generates community stability, and that this stability is obtained at the cost of productivity. In the grassland, however,

MeNaughton found no relationship tying stability to productivity, dominance or diversity.

One of the imposing ecological characters of the California grassland is the direct control of seasonal development on a host of species by environmental factors. Because of the mismatch between times when water is sufficiently available and the times temperatures are conducive

(Burcham, 1975), a situation exists where moisture is often limiting when temperatures are conducive, and temperatures are limiting when soil water Is readily available (Menke and Williams, 1975, Fig. 5).

Major (1963) has observed that growth in the grasslands of California is limited first by insufficient moisture and then by low temperatures in the fall and winter, by low temperatures in the winter and spring, and by soil drought in the summer. An examination of the relationship of southern California grassland species to precipitation and temperature has found that dominant species are certainly limited by these factors, and suggests that sub-dominants may be limited by competition for light as well (aufstader, 1976).

Another important ecological consideration is alluded to by Duncan

(1975) in reference to production studies in the annual grassland of the

San Joaquin Experimental Range. A distinct segregation of spring annuals

(e.g. Bromus, Festuca, Erodium, Trifolium) and summer annuals (Hemizonia) is apparent, with development of the early-maturing species finishing 19 abruptly as soil moisture declines, and development of the late-maturing

tarweeds continuing through the summer. In an ecosystem where physical

and biotic aspects of niches are likely to overlap, segregation of species

along a time gradient according to their individual responses to environ-

mental opportunities and stresses provides a temporal niche refuge. A

succession of phases, in which the ecosystem is dominated first by spring

forbs (herbaceous plants other than grasses), then by annual grasses, and

finally by summer annuals, provides for the coexistence of the various

species by allowing them to make their major demands on environmental

resources at different times. In this way, an ecosystem which furnishes

certain resources at a limited rate is enabled to support greater total production.

RECENT APPROACHES

Waring and Major (1964) distinguish between two long-standing

fundamental approaches to plant ecology problems: the correlative

approach and the operational approach. This distinction does not imply

mutual exclusion, as the areas of application of the two approaches ofte

overlap. It should be noted also that a complete understanding of most

ecological problems usually requires, at one stage or another, the

application of each of the approaches. The correlative approach,

assuming some type of correlation between measurable habitat factors and

plant responses, has the convenience of using environmental factors as the independent, and plant responses as the dependent, variables (Major,

1951), Another advantage is that commonly available environmental observations (e.g. weather records) may be used to obtain the data for the independent variable. Also, troublesom consideration of cause and 20

effect mechanisms is avoided (Major, 1958, 1961). The main drawback,

however, is the dissatisfaction generated by not being able to pursue

these mechanisms, to establish a cause once an effect is known.

The operational approach, on the other hand, considers only the

effective factors of the environment, those forming the operational

environment of the plant Masan and Langenheim, 1957). The tolerance

ranges of individual species to variations in particular environmental

factors are studied, usually employing an experimental approach in which

certain elements of the environment are controlled. Once physiological

and phenologial responses are established for individual species, then

descriptions of structure and function within an ecosystem are attempted

for a determined group of species affected by a defined set of environ-

mental factors.

Another approach recently receiving heavy emphasis in ecosystems

research is gradient analysis. According to Whittaker (1969, 1972), the

displacement of species along environmental gradients is a necessary

result of competitive interaction. Analysis of species' response to

gradients of given environmental parameters, then, should give an indica-

tion of the individual species' relative probability of success when

. meeting these parameters in natural associations with other species..

Waring and Major (1964) used an operational approach to position individual species of the redwood region of California along environmental gradients of soil moisture, nutrients, light and temperature. Response to seasonal (temporal) and microtopographic gradients have been described for herbaceous understory species in the Great Smoky Mountains of

- Tennessee. (Br4tton, 1976), and the divergence of two .successional annuals 21 in response to a soil moisture gradient has been demonstrated for old- field succession in Illinois (Pickett and Bazzaz, 1976). Gradients examined in relation to• plant response may be totally environmental, temporal, or even successional.

A theoretical notion recently examined by plant ecologists concerns the relationship of the demographic parameters of a population to its ecological niche. Currently approached in the framework of r- and K- selection, this relationship has been pursued recently by experiments both in the laboratory and in the field. The fundamental premise of r- and 1(7-selection is that r-strategists, which live in environments imposing high density-independent mortality will be selectively favored to allocate a greater proportion of resources to reproduction, while

K-strategists, which live in environments imposing high density-dependent regulation will be selectively favored to allocate a greater proportion of resources to non-reproductive activities (Gadgil and Solbrig, 1972).

In one study of the effects of environmental factors dn determining resource allocation it was concluded that reproductive allocation in the annual forb Polygonum cascadense was environmentally cued (Hickman,

1975). Roos and Quinn (1977) have found in field and greenhouse studies that significant differences in phenology and reproductive effort of

AndroTogon scoparius were attributable to local environmental factors.

Mott and McComb (1975b), on the other hand, examining the effects of moisture stress on phenology and reproduction of certain arid region annuals, found no evidence to suggest that these species advance more rapidly to a reproductive stage under stress.

The current trend in ecological examination of grassland ecosystems 22

seems to be away from community description and classification. Reliance

upon floristic results enables one only to say that communities are

similar or different (HcNaughton, 1968). This type of conclusion, which

says nothing about function in the ecosystem, is no longer satisfying to many ecologists. The major interest today is in the area of function

and process--energy flow, production flux, interrelationships between producers, consumers and micro-environmental factors Menke and Williams,

1975). The emphasis currently is strongest on examining annual grassland

communities to discover the mechanisms of their function under the influence of the biotic and abiotic components of the environment.

DESCRIPTION OF THE PRESENT STUDY

Physiological and phenological responses to environmental influences in the southern California grassland resemble those described for the

California annual grassland as a whole. Annual species germinate together in the fall, grow very little Over winter, then are segregated in time during the rapid growth in spring (Talbot et al., 1939; Biswell,

1956; Burcham, 1957; Heady, 1958; Major, 1963; Duncan, 1975). The importance of this segregaiion into dominance phases can hardly be overestimated, since it is by this means that coexistence of many species is assured by spreading their individual demands across a time gradient.

A problem of intense interest to plant ecologists is the meameans by which this segregation into phases is accomplished. Is it possible that it operates inherently, independent of environmental influences? If so, then what are the mechanisms? If not, then which environmental factors serve as cues indicating to each species when its time for action has come? Is a different factor or combination of factors involved for 23 each species, or do all respond to the same factors differently?

The objective of this study is to determine what value specific environmental factors have in the segregation of southern California grassland species along a time gradient.

The study is approached in four stages. First, growth and phenologic development of several grassland species are observed throughout the season in the field, while simultaneously monitoring pertinent environmental and micro-environmental factors. Second, field growth and phenology observations are correlated with the observed environmental factors. Third, influences of community composition are experimentally tested under field conditions. And fourth, effects of abiotic environmental factors are experimentally tested under controlled-environment conditions. THE STUDY AREA

LOCATION AND TOPOGRAPHY

The site chosen for environmental observations and plant growth experiments under field conditions was located near the center of Mesa de Colorado, Riverside County, California (Fig. 6). One of several similar flat-topped topographic features characteristic of this area, the mesa is a part of the Santa Rosa Plateau region of the Santa Ana

Mountains, the northernmost extension of the Peninsular Ranges in southern California (Pequegnat, 1951; Lathrop and Thorne, 1968, 1978).

This plateau, bounded on the North and East by the agricultural valleys of Marietta and Temecula, on .the South by Temecula Canyon and the

Santa Margarita River, and on the West by the higher slopes of the Santa

Ana Mountains, consists of some 18,100 hectares (Lathrop and Thorne, 1968) of broad valleys and low hills, dissected by canyons with intermittent streams and studded with steep-sided mesas (Zuill, 1967). Located about

30 km. (18.6 mi.) due east from the Pacific Coast at 33030'20" N. latitude and 117017'10" W. longitude, the study site is situated at an elevation of 625 m. (U.S.G.S. 1953), (Fig. 7).

GEOLOGY AND SOILS

Early descriptions of the Santa Ana Mountains suggest a basement complex of metamorphosed and partly metamorphosed Triassic limestones with granitic intrusives (Packard, 1916; Mendenhall, 1912; English, 1926).

This complex, with its mesozoic granite concentrated in upper layers, is overlain by local deposits of Jurassic marine shales. Subsequently elevated along the Elsinore fault system and tilted southwestward, the

24 25

Figure 6 Location map of the Santa Rosa Plateau in the Santa Ana Mountains of southern California. 26

San Francisco •• •

Figure 7 A mesa typical of the Santa Rosa Plateau, covered on its top by southern California annual grassland, on its rim and near certain rocky outcrops by oak woodland, and on its steep side slopes by chamisal. 28 29 complex forms a fault block system with a ragged fault scarp and ephemeral

streams on its eastern side (Vogl, 1973, 1976). The Santa Rosa Plateau,

a shelf in the southeastern scarp, was formed by flat-spreading lava flaws.

Severely eroded since, the plateau today is studded with mesas held up

by caps of hard, basic, Pleistocene olivine basalt, visible in outcrops

around the edges of the mesas (California Division of Mines and Geology, - 1966).

The soils of Mesa de Colorado are Murietta stony clay loam over the

entire mesa top (where the study site is located) and Las Posas rocky

loam on the steep side slopes (U.S.D.A. Western Riverside Area Soil

Survey, 1971). The Murietta series soils are derived from the olivine

basalts of the mesa cap and average 43 cm. in depth. A typical soil

profile shows the surface layer, or A horizon, to be a dark reddish-

brown stony clay loam with a moderate, fine angular blocky structure,

ranging from 7.6 to 20 cm. thick, medium acid (pH = 5.6), with a clear,

wavy boundary. The subsoil, or B horizon, is a dark red to dark reddish-

grey heavy loam with a moderate, medium, angular to strong, coarse

prismatic structure; ranging from 22 to 50 cm. thick, medium. acid

(01 = 5.8), and having an abrupt, wavy boundary. The parent material., or R horizon, is of grey olivine basalt mottled with red and yellow, and

may be several meters thick. These soils are usually well-drained, have slow permeability and moderate runoff, an available water holding capacity of 5.08 to 7.62 cm., and moderate fertility.

CLIMATE

A semi-arid Mediterranean type climate, with its characteristic 30

winter rains and summer drought, prevails over the Santa Rosa region.

The rugged topography, however, produces varied climatic patterns, so

that., local weather conditions may vary considerably from the. general southern California climate (Lathrop and Thorne, 1978). Pequegnat (1951)

observed that 90% of the precipitation in the Santa Ana Mountains falls

during the four months from December through April, and Heady (1956)

indicates that regardless of yearly rainfall total, in areas where the

California annual type prevails less than five percent of the precipita-

tion falls from June through September. Talbot et al., (1939) and. Biswell, (1956) note that precipitation in the grassland areas usually

begins in October or November and ends by April or May, with about two-

thirds falling from December through March.

With most of the precipitation obtained from a few intense storms,

rainfall amounts and distribution may vary considerably from year to

year. The U.S.F.S., Tenaja Station, located 7.23 km. West of the study

site, recorded a mean annual precipitation of 42.2 cm. for the period of

1960 to 1966 (Lathrop and Thorne, 1968). Mean annual precipitation

recorded at the Santa Rosa Ranch, 1.69 km. North-east of the study site, was 52.8 cm. for the period 1949-1971, with January and February being

the highest rainfall months in 16 of the 23 seasons, and with 16 of the 23 seasons having totals below the 23-year mean (Snow, 1972). O'Brien and associates (1973) have estimated the mean annual precipitation for

Mesa de Burro, 4.46 km.- northeast of the study site, to be 33 cm. Mean annual precipitation recorded at the study site during the course of this investigation (July, 1974-June 1977) was 44.3 cm. with 67..82% falling from December through March and 8.25% falling from June through 31

•September. Zuill (1967), in a study done on the Santa Rosa Plateau in 1966, reports a mean January temperature of 10.27°C and a mean July temperature of 22.22°C. These values are quite close to the long-term averages for

the Escondido station, 43 km. to the south (U.S. Environmental Science

Services Administration, 1960. Temperatures recorded at the study site

on the mesa top from 1974 to 1977 indicated a mean temperature for

January of 12.370C, and for July, 21.58°C.

Pequegnat (1951) observed the considerable occurrence of fog in the

Santa Ana Mountains and considered fog important in the distribution of

certain plant species. In the late spring and early summer, morning t fog

is often observed to boil up out of de Luz and Sandia Canyons and then

spread in a low, dense layer over the top of Mesa de Colorado.

In contrast to most other California annual grassland areas, where

significant wind effects are rare (Talbot et. al., 1939), the Santa Rosa

Plateau is frequently swept by the "Santa Anal winds during spring and

autumn months, when relative humidity may be lowered to 10% or less and

the vegetation severely dried (Snow, 1972; Pequegnat, 1951).

VEGETATION The plant communities of the Santa Ana Mountains have been studied

and described in considerable detail (Cooper, 1922; Pequegnat, 1951;

Vogl, 1976). Munz (1959, 1974) gives a generalized description of plant

communities in California without referring specifically to the Santa

Ana Mountains. Most recently, Lathrop and Thorne (1978) have produced

a flora of the Santa Ana Mountains which recognizes the plant communities

as defined by Thorne (1976). 32 On the Santa Rosa Plateau are found the chamisal (Adenostoma

chaparral), southern oak woodland, southern California grassland, vernal

pool ephemeral, riparian woodland and ruderal communities (Thorne, 1976).

Mesa de Colorado itself is covered on its side slopes by chamisal and on

its rim and near certain rocky outcrops by southern oak woodland. Other-

wise, the entire mesa top is covered by southern California grassland,

with the exception of five locations where ephemeral vernal pools exist.

The study site is located in a representative part of this mesa-top

annual grassland.

HISTORY

The annual grasslands of the Santa Rosa Region were probably first

used for livestock grazing around 1800, when the land was controlled by

the San Luis Rey Mission. From the time the mission was secularized by

the Mexican government in 1834 there seems to have been little use by

livestock up until about the middle of the century. At that time, an

intense interest in cattle ranching developed in response to •the demand

of gold-mining operations in the northern part of the state. From about

1850 until the 1890's these rangelands were grazed intensively by cattle and, prior to 1877, by sheep as well. Around the turn of the century the land was bought by the Vail family, who continued to manage the rangelands and to graze cattle until the property was sold in 1965

(Snow, 1972). The lands of the old Vail ranch, Rancho Santa Rosa, are now owned by the Kaiser-Aetna Corporation, which is subdividing and developing the property as part of its 36,000 hectare Rancho California development. METHODS AND MATERIALS

FIELD OBSERVATIONS

Beginning at germination time in November, 1974, vegetative elongation and phenologic stage of southern California grassland species were recorded during three growing seasons. During the first season, 1974-

1975, growth was observed for several grasses and forbs. On the basis of these observations, three representative species were chosen for particular growth and development observations during the growing season

1975-1976. The three species chosen were: filaree (Emiium obtusiplicatum

[K., W. & W.] J. T. Howell), slender oat (Avena barbata Brot.) and a tarweed Caplocarpha vir3pata .[A. Gray] Keck ssp. elongata Keck), which represent, respectively, the spring forbs, the early summer annual grasses and the late summer forbs (qunz, 1973, 1974).

In the annual grassland, permanent plots were established and divided into one-meter squares for reference (Figs. 8, 9, 10). Observations of growth and development were obtained weekly by measurement of ten randomly selected plants of each species in each of six study plots. A five-strand barbed-wire exclosure, 20 meters X 10 meters, prevented damage to study plots by grazing cattle. An adjacent exclosure, five meters X three meters, provided space for weather-monitoring instruments.

For each species studied, two types of information were recorded at each observation date: vegetative elongation and phenoiogic stage.

Height and length measurements as response parameters in plant growth are usually avoided (Pickett and Bazzaz, 1976; Heady, 1957) since they disregard other important avenues of the plant's expression of its

33 34 response. However, these measurements are useful in illustrating structural relationships within a vegetation and when growth observations on plants in permanent plots must be obtained by non-destructive sampling. Thus, they have seen effective application in several studies

(Pickett and Bazzaz, 1976; Raynal and Bazzaz, 1975, 1976; Bernard and

MacDonald, 1974; Mott and McComb, I975a; Harris, 1970; Harris and Wilson,

1977). • Taking into account Heady's (1957) distinction between height and length measurements, vegetative growth in this study was monitored by weekly measurement of plant length, from point of emergence from the soil to the farthest extent of vegetative material (i.e. excluding flowers, fruits). From these weekly total-length measurements, the length incre- ment for each weekly period was determined.

Phenological events in the development of each species were recorded, based on an arbitrary scale with values from one to six:

1 = GERMINATIVE: From emergence until the first true leaves appear

for forbs, until coleoptile is penetrated for

grasses;

2 = VEGETATIVE : from appearance of true leaves (penetration of

coleoptile) until first floral bud appears;

3 = ELONGATING : from appearance of flowering bud until anthesis;

= FLOWERING : duration of time stamens are exserted;

5 = FRUITING : from beginning of fruit development until either

seed is cast or plant senesces;

6 = SENESCENCE : period during which chlorophyll is lost, plant is

dying.

From November, 1974 until July, 1977, environmental factors were 35 monitored by means of instruments installed at the study site. Rainfall, air temperature, relative humidity and total solar radiation were

continuously recorded. Rainfall was measured by a remote recording rainguage (Weathermeasure Corp., Model P501-I coupled to the Model P521

event recorder). Back-up corroborative observations were obtained by weekly reading of a standard 8-inch (20.32 cm. diameter) U.S.D.A. Forest

Service type bucket rainguage (Western Fire Equipment Co., Model 91200).

Air temperature and relative humidity were charted by a recording hygrothermo graph (Weathermeasure Corp., Model H311). Weekly readings of

maximum and minimum air temperatures (Taylor No. 5458 self-registering

maximum-minimum thermometer) and point relative humidity (sling

psychrometer, Taylor Instrument Companies) served for calibration. Data

obtained included mean daily temperature, maximum and minimum daily

temperatures, daily duration above 200C and daily duration below 10°C,

maximum and minimum daily relative humidity, duration above 70% RH and

duration below 50% BR. Daylength and solar radiation were recorded by

a recording actinograph (Kahlsico, Model 01AM100).

Soil temperatures were recorded weekly from three remote-probe

maximum-minimum soil thermometers (Palmer Instruments, Model 35-B) with

their probes buried at 5 cm., 10 cm. and 15 cm. soil depths. Data obtained included maximum, minimum and mean weekly temperatures for each

depth. Soil moistures during the 1975-1976 season were gravimetrically

determined every two weeks. Soil samples from three depths (0-5 cm,,

5-10 cm., 10-15 cm.) were taken from five random sites inside the

exclosure but outside any plant measurement plots. These were sealed

individually in plastic bags and transported to the laboratory, where 36

they were weighed, oven-dried at 1050C for 24 hours and reweighed.

During the 1976-1977 season, soil moisture readings were obtained from

21 Bouyoucos gypsum-type soil moisture blocks (Soiltest, Inc., Model

A-70) buried at the 10-15 cm. soil depth. Readings were made weekly

using the Soiltest Model MC-300A soil moisture meter.

Percent soil moistures obtained gravimetrically were converted to • negative soil moisture tension values (bars) by means of retention curves

developed for the particular soil. A pressure membrane extraction

apparatus (Soilmoisture Equipment Corp., Model 1000 I5-bar pressure membrane extractor and Model 1700 100-bar pressure membrane extractor) was used according to a modification (Johnston, 1976) of the method outlined by Richards et al. (1969) and Reitemeyer and Richards (1944).

The Bouyoucos soil blocks were calibrated directly, using a 15-bar ceramic plate extraction apparatus (Sollmoisture Equipment Corp.,

Model 1500), so that readings in micro-Amperes were converted directly to bars of soil moisture tension.

Finally, on the basis of these field observations, the species' individual and collective patterns of seasonal growth and development were characterized and quantitatively described. The climatic and microenvironmental factors simultaneously monitored were examined for relationships to plant growth. These apparent patterns and relationships were then used to suggest hypotheses for subsequent experimental testing in manipulated associations and in controlled environments.

THE MANIPULATED-ASSOCIATION EXPERIMENTS

In November and December, 1976, three plots three meters X seven meters in the annual grassland study area were tilled and then sterilized 37 with methyl bromide at the rate 0.0489 .kg/m2.• Each plot was subdivided

into 21 one-meter square plots, then in early January, 1977, seeds of

the three annual species were sown into the plots. The planting scheme

provided for all possible combinations of the three species (i.e. seven

different species combinations, with each species involved in four of

the combinations). Each of these combinations was then planted in three

different densities (200, 400 and 800 plants per species per square

meter), which produced 21 plots in all, with any one species involved in

twelve treatments in the experiment. The entire experiment was then -

replicated three times (Figs. 11, 13A).

Ten 'randotay chosen plants of each species in each of the 12 .

treatments in each of the three replicates were examined periodically

from January until July, 1977. Phenologic stage was recorded, rated

according to the previously described scale from one to six. Analysis

of the phenological results in manipulated associations was by Dixon's (1967)

multivariate analysis of variance (Biomedical Computer Program BMD08V).

THE CONTROLLED-ENVIRONMENT EXPERIMENTS

Between September, 1976 and June, 1977 the effects on the three

annual grassland species of air temperature, soil moisture and day

length were studied in controlled-environment rooms. Choice of the

three environmental factors used was based on observations made during

the 1974-1976 field study.

Three separate environmental rooms were used to provide respective

• day/night air temperatures of 13°1180C, 22°1117°C, and 30/25°C. Each of

the environmental rooms was divided by an opaque partition into two

compartments, one with a 10-hour light day, the other with a I6-hour 38 light day. Light in each compartment was provided by eight F4OCW

"cool white" fluorescent tubes and two 100-watt incandescent bulbs,

which supplied a light intensity of 4.52 X 103 lux (measured with a •

Kahlsico light meter, No. 268WA620) at the canopy level of the growing

plants (Figs. 12, I3B, 14, 15).

In each light/temperature compartment, three levels of soil moisture

were provided by means of soil columns. A water table tray, 1 m. X 2 m. X

15 cm. deep, coated with asphalt emulsion and lined with 6 mil polyethy-

lene, was constructed in each environmental room, then filled 5 cm. deep

with clean sand. Three sections of 30.5 cm. (12 inch diameter) sheet

metal casing for each of three soil column heights were then erected on

the sand bed of each light/temperature compartment. Heights of columns

required for desired soil moisture tensions in this soil had been • empirically determined in advance. The columns Were then packed with

dry, crushed field soil from the Mesa de Colorado study site, the water.

table trays filled with water, Bouyoucos gypsumr-type soil moisture blocks

imbedded 12 cm. deep in each column, and the. columns allowed to reach hydraulic equilibrium. This treatment provided soil moisture tensions

in the three levels of 5.27 + 1.5 bars, 2.29 + 0.5 bars and. 0.83 + 0.3

bars. at the time of planting.

Seeds of the three annual grassland species were planted, into the • top of each column at the rate of 200 plants/species/m2. All treatments were then watered once from the surface to insure germination, then allowed to. return to soil moisture conditions maintain ed by the soil column heights..

• The experimental design provided all possible full combinations of 39 two daylengths, three air temperatures and three soil moisture levels:

18 treatments in all. The Bouyoucos blocks were read periodically by means of a Soiltest NC-300A soil moisture meter. Thirty plants per treatment for each species, randomly chosen at each observation date, were examined and their phenologic stage recorded according to the previously described scale of one to six. Results were analyzed by simple regression; differences in days to anthesis (time to phenologic stage #4) were evaluated by T-test Oilcan and Massey, 1969; Snedecor,

1956). Figure The study site on Mesa de Colorado of the Santa Rosa Plateau. Visible are the barbed-wire exclosure, instrument shelters, raingauge buckets, soil thermometer housing and experimental plots. Photograph was made in January, 1977, before plants, which germinated a month and a half earlier, had begun their rapid elongation. 41 42

Figure 9 Measuring elongation during BArch, while filaree is experiencing its rapid elongation but slender oat and tarweed have not yet begun their rapid phase. 43 44

Figure 10 Schematic plot plan of the study site on Mesa de Colorado. Protected by a five-strand barbed-wire exclosure, the 200 m.2 area is divided into square-meter study plots for reference. Particular instrument installations are indicated by the letters:

A Instrument shelter containing rainguage recording apparatus and maximum-minimum air thermometer. B : Instrument shelter containing recording hygrothermo graph. C : Instrument shelter containing ground-level hygrothermograph and maximum-minimum air thermometer. . D Installation of recording actinograp4. E and F : Installation of standard bucket raingu ages. Installation of collection bucket for remote recording rainguage. H : Instrument shelter containing guages for remote probe maximum-minimum soil thermometers. 45

Five -strand Barbed Wire * Exclosure

Study Plots Figure •11 Study plots tilled and planted in preparation for the manipulated-association experiments. The movable quadrat frame is of PVC pipe and served for reference in the evaluation of development of species in the various treatment plots. 4 7 48

Figure 12 Spectral distribution of light at the study site on Mesa de Colorado and in the controlled-environment rooms in the laboratory. Measurements were made with an ISCO Model SR spectroradiometer under clear skies on 26 September 1975 at the study site. Measurements were made with the same instrument in the controlled-environment rooms with all apparatus in place. 49

14 Sunlight 13 10.00 hrs. 12.00 hrs. 12 14.00 hrs.

ity s ten in l a tr 3 Controlled ec Environment sp 2 Light Treatment

II 111 400 500 600 700 Wavelength (mu) 50

Figure 13 Experimental design of (A) manipulated-association experiments in the field (F = filaree, 0 = slender oat, T = tarweed), and (B) controlled-environment experiments in the laboratory, where d1=10-hour light day, d2=16 hour light day; at1=13/8°C air temperature, at2=22/170C air temperature, at3=30/25°C air temperature; sm1=5.27 bars soil moisture tension, sm2=2.29 bars soil moisture tension, sm3=0.83 bars soil moisture tension. T(subscript) indicates treatment number. 51

species combinations FO FT TO FTO

(NI zr, 200 Zi5

co(6 a 400

800

14 SM 11 17 T T i io 13 116

15 T SM2 12 8 11 114 117

12 118

at3 Figure 14 Schematic representation of construction of soil columns established in each light/temperature compartment. The three necessary levels of soil moisture tension were provided by the three different heights of soil column. Seeds of filaree, slender oat and tarweed were planted into the top of each column. ( VERTICAL)

Soil Columns

Water Tray 54

Figure 15 Plant sgecies growing at the top of soil columns in one of the environmental treatment compartments during the controlled-environment experiments. 5 55 • RESULTS AND DISCUSSION

FIELD GROWTH AND PHENOLOGY

During the 1975-1976 season, filaree, slender oat and tarweed were

all observed to germinate in approximate unison near the end of November

and beginning of December. In all three of the species., a short • period

of rapid elongation immediately after germination was followed by an

extended period of very little growth which lasted through the winter

and into early spring. Beginning in early March, filaree experienced

its Tapia elongation up until the end of April, with maximum elongation

rate occurring in late March and early April and maximum length attained

in the first week of May. Within.three weeks after reaching maximum

length, filaree plants had all dried and disintegrated, their brittle

stems, leaves and remaining seeds scattered by the wind (Fig. 16).

Slender oat, which 'followed filaree in spring development, began

its rapid elongation as filaree reached its peals. Experiencing its

maximum rate of elongation as the filaree began .to decline in early May,

slender oat remained alive until July, attaining its maximum length in

mid-June. The dry.culms then remained erect and bright yellow through

the summer until the first rains, When they suddenly turned grey and

. began to break down.

Tarweed began its rapid. elongation about the same time slender oat

began, but at a slawer rate and continuing through the summer. 'Maximum

elongation rate was experienced as slender oat reached its. peak, while

maximum length was reached in late August and early September. The

leaves began to die in the autumn, but the dry, naked stems remained

t• 57 standing until broken down by winter rains.

. This same general pattern in the seasonal development of filaree, slender oat . and tarweed was evident in eachof the three years for which

Observations were made. It corresponds well with Duncan's (1975) description of phase segregation and with the general picture of seasonal development in the California. annual grassland given by Biswell.(1956) and by Heady (1958).

When examined together (Fig. 16A), the individual patterns of development for the three species illustrate the segregation of southern

California grassland species into three.temporal phases: an early spring phase dominated by filaree, an early summer phase dominated by slender oat, and a late summer phase characterized by tarweed. Because of their relationship in time, these three phases seem . to imply the involve- pent of phytosociological factors. with the start of rapid elongation in slender oat- and tarweed coinciding with the slowing of vegetative growth in filaree, and with the Maximum rate of elongation of each phase coinciding with the decline of the preceding phase, some type of competitive inhibition could be -suggested. Muller (1969) and Tinnin and Muller•

(1971, 1972) have demonstrated. that allelopathy and competition may effectively work together to modify the distribution and development of annual grassland. plants.

The possibility of environmental control in the timing of phase appearance must not be overlooked, however. Bokliari (1976) has shown that peak times for productivity and physiological activity (e.g.

Chlorophyll production) in western wheatgrs.s can be altered markedly as a result. of environmental conditions imposed. MCNaughton (1968) ,has 58

Figure 16 Vegetative elongation (A) and phenological development (B) observed in the field study of filaree, slender oat and tarweed, growing in natural association under field conditions from December, 1975 to October, 1976 at the study site on Mesa de Colorado.

100- •..••••• *. • . • Slender AV Oat

Filaree Tar weed

o•4044" Filaree ti Slender Oat

Tarweed

A 60

Figure 17 Environmental conditions at the study site on Mesa de Colorado as reflected by rainfall, soil moisture tension, mean soil temperature, mean air temperature, daily duration above 200C, and daylength monitored from December, 1975 to August, 1976.

50-

Rainfall bars Soil or %Moisture mm. Tension

10-

'o se-e. 30 '-o-o

P\ 25 Mean Soil Temperature

20 gLr, oc Q MQ "1, , .1 151- 'fa,. \ / Mean Air

Temperature 10

20--

15 - •••••• hours Dayiengthft, •••• • --Al • 10 -• , • •••••• ••••••• Daily Duration 5-- • Above 20 °C 62

Figure 18 Environmental conditions at the study site on Mesa de Colorado as reflected by maximum and minimum air temperatures, maximum and minimum relative himidities, and daily duration above 70% relative humidity monitored from - December, 1975 to August, 1976. 63

35- 30

25- Daily Temperature Range 20 °C 15 10

100 80 60 40 20 Daily Relative Humidity Range

20 15 hours 10 Daily Duration Above 70 % Relative Humidity J F M A M J J A

Figure 19 Accumulated total rainfall at the study site on Mesa de Colorado for the three seasons from July, 1974 to June, 1977. 472.01 mm. U I I 1976-1977

338.16 mm. 518.84 MM.

ACCUMULATED RAINFALL Figure 20 Variations in soil moisture tension across two growing seasons at the study site on Mesa de Colorado. 60P-

50 POW

joy..

FMA MUU A S 0 N D MA MU 19751 1976 1977 Figure 21 Empirically determined soil moisture retention characteristic of the soil used both at the study site and in the controlled- ' environment rooms. Curves fit to the obtained points are described by the equations:

M = (logT-0.829)/-0.0455 (if T4(1.0 bar)

M = (logT-2.602)/-0.1335 (if T>1.0 bar)

• . . where 14 = gravimetric soil moisture expressed as percent of dry weight and T = soil moisture tension expressed as bars. 70-

M.: (log T- 2.602)/-0. 335

10- • • ..... • • • .. .. ......

•••

I I 2.3 4 5 6 78 9 10 Ii 12 13 14 15 16 17 18 19 20 21 22 SOIL MOISTURE TENSION (bars) Figure 22 Empirically determined soil moisture block/meter calibration curves developed using Bouyoucos gypsumtype soil blocks and a Soiltest HC-300A meter with soil from the study site on Mesa de Colorado. With the meter in high range, the curve is described by the equation:

T = (2.439-logA)/0.0618

. . . where T = soil moisture tension expressed in bars and A =• meter reading expressed in micro-Amperes. With the meter in low range, the curve is described by the equations:

T -4(A-186V-46.28= (if A>120 u-A.)

T = 158/(A+8) (if A<120 u-A.) 71

200E

High Range

150- T= (2.439-log A) /0.0618

(1)

E < - :L100- % It i t 'tj T= A-I86)/--4628

Low Range

\\411= 158n A +8 )

t ( ) 2 34 5 6 7 8 910 Ii 12 13 14 15 16 soil moisture tension (bars ) 72 indicated that even such factors as soil type may determine how a

vegetation responds to environmental gradients.

Development through phenologic stages demonstrates even more

distinctly the same three-phase segregation evident in patterns of

elongation (Fig. 16B). That phenologic stage works well in distinguish-

ing phase segregation should not be surprising, as it was essentially

this characteristic of the ecosystem to which early observers referred

in their descriptions of striking seasonal changes in the California

grassland (Talbot et al., 1939; Burcham, 1957). Accordingly, phenology

and phenologic stage have had a variety of applications to problems in

ecology (Lieth, 1970; Harris, 1977; Fernandez and Caldwell, 1970).

Raynal and Bazzaz (1975), Regehr and Bazzaz (1976) and Pickett and

Bazzaz (1976) have shown that certain successional annuals, by differen-

tial phenological responses to environmental situations, obtain a

competitive advantage or experience divergence along environmental

gradients.

RELATION TO ENVIRONMENTAL FACTORS

• Rainfall

Comparison of Figure 16 with Figure 17 and Figure 18 reveals the

temporal relationship of species development to environmental conditions.

Cumulative rainfall for each season from 1974 to 1977 is illustrated in

Figure 19. Statistical correlations of elongation rate with certain

environmental factors are • shown in Table 2, while monthly rainfall

distribution for 1974-1977 appears in Table 3.

The dominant pattern of rainfall emerging from these observations 73 Table 2. Results of statistical correlation of mean elongation rate

(ram/day) of each species, with selected environmental factors

observed during the 1975-1976 season.

Factor Species r pl

Rainfall •Filaree -0.0703 * Slender Oat -0.1544 *

Tarweed . .-0.1179 • *

So.1.1 Moisture Filaree - ,i0.2319 * Tension Slender Oat 0.2101 *

Tarweed. •0.4035 *

Mean Daily Air Filaree -0.0094 *• Temperature Slender Oat 0.4355 0.05 .* Tarweed . 0.2122

Mean Weekly Soil Filaree • 0.4305 ' 0.10 Temperature Slender Oat 0.4733 0.02

. Tarweed 0.1804 *

Daylength Filaree 0.4213 '0.10

Slender Oat 0.5308 . 0.01

Tarweed 0.3599 0.05

Hours Above 20° C. Filaree -0.26.2 *• , Slender Oat 0.3125 0.10 .

Tarweed 0.2451 * l/"*" indicates IP. 0.1. 74 Table 3: Monthly distribution of rainfall on the Santa Rosa Plateau and three-year average monthly rainfall for 1974-1977.

Point Rainfall (mm)

Month 1974-1975 1975-1976 1976-1977 3 - year average

July 0.0 0.0 0.0 0.0 August 0.0. 0.0 0.0 • .0,0.

September 0.0' 0.51 89.45 29.99 October 21.59 7.61 7.10 12.10. , November 1.52 - 29.72 17.0 16.08 December 114.56 18.05 41.15 57.92. January 13.45 0.0 . 128.99 47.48 - February 87.11 175.55 41.15 101.27 , March 171.19 63.71 - 46.48 93.79 April • 80.52 .36.70 5.06 40.76 May . 13.44 3,76 93.98 37.06 June 15.46 2.55 1.65 6.55

Total 518.84 338.16 472.01 443.00 75 is consistent with the characteristics of the Mediterranean climate

prevailing in the Santa Rosa region. The three-year mean annual

precipitation total of 443 mm., recorded at the study site from 1974 to

1977, is quite similar to the six-year (1960-1966) mean of 422 ma.

recorded at the U.S.F.S. Tenaja station, 7.23 km. west of the study site

(Lathrop and Thorne, 1968). Most of the rain falls from December through

March, but monthly totals show great variability due to the fact that

the majority is obtained from a few isolated storms. The times of

heaviest rainfall, usually during the months of February and March,

coincide approximately with the beginning of the period of rapid elonga-

tion in early spring. However, the time of maximum length for filaree,

and the tines of maximum elongation rates for slender oat and tarweed occur in periods of scant rainfall.

That growth rates of annual grassland plants should show a definite

relationship to rainfall seems a reasonable expectation. Raynal and

Bazzaz (1976) have shown that certain annuals experience significant

height growth differences, depending on rainfall. Hufstader (1976), in a study of production in the southern California annual grassland, found that dominant species showed a strong relationship to precipitation.

Encountering, then, a lack of significant correlation between elongation rate and precipitation in the present study (Table 2), one is reminded of the uncertainty inherent in the correlative approach to limited field ecology problems. Efforts to predict California annual grassland yield by correlation with precipitation, suggested by Liacos (1962) and undertaken by Murphy (1970) and by Duncan and Wbodmansee (1975), have abundantly demonstrated this uncertainty. 76 • Soil Moisture

A comparison of Figure 16 and Figure 17 will reveal the temporal

relationship between elongation rate and soil moisture tension, while

Table 2 shows the results of statistical correlation. Figure 20

illustrates variations in soil moisture tensions through• the seasons• from December, 1975 to June, 1977.

Empirically determined soil moisture retention characteristics of

the soil at the study site are illustrated by the curve in Figure 21.

Use of this curve permitted direct translation of the gravimetrically

determined soil moisture percentages into soil moisture tensions

expressed in bars. The use of "average" retention values in this trans-

lation was thus avoided, since the curve was determined specifically

for the soil in use. Soil moisture block/meter calibration (Fig. 22),

done specifically for this study, eliminated reliance upon assumptions

concerning the relationship of meter reading to actual soil moisture tension.

Initiation of the period of rapid elongation for all species in

the 1975-1976 study occurred while soil moisture tensions were quite

low. While maximum elongation rate for filaree took place at soil • moisture tensions below 5 bars, maximum rate for slender oat occurred

at soil moisture tensions of approximately 15 bars, and the maximum

rate for tarweed at tensions in excess of 40 bars. This result corrob-

orates Duncan's (1975) observation that tarweed accomplishes most of

its growth and phenological development while soil moisture is held at

tensions in excess of 15 bars.

Major (1963), who suggests that temperature and moisture conditions 77 are the controlling factors in the seasonal development of California

annual grassland, also indicates that later-developing plants (especially

tarweeds) root deeper, exploiting water supplies not available to the

earlier-maturing, shallower-rooting species. Wieland and Bazzaz (1975)

have shown that certain successional annuals coexist by exploiting

different soil levels, and that the tolerance of these species varies

according to the moisture characteristics of the soil level exploited.

However, it has also been found that even very deep rooting plants (e.g.

alfalfa) draw most of their water from the upper 30 cm. of the soil

(111man et al., 1961). In a study in the southern California annual

grassland, Hull and Muller (1976) found that their sampling depths of

0-5, 10-15 and 25-30 cm. corresponded to the root depths of all the annual

grasses concerned in their study. In the present study, examination of

plant samples and profile trenches at several times through the season

indicated that roots of all three species under study tended to be

concentrated between 5 cm. and 15 cm. soil depth, and later, between 10

and 15 cm. Even roots of tarweed, at this site, seldom exceeded 15 cm.

root depth. It is thus felt that the soil moisture sampling depths

employed in this study adequately represent the moisture conditions at

the level actually encountered by the plants.

Temperature of Air and Soil

The effects of temperature and daylength on growth and flowering of

• grassland species have been appreciated for several decades already

(Benedict, 1940). In addition, we have Major's (1963) observation that

seasonal development in the California annual grassland in particular

seems to be partially cued by temperature. While elongation rate of 78 filaree in the present study shows no correlation with air temperature

and only moderate positive correlation with soil temperature, elongation

rates of both slender oat and tarweed exhibit moderate positive correla-

tions with both air and soil temperatures (Table 2, Figs'. 16, 17, 18).

Stubbendieck and Burzlaff (1970) and Stubbendieck and McCully (1976)

have observed that temperatures which may be optimal for certain of a

plant's activities may not be optimal for other activities of the same

plant. Accordingly, in a study of production in southern California an-

nual grassland, Hufstader (1976) found that production in dominant

species showed a strong relationship to precipitation but not to temper-

ature, while production in sub-dominants showed no relationship to either.

With these documented conclusions in mind, then, we are little troubled by

a lack of consistant relationship between growth of species and temperature.

Daylength

Although photoperiodic requirements for a variety of types of plants

have been examined in considerable detail (e.g. Tompsett, 1976; Zehni

and Morgan, 1976), particular requirements for many California annual

grassland species are still unknown. As might be expected in the present

study, since most of the growing season coincides with lengthening days

(Fig. 16 and Fig. 17), all species exhibit a moderate positive correlation with daylength (Table 2). Tarweed, which experiences its maximum

development during the summer, nevertheless has the lowest correlation of

the three species, due to its period of development overlapping periods

of both increasing and decreasing daylength. 79 MANIPULATED-ASSOCIATION EXPERIMENTS

Effects of Species Combinations

Early studies of pasture production suggested that. grasses and forbs compete and that grasses Will suppress the forbs (Blackman, 1938;

Blackman and Templeman, 1938). . In their work with successional annual

species, Raynal and Bazzaz (1975) demonstrated that certain winter

annuals will suppress summer annuals and that their competitive advantage

is derived from the fact these winter annuals•are able to establish

certain growth forms before later annuals are able to compete. Tinnin

and Miller (1972), moreover, indicate that competition and allelopathy

combine in the California grassland to determine to a large degree the

distribution and development of associating species. In addition,

Guerrero and Williams (1975) have demonstrated the competitive advantage

of filaree in the presence of available nitrogen in the grassland.

In the present study, Tables 4, 5, and 6 show the iesults of

comparisons of phenologic stage at given dates for filaree, slender oat and tarweed in various combinations and densities. Analysis by multi-

dimensional analysis of variance (Biomedical Computer Program BMDO8V) used phenologic stage of each species as the observed variable, presence or absence of each of the other two species (2 levels) as one classification dimension, density (3 levels) as another classification dimension, and replication (3 levels) as the third classification dimension.

.Although subtle differences in mean phenologic stage appear to exist between treatments, they are in no case statistically significant

(p.0.1 in all cases). By 4 April 1977, filaree (Table 4) had attained a mean phenologic stage of 3.72 4- 0.69 in the absence of slender oat, 80

as compared to 3.78 + 0.70 in the presence of slender oat. In the absence

of tarweed, the mean was 3.70 + 0.67, while in the presence of tarweed

it was 3.80 + 0.72.

• By 2 May 1977, slender oat (Table 5) had attained a mean phenologic

stage of 3.19 + 0.38 in the absence of filaree, and 3.15 + 0.34 in the presence of filaree. In the absence of tarweed the mean was 3.19

+ 0.38; while in the presence of tarweed it was 3.14 + 0,34.

By 7 June 1977, tarweed (Table 6) had attained a mean phenologic stage of 2.48 + 0.50 in the absence of filaree, and 2.35 + 0.48 in the presence of filaree. In the absence of slender oat the mean was 2.44 +

0.49, while in the presence of slender oat it was 2.39 + 0.48.

Effects of Density

Means of phenologic stage at the dates indicated above for filaree and slender oat were lowest, medium and highest for corresponding densities of 200, 400, and 800 plants/species/m2, respectively. Means for tarweed were highest, lowest, and medium for the same densities, respectively. Although these differences do appear, they are not statistically significant (p>0.1 in all cases).

Competition .a Cause of Phase Segregation

Harris (1977) points out that phenology (especially root phenology) plays a highly significant part in plant competition. Raynal and Bazzaz

(1976) and Regehr and Bazzaz (1976) have demonstrated the competitive effects of differential phenological response in successional annuals.

However, the inverse effect, that of competition on phenology, has not been clearly demonstrated. While a casual observer of the California annual grassland might visualize a simple competition problem (e.g. Fig. 16,

81 Table 4. Phenologic stage at given date (4 April 1977) and analysis

of variance results for Filaree grown in manipulated

associations in the field.1

Slender Oat Slender Oat absent present Means

Tarweed 3.43+ 0.632 3.70 + 0.70 3.57 + 0.67 absent 3.86 -1-7 0.68 3.73 + 0.78 3.80 + 0.72 3.73 T- 0.58 3.73 + 0.64 3.73 + 0.61

Tarweed 3.73 + 0.91 3.63 + 0.62 3.68+- 0.81 present 3.63 + 0.76 3.87 + 0.63 3.75 0.70 3.93 + 0.58 4.00 -7±0.74 3.96±0.66

3.58 + 0.78 3.67 + 0.71 3.63 + 0.74 Means 3.75 + 0.72 3.80 + 0.71 3.77 + 0.71 3.83 + 0.58 3.87 + 0.69 3.85 + 0.63

Analysis of Variance: < arigiaimIddidalum

Density 2.7391 0.20 Slender Oat: present/absent 7.6923 0.15 Tarweed: present/absent 1.6119 0.35

In each group of values, the upper, middle and lower figures represent results of plants grown in densities of 200, 400, and 800 plants/species/m2, respectively. 2/ Values indicated are mean phenologic stage + standard deviation.

82 Table 5. Phenologic stage at given date (2 May 1977) and analysis of

variance results for Slender Oat grown in manipulated

association in the field.1

Filaree Filaree absent present Means

Tarweed 3.23 + 0.432 3.03 -I- 0.18 3.13 + 0.33 absent 3.33 -- 0.47 3.13 + 0.34 3.25 + 0.41 3.20 71-7 0.40 3.20.± 0.40 3.20 + 0.40

Tarweed 3.03 + 0.18 3.13 + 0.34 3.08 + 0.27 present 3.10 + 0.30 3.16 + 0.37 3.13 ÷ 0.34 3.26 + 0.44 3.20 + 0.40 3.23 ÷ 0.42

3.13 + 0.33 3.08 + 0.27 . 3.11 + 0.30 Means 3.22-T 0.39 3.15 + 0.36 3.19 + 0.38 - 3.23 0.42 3.20 + 0.40 3.22 + 0.41

Analysis of Variance: p<

Density 0.9938 0.55 Filaree: present/absent 1.0105 0.45 Tarweed: present/absent 1.0066' 0.45

if In each group of values, the upper, middle and lower figures represent results of plants grown in densities of 200, 400, and 800 plants/species/m2, respectively. 2/ Values indicated are mean phenologic stage + standard deviation.

83 Table 6. Phenologic stage at given date (7 June 1977) and analysis of variance results for Tarweed grown in manipulated associations in the field.1

Filaree Filaree absent present Means

•INO

Slender Oat 2.50 + 0.502 2.43 + 0.51 2.47 + 0.51 absent 2.50 71-7 0.50 2.50 + 0.50 2.50 + 0.50 2.46 + 0.48 2.46 :17 0.48 2.46 + 0.48

Slender Oat 2.46 + 0.51 2.36 + 0.39 2.41 + 0.50 present 2.30 + 0.46 2.30 + 0.46 2.30 + 0.46 2.40 + 0.49 2.30 + 0.46 2.35 + 0.48

2.48 + 0.51 2.40 + 0.50 2.44 + 0.51 Means 2.40 7;0.48 2.40 + 0.48 2.40 + 0.48 2.43 T0.49 2.38 + 0.47 2.41 + 0.48

Analysis of Variance:

Density 3.5000 0.20 Slender Oat: present/absent 6.6301 0.15 Filaree: present/absent 0.4812 0.85

In each group of values, the upper, middle and lower figures represent results of plants grown in densities of 200, 400, and 800 plants/species/m2, respectively. Values indicated are mean phenologic stage + standard deviation. 84

successive phases appear to depend for their cue on the passing of the

preceeding phase), results of the present study do not indicate competi-

tion to be a statistically significant cause of phase segregation in

the southern California annual grassland.

CONTROLLED-ENVIRONHENT EXPERIMENTS

Phenological development of the species in controlled environments

(Pig. 23) reflected the different conditions imposed by the 18

environmental treatments accorded each species (Fig. 13). Results of

regression and correlation analysis of the relationship between phenologic

stage and time since germination for species in various environmental

situations are shown in Table 7. Table 8 compares number of days

required to reach anthesis (phenologic stage 4) by species in the various treatments.

Filaree

Of the 18 environmental treatments accorded filaree, only treatments

Ti (short day, law temperature, high soil moisture tension) and T4 (long

day, law temperature, high soil moisture tension) elicited phenological

responses past vegetative stage. Phenology in all other treatments

remained at vegetative stage until the experiment's end. Phenologic

stage of filaree, then, was advanced by law temperatures and high soil

moisture tension (p<0.0001), and appeared to be relatively unaffected

by daylength (p<0.1). Comparison of the time to reach anthesis in the

two treatments producing response (i.e. 134.63 days in Ti and 137.20 days in T4), however, does indicate that a significant difference (p<0.025,

means compared by T-test) does exist, with short days reducing the time to anthesis. 85

Slender Oat

Of the 18 environmental treatments accorded slender oat, T5 (long

day, law temperature, medium soil moisture tension) and T4 • clang day, law

temperature, high soil moisture tension) produced the earliest response,

followed later by T2 (short day, law temperature, medium soil moisture

tension) and TI (short day, law temperature, high soil moisture tension).

Phenology of all other treatments remained at vegetative stage until

the end of the experiment. Phenologic stage of slender oat, then, was.

advanced by long days as opposed to short - days (p <0.001), but only where low temperatures also existed. Differences due to soil moisture tension were slight, but significant (p<0.005), with medium soil moisture

.tensions producing slightly advanced phenologies as compared to high soil moisture tensions. Comparison of time to reach antheis in the four treatments responding through stage four (i.e. 132.75 days in Tl,

128.16 days in T2, 108.74 days in T4, 105.73 days in T5) indicates that antheis is advanced significantly by long days as compared to short days (p<0.001), and that the difference between the effects of high and low soil moisture tensions on timing of anthesis is not highly. significant

(p>0.2). Root respiration problems at excessive soil moisture levels are. suspected as a cause of the total lack of response atlow soil moisture tensions.

Tarweed

Of the 18 environmental-treatments accorded tarweed, T17 (long day, high temperature, medium soil moisture tension) elicited the first response, and was the only treatment to produce phenological development through all stages. T16 (long day, high temperature, low soil moisture 86

Figure 23 Phenological response of filaree, slender oat and tarweed to each of the 18 controlled-environment treatments provided, plotted against time since germination. Response is remarkably clear-cut, with plants in most treatments' remaining at vegetative stage (!ol[Feriologic stage 2), while only certain environmental treatments produce responses past vegetative stage. T(subscript) indicates treatment number.

5 Tarweed

4 / T16% All Other 3 ••• Treatments 118 2 •

CD CI) T5% co 5 - Slender Oat .. / 4- All Other cm 3... Treatments a 2r1,7-13 • • •

ci. 1

5 _ Filaree

i N All Other /••• 3- 4.• Treatments A 2 - .41..

20 40 60 80 100 120 140 160 days

88 Table 7: Results of statistical analysis of correlation between phenologic stage and days 'since germination for plants grown in each of 18 environmental treatments.

Treatment Treatment Correlation Coefficients (R) # Typel Filaree Slender Oat Tarweed

1D1MI .9146 .6193 *3 2 .6696 3

4 .8911 .6669 5 T1 D2 M 2 .6832 6 T1 D2 M3 7 T D M 2 1 1 8 T 2D 1M 2 .9 T D M 2 1 3 10 T D M 2 2 I 11 T D M 2 2 2 12 T D M 2 2 3 13 T D M 3 1 1 14 T D M 3 1 2 15 T3 D1 3 16 T D M 3 2 1 .5542 17 T3D2M2 .8825 18 T D M 3 2 3 .5798 1/ T and T 1, T2 3 indicate low, medium and high temperatures, respectively; D and D 1 2 indicate short and long days, respectively; 111, M2 and M3 indicate high, medium and low soil moisture tensions, respectively. 2/ p<0.001 in all cases. 3/ "*" indicates no change in phenologic stage during time period exam ined, thus no correlation coefficient computed. 89

Table 8: Average number of days required to reach anthesis (phenologic stage 4) as determined from regression line characteristics for plants grown in each of 18 environmental treatments.

• Treatment Treatmentl Filaree2 Slender Oat Tarweed # Type

1 * 3 1 D1 M 1 134.63 + 4.61 132.75 + 19.29 • 2 T1D1M2 128.16 + 17.60

3 T1 D 1 M 3

T1 D 2 M 1 137.20 + 5.21 108.74 + 13.01 5 T D M 1 2 2 105.73 + 12.52 T D M 1 2 3

7 .T2 D 1 M 1 T D M 2 1 2

T2 D 1 M 3

10 T2 D 2 M 1 11 T D M 2 2 2 12 T D M 2 2 3 13 T D M 3 1 1

14 T3 D 1 M 2 15 T D M 3 1 3 16 T3D2Mi 87.28 + 10.42

17 T3 2 M 3 2 2 71.11 + 6.01

18 T3 D 2 M 3 87.62 + 10.64

1/ TI' T2 and T3 indicate low, medium and high temperatures, respectively; D1 and 12 indicate short and long days, respectively; .14 1' 2 and 14/13 indicate high, medium and low soil moisture tensions, respectively. 2/ Values are mean + standard deviation . 3/ "*" indicates anthesis not reached. 90

tension) and T18 (long day, high temperature, high soil moisture tension)

later produced responses into the third and fourth phenologic stages.

Species in all other treatments remained at vegetative stage until the

experiment's end. Phenologic stage of tarweed, then, was advanced by

long days and high temperatures, with maximum development occurring at

medium soil moisture tensions (p<0.001). Comparison of time to reach

anthesis in the three treatments responding to stage four (i.e. 87.28

days in T16, 71.11 days in T17, 87.62 days in T18) indicates that

anthesis is advanced by medium soil moisture tensions as opposed to high

or low soil moisture tensions (p<0.001), and that differences between

effects of low and high soil moisture tensions are of questionable

significance (p.>0.5).

Environmental Stress and Phenoldgical Development

While the thought that annual plants should respond to environmental

stresses by advancing more rapidly toward a reproductive stage might

seem - intuitively appealing to some, Mott and McComb (1975b) point out

that critical observations have not generally supported this conclusion.

They go on, furthermore, to demonstrate that certain annual species of

arid regions of Australia show no phenologic advancement whatsoever in

response to environmental stress. In the present study, however,

filaree seems to advance to a reproductive stage more effectively at

• higher soil moisture tensions.. Slender oat and tarweed, on the other

hand, both advance more rapidly at medium than at high soil moisture

tensions. Temperature and photoperiod have traditionally been recognized

• as important controlling factors in growth and phenology of many species

(Benedict, 1940; Tompsett, 1976; Zehni and Morgan, 1976), and the present 91 study reinforces that position. While filaree seems to be little

affected by day length, its best development does appear to require

lower temperatures. Slender oat and tarweed are both particular not

only to temperature, but also and especially to day length.

CONCLUSIONS

The fundamental contributions of this study appear to fall

naturally into two groupings. First, temporal phase segregation of

representative species in the southern California grassland is quant-

itatively and graphically described. We believe this description is

long overdue. Second, controlled-environment laboratory experiments,

examining hypotheses suggested by field correlation studies, indicate

that filaree, slender oat and tarweed are segregated along a temporal

gradient by their differing individual responses to particular combi-

nations of temperature, daylength, and soil moisture tension.

Bearing in mind the fact that results obtained in controlled

environments are not directly transposable to the field, (Baker and

Jung, 1968), where a multitude of possibly unrecognized factors may be

effective (Waring and Major, 1964), certain limited conclusions appear

to be warranted by the present study. Phenologic advancement of filaree

appears to be favored by lower temperatures, shorter days and higher

soil moisture tension. Slender oat is advanced more rapidly by moderate

temperatures and soil moisture tensions, and by long days. Tarweed

shows marked advancement at higher temperatures and longer days, when soil moisture tensions are moderate.

Statistical correlation of seasonal growth or phenological development with local environmental factors, although intuitively appealing, 92 is of little use in determining causal relationships. One reason is that the dependent variable (plant growth or phenology) is an expression of physiological processes that may not be the sane from time to time throughout the season. Also, the questionable assumption is made that successive phenological events are independent. For these reasons, correlative results obtained from limited ecological studies are most profitably used only to suggest hypotheses for subsequent experimental testing.

Intra-specific and inter-specific competition, while slightly affecting individual species' development, are not significantly important in temporal phase segregation of southern California annual grassland species. But if these factors are not significant, others exist which definitely are. This study indicates that the time a southern California grassland species spends in the vegetative stage is not an inherent constant. Rather, it is determined by the individual species' physiological and phenological responses to the quantitative availability of water, heat and light. It is the synergy of individual responses which accomplishes the temporal segregation described in this study. LITERATURE CITED

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APPENDIXES 101

APPENDIX I

Simmarized Data for

Rainfall, Soil Moisture and Soil

Temperature, 1974-1977 CATE RAINFALL SOIL MOISTURE • MEAN SOIL TENSION TEMPERATURE (MM) (BARS) (DEGREES C)

22 NOV 74 1.52 23 NOV 74 0.00 411. 41110 6 DEC 74 81.52 4.00 Oft 13 DEC 74 0.00 SIM .111. 19 DEC 7 4 0.00 011101. '23 DEC 7 4 0.00 41=00 12.50 3 JAN 75 33.02 OPP MID 8.50 10 JAN 75 5.07 9.50 1/ JAN 15 0.00 12.50 24 JAN 75 0.00 15.50 31 JAN 75 8.37 13.50 IMIP 7 1.- B 15 47 . 48 9.50 14 FEB 75 39.62 11.50 21 • FEB 15 0.00 10.00 23 FEB 7 5 0.00 411, 13.00 7 MAR 15. 60.20 =IWO 15.50 14 MAR.15 87.11 0.10111, 10.50 23 MAR /5 0.75 12.00 21 MAR 15 18.02 12.50 4 APR /5 6.10 13.00 10 APR 75 69.84 9.00 18 APR 15 6.60 9.00 25 APR 75 3.04 011. 14.50 2 MAY 7 5 0.00 16.00 9 MAY 75 1.7T dal 17.00 16 Ni ?\Y 15 1.00 21.50

DA• TE RAINFALL SOIL MOISTURE MEAN SOIL TENSION TEMPERATURE (MM) (BARS) (DEGREES C) .00 OM 00 10 .6 0* 00 01 011 ...... 23 MAY 75 9.89 17.50 30 MAY 75 0.49 *MP 21.00 6 JUN 75 1.24 4110 22.50 13 JUN 75 0.49 23.00 20 JUN 75 13.70 016 21.00 26 JUN 75 0.24. Ob 20.50 4 JUL 75 0.00 27.00 11 JUL /5 0.60 23.00 13 JUL 75 0.00 28.50 27 JUL 75 0.00 28+59 1 AUG 75 0.00 29.00 7 AUG 75 0.00 31.00 15 AUG 75 0.00 29.00 22 AUG 75 0.00 26.00 29 AUG 75 0.00 29.00 5 SEP 75 000 30.00 12 SEP 75 0.24 28.50 18 SEP 15 0.24 30.50 26 SEP 75 0.00 31.50 3 OCT 75 0.00 31.00 10 OCT 75 3.30 26.00 17 OCT 75 0.75 22.50 24 OCT 75• 0.00 22.00 31 OCT 75 3.03 21.00 7 NOV 75 0.00 21.50 14 NOV 75 0.00 20.55 21 NOV 75 0.00 18.33

DATE RAINFALL SOIL MOISTURE MEAN SOIL TENSION TEMPERATURE (MM) ( BARS) ( DEGREES C) .10104.6411041100.4010111411,040, 23 NOV 75 1.17 16.11 5 DEC 75 0.00 3.02 13.33 12 DEC 15 11.20 17.49 19 DEC 75 6.85 8.24 12.22 31 DEC 75 6.60 14.44 11 JAN 76 0.00 20.86 13.61 18 JAN 76 0.00 17.77 25 JAN 76 0.00 24.61 16.94 1 FEB 76 0.00 17.77 8 FEB 16 151.10 17.49 13 FEB 76 24.20 1.15 17.49 22 FEB 76 0.25 14.44 29 FEB 76 0.00 1.51 17.22 1 MAR 76 61.20 13.61 14 MAR 76 2.51 0.87 13.88 21 MAR 76 0.00 16.94 26 MAR "76 0.00 5.08 19.99 1 APR .76 0.00 Ali MS 19.44 8 APR 76 8.70 18.05 15 APR 76 27.51 2.04 15.55 22 APR 76 0.00 4.78 ;6.38 29 APR 76 0.50 19.16 6 MAY 76 0.50 14.50 21.66 13 MAY 76 2.50 22.22 20 MAY /6 0.00 36.14 27.49 2/ MAY 76 0.76 40.05 25.55 4 JUN 76 0.25 >50 25.27

DATE RAINFALL . SOIL MOISTURE MEAN SOIL TENSION TEMPERATURE ( MM ) ( BARS) ( DEGREES C)

10 JUN 16 2.30 fliP WI) 26.38 17 JUN 76 0.00 44.68 26.38 24 JUN • 0.00 29.44 1 JUL 16 0.00 3.1.38 8 JUL 76 0.00 >50. 33•33 15 JUL 76 0.00 .1040111 33.61 22 JUL 16 0.00 MR0110 31•66 29 JUL 76 0.00 30.83 5 AUG 76 0.00 >50 31.11 12 AUG 76 0.00 41•11 30.55 19 AUG 76 0.00 q/P dill 30.27 26 AUG 76 0.00 30.27 5 SEP 76 7.40 31•38 13 SEP 76 75.70 1 .97 26.11 2) SEP /6 1.50 0 .48 22..77 a3 SEP 76 4.85 22.49 5 OCT 76 4.80 0.34 22.49 12 OCT 76 0.00 21•94 17 OCT 76 0.50 0.79 22.22 24 OCT 76 1.80 0.52 21.66 31 OCT 76 0.00 0.99 21.11 8 NOV 76 0.00 2.13 21.38 14 NOV 76 10.70 1.14 19•44 21 NOV 16 0.00 '2.05 11.50 29 NOV 76 6.30 1.55 15.55 5 DEC 76 0.00 1.92 14•44 12 DEC 16 0.00 6..18 14.12

MEAN SOIL IATE RAINFALL SOIL MOISTURE TENSION TEMPERATURE (MM) (BARS) (DEGREES C)

A.Mbead00000 .0.0fta0 .. NO . elk ..... 4.11.01 oft 19 DEC 76 0.00 13•42 14.72 28 DEC 76 0•00 14.98 13.61 89•15 0.49 12•50 4 JAN 77 .0 air 9.99 9 JAN 77 77.72 16 JAN •77 0•24 0.48 9..49 23 JAN 77 0.51 12.77 33 JAN 77 2.52 0.51 14.16 7 FEB 7'7 0.00 0..45 13.61

14 FEB 77 0.00 4.1 16.94 21 FEB 77 0.00 1.84 13.33 15•27 27 FEB 77 41.14 0.45 6 MAR 77 0.00 0.63 13.61 13 MAR 77 0.00 1.31 14.16 13.61 21 MAR 77 • 9.15 1.49 15•27 27 MAR 77 34.54 o..49 4 APR 77 7.10 0.49 14.16 10 APR 77 0.25 1.78 17.49 al APR •77 0.50 8.16 18.88 25 APR 77 0.00 14.14 21.11 2 MAY 77 0.00 18.81 21.94 9 MAY -77 85•34 0.42 19.72 16 MAY 77 2.29 0.42 17.22 24 MAY 77 6.10 0.83 20•55 33 MAY 77 0.25 1.12 21.11 7 JUN 77 • 0.00 5.17 25.27 14 JUN 77 1.65 8.11 26.11 21 JUN 77 0.00 20.60 26.11 107

APPENDIX II

Summarized Data for

Maximum, Minimum and Mean Daily

Air Temperatures, 1974-1977 AVERAGE DATE AVERAGE AVERAGE DAILY MEAN DAILY MAXIMUM DAILY MINIMUM TEMPERATURE TEMPERATURE TEMPERATURE (DEGREES C) (DEGREES C) (DEGREES C)

agi sift ... 12.62 16.62 8.62 22 NOV 74 5.50 28 NOV 74 12.75 20.00 10.68 15.00 6.37 6 DEC 74 6.14 13 DEC 74 11.21 16.28 13.16 18.33 8.00 19 DEC 74 2.37 27 DEC 74 7.12 11.87 5.99 9.71 2.28 3 JAN 75 4.42 10 JAN •75 8.49 12.57 15.57 21.57 9.57 17 JAN 75 9.14 24 JAN 75 14.78 20.42 6.28 10.57 2.00 31 JAN 75 5.28 7 FEB 75 8.78 12.28 9.35 13.42 5.28 14 FEB 75 1.42 21 FEB 75 5.64 9.85 11.14 17.14 5.14 28 FEB 75 2.00 7 MAR 75 6.35 10.71 8.00 14.00 2.00 14 MAR 75 5.83 20 MAR 75 10.74 15.66 8.42 12.57 4.28 27 MAR 75 3.87 4 APR 75 8.12 12.37 6.25 9.00 3.50 10 APR 75 10.62 3.25 18 APR 75 6.93 10.85 14.71 7.00 25 APR 75 6.85 2 MAY 75 12.42 18.00 13.51 19.42 7.71 9 MAY 75 12.85 16 MAY 75 17.78 22.71 DATE AVERAGE AVERAGE AVERAGE DAILY MEAN DAILY MAXIMUM DAILY MINIMUM TEMPERATURE TEMPERATURE TEMPERATURE (DEGREES C) (DEGREES C) (DEGREES C)

SW WI OM .11. 41.10 410 41110 4WIS 0111. 41D OW OF air ow me mo on ow ow 23 MAY 75 12.28 16.57 8.00 30 MAY 75 16.64 22.71 10.57 6 JUN 75 17•14 23.28 11.00 13 JUN 75 18.57 24.85 12.28 20 JUN 75 13.00 17.00 9.00 26 JUN 75 15•50 21.00 10.00 4 JUL 75 17.93 25.12 10.75 11 JUL 75 24.92 31.14 18 JUL 75 19.28 26.57 12.00 27 JUL 75 20.27 27.55 13.00 1 AUG 75 22.00 29.00 15.00 7 AUG 75 27.74 34.83 20.66 15 AUG 75 23.87 0.62 17.12 22 AUG 75 18.92 26.00 11.85 29 AUG 75 22.42 29.57 15.28 5 SEP 75 25.49 31.57 19.42 12 SEP 75 20.14 24.71 15.57 18 SEP 75 21.66 30.83 12.50 26 SEP 75 24.00 30.12 17.87 3 OCT 75 23.21 31.85 14.57 10 OCT 75 17 •42 22.71 12.14 17 OCT 75 15.35 21.71 10.00 24 OCT 75 12.28 17.28 7.28 31 OCT 75 14•78 20.85 8.71 7 NOV 75 18.11 26.66 9.55 14 NOV 75 18.88 26.66 11.11 21 NOV 75 13•33 22.22 44.44 DATE AVERAGE AVERAGE - AVERAGE DAILY MEAN DAILY MAXIMUM DAILY MINIMUM TEMPERATURE TEMPERATURE TEMPERATURE (DEGREES C) (DEGREES C) (DEGREES C) Ors we ea am SO 28 NOV 75 7• 49 12.77 2.22 5 DEC 75 12.49 21.11 . 3.88 12 DEC 75 13.05 20.00 6.11 19 DEC 75 12.49 17.77 7.22 31 DEC 75 12.68 16 • 40 6.96 11 JAN 76 9.29 14.89 3.68 18 JAN 76 •17 • 65 23.57 11.74 25 JAN 76 13.92 18.73 9.12 1 FEB 76 17.57 24.52 10.63 8 FEB 76 9.64 11.82 7.46 13 FEB 76 10.99 14.55 7.44 22 FEB 76 10.70 14.93 6.48 29 FEB 76 12.06 17.85 6.26 7 MAR 76 7.18 9.99 4.36 14 MAR 76 ,9.20 13.09 5.31 21 MAR 76 14.00 19.84 8.17 26 MAR 76 10.11 16.33 3.88 1 APR 76 8.79 14.99 2.59 8 APR 76 8.73 12.22 5.23 15 APR 76 9.00 13.65 .4.36 22 APR 76 12 • 61 18.25 6.98 29 APR '76 12 • 18 17 • 30 7.06 6 MAY 76 17.38 21.82 12.93 13 MAY 76 19.64 26.03 13.25 20 MAY 76 19.43 25.39 13.57 27 MAY 76 16.50 22.38 10.63 4 JUN 76 16.94 21.45 12.43 DATE AVERAGE • AVERAGE AVERAGE DAILY MEAN DAILY MAXIMUM DAILY MINIMUM TEMPERATURE TEMPERATURE TEMPERATURE (DEGREES C) (DEGREES C) (DEGREES C) .416400040.114m., 10 JIM 76 17 .73 23.14 12.31 17 JUN 76 21 • 50 28.25 14.76 24 JUN 76 23 • 05 28.72 17.38 1 JUL 76 28.80 35.87 21.74 8 JUL 76 24.24 30.63 17.85 15 JUL 76 20.47 25 • 55 15.39 22 JUL 76 .20.03 26.03 14.04 29 JUL 76 24.56 31.03 18.09 5 AUG 76 20.91 27..46 14.36 12 AUG 76 23.80 31 •11 16.50 19 AUG 76 19.44 24.92 13.96 26 AUG 76 22.53 28.96 16.11 5 SEP 76 25.83 31 •77 19.88 13 SEP 76 21.31 25.13 17.49 20 SEP 76 15.31 17.77 12.85 23 SEP 76 16.14 18.54 13.74 5 OCT 76 18.61 23.96 13.25 12 OCT 76 24.84 30.87 18.80 17 OCT 76 19.94 26.44 13.44 24 OCT 76 17.02 21.42 12.61 31 OCT 76 18.25 24.20 12.30 8 NOV 76 24•37 30.55 18.19 14 NOV 76 13.70 17.49 9.90 21 NOV 76 18.84 24.20 13.49 29 NOV 76 14.40 19.16 9.65 5 DEC 76 16.27 22.22 10.33 12 DEC 76 15.19 21.58 8.80 DATE AVERAGE AVERAGE AVERAGE DAILY MEAN DAILY MAXIMUM DAILY MINIMUM , TEMPERATURE TEMPERATURE TEMPERATURE (DEGREES C) (DEGREES C) (DEGREES C)

11•1 .11 O. 4.111 10, 1111, 0116MMOI ...... 004110 19 DEC 76 16•34 21•90 10.79 28 DEC 76 13.39 19.56 7.22 4 JAN 77 8.13 10.95 5.31 9 JAN 77 7.11 10.22 3.99 16 JAN 77 11.42 17 •1 4 5.71 23 JAN 77 15.51 19.99 11.03 30 JAN 77 13.33 18•49 8.17 7 FEB 77 13.43 19.44 7.43 14 FEB 77 17.30 23•96 10.63 21 FEB 77 19.04 24.84 13.25 27 FEB 77 9.12 13.88 4.35 6 MAR 77 10.03 16.03 4.04 13 MAR 77 11.22 16.98 5.47 21 MAR 77 9.13 14.79 3.47 27 MAR 77 8•14 12.40 3.ss 4 APR 77 6.45 9.72 3.19 10 APR 77 14.67 20.55 8.79 20 APR 77 13.91 20.66 7.16 25 APR 77 19.77 27•11 12.44 2 MAY 77 14.16 20.47 7.85 9 MAY 77 10.31 1 4.28 6.34 16 MAY 77 8.33 10.55 6.11 24 MAY 77 11•66 15.55 7.77 30 MAY 77 14.44 19.90 8.98 7 JUN 77 20.13 26..45 13.81 14 JUN 7 7 15.03 19.92 10.15 21 JUN 77 18•01 24.52 11.50 113

APPENDIX III

Summarized Data for

Daily Duration at High and Law Air

Temperatures and Relative Humidities, 1974-1977

DATE AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY HOURS ABOVE HOURS BELOW HOURS ABOVE HOURS BELOW 20 DEGREES C 10 DEGREES C 70 X RH 50 % RH . .... 22 NOV 74 0.50 7.25 21.37 0.75 28 NOV 74 2.00 8.33 0.83 21.33 6 DEC 74 0.00 14.87 12.00 7.62 13 DEC 74 0.00 11.71 5.42 13.42 19 DEC 74 0.66 6.66 0.00 20.33 27 DEC 74 0.00 18.87 4.75 18.00 3 JAN 75 0.00 22.42 8.14 11.71 10 JAN 75 0.00 19.00 12.57 7.42 17 JAN 75 3.85 4.71 0.85 22.85 24 JAN 75 2.57 5.57 0.57 17.14 31 JAN 75 1.00 18.57 12042 6.28 7 FEB 75 0.00 17.14 20.42 0.85 14 FEB 75 0.00 17.14 21.28 1.28 21 FEB 75 0.00 21.71 12.00 8.71 28 FEB 75 0.28 11.71 7.85 9.28 7 MAR 75 0.00 20.28 17.14 2.85 14 MAR 75 0.00 20.00 19.00 4.00 20 MAR 75 0.00 12.16 17.83 2.16 27 MAR 75 0.00 18.71 15.85 4.85 4 APR 75 0.00 19.37 10.25 11.37 10 APR 75 0.00 22.66 21.66 0.33 18 APR 75 0.00 21.62 23.50 0.00 25 APR 75 0.71 12.14 22.71 0.57 2 MAY 75 1.14 10.42 18.00 1.85 9 MAY 75 1.57 6.71 16.85 2.71 16 MAY 75 6.57 0.00 16.71 2.85

WTE AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY HOURS ABOVE HOURS • BELOW HOURS ABOVE HOURS BELOW 20 DEGREES C 10 DEGREES C 70 % RH 50 % RH . 01.0014104011., . 01,01104111110110.1 MOMS...... 40100011. 23 MAY 75 . 1.57 7.57 20.42 0.00 30 MAY 75 5.42 1.28 17.42 0.42 6 JUN 75 • 5.28 0.14 23.00 0.14 13 JUN 75 6.71 0.00 16.00 3.85 20 JUN 75 0.00 0.85 16.57 3.00 26 JUN 75 4.33 0.33 11.66 7.66 4 JUL 75 7.87 0.12 15+50 4.12 11 JUL 75 18.7,1 0.00 13.00 3.14 18 JUL 75 9.57 0.00 17.14 1.71 27 JUL 75 11.44 0.00 14.00 2.33 1 AUG 75 20.00 0.00 9.20 1.20 7 AUG 75 23.16 0.00 1.83 15.83 15 AUG 75 16.87 0.00 10.75 6.00 22 AUG 75 7.85 0.14 12.57 7.28 29 AUG 75 11.71 0.00 5.85 10.42 5 SEP 75 17.71 0.00 10.42 5.42 12 SEP 75 11.00 0.00 22.00 0.00 18 SEP 75 11.16 0.00 18.66 0.00 26 SEP 75 16.00 0.00 5.50 '9.75 3 OCT 75 16.71 0.00 1.42 - 7.57 10 OCT 75 7.28 3.85 14.71 4.28 17 OCT 75 3.42 1.14 17.85 3.14 24 OCT 75 0.00 10.71 16.85 1.00 31 OCT 75 2.00 1.28 21.00 0.00 7 NOV 75 8.40 0.40 3.80 13.60 14 NOV 75 10.00 1.50 2.00 12.00 21 NOV 75 1.30 4.60 3.00 13.00 AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY HOURS BELOW DATE HOURS BELOW HOURS ABOVE HOURS ABOVE 70 % RH 50 % RH 20 DEGREES C 10 DEGREES C .. mimmtsatrApiiimet. 14.20 13.70 10.00 28 NOV 75 0.00 8.00 3.00 1.10 14.40 8.00 5 DEC 75 10.60 5.00 12 DEC 75- 0.00 1.00 7.00 0.00 14.00 14.15 19 DEC 75 11.38 '3.53 31 DEC 75 0.23 3.72 17.27 0.18 15.36 21.71 11 JAN 76 3.14 0.14 18 JAN 76 5.85 5.71 13.71 1.28 6.28 23.57 25 JAN 76 1,71 0.00 1 FEB 76 6.42 19.28 4.00 1.14 14.71 3.00 8 FEB 76 14.60 16.20 13 FEB 76 0.00 11.66 9.11 0.00 10.88 5.42 22 FEB 76 8.57 10.57 29 FEB 76 0.42 12.85 5.28 7 MAR 76 0.00 22.14 8.71 0.00 18.28 12.28 14 MAR 76 7.00 4.00 15.71 21 MAR 76 3.00 12.40 9.40 1.00 14.00 6.83 26 MAR 76 16.50 15.00 1 APR 76 0.00 17.71 2'14 0.14 18°42 1.28 8 APR 76 17.14 16.28 15 APR 76 0.00 18.14 0.57 22 APR 76 2.85 8.85 2.00 0.00 104..85 15.14 29 APR 76 6.14 15.57 5.00 6 MAY 76 34.00 11.42 4.28 13 MAY 76 9.71 2.14 6.00 10.00 0.00 12.71 20 MAY 76 0.28 15.71 4.00 27 MAY 76 4.57 20.50 0.87 4 JUN 76 4.50 0.00

LATE AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY HOURS ABOVE HOURS BELOW HOURS ABOVE HOURS BELOW 20 DEGREES C 10 DEGREES C 70 % RH 50 % RH 10 JUN 76 4050 0.00 14.00 5016 17 JUN 76 12057 0.71 7.28 11.28 24 JUN 76 17.14 0.00 4.71 3000 1 JUL 76 23.71 0.00 3.71 2.71 8 JUL 76 17.00 0.00 10.00 5.00 15 JUL 76 10.85 0.00 14.14 4.14 22 JUL 76 9.28 0.00 14.71 4.42 29 JUL 76 18000 0.00 9.57 8071 5 AUG 76 10.57 0.00 13.14 7.28 12 AUG 76 13.14 0.00 7.57 10028 19 AUG 76 6.14 0.00 12.14 5.71 26 AUG 76 11.71 0.00 5.42 10.14 5 SEP 76 18.70 0.00 6.60 12.30 13 SEP 76 9075 0.00 15.75 3.50 20 SEP 76 0.00 0.00 20.14 0.57 28 SEP 76 1.12 0.00 21012 0.75 5 OCT 76 11028 0.00 11.14 6.42' 12 OCT 76 19.57 0.00 . 1057 17.42 17 OCT 76 7.80 0.00 13.20 5.00 24 OCT 76 2042 0.00 19.71 0.57 31 OCT 76 6.57 0.00 5.00 15.28 8 NOV 76 16.50 0.00 0.00 24.00 14 NOV 76 .2.50 1.83 15.50 4.66 21 NOV 76 8014 1.00 2.14 17.00 29 NOV 76 2.87 6.00 4.75 16.12 5 DEC 76 4.00 2.80 •3.60 19.60 12 DEC 76 3.85 3.71 3.57 19.42

CATE AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY AVERAGE DAILY HOURS ABOVE HOURS BELOW HOURS ABOVE HOURS BELOW 20 DEGREES C 10 DEGREES C 70 % RH 50 % RH

OU0041,m0 . ... oW=04010,0its.ft .... 0.40,00 19 DEC :76 3.85 2.71 5628 16.85 23 DEC 76 1.55 7:33 4.22 17077 4 JAN. 77 0.00 20.28 20.57 0.71 9 JAN 77 . 0.00 21.60 20020 2.20 16 JAN 77 0.71 11028 6.28 15.00 ?3 JAN 77. 2.42 3•00 9.00 1,0042 30 JAN 7.7 0.71 6.14 10.42 8028 717E8. 77' 1087 6.87 4.37 16050 14 FEB 77 6.28 2.28 3.00 19.71 21 FEB 77 7.42 0.57 3000 18.00 27 'FEB 77 0.00 16.83 10.66 8.33 6. MAR 77 0.00 12.71 3028 17.85 13 MAR 7. 7 0.71 11023 5.57 14.42 21 MAR 77. 0.75 15650 13.75 5.62 27 MAR 77 0.50 19.16 19.50 3.50 4 APR, 77 0.00 22.25 15012 4025 10 APR 77 4.66 8.00 11633 8.00 20 APR 77 2.20 9040 16.00 2.50 25 APR 77 9020 0000 0.60 20640 •2 MAY 77 2.28 8.71 14085 .4.00 9 MAY 77 0600 16000 19000 2.14 16 MAY 77 0.00 21666 18017 0000 24 MAY 77 0000 7.00 13.67 4.11 33 MAY 77 1.16 5.50 11.66 1033 7 JUN 77 9012 0.00 12-.12 4075 14 JUN 77 1657 2057 18057 1.71 21 JUN 77 H 7.00 0000 10.57 7..42 H Co 119

APPENDIX IV

SummArized Data for

Daylength, Maximum and Minimum Daily

Relative Humidities, 1974-1977

AVERAGE AVERAGE DAILY AVERAGE DAILY DAYLENGTH MAXI MUM MINIMUM RELATIVE HUMIDITY RELATIVE HUMIDITY (HOURS) ( PERCENT) ( PERCENT) OW OW .... 400 40, • 22 NOV 74 4000000 97 . 50 72.25 28 NOV 74 41110400400 53.66 8.50 6 DEC 74 0000400 87.12 52.75 13 DEC 74 0110.1010 75.71 34.14 19 DEC 74 101.600 52 . 00 26.50 27 DEC 74 00442000. 67 .87 22.25 3 JAN 75 83 .57 35.28 10 JAN 75 MOO 89.71 53.42 17 JAN 75 00 0146 00 ' 37.71 13.71 24 JAN 75 0000 00 60 . 42 33.42 31 JAN 75 000000 92 . 57 51.57 7 FEB 75 4.04000044 100.00 70.57 14 FEB 75 41.16 ago 100.00 70.57 21 FEB 75 40.4MOOM 89 * 57 45.00 23 FEB 75 OM MID O. 87.71 33 . d/i2 7 MAR 75 00=0404 100 . 00 53.85 14 MAR 75 001/000 100.0.0 36 .00 20 MAR 75 99 .50 49.00 27 MAR 75 99 . 71 44 . 57 4 APR •75 86. 12 44.12 10 APR 75 100.00 67 • 66 18 APR 75 100.00 82.62 25 APR 75 100.00 69.42 2 MAY 75 100.00 52.28 9 MAY 75 100.00 46.42 16 MAY 75 110 OW OINI 99.14 50.00 D4TE AVERAGE AVERAGE . DAILY AVERAGE DAILY DAYLENGTH MAXIMUM MINIMUM RELATIVE HUMIDITY RELATIVE HUMIDITY (HOURS) (PERCENT) (PERCENT)

23 MAY 75 OID 100.00 69.42 30 MAY 75 016 100.00 55.00 6 JUN 75 . 100.00 68•00 13 JUN 75 000000 • 100.00 45.71 20 JUN 75 004010., 100.00 42.00 26 JUN 75 WOOM.0,0 92.66 36.33 4 JUL 75 00 OM 00 99.75 46.75 11 JUL 75 .10000 94.00 43.14 18 JUL 75 0041000 100.00 49.85 27 JUL 75 600ftm. 97.22 43•77 1 AUG 75 004M410 93.20 47.00 .7 AUG 75 01001000 82.83 23.00 15 AUG 75 0.046000 95.75 29.62 22 AUG 75 010 Mb IMP 100.00 25.57 29 AUG 75 86.85 35.14 5 SEP 75 97.57 40.42 12 SEP 75 100.00 70.71 18 SEP 75 93.00 61.66 26 SEP 75 4101 OM OD 90.50 36.50 3 OCT 75 76.28 31.42 10 OCT 75 401140,00 -91.57 49.57 17 OCT 75 40, 01040 97.42 35.42 24 OCT 75 40411000_ 100.00 48•14 31 OCT 75 0,0004m 100.00., 66.00 7 NOV 75 00 Mb 00 77.00 26.00 14 NOV 75 en,romer. 67.00 31.00 21 NOV 75 69.00 28.00 !ATE _ AVERAGE AVERAGE DAILY AVERAGE DAILY DAYLENGTH MAXIMUM MINIMUM RELATIVE HUMIDITY ' RELATIVE HUMIDITY (HOURS) (PERCENT) (PERCENT)

28 NOV 75 4/414 4/. 88.00 51.00 5 DEC 75 82.00 47.00 12 DEC 75 9.84 75.00 30.00 19 DEC 75 9.79 76.00 26.00 31 DEC 75 9.83 65030 26.84 11 JAN 76 9.95 76.36 26 • 45 18 JAN 76 10 • 16 42.57 17.85 25 JAN 76 10.28 68.00 29.85 1 FEB 76 10.43 34.28 7.•85 8 FEB 76 10.71 88 • 28 63 • 57 13 FEB 76 10.88 96.80 57.80 22 FEB 76 11.18 '79.88 35.77 29 FEB 76 11.39 91 •28 42.57 7 MAR 76 11.63 91.00 48.42 14 MAR 76 11.94 86.85 37 • 28 21 MAR 76 12.15 71.71 24.71 26 MAR 76 12.33 89.00 36.80 1 APR 76 12.51 91.00 37.66 6 APR 76 12.33 98.85 46.42 15 APR 76 13.08 99.57 48.57 22 APR 76 13.31 98.28 54.14 29 APR 76 13.54 95.42 47.42 6 MAY 76 13.76 93.71 50.00 13 MAY 76 13.94 91.42 46.28 20 MAY 76 14.11 97.00 36.00 27 MAY 76 14.26 100.00 45.00 4 JUN 76 14.38 95.00 57.87 DATE AVERAGE AVERAGE DAILY AVERAGE DAILY DAYLENGTH MAXIMUM MINIMUM RELATIVE HUMIDITY RELATIVE HUMIDITY (HOURS) (PERCENT) (PERCENT)

10 JUN 76 14.46 92.50 37.00 17 JUN 76 14•49 85•85 28.85 24 JUN 76 14.51 86.23 53.85 '1 JUL 76 14.48 86•85 54.57 8 JUL 76 14.39 97•14 45.57 15 JUL 76 14.25 95.14 44.14 22 JUL 76 14•14 94.14 38.71 29 JUL 76 13.96 91.85 32.71 5 AUG 76 13.78 96.85 30.57 12 AUG 76 13.56 92.00 24.42 19 AUG 76 13.34 98.71 39.28 26 AUG 76 13.09 82.42 24.42 5 SEP 76 12.76 85.10 27.50 13 SEP 76 12.49 96.37 55.75 20 SEP 76 12.21 99.85 57•42 23 SEP 76 11.91 99.25 76.50 5 OCT 76 11.66 93.57 36.14 12 OCT 76 11•41 64.71 22.14 17 OCT 76 11•24 99.00 32.60 24 OCT 76 10.99 99.14 60.57 ••• 31 OCT 76 10.73 69.71 22.00 8 NOV 76 10.53 32.57 14.12 14 NOV 76 10.36 94.50 52.50 21 NOV 76 10.19 59.57 20.00 29 NOV 76 10.01 62.62 20.62 5 DEC 76 9•91 53.60 11.30 12 DEC 76 9.84 46.71 10.42 DATE AVERAGE AVERAGE DAILY AVERAGE DAILY DAYL ENGIN MAXIMUM MINIMUM RELATIVE HUMIDITY RELATIVE HUMIDITY OURS) (PERCENT) (PERCENT)

OW Mb 4110 OW flab all MO OW Oa IMO 00 Ole OM aft. OW OS MID .oro iso ...... ale imp aro ow or 19 DEC 76 9.91 62.57 22.14 28 DEC 76 9.33 63.00 15.33 4 JAN 77 9- .86 100.00 66.85 9 JAN 77 9.93 . 100.00 64.20 16 JAN 77 10.06 71.71 24.28 23 JAN 77 10.23 72.14 36.71 30 JAN 77 10.41 92.35 33.28 7 FEB .77 10.64 70.12 21.87 14 FEB 77 10.89 55.00 13.85 21 FEB 77 11.09 63 • 85 18.28 27 FEB 77 11.33 87.50 36.50 6 MAR 77 11.61 74.85 14.71 13 MAR 77 11.88 91.28 23.57 21 MAR 77 12.16 97.00 38.62 27 MAR 77 12.38 100.00 54.66 4 APR 77 12.68 97.00 48.12 10 APR 77 12.91 85.00 39.33 20 APR 77 13.24 99.50 46.80 25 APR 77 13 • 41 60.40 12.20 2 MAY 77 13.69 100.00 41.7. 1 9 MAY 77 13.84 100.00 56.57 16 MAY 77 14.01 100.00 60.22 24 MAY 77 14.20 97.20 62.30 30 MAY 77 14 • 33 99.33 58.16 7 JUN 77 14.43 96.50 37.37 14 JUN 77 14.50 100.00 55.71 21 JUN 77 14.48 95.14 32.71 125

APPENDIX V

Sumtarized Data for

Elongation of Filaree, Slender Oat and Tarweed in the Field, 1974-1975 FILAREE SLENDER OAT TARWEED

CATE N LENGTH ST.D• N LENGTH ST • D• N LENGTH iST•D. ..--- ...... -- --..--

22 NOV 74 40. 14.85 3.22 40 46.25 13.89 40 10.92 2•83 6 DEC 74 60 17..73 2.64 60 51.73 3•71 60 14.20 1.26 19 DEC 74 60 19•22 1.69 60 55.70 6.94 60 16•10 1•83 3 JAN 75 30 21.17 1.25 30 77.87 13.06 30 17•33 2.53 17 JAN "75 60 25.27 2.24 60 78.15 8.42 50 16.60 5.00 31 JAN 75 60 26.87 3.84 60 87.48 5.76 60 20.51 3.69 14 FEB 75 60 36.20 4•27 60 90.25 12•13 50 28•69 3•39 aS, FEB 75 60 37.65 5.01 60 97.62 12.12 60 32.17 2•69 14 MAR 75 60 48.08 4.06 60 82.53 7.09 60 39.53 3.55 27 MAR 75 60 99.72 16.38 60 103.73 15.83 ,60 50.58 11•33 10 APR 75 60 125.92 20.14 60 148.75 19.22 60 55.62 7.92 25 APR 75 60 192.50 21.17 60 227.25 40.26 60 79.57 11.92 9 MAY 75 60 141•20 28.98 60 425.60 25.26 60 110.65 16.02 16 MAY 75 ## ###•## ##•## 60 643.40 36.80 60 144.00 9.66 23 MAY 75 ## ###•## ##•## 60 761.08 42.61 60 171.33 18.21 ,133 MAY 75 ## ###•## ##.#ft 60 804.25 56.31 60 209.58 9.16 6 JUN 75 ## ###•## ##•## 60 880.58 70.91 60 255.33 19.51 13 JUN 75 " ###•## "•" 60 883.17 74.18 60 296.50 22.38 20 JUN 75 ## ###.## ##•## 60 923.90 38.79 60 333.58 38.59 a. JUN 75 ## ###•## ##.## ## ###.## ##.## 60 388.50 23.35 4 JUL 75 ## ###.## ##.## ## ###.## ##.## 60 432.83 45.45 11 JUL 75 ## ###•## ##•## ## ###•## ##.## 60 469.67 27.55 18 JUL 75 ## ###•## ##.## ## ###.## ##•## 60 478•31 34.36 27 JUL 75 ## ###.## ##•## ## ###.## ##•## 60 530.28 21.42 1 AUG 75 ## ###.## ##.## ## ###•## ##.## 60 518.82 25.98 7 AUG 75 ## ###•## ##•## ## ###•## ##•## 60 504.46 19.60 15 AUG 75 ## ###.## ##•## ## ###•## ##•## 60 451..75 26.64 22 AUG 75 ## ###.## ##•## ## ###•## ##.## 60 489.17 32.68 29 AUG 75 " "If*" "*" ## ###•## ##•## 60 522.67 33•55 5 SEP. /5 ## ###.## ##•## ## ###.## ##•## 60 542.42 30.92 12 SEP 75 ## ###•## ##.## ## ###.## ##•## 60 510.83 26.30 18 SP 75 ## ###•## ##.## ## ###.## ##•## 60 582•88 55•67 127

APPENDIX VI

Summarized Data for

Elongation of Filaree, Slender Oat and Tarweed in the Field, 1975-1976

FILAREE SLENDER OAT TARWEED

00 MO 00 00 00 .... 4110 ... 00 00 00 00 DATE LENGTH ST•D• LENGTH ST • D. N LENGTH ST.D•

0000 40 44, 00 00 MD 01D 4000 0000.4040400 .40 we as 00 ODD 00

12 DEC 75 60 19.38 4..12 60 37.25 11.06 ## ###•## ##.## 19 DEC 75 60 19.93 3•31 60 50.76 19.52 60 15.25 2.79 31 DEC 75 60 23.06 4.09 60 52.33 16.84 60 20.16 6.84 11 JAN 76 60 23.75 5.0.0 60 60.16 17.06 60 21.51 5.50 18 JAN 76 60 23.01 3.77 60 54.50 19.87 60 23.23 6.33 25 JAN 76 60 22.95 4.28 60 57.46 13.78 60 24.16 5.78 1 FEB 76 60 23.16 3.81 60 56.80 13.90 60 22•15 4.26 8 FEB 76 60 24.21 3.63 60 63.60 17.44 60 24.28 5.11 13 FEB 76 60 24.61 2.66 60 66.08 15.71 60 24.55 4.20 22 FEB 76 60 26.91 2.59 60 67.88 11.78 60 28.25 4.84 29 FEB 76 60 29.41 4.77 60 69.85 16.64 60 32.11 9.02 7 MAR 76 60 32.65 6.42 60 73.21 20.23 60 33.95 8.45 14 MAR 76 60 37.83 8.29 60 83,38 20.76 60 37.16 10.35 21 MAR 76 60 48.36 17.66 60 87.21 24.64 60 40.73 11.72 26 MAR 76 60 62.86 17.20 60 91.01 16.45 60 47.40 12.28 1 APR 76 60 73.30 15.49 60 110.58 24.20 60 55.71 15.39 8 APR 76 60 35.56 24.23 60 116.78 23.37 60 58.60 16.91 15 APR 76 60 115.90 22.84 60 . 130.73 24.74 60 66.81 12.08 22 APR 76 60 96.61 18.35 60 172.25 44.84 60 76.76 18.01 29 APR 76 60 119.11 40.40 60 201.25 61.93 60 82•28 23.33 6 MAY 76 60 141.33 30.72 60 317.83 6307 60 102•46 22.14 13 MAY 76 ## ###.## ##•## 60 514.83 71.63 60 115.40 23.87 23 MAY 76 ## ###.## ##.## 60 610.33 87.03 60 129.33 29.91 27 MAY 76 ## ###.## ##.## 60 662.50 67.96 60 153.33 38.47 4 JUN 76 ## ###.## ##•## 60 707.33 70.56 60 182.81 49.04 FILAREE • SLENDER OAT TARWEED

CATE N LENGTH ST .D • N LENGTH ST •D • N LENGTH ST.D • Ws or GO Or ON

10 JUN 76 ## ##//.## ##•## 60 1324.16 93.62 60 199.89 55.61 17 JUN 7.6 ## ###•## ##•## 60 816.66 68.47 60 192.51 46.49 24 JUN 7.6 ## ###•## ##•## 60 830.66 78.64 60 209.56 43.72 1 JUL 16 ## ###•## ##•## ## ###.## ##.## 60 218.25 54.10 8 JUL 16 ## ### • ## ##.## ## ###.## ##•## 60 225.66 53.18 15 JUL 7 ## ### •## ##•## ## ###•## ##•## 60 240.91 56.06 JUL 76 ## ###•## ##•## ## ##.#•## ##•## 60 247.00 52.79 29 JUL 7..6 ## ###•## ## • ## ## ###•## ##•## 60 264.16 54.09 5 AUG 76 ## ###•#/# ##•## ## ###.## ##•## 60 282.16 62.35 12 AUG 76 ## ###.## ##•## ## ###•## ## • ## 60 296.83 58.06 19 AUG 76 ## ###.## ## • ## ## ###•## ##•## 60 316.33 69.74 130

APPENDIX VII

Summarized Data for

Phenologic Stage of Filaree Growing in

Eighteen Controlled-Environment Treatments

131

DATE DAYS T# NUM MEAN ST:DEV. 411WWIDWO .11100411111140,

9 FEB 77 29 30 1.86 0:34 30 2.00 0.00 30 2.00 0.00 4 30 1.86 0.34 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 1.96 0.18 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 30 2.00 0.00 14 _ 15 30 2.00 . 0.00 16 30 1.86 0.34 17 30 2.00 0.00 18 30 2.00 0.00

28 FEB 77 44 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 •2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00

132

DATE DAYS T# NUM MEAN ST.DEV.

immersoareamommoirommo OSOMI 411001110/6 011101111MOM

15 MAR 77 63 1 30 2.00. 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00 8 APR 77 91 1 30 2.00 0.00 - 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00

133

DATE DAYS T# NUM MEAN ST.DEV.

INN= in OS a. Int alW 413 4101.b 404041M .0rn OIDOMMOMW

1 MAY 77 119 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00. 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00 29 MAY 77 126 1 30 2.10 0.30 2 30 2.00 0.00 - 3 30 2.00 0.00 4 30 2.13 0.34 5 30 2.00 0.00 . 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00

134

DATE DAYS T# NUM MEAN ST.DEV. arms. mik .irs .. IP amo ex& dm as WOWS 410401.0 40. MO 0111 SID .6.410,11110A.101.411.

5JUN 77 136 1 30 2.90 0.80 2 30 2.00 0.00 3 30 2.00 0.00 • 4 30 2.90 0.75 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 •0.00

11 30 • 2.00 0.00 12 30 2.00 0.00 13 • 30 •2.00 0.00 14 30 2.00 •0.00 15 • 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 •0.00 18 30 2.00 0.00

15 JUN 77 • 150 1 30 4.16 0.79 :2 30 2.00 0.00 3 30 2.00 0.00 4 30 3.80 0.71 5 30 2.00 0.00

6 • 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00

11 30 • 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30' 2.00 0.00 15 30 •2.00 0.00 16 30 2.00 0.00

17 30 2.00 • 0.00 18 30 2.00 0.00

135

D4TE DAYS T# NUM MEAN ST.DEV. weir, ar se 40 40 00 OW 00 MOD M440 404040 40M er....40401,0040

29 JUN 77 160 1 30 5.76 0.43 2 30 2.00 0.00 3 30 2.00 0.00 4 30 5.06 0.25 5 30 2.00 0.00 6 30 2.00 0.00 7 3,0 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2,.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 -30 2.00 0.00 136

APPENDIX VIII

Summarized Data for

Phenologic Stage of Slender Oat Growing in

Eighteen Controlled-Environment Treatments

137

DATE DAYS T# NUM MEAN ST.DEV.

Olb gip on me am mos rooms ime: as ..ao 4in

17 FEB 77 36 1 30 2.00 0.00 2, 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 1. 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00 7 MAR 77 91 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0:00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00

138

DATE ,DAYS T# NUM MEAN ST.DEV. IMAMS *lb 111111. 111. OS AMP 4I• •MI 4AMWMPIIM

1 MAY 77 98 1 30 2.30 0.46 2 30 2.46 0.50 3 30 2.00 0.00 4 30 3.40 0.56 5 30 3.43 0.56 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0600 11 30 • 2.00 0.00 12 30 2.00 0.00' 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00 8 MAY 77 105. 1 30 2.50 0.50 2 30 2.60 0.49 3 30 2.00 0.00 4 30 3.53 0.50 1 5 30 3.66 0.47 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00

139

-DAYS T# NUM MEAN ST.DEV.

4111M011o 4.410MWO 47)40.41.00 41,041M410.,WPOis.

15 MAY 77 112 1 30 2.54 0.50 • 2 30 2.70 0.44 3 30 2.00 0.00 4 30 3.66 0.54 5 30 4.03 0.55

6 • 30 2.00 0.00 7 30 2.00 0.00 S 30 2.00 0.00

9 • 30 2.00 • 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2+,00 0.00 18 30 2.00 0.00 22 MAY 77 119 1 30 2.70 0.46 2 30 2.93 0.52 3 30 2.00 0.00 4 30 4.03 0.55 5 30 4.20 0.66 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00

140

124TE DAYS Tfi NUM MEAN ST.DEV• - 40 am WO ellb 411160.W.D 1=0.4=110.1110

29 MAY 77 •.126 1 30 2.90 0.60 2 30 3.36 0.61 3 30 2.00 0.00 4 30 4.26 0.73 5 30 4.36 0.71 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 • 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 • 0.00 13 30 2.00 0.00

14 • 30 2.00 0.00 15 30 2.00 0.00 16 • 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00

5 JUN 77 136 1 30 3.00 0.58 2 30 3.46 0.68 3 • 30 2.00 •0.00 4 30 4.76 0.56 5 30 4.93 0.52 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2:00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 .30 2.00 0.00 18 30 2.00 0.00

141

BATE DAYS T# NUM MEAN ST.DEV.

.0maiter MOO DOMOIDOSOO

15 JUN 77 150 1 30 3.90 0.66 2 30 4.06 0.69 3 30 2.00 0.00 4 30 4.83 0.59 5 30 5.03 0.55 6 30 2.00 0.00 7 30 3.83 0.64 8 30 2.90 0.66 9 30 2.00 0.00 AO 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0'00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 3.20 0.71 17 30 2.70 0.74 18 30 2.00 0.00

29 JUN. 77 165 1 30 5.63 0.49 2- 30 5.66 0.47 3 30 2.00 0.00 4 30 5.16 0.37 5 30 5.10 0.30 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 , 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00

142

DATE DAYS T# NUM MEAN ST.DEV.

4110411W mem*. 00.011p0War 00.1001M004111.4MAND

14 JUL 77 178 1 30 6.00 0.00 2 30 6.00 0.00 3 30 2.00 0.00 • 4 30 5.90 0.30 5 30 5.53 0.50 6 30 2.00 0.00 7 30 2.00 0.00 S 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 • 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 • 0.00 17 30 2.00 •0.00 IS 30 2.00 0.00

•27 JUL 77 53 1 30 6.00 0.00 2 30 6.00 0.00 3 30 2.00 0.00 4 30 6.00 0.00 5 30 6.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00 143

APPENDIX IX

SummArized Data for

Phenologic Stage of Tarweed Growing in

Eighteen Controlled-Environment Treatments

144

CATE DAYS T# NUM MEAN ST.DEV.

IMP MO MID OD MO OW 401,,1106410 4...mmipaftdmio.mo

23 FEB 77 53 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 • 30 2.00 0.00 10 30 2.00 0.00 11 _ 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 . 16 30 2.00 0.00 17 30 2.00 0.00 18 30 2.00 0.00 24 MAR 77 63 1 30 2.00 0.00 2 30 2.00 0.00 3 30 . 2.00 0.00 4 30 .2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.00 0.00 17 30 2.36 0.49 18 30 2.00 0.00

145

DATE DAYS T# NUM MEAN ST.DEV.

Ole 441, 0111 , 41111 411WOW 00.41M.10 41160.11WAID 41110001,11111,010.416411MAIO

3 APR 77 70 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 "2.40 0.62 17 30 3.20 0.80 18 30 2.30 0.53 10 APR 77 77 1 30 - 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.09 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.50 0.62 17 30 3.96 0.61 18 30 2.46 0.57

146

laccrE DAYS T# NUM MEAN ST.DEV. gibe, . ea .. 4IAR 4.04, .01,011,4M 1.00.011.4111.0 40100.1.1.010.11111101114110

17 APR 77 84 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00 16 30 2.80 0.71 17 30 4.60 0.77 18 30 2.66 0.60 24 APR 77 91 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 30 2.00 0.00 14 30 2.00 0.00 15 30 2.00 0.00. 16 30 3.00 0.74 17 30 5.26 0.86 18 30 2.96 0.66 147

APPENDIX X

SommArized Data for

Phenologic Stage of Filaree Growing, in

Twelve Manipulated-Association Treatments

148

D;TE DAYS T# NUM MEAN . ST.DEV.

.....00.1MOMOOMOOMI004M 1.10.11410110 01100.. 00.100 unimammr

3) JAN 77 49 1 30 1.96 0.18 a 30 1.96 0.18 30 2.00 0.00 4 30 1.93 0.25 30 1.96 0.18 30 1.96 0.18 - 7 , 30 1.93 0.25 8 30 1.96 0.18 9 30 1.96 0.18 10 30 1.93 0.25 11 30 1.93 0.25 12 30 1.96 0.18 27 FEB 77 63 1 30 2.00 0.00 2 30 2.00 0.00. 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 MAR 77 77 1 30 2.53 0.50 2 30 2.76 0.56 3 30 2.60 0.49 4 30 2.63 0.55 5 30 2.63 0.61 6 30 2.60 0.49 7 30 2.76 0.62 8 30 2.66 0.54 9 30 2.46 0.57 10 30 2.53 0.57 11. 30 2.40 0.49 12 30 2.63 0.66

149

DATE DAYS T# NUM MEAN ST.DEV.

4111110Wer 4111. IWO !O. • 41IP OS MO 0111 4.110 MID

27 MAR 77. 1 30 3.30 0.59 2 30 3.43 0.77 3 30 3026 0.69 4 30 3.43 0.50 5 30 3.76 0.81 6 30 3.30 0.70 7 30 3.40 0.72 8 30 3.50 0.77 9 30 3.53 0.68 10 30 3.40 0.67 11 30 3.40 0.67 12 30 3.50 0.77 4 APR 77 91 1 30 3.43 0.62 2 30 3.73 0.90 3 30 3.70 0.70 4 30 3.63 0.71 5 30 3.86 0.68 6 30 3.63 0.76 7 30 3.73 0.78 8 30 3.86 0.62 9 30 3.73 0.58 10 30 3.93 0.58 11 30 3.73 0.63 12 30 4.00 0.74 10 APR 77 113 1 30 4.16 0.46 2 30 4.36 0.49 3 30 4.16 0.46 4 30 4.26 0.44 5 30 4.36 0.61 6 30 4.20 0.61 7 30 4.26 0.52 8 30 4.33 0.47 9 30 4.30 0.53 10 30 4.26 0.52 11 30 4.06 0.58 12 30 4.23 0.43

150

DkTE DAYS T# NUM MEAN ST.DEV. obOOOo406.4$640.o OOO OPOOPO

2 MAY 77 .120 1 30 5.00 0.00 2 30 5.00 0.00 3 30 5.00 0.00 4 30 5.03 0.18 5 30 5.03 0.18 6 30 5.00 0.00 7 30 5.03 0.18 8 30 5.13 0.34 9 30 5.13 0.34 10 30 5.00 0.00 11 30 5.10 0.30 12 30 5.23 0.43 9 MAY 77 127 1 30 4.06 0.25 2 30 4.23 0.43 3 30 4.10 0.30 4 30 4.36 0.49 5 30 4.10 • 0.30 76 30 4.56 0.50 30 4.10 0.30 8 30 4.56 0.50 9 30 4.13 • 0.34 10 30 4.73 0.44 11 30 4.13 • 0.34 12 3() 4.76 •0.43 16 MAY 77 141 1 30 4.93 •0.36 2 30 4.96 0.31 3 30 5.00 0.37 4 30 5.06 0.52 5 30 4.96 0.41 6 30 4.96 0.41 7 30 5.13 0.50 8 30 5.21 0.50 9 30 5.03 0.49 10 30 5.00 0.45 11 30 5.23 0.50 12 30 5.26 0.58

151

DATE DAYS T# NUM MEAN ST.DEV. ONNWIN AI Olt 'WO Oa OW .11111 ON WIMP 411060110011, 410111,4,00000

3) . MAY 77 149 1 30 4.76 0.81 2 30 4.83 0.79 3 30 4.83 0.83 4 30 4.76 0.77 5 30 4.73 0.78 6 30 4.86 0.86 7 30 5.03 0.80 8 30 5.06 0.82 9 30 4.80 0.80 10 30 5.00 0.83 11 30 5.13 0.77 12 30 5.20 0.80

7 JUN 77 163 1 30 5.20 0.40 2 30 5.20 0.40 3 30 5.36 0.49 4 30 5.36 0.49 5 30 5.20 0.40 6 30 5.20 0.40 7 30 5.46 0.50 S 30 5.50 0.50 9 30 5.26 0.44 10 30 5.23 0.43 11 30 5.56 0.50 12 30 5.56 0.50 21 JUN 77 101 1 30 6.00 0.00 2 30 6.00 0.00 3 30 6.00 0.00 4 30 6.00 0.00 5 30 6.00 0.00 6 30 6.00 0.00 7 30 6.00 0.00 8 30 6.00 0.00 9 30 6.00 0.00 10 30 6.00 0.00 11 30 6.00 0.00 12 30 6.00 0.00 152

APPENDIX XI

Summarized Data for

Phenologic Stage of Slender Oat Growing in

Twelve Manipulated-Association Treatments

153

LATE DAYS Ill NUM MEAN ST.DEV.

.11,0 .11 Vib 110

21 FEB 77 56 1 30 2.00 ' 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 - 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 6 MAR 77 71 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 • 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 • 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 • 0.00 21 MAR 77 106 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 .0.00

154

DIATE DAYS T# NUM MEAN ST.DEV. emommasommaromim . 011,rn 0110,00 00.04111,0 4.04101004111.0 01041M4110.1a4111041116

25 APR 77 113 1 30 2.80 0.40 2 30 2.70 0.46 3 30 2.73 0.44 4 30. 2.93 0.25 5 30 2.90 0.30 6 30 2.80 0.40 7 30 2.80 0.40 8 30 3.03 0.18 9 30 3.03 0.18 10 30 2.80 0.,40 11 30. 2.96 0.18 12 30 3.13 0.34

2 MAY 77 127 1 30 3.23 0.43 2 30 3.03 0.18 3 30 3.03 0.18 4 30 3.13 0.34 5 30. 3.33 0.47 6 30 3.13• 0.34 7 30 3.10 0.30 8 30 3.16 D.37 9 30 3.20 0.40 10 30 3.20 0.40 11 30 3.26 0.44 12 30 3.20 0.40

16 MAY 77 149 1 30 4.00 0.00 2 30 4.00 0.00 3 30 4.00 0.00 4 30 4.00 0.00 5 30 4.00 0.00 6 30 4.00 0.00 7 30 4.00 0.00 8 30 4.00 0.00 9 30 4.00 0.00 10 30 4.00 0.00 11 30 4.00 0.00 12 30 4.00 0.00

155

CATE DAYS T# NOM MEAN ST.DEV.

- 0.60.110104M 4100ft ,01. M4110 411.4.11110.41MAIM.14.1 _ 7 JUN 77 163 1 30 4.86 0.34 2 30 4.76 0.43 3 30 4.80 0.40 4 30 4.76 0.43 5 30 4.83 0.37 6 30 4.70 0.46 7 30 4.73 0.44 8 30 4.66 0.47 9 30 4.76 0.43 10 30 4.63 0.49 11 30 4.63 0.49 ' 12 30 4.60 0.49 156

APPENDIX XII

ummarized Data for

,Phenologic Stage of Tarweed Growing in

Twelve Manipulated-Association Treatments

157

CATE DAYS T# NUM MEAN ST.DEV.

1111, Mal 41116 .01.4MOM MS.111.11141.0 .1111-004104M...1410000

7 FEB 77 63 1 30 2.00 0.00 2 30 2.00- 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 000 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 13 MAR 77 127 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 16 MAY 77 149 1 30 2.00 0.00 2 30 2.00 0.00 3 30 2.00 0.00 4 30 2.00 0.00 5 30 2.00 0.00 6 30 2.00 0.00 7 30 2.00 0.00 8 30 2.00 0.00 9 30 2.00 0.00 10 30 2.00 0.00 11 30 2.00 0.00 12 30 2.00 0.00 , 158

------D!\TE .DAYS TII NUM MEAN----- St.DEV•------1 JUN 11 163 1 30 2.so o.so 2 30· 2.43 o.so 3 30 2•46 a.so 4 30 2·36 0 .49 5 30 2.so o.so 6 30 2.so a.so 7 30 2•30 0·46 8 30 2.30 Q.46 9 30 2·46 a.so 10 30 2•46 a.so 1 l 30 2.40 0•49 12 30 2•30 0·46