DOCSLIB.ORG

Stand Density Management: an Alternative Approach and Its Application to Douglas-Fir Plantations

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Stand Density Management: an Alternative Approach and Its Application to Douglas-Fir Plantations Forest Sci., Vol. 25, No. 3, 1979, pp. 518-532 Copyright 1979, by the Society of American Foresters Stand Density Management: an Alternative Approach and Its Application to Douglas-fir Plantations T. JOHN DREW JAMES W. FLEWELLING ABSTRACT. A methodof viewing standdensity as it relatesto volumeproduction and tree size is developedin the form of a simple density management diagram applicableto plantationsof coastal Douglas-fir, Pseudotsugarnenziesii (Mirb.) Franco, on all sites. Three prominentpoints in stand development,crown closure, imminent competition-mortalityand the maximum size- density relationshipare definedin terms of tree size and stand density, and their implicationfor standdynamics is discussed.A relativedensity index is presentedas a basisfor quantifyingtree growthand standyield as a functionof density.The trade-offbetween maximizing individual tree size or standyield is considered;this recurringdilemma for forest managerscan be rationalized on the basis of the density management diagram. FORESTSCl. 25:518-532. ADDITIONALKEY WORDS. Pseudotsuga menziesii, tree size, standyield, managementregimes. IN AN EARLIERMANUSCRIPT (Drew and Fiewelling 1977), we discussedthe the- oretical developmentof a generalprinciple of plant populationbiology, the max- imum size-densityrelationship, together with elements of yield-density theory, and introduced a concept of imminent competition-mortality.Here, we develop these conceptsinto an applied forest managementtool, which will take the form of a simple modelling approachto stand development. Our model adds to some of the fundamentalconcepts of growth, yield, and stand density that have arisen in the fields of forestry, biology, or ecology through the last century. Growth and development of forest standscan be forecast by a variety of models with differing objectivesand degreesof complexity. These modelscan be incor- porated into economic simulationswhich select optimum managementregimes. Most models, with few exceptions, such as Stage's (1973) prognosismodel, as- sume that random effects can be ignored; i.e., only mean trends for a class of standsare forecast. Thus, a consequenceof this assumptionis a possibility that the managementregime chosen as being optimum for the mean stand is not necessarilythe optimum regime for any particular stand. However, Adams and Ek (1974) have proposedusing stochasticmodels, which admit to uncertainty, in the evaluation of managementregimes. The uncertainty in growth and mortality patterns,particularly at high densities,are too importantto be ignored.Stochastic growth models have not been developed to any great extent, possibly because The authorsare, respectively,Tree ImprovementSpecialist, Tropical ForestryResearch, and For- estryBiometrician (currently enrolled in a Ph D programat the Universityof Georgia),both from the WesternForestry Research Center, WeyerhaeuserCompany, Centralia, WA 98531.Acknowledgment is madeto the many colleagueswho encouragedand contributedto the developmentof this manu- script;to the New ZealandForest Service, Nelson Conservancy for providingDouglas-fir growth and yield data; and the WeyerhaeuserCompany for supportingand authorizingpublication of this manu- script. Manuscriptreceived 23 August 1978. 518 / FOREST SCIENCE foresters are generally more comfortable with the assumptionof certainty (Bell 1977), needed error distributionsare not known, or becauseanalytical solutions are exceedingly difficult to obtain (Chapman 1967). The error distributions in growth and mortality are quite complex and cannot yet be determinedfrom ex- isting data bases with the precision required for the dynamic programmingmeth- ods (Hool 1966, Lembersky and Johnson 1975) available in forestry. We are proposinga simpler model which attempts to delimit stand conditions likely to result in particular patterns of growth and development. The error dis- tribution in mortality trends is recognized,though not specificallydefined. The resulting model, not a growth model per se, is similar in some respects to earlier hardwood stocking guides (Ginrich 1967, Leak and others 1969). This modelshould be easilycomprehended by nonbiometriciansand can, we feel, be extrapolated to untested management regimes with no more "heroic" as- sumptionsthan are required by the more complex approaches. Stand density manipulationhas the potential to make a major impact on indi- vidual tree size and stand yield. While the literature on spacing, thinning, and stand yield is voluminous,research to date has achievedlittle more than confirm "... what was formerly based on informal observation, namely, that there is an associationbetween the initial spacingand various tree and stand characteristics .... "(Evert 1971). In 1971 Evert could state that spacingand thinning studies have contributedlittle to the assessmentof differencesin degree in tree size and standyield that would allow decisionmakingfor the achievementof any particular managementobjective. His statementis essentiallytrue today, and thoughgrowth modelsfor somespecies give goodresults over limited rangesof age and density, there is still no general framework for relating tree size, stand yield, and stand density. Central to a discussionof stand density managementis an index to quantify the effects of density (trees per unit area) on growth. Stand density indices, functions which are used to estimate the effects of density, have historically been comparisonsof standsto reference stands,either in maximum stockingsituations or at crown closure. Examples of these are, respectively, Reineke's (1933) stand density index and crown competitionfactor (Krajicek and others 1961). These and other indices are discussedby Curtis (1970), who regards them as having approximately equal utility. One drawback to many of these indices is that they relate standsin terms of diameter and do not reflect the fact that "the space a ß . tree can utilize is related to both its diameter and height" (Briegleb 1952). Briegleb's (1952) index, based on a standardnumber of trees per acre by average diameter and average height, is highly regarded by Worthington and Staebler (1961) and Vezina (1964). However, Briegleb'sconclusion, that for standswith the samemean diameterthe taller standcan supporta greater numberof trees, may be subject to dispute: his conclusionis based on observed stand structuresimme- diately after thinning and cannot reflect tree space requirementsor growth po- tential. We define a relative density index, Pt, as the ratio of actual stand density to the maximum stand density attainable in a stand with the same mean tree volume. Because tree volume varies with both height and diameter, our density index reflects the same factors as does Briegleb's (1952) index; however, the effect of a greaterheight for a given diameteris viewed differently. The proposeddensity index is equivalentin conceptto a density indexing systemproposed by Tadaki (1964), first called a "management base line" and subsequently"relative den- sity." Tadaki's index is proportional to the ratio of a stand's mean tree volume to the maximum mean tree volume attainable at the same density. Though our relative density index and Tadaki's index have identical utility from a computa- tional viewpoint, the relative density which we have defined is directly propor- VOLUME 25, NUMBER 3, 1979 / 519 Mean Tree Volume (ms) (ft 3) 4.0 3.0 2.0 Maximum size-densityreiationship = 12.644-1.5 In 0(TPA)] 1.0 0.5 0.3 0.1 100 200 400 600 800 1000 2000 (trees/acre) I I I i 'l I I I i I i I I I I I I 300 500 1000 1500 2000 3000 5000 (trees/hectare) Density Figure 1. The maximum size-densityrelationship and the natural stand data used in positioning this relationship. tional to density. Thus, the new index may be more useful than Tadaki's for understandingthe effectsof densitymanipulation. The model discussedhere is partly quantitative and partly conceptual;above all it is simple.The approachwas adoptedin place of other modellingalternatives in part becauseof its easeof comprehension,especially by nonbiometricians,and its applicabilityto a wide range of stand conditions. THE DENSITY MANAGEMENT DIAGRAM FOR DOUGLAS-FIR The densitymanagement diagram, a graphicaltool for relating stand density, tree size, and stand yield, is a graph of mean tree volume and stand density on which the following relationshipshave been superimposed. Maximum Size-DensityRelationship.--We acceptthe conceptof maximumsize- density as a general principle of plant populationbiology: in pure even-aged 520 / FOREST SCIENCE stands, the maximum mean tree size attainable for any density can be determined by a relationshipknown as the -3/2 power law. v = a p-a/• (1) where v = mean tree volume a = constant p = standdensity. A review of the derivation and an example of the application of this relationship is presented by Drew and Fiewelling (1977). There is no rigorous statistical procedure available for selecting the limiting boundaryof a zone, given that someunknown randomvariation is to be expected. We chose to position the maximum size-density relationship by the following procedure. Volume computationsfor 1 to 9 repeat measurementsof 313 growth and yield plots in natural stands of coastal Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, from Washington and Oregon were graphically summarized on log-log scale (Fig. 1). The data base is essentially that described by King (1970), with some additions. The maximum size-density parameter in Equation 1 was selected for this data set by positioning a line of -3/2 slope near
Load more

Recommended publications
  • Variant Overview Agriculture Forest Vegetation Simulator Forest Service Forest Management Service Center Fort Collins, CO 2008 Revised: June 2021
    United States Department of Tetons (TT) Variant Overview Agriculture Forest Vegetation Simulator Forest Service Forest Management Service Center Fort Collins, CO 2008 Revised: June 2021 Spread Creek, Bridger-Teton National Forest (Liz Davy, FS-R4) ii Tetons (TT) Variant Overview Forest Vegetation Simulator Authors and Contributors: The FVS staff has maintained model documentation for this variant in the form of a variant overview since its release in 1982. The original author was Gary Dixon. In 2008, the previous document was replaced with an updated variant overview. Gary Dixon, Christopher Dixon, Robert Havis, Chad Keyser, Stephanie Rebain, Erin Smith-Mateja, and Don Vandendriesche were involved with that update. Don Vandendriesche cross-checked the information contained in that variant overview update with the FVS source code. In 2010, Gary Dixon expanded the species list and made significant updates to this variant overview. FVS Staff. 2008 (revised June 28, 2021). Tetons (TT) Variant Overview – Forest Vegetation Simulator. Internal Rep. Fort Collins, CO: U. S. Department of Agriculture, Forest Service, Forest Management Service Center. 56p. iii Table of Contents 1.0 Introduction................................................................................................................................ 1 2.0 Geographic Range ....................................................................................................................... 2 3.0 Control Variables .......................................................................................................................
    [Show full text]
  • Stand Density Management for Optimal Volume Production
    Stand Density Management for Optimal Volume Production Micky Gale Allen II Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy In Forestry Harold E. Burkhart, Chair Philip J. Radtke Thomas R. Fox Inyoung Kim March 25, 2016 Blacksburg, Virginia Keywords: growth-density relationship, periodic annual increment, Langsaeter’s hypothesis, planting density, thinning intensity, loblolly pine Copyright 2011, Micky Gale Allen II Stand Density Management for Optimal Volume Production Micky Gale Allen II ABSTRACT The relationship between volume production and stand density, often termed the “growth-density relationship”, has been studied since the beginnings of forestry and yet no conclusive evidence about a general pattern has been established. Throughout the literature claims and counterclaims concerning the growth-density relationship can be found. Different conclusions have been attributed to the diverse range of definitions of volume and stand density among problems with study design and other pitfalls. Using data from two thinning studies representing non-intensively and intensively managed plantations, one spacing trial, and one thinning experiment a comprehensive analysis was performed to examine the growth-density relationship in loblolly pine. Volume production was defined as either gross or net periodic annual increment of total, pulpwood, or sawtimber volume. These definitions of volume production were then related to seven measures of stand density including the number of stems per hectare, basal area per hectare, two measures of relative spacing and three measures of stand density index. A generalized exponential and power type function was used to test the hypothesis that volume production follows either an increasing or unimodal pattern with stand density.
    [Show full text]
  • Developing Optimal Commercial Thinning Prescriptions: a New Graphical Approach
    Developing Optimal Commercial Thinning Prescriptions: A New Graphical Approach KaDonna C. Randolph, USDA Forest Service Forest Inventory and Analysis, Knoxville, TN 37919; and Robert S. Seymour and Robert G. Wagner, Department of Forest Ecosystem Science, University of Maine, Orono, ME 04469. ABSTRACT: We describe an alternative approach to the traditional stand-density management diagrams and stocking guides for determining optimum commercial thinning prescriptions. Predictions from a stand-growth simulator are incorporated into multiple nomograms that graphically display postthinning responses of various financial and biological response variables (mean annual increment, piece size, final harvest cost, total wood cost, and net present value). A customized ArcView GIS computer interface (ThinME) displays multiple nomograms and serves as a tool for forest managers to balance a variety of competing objectives when developing commercial thinning prescriptions. ThinME provides a means to evaluate simultaneously three key questions about commercial thinning: (1) When should thinning occur? (2) How much should be removed? and (3) When should the final harvest occur, to satisfy a given set of management objectives? North. J. Appl. For. 22(3):170–174. Key Words: Nomogram, silvicultural system, financial analysis, FVS, simulation. Careful regulation of stand density through thinning North America in the late 1970s (Drew and Flewelling arguably distinguishes truly intensive management above 1979, Newton 1997a). SDMDs graphically depict the rela- all other silvicultural treatments (Smith et al. 1997), and in tionship between stand density and average tree size (either every important forest region, rigorously derived thinning quadratic mean dbh or stemwood volume, and frequently schedules are crucial in meeting production objectives. Typ- supplementary isolines depicting tree height; Newton ically thinnings are prescribed using stocking guides or 1997b, Wilson et al.
    [Show full text]
  • Comparing MODIS Net Primary Production Estimates with Terrestrial National Forest Inventory Data in Austria
    Remote Sens. 2015, 7, 3878-3906; doi:10.3390/rs70403878 OPEN ACCESS remote sensing ISSN 2072-4292 www.mdpi.com/journal/remotesensing Article Comparing MODIS Net Primary Production Estimates with Terrestrial National Forest Inventory Data in Austria Mathias Neumann 1,*, Maosheng Zhao 2, Georg Kindermann 3 and Hubert Hasenauer 1 1 Institute of Silviculture, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Vienna, Peter-Jordan-Str. 82, A-1190 Vienna, Austria; E-Mail: [email protected] 2 Department of Geographical Sciences, University of Maryland, College Park, MD 20742, USA; E-Mail: [email protected] 3 Natural Hazards and Landscape, Department of Forest Growth and Silviculture, Federal Research and Training Centre for Forests, Vienna, Seckendorff-Gudent-Weg 8, A-1130 Vienna, Austria; E-Mail: [email protected] * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +43-1-47654-4078; Fax: +43-1-47654-4092. Academic Editors: Randolph H. Wynne and Prasad S. Thenkabail Received: 11 December 2014 / Accepted: 17 March 2015 / Published: 1 April 2015 Abstract: The mission of this study is to compare Net Primary Productivity (NPP) estimates using (i) forest inventory data and (ii) spatio-temporally continuous MODIS (MODerate resolution Imaging Spectroradiometer) remote sensing data for Austria. While forest inventories assess the change in forest growth based on repeated individual tree measurements (DBH, height etc.), the MODIS NPP estimates are based on ecophysiological processes such as photosynthesis, respiration and carbon allocation. We obtained repeated national forest inventory data from Austria, calculated a “ground-based” NPP estimate and compared the results with “space-based” MODIS NPP estimates using different daily climate data.
    [Show full text]
  • Development of a Stand Density Management Diagram for Teak Forests in Southern India
    Regular Article pISSN: 2288-9744, eISSN: 2288-9752 J F E S Journal of Forest and Environmental Science Journal of Forest and Vol. 30, No. 3, pp. 259-266, August, 2014 Environmental Science http://dx.doi.org/10.7747/JFS.2014.30.3.259 Development of a Stand Density Management Diagram for Teak Forests in Southern India Vindhya Prasad Tewari1,* and Juan Gabriel Álvarez-Gonz2 1Institute of Wood Science and Technology, Bangalore 560003, India 2Universidad de Santiago de Compostela, Lugo 27002, Spain Abstract Stand Density Diagrams (SDD) are average stand-level models which graphically illustrate the relationship between yield, density and mortality throughout the various stages of forest development. These are useful tools for designing, displaying and evaluating alternative density regimes in even-aged forest ecosystems to achieve a desired future condition. This contribution presents an example of a SDD that has been constructed for teak forests of Karnataka in southern India. The relationship between stand density, dominant height, quadratic mean diameter, relative spacing and stand volume is represented in one graph. The relative spacing index was used to characterize the population density. Two equations were fitted simultaneously to the data collected from 27 sample plots measured annually for three years: one relates quadratic mean diameter with stand density and dominant height while the other relates total stand volume with quadratic mean diameter, stand density and dominant height. Key Words: stand density diagram, yield, relative
    [Show full text]
  • Reineke's Stand Density Index
    Reineke’s Stand Density Index: Where Are We and Where Do We Go From Here? John D. Shaw USDA Forest Service, Rocky Mountain Research Station 507 25th Street, Ogden, UT 84401 [email protected] Citation: Shaw, J.D. 2006. Reineke’s Stand Density Index: Where are we and where do we go from here? Proceedings: Society of American Foresters 2005 National Convention. October 19-23, 2005, Ft. Worth, TX. [published on CD-ROM]: Society of American Foresters, Bethesda, MD. REINEKE’S STAND DENSITY INDEX: WHERE ARE WE AND WHERE DO WE GO FROM HERE? John D. Shaw USDA Forest Service Rocky Mountain Research Station Forest Inventory and Analysis 507 25th Street Ogden, UT 84401 Email: [email protected] Abstract: In recent years there has been renewed interest in Reineke’s Stand Density Index (SDI). Although originally described as a measurement of relative density in single-species, even-aged stands, it has since been generalized for use in uneven-aged stands and its use in multi-species stands is an active area of investigation. Some investigators use a strict definition of SDI and consider indicies developed for mixed and irregularly structured stands to be distinct from Reineke’s. In addition, there is ongoing debate over the use of standard or variable exponents to describe the self-thinning relationship that is integral to SDI. This paper describes the history and characteristics of SDI, its use in silvicultural applications, and extensions to the concept. Keywords: Stand Density Index, self-thinning, density management diagrams, silviculture, stand dynamics INTRODUCTION Silviculturists have long sought, and continue to seek, simple and effective indicies of competition in forest stands.
    [Show full text]
  • A Crown Width-Diameter Model for Natural Even-Aged Black Pine Forest Management
    Article A Crown Width-Diameter Model for Natural Even-Aged Black Pine Forest Management Dimitrios Raptis 1 , Vassiliki Kazana 1,* , Angelos Kazaklis 2 and Christos Stamatiou 1 1 Eastern Macedonia & Thrace Institute of Technology, Department of Forestry and Natural Environment Management, 1st km Drama-Mikrohori, 66100 Drama, Greece; [email protected] (D.R.); [email protected] (C.S.) 2 OLYMPOS, Centre for Integrated Environmental Management, 39 Androutsou Str., 55132 Kalamaria, Thessaloniki, Greece; [email protected] * Correspondence: [email protected]; Tel.: +30-25210-60422 Received: 26 July 2018; Accepted: 2 October 2018; Published: 3 October 2018 Abstract: Crown size estimations are of vital importance in forest management practice. This paper presents nonlinear models that were developed for crown width prediction of Black pine (Pinus nigra Arn.) natural, pure, even-aged stands in Olympus Mountain, central Greece. Using a number of measured characteristics at tree and plot level from 66 sample plots as independent variables, an attempt was made to predict crown width accurately, initially based on Least Square Analysis. At the second stage, nonlinear mixed effect modeling was performed in order to increase the fitting ability of the proposed models and to deal with the lack of between observations independence error assumption. Based on the same form, a generalized crown width model was developed by including six main regressors, such as the diameter at breast height, the total height, the canopy base height, the basal area, the relative spacing index and the diameter to quadratic mean diameter ratio, while at the final stage, the same model was expanded to mixed-effect.
    [Show full text]
  • PERFECTING a STAND-DENSITY INDEX for EVEN- AGED FORESTS' by L
    PERFECTING A STAND-DENSITY INDEX FOR EVEN- AGED FORESTS' By L. H. REINEKE Associate SilvicuUurist, California Forest Experiment Station, Forest Service, United States Department of Agriculture INTRODUCTION An adequate expression for density of stocking in even-aged forests has long been sought by foresters. Comparison of total basal area of the stand with yield-table values of basal area for the same age and site quality has been the usual method of evaluating stand density. Other methods have been proposed, but none has given results good enough to warrant general adoption or displacement of the basal-area method. It is the purpose of this paper to present a stand-density index which does not require a yield table and which is not affected by possible errors in shape of the total basal area-age curve. This stand- density index, based on the relationship between number of trees per acre and their average diameter, is premised on the characteristic distribution of tree sizes in even-aged stands. It is a well-estabHshed fact that in any given stand a curve showing the relative (percentile) frequency of occurrence of the various tree sizes (diameters) has a characteristic form, often approximating that of the ^^normal frequency curve'' or '^normal curve of error" (1, 2, STATISTICAL BASIS This frequency-curve form may differ with species; the departures from normal may embody positive or negative skewness {6), or a logarithmic form may be assumed {4). Within a given species, however, stands of all ages on all sites have essentially the same characteristic frequency-curve form (4, 7, 9).
    [Show full text]
  • Relation of Initial Spacing and Relative Stand Density Indices to Stand Characteristics in a Douglas-Fir Plantation Spacing Trial Robert O
    United States Department of Agriculture Relation of Initial Spacing and Relative Stand Density Indices to Stand Characteristics in a Douglas-fir Plantation Spacing Trial Robert O. Curtis, Sheel Bansal, and Constance A. Harrington Forest Pacific Northwest Research Paper April Service Research Station PNW-RP-607 2016 In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights regulations and policies, the USDA, its Agencies, offices, and employees, and institutions participating in or administering USDA programs are prohibited from discriminating based on race, color, national origin, religion, sex, gender identity (including gender expression), sexual orientation, disability, age, marital status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal or retaliation for prior civil rights activity, in any program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing deadlines vary by program or incident. Persons with disabilities who require alternative means of communication for program information (e.g., Braille, large print, audiotape, American Sign Language, etc.) should contact the responsible Agency or USDA’s TARGET Center at (202) 720-2600 (voice and TTY) or contact USDA through the Federal Relay Service at (800) 877-8339. Additionally, program information may be made available in languages other than English. To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at http://www.ascr.usda.gov/complaint_filing_cust. html and at any USDA office or write a letter addressed to USDA and provide in the letter all of the information requested in the form.
    [Show full text]
  • Suggested Stocking Levels for Forest Stands in Northeastern
    Suggested Stocking Levels for Forest Stands in Northeastern United States Oregon and Southeastern Department of 1 Agriculture Washington Forest Service Pacific Northwest P.H. Cochran, J.M. Geist, D.L Clemens, Rodrick R. Research Station Clausnitzer, and David C. Powell Research Note PNW-RN-513 April 1994 Abstract Catastrophes and manipulation of stocking levels are important determinants of stand development and the appearance of future forest landscapes. Managers need stocking level guides, particularly for sites incapable of supporting stocking levels presented in normal yield tables. Growth basal area (GBA) has been used by some managers in attempts to assess inherent differences in site occupancy but rarely has been related to Gingrich-type stocking guides. To take advantage of information currently available, we used some assumptions to relate GBA to stand density index (SDI) and then created stocking level curves for use in northeastern Oregon and southeastern Washington. Use of these curves cannot be expected to eliminate all insect and disease problems. Impacts of diseases, except dwarf mistletoe (Arceuthobium campylopodum Engelm.), and of insects, except mountain pine beetle (Dendroctonusponderosea Hopkins) and perhaps western pine beetle (Dendroctonus brevicomis LeConte), may be independent of density. Stands with mixed tree species should be managed by using the stocking level curves for the single species pre- scribing the fewest number of trees per acre. Keywords: Forest health, growth basal area, mountain pine beetle, stand density index, stressed sites, Oregon—northeast, Washington—southeast. Introduction Concerns about forest health east of the crest of the Cascade Range in Oregon and Washington have highlighted the need for site-specific information for a range of management practices, including stocking level control.
    [Show full text]
  • South Central Oregon and Northeast California (SO) Variant Overview
    United States Department of South Central Oregon and Agriculture Northeast California (SO) Forest Service Forest Management Variant Overview Service Center Forest Vegetation Simulator Fort Collins, CO 2008 Revised: June 2021 Ponderosa pine stand in Northern California (Amy Jo Krommes, FS-R6) ii South Central Oregon and Northeast California (SO) Variant Overview Forest Vegetation Simulator Authors and Contributors: The FVS staff has maintained model documentation for this variant in the form of a variant overview since its release in 1984. The original author was Gary Dixon. In 2008, the previous document was replaced with this updated variant overview. Gary Dixon, Christopher Dixon, Robert Havis, Chad Keyser, Stephanie Rebain, Erin Smith-Mateja, and Don Vandendriesche were involved with this update. Stephanie Rebain cross-checked information contained in this variant overview with the FVS source code. FVS Staff. 2008 (revised June 28, 2021). South Central Oregon and Northeast California (SO) Variant Overview – Forest Vegetation Simulator. Internal Rep. Fort Collins, CO: U. S. Department of Agriculture, Forest Service, Forest Management Service Center. 100p. iii Table of Contents 1.0 Introduction................................................................................................................................ 1 2.0 Geographic Range ....................................................................................................................... 2 3.0 Control Variables .......................................................................................................................
    [Show full text]
  • Guidelines for Thinning Ponderosa Pine for Improved Forest Health
    GUIDELINES FOR THINNING PONDEROSA PINE FOR IMPROVED FOREST HEALTH AND FIRE PREVENTION PUBLICATION AZ1397 03/2006 ISSUED MARCH, 2006 Past land management practices have often distant from edges. Using this point as the first plot TOM DEGOMEZ center, measure a radius of 26.3 feet. Use powdered Forest Health resulted in ponderosa pine stands that are overly chalk or other marking method to delineate the Specialist dense and prone to catastrophic wildfire or bark beetle outbreaks (Covington and Moore 1994a, boundaries of the plot. 1994b; Kolb et al. 1994). Landowners and property cals.arizona.edu/ Determining stand density managers in the Southwest are now faced with pubs/natresources/ determining appropriate ways to prevent these Count all the trees within the 1/20th acre circle, az1397.pdf potentially stand-replacing events. The best way to then multiply times 20. This will give you an reduce wildfire threat, drought damage and attack estimate of the number of trees per acre. At this by bark beetles is to lower stand density through point it will be good to determine how many th mechanical thinning. This publication will help those 1/20 acre plots you will be measuring. Use your This information landowners with little or no experience to determine map to help layout a grid work of plots in a manner has been reviewed by existing stand density and choose an appropriate that is uniformly spaced and represents variation university faculty. method to select trees for removal where needed. in stand composition across the property. An additional benefit from reducing stand density Determining basal area is that remaining trees will grow more rapidly than when in an over-stocked condition.
    [Show full text]