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Models

This page contains links to descriptions about models of dead tree dynamics. We have not looked extensively for models. Originators of models not described here are welcome to submit information on their models to the webmaster. For authors of models described here (and you never knew it) feel free to provide an update or qualifiers.

Deadwood Management

• DecAID
• Deadwood Habitat in Spruce - Subalpine Fir Forests

Standing Dead Tree Fall Models

• Snag Recruitment Simulator (SRS1)
• Snag Dynamics Projection Model (SDPM)
• UNITPLAN
• FVS - Fire model
• TASS Dynamics of Dead Trees - Tree Level (DDT-TL)
• TIPSY Snag Model
• CWD - Woody Debris Recruitment Simulator

Down Dead Tree Models

• TASS CWD Model
• TIPSY CWD Model

Models: Deadwood Management

DecAID Advisor

Authors

Availability

Brief Description

Software Requirements

Documentation and Publications Available

Input

Output

DecAID allows the user to specify a vegetation condition, and to:

• view a synthesis of empirical data on wildlife use of wood decay elements in Washington and Oregon;
• determine which selected wildlife species would be associated with specific sizes or amounts of snags or down wood at various statistical levels;
• determine the sizes or amounts of snags or down wood to meet specified wildlife species objectives;
• view a narrative interpretation of these data along with the literature sources;
• view summaries of the range of snag and down wood levels in unharvested forest, representing ranges of natural conditions, and across all current forest conditions;
• determine effects of present or expected stand conditions on wildlife using wood decay elements;
• determine implications of insect and pathogen activity on the creation and management of snags and down wood for wildlife habitat;
• view advice on the roles of insects and pathogens in creation and dynamics of snags and down wood; and
• determine implications of snag and down wood levels on managing for overall forest ecosystem health.

Species and Geographic Applicability

1 Westside Lowlands Conifer-Hardwood Forest
2 Westside Oak and Dry Douglas-fir Forest and Woodlands
3 Southwest Oregon Mixed Conifer-Hardwood Forest
4 Montane Mixed Conifer Forest
5 Eastside Mixed Conifer Forest
6 Lodgepole Pine Forest and Woodlands
7 Ponderosa Pine and Eastside White Oak Forests and Woodlands
8 Upland Aspen Forest
9 Subalpine Parkland
13 Western Juniper and Mountain Mahogany Woodlands

See http://www.fs.fed.us/wildecology/decaid/decaid_background/decaid_whs.htm.

Data Used for Parameterization

The information presented on ranges of snag and down wood amounts under natural and current conditions is based on forest inventories, research studies, and other sources. Forest inventories include: the Current Vegetation Survey (CVS), conducted by USDA Forest Service, Pacific Northwest Region, on National Forest lands; the Forest Inventory and Analysis (FIA), conducted by USDA Forest Service, Pacific Northwest Research Station, on non-federal lands; and the Natural Resource Inventory (NRI), conducted by USDI Bureau of Land Management (BLM) on BLM lands in western Oregon. Inventory plot data are unavailable for reserved areas outside BLM lands and National Forests, such as on National and State Parks.

The information on insects and pathogens is based on empirical studies, CVS, NRI, and FIA inventory data, and expert understanding of potential effects.

See http://www.fs.fed.us/wildecology/decaid/decaid_background/decaid_stbasis.htm

Authors

Availability

Brief Description

The model projects hybrid white spruce and subalpine fir snag densities and downed log volumes into the future in response to treatment scenarios specified by the operator. Densities and volumes are tracked by decay class. Remnant "stubs" - created by management or from snapped-off snags - are also tracked. The model simulates harvesting, road building, and snag felling along road and block edges (related to worker safety regulations) and the establishment of different types and amounts of within-block reserves.

Software Requirements

Hardware Requirements

Documentation and Publications Available

Input

Harvesting sub-module - one mode is driven by an input harvest schedule and simply "replays" a harvest schedule by harvesting cells for each five years, identified in an input layer. Stand age is reset and roads are updated. The second mode is driven by a harvest target, specified as an area per year.

Access management sub-module - activates and builds road segments based on an input road layer that identifies existing and proposed roads.

Output

Deadwood dynamics sub-model - we conceptualize the deadwood system as a flow of stems (individuals) and volume (m3) from live trees through to down wood (and eventually soil) and stumps. We don't directly represent the live canopy, but rather use parameter estimates of recruitment rates by species type and size class. We divide standing snags and stumps into 5 decay classes and downed wood into 4 decay classes. We also grouped deadwood proportionally into three size classes.

Deadwood management sub-model - snags are removed as a direct consequence of logging and road construction. This sub-model is designed to apply the effects of the management actions from the forest projection component. All deadwood is removed on roads. In blocks, all snags are felled. Parameters specify if this wood is left on site or removed.

Models run using the SELES landscape modelling environment and output can be analysed with Excel or statistics packages such as SYSTAT or SAS.

Species and Geographic Applicability

Data Used for Parameterization

Models: Standing Dead Tree Fall Models

******************** SRS ********************

Snag Recruitment Simulator SRS1

The following description is based on a review of SRS1 done around 1994 by Jeff Stone, Ministry of Forests, Kamloops, BC. This review should be checked to ensure that no changes have occurred to the model.

Author

Bruce G. Marcot

USDA Forest Service, Pacific Northwest Research Station, 333 SW 1st Avenue, P.O. Box 3890, Portland, OR 97208. Tel: 503-326-4952.

Availability

Brief Description

SRS1 is a snag dynamics projection system. The model simulates snag densities through time and their transition among decay classes. The user must supply the initial snag densities by size and decay class, density of green trees killed by size class, and density by size of snags recruited in the stand over 10-year periods. Several versions of SRS1 exist. The "west side" version is based on data (falldown and decay) from Douglas-fir stands west of the Cascade crest in Oregon. The "east side" version is based on data (falldown) from ponderosa pine stands in eastern Oregon. The models are based on the life-table approach of Neitro et al. (1985). The complete SRS system also includes SRS2 which projects the density and decay classes of snags required to support a given level of primary cavity excavators.

Software Requirements

Operating System:

DOS 3.3 or later

Specific Software:

SRS1 is available in a spreadsheet format (LOTUS 1-2-3 or QUATTRO) and as a DOS executable runtime version of the spreadsheet. The model also appears to work in EXCEL.

Documentation and Publications Available

Documentation of the program is provided digitally with the program. This manual provides a brief overview of the model, details differences among the model versions and types, discusses the model limitations, and describes the model use for the original spreadsheet format. Additionally, the author provides two background documents: (1) an outline of a presentation on analysing snag habitat and modelling snag recruitment and (2) an annotated review of selected literature on snag distribution. Online documentation is available both in the runtime and spreadsheet formats.

Input

There are 3 sources of snags a) snags from previous forest left on site at time 0, b) snags created by killing live (green) trees, and c) snags recruited due to suppresion mortality in the stand.

Snags from the previous forest left on site are entered as snags/100 acres by dbh class and decay class. The mean dbh of the 25+" class must also be entered. No snag ages are required. SRS1 assumes the mid-point ages for a snag in the hard decay class (i.e., half of the transition age of hard to soft) and the soft decay class (i.e., midpoint between transition age and maximum snag age).

Snags created by killing live (green) trees are entered as snags/100 acres by the year (i.e., stand age) of creation and the dbh class. These snags are assumed to all have a hard decay class and 0 age.

Snags recruited due to supression mortality in the stand are entered by one of two methods. The first method requires the quadratic mean dbh (inches) of the newly recruited snags and the yearly rate of snag recruitment (snags/100 acres) for each decade of stand age. The second method requires the quadratic mean dbh (inches) of the newly recruited snags and the basal area of the trees which die during the decade (i.e., this information enables the calculation of snag numbers). The yearly and decadal rates of snag recruitment are calculated.

Output

SRS1 provides tabular and graphical output. The spreadsheet and runtime versions provide similar information except that the runtime version does not present snag life tables for individual size classes.

The tables provided are (1) a summary of snag density by decay class and stand age (Figure 7) and (2) snag life tables for individual size classes (Figure 8). Additionally, input tables (Figures 4, 5, 6) provide basic summary information and background tables demonstrate the parameters used in the model.

Graphs are available for (1) snag density by size and decay class, (2) snag density by size class for the combined decay classes, and (3) graphs of the assumptions of the midpoint of ages of snags by decay class, cohort survivorship of snags by size class, and age-class survivorship of snags by size class.

Species and Geographic Applicability

The model is applicable to Oregon and Washington

Douglas-fir - west of the Cascade crest
Ponderosa pine - east of the Cascade ridge

Data Used for Parameterization

Douglas-fir - from Cline et al. 1980
Ponderosa pine - provided by E. Bull, USDA Forest Service, PNW Research Lab, La Grande, Oregon
****************** SDPM ***********************

Snag Dynamics Projection Model SDPM

The following description is based on a review of the original SDPM done around 1994 by Jeff Stone, Ministry of Forests, Kamloops, BC. This review should be replaced with a description of the newer model.

Authors

Bill McComb

Department of Forest Science, Oregon State University, Corvallis, OR

Abdel-Azim Zumrawi

Department of Forest Science, Oregon State University, Corvallis, OR

Janet Ohmann

USDA Forest Service, Forest Inventory and Analysis, Forest and Range Experiment Station, Portland, OR

Martin G. Raphael

USDA Forest Service, Forest Inventory and Analysis, Pacific Northwest Forest and Range Experiment Station, Olympia, WA

Michael Morrison

Department of Forestry, University of California, Berkeley

Availability

Brief Description

SDPM is a snag dynamics model for Douglas-fir, western hemlock, and ponderosa pine. The model projects the fall down of hard and soft snags and the transition of snags from a hard to a soft decay class. The user must supply the initial and recruited individual snag densities and sizes (i.e., not stand level summaries) and site information. The model is designed to be used in conjunction with individual-tree growth and yield models.

Software Requirements

Operating System:

DOS 3.3 or later

Specific Software:

SDPM is available in a stand alone DOS executable format. The program was written in FORTRAN. Additionally, spreadsheet (LOTUS 1-2-3 or QUATTRO) worksheets are available for the creation of input data sets.

Documentation and Publications Available

Documentation of this program is weak. Only a README.DOC with the program is currently available. This file describes briefly the background and operation of the program. No specific user manual is present.

Input

The program requires input data sets and interactively provided information. The information required includes site information such as slope (%), aspect (degrees), and stand basal area (initial and growth between projected periods). Individual snag information includes dbh (inches), decay class (soft or hard), species (Douglas-fir, western hemlock, or ponderosa pine), and the expansion factor (snags per acre) each tree represents (based on a single sample point). Figures 1 and 2 demonstrate the input files. Note that the maximum accumulated number of snags in the input data is 1000 (i.e., array limitations of the model).

The program runs interactively. The user is prompted first for the remaining snag data set, the number of sample points, output data set name, a label for the output, and the number of 10-year cycles. The number of sample points assume that the expansion factors per tree are based on a single sample point (thus if 2 sample points all expansion factors are divided by 2). Note the data sets should be in the same sub-directory as the program. For each 10-year cycle, the program asks for the basal area (ft2/Ac) of the stand at the end of the previous period (i.e., at the beginning of the new period), number of sample points, and an input file of newly recruited snags. For input, the program asks if you first have an input file of newly recruited snags. If you do not, it assumes no snags are recruited in that decade. Do not use a blank file as input as the program will fail.

Output

The output consists of tables outlining the snags per acre by diameter class and decay class. For each 10-year period the beginning, 10-year change, and ending values are noted. Tables are outputted by species and for all species combined.

Species and Geographic Applicability

The model is for 3 species and is applicable to Washington, Oregon and northern California. Specifically,

Douglas-fir - west of Cascade crest
Western hemlock - west of Cascade crest
Ponderosa pine - east of Cascade crest and northern California

Data Used for Parameterization

Douglas-fir - western Washington (ask McComb for specifics)
Western hemlock - western Washington (ask McComb for specifics)
Ponderosa pine - eastern Oregon and northern California

UNITPLAN

The following description is based on a review of UNITPLAN around 1994 by Jeff Stone, Ministry of Forests, Kamloops, BC. This review should be checked to ensure that no changes have occurred to the model.

Author

Matthew G. Hunter

USDA Forest Service, Willamette National Forest,

P.O. Box 199, Blue River OR 97413

Tel: 503-822-3317 ext 268

Brief Description

UNITPLAN is a snag dynamics projection system. The model tracks the densities of snags over time and their transition among decay classes. The user can also assign a value (e.g., for nests of a certain species) to a snag class. The user supplies input information such as the number of natural snags at stand initiation, the number of green trees converted to snags at stand initiation, the number of green trees left from the previous stand for later conversion to snags, and the number of snags naturally recruited (i.e., suppresion mortality). The model was designed to be integrated with other models used on the Willamette National Forest.

Software Requirements

Operating System:

DOS 3.3 or later

Specific Software:

UNITPLAN is a Lotus 1-2-3 spreadsheet but should operate with Quattro Pro and Excel.

Documentation and Publications Available

A four page "Overview of UNITPLAN" (Hunter 19 May 1990) and a printed example of the spreadsheet was provided with the software. The overview describes the model and input.

Input

The user supplies input for 4 user defined snag classes. These classes may be a species or size class. For example, class A may be defined as snags 0-7.2", class B as snags 7.3-10.9", class C as snags 11-18.9", and class D as snags greater than 19.0" dbh. Input is then based on these classes. For snag creation the user supplies information on the number of snags in each class for (1) the natural snags remaining at the beginning (Figure 11), (2) green trees immediately converted to snags (Figure 12), (3) green trees left from previous stand converted to snags at a later date (Figure 13), (4) mortality of green trees from new stand (Figure 14), and (5) the density of "valuable" snags present in a stand over time for up to 6 management scenarios (Figure 15). The user can manipulate the various input classes to suit their individual needs.

The user must supply the transition parameters for (1) the survival of snags from one period to the next (Figure 16), (2) the percent of surviving snags that are valuable (Figure 17), and (3) the mid-point age for the decay class (Figure 18). Space is also provided on each spreadsheet for user provided background notes.

Output

UNITPLAN has 2 main summary tables. These tables provide (1) the summary of valuable snags per acre of the 5 classes of input trees (Figure 19) and (2) identification of management action needed (Figure 20). Intermediate summary tables are provided for each type of snag input (e.g., natural snags remaining) that tracks by 10-year time periods the density of the input snag information (Figures 21-24). All the tables provide total summaries and do not divide the snags by user defined class.

Species and Geographic Applicability

The model is general. The user supplies specific information.

Data Used for Parameterization

All parameters in UNITPLAN are user supplied. Example parameters based on Cline et al. (1980) and Graham (1981) are shown in the example.

******** FVS - Fire Model ***************

FVS - Fire Model

Sorry, we still need to obtain appropriate information on this model

Authors

Availability

Brief Description

Software Requirements

Documentation and Publications

Input

Output

Species and Geographic Applicability

Data Used for Model Parameterization

******** TASS DDT-TL ***************

TASS Dynamics of Dead Trees - Tree Level DDT-TL

Authors

Jeff Stone

Southern Interior Forest Region
B.C. Ministry of Forests

515 Columbia Street

Kamlops BC V2C 2T7 Canada

jeff.stone@gems7.gov.bc.ca

Availability

The TASS model is not distributed. A Windows program (TIPSY) incorporating a database of thousands of TASS runs is available for download.

Brief Description

TASS is a growth and yield model that simulates the growth of individual trees within a stand. The growth of a tree (i.e., the stem) is based on the development of the tree’s crown in response to internal growth regulation, the physical restrictions imposed by neighbouring trees, stochastic environmental factors, and imposed silvicultural treatments. Because of its individual tree and crown structure, many silvicultural practices (e.g., planting patterns, thinning) can be simulated.

A logistic fall model for dead trees was incorporated into the TASS model. The fall model calculates a probability that a tree will fall based on the tree's diameter and the time since a tree's death. A tree is assumed to fall when this probability is equal to a randomly chosen probability. Parameters for the model have been derived from permanent sample plot data.

Documentation and Publications

Currently, there is no published documentation of the standing dead tree model. An early example of the standing dead tree model is described in Stone, J.N. 1996. Modelling the dynamics of dead trees in TASS and WinTIPSY. FRDA Research Memo 227, Ministry of Forests, Victoria BC. This memo can be viewed at http://www.for.gov.bc.ca/hfd/pubs/docs/frm/frm227.pdf

Input

TASS requires a variety of start-up information (e.g., initial planting density and distribution, species, site index). The standing dead tree model other than identifying that the output is desired requires no input. Modification to parameters is accomplished by directly modifying the C code.

Output

For each time step in the stand's development, the snag summary table provides information on the current stems per ha of standing dead trees, the mean time since their death, mean quadratic diameter at 1.3 m height, mean total height, basal area, total volume, and a dbh size class distribution in stems per ha.

Species and Geographic Applicability

TASS has been parameterized for many of the commercial tree species of British Columbia. The standing dead tree model has only been parameterized from a limited data set for coastal Douglas-fir, coastal western hemlock, and lodgepole pine. Other species default to the coefficents for Douglas-fir.

Data Used for Model Parameterization

Standing dead tree data for Douglas-fir and western hemlock were collected from permanent sample plots of a single growth and yield research project located at 85 locations on Vancouver Island and coastal mainland British Columbia. Lodgepole pine parameters were derived from permanent sample plots near Canal Flats in the Southern Interior Forest Region of British Columbia. Further data are to be collected as part of the existing provincial wide growth and yield permanent sample plot program.

******** TIPSY Snag Model ***************

TIPSY Snag Model

Authors

Jeff Stone

Southern Interior Forest Region
B.C. Ministry of Forests

515 Columbia Street

Kamlops BC V2C 2T7 Canada

jeff.stone@gems7.gov.bc.ca

Ramsoft Ltd.

Victoria, BC

ramsoft@islandnet.com

Availability

TIPSY is available free of charge at the following web site http://www.for.gov.bc.ca/hre/gymodels/Tipsy/

Brief Description

TIPSY (Table Interpolation Program for Stand Yields) is a growth and yield model used in silvicultural decisions and timber supply analysis in British Columbia. TIPSY is based upon the interpolation of a set of yield tables from TASS, a British Columbia Ministry of Forests and Range individual tree growth and yield model. Additional features such as economic analysis have been developed specifically for TIPSY.

The snag model option of TIPSY estimates the number of standing dead trees by applying the dead tree fall probability from a logistic model to stand level estimates of the number of standing dead trees in diameter classes.

Software Requirements

Windows-based personal computer.

Documentation and Publications

The Snag model within TIPSY is described in the Help files contained with the program. An early example of the model is also described in Stone, J.N. 1996. Modelling the dynamics of dead trees in TASS and WinTIPSY. FRDA Research Memo 227, Ministry of Forests, Victoria BC. The memo can be viewed at http://www.for.gov.bc.ca/Hfd/pubs/docs/Frm/frm227.pdf

Input

In additon to standard TIPSY input, the snag model enables you to input the coefficients from a logistic regression model associated with the diameter class, years since death, and the interaction of years since death and diameter class. Default coefficients are provided.

Output

A table of the number of snags per hectare by diameter class for each age step is provided.

Species and Geographic Applicability

TIPSY provides yields for most of the commerically important coniferous species in coastal and interior British Columbia forests. The snag model default parameters for coastal Douglas-fir (Fdc) and western hemlock (Hwc) and for lodgepole (Pl) are derived from growth and yield permanent sample plot data. Snag model defaults for other species were arbitrarily derived relative to these 3 species.

Data Used for Model Parameterization

Standing dead tree data for Douglas-fir and western hemlock were collected from permanent sample plots of a single growth and yield research project located at 85 locations on Vancouver Island and coastal mainland British Columbia. Lodgepole pine parameters were derived from permanent sample plots near Canal Flats in the Southern Interior Forest Region of British Columbia. Further data are to be collected as part of the existing provincial wide growth and yield permanent sample plot program.

The default cofficients used only non-treated (control) plots. The sample size for each species is:

Species	Locations	PSPs	Max.Yrs	Trees Up	Trees Down
Fdc	23	46	22	1518	2468
Hwc	8	16	21	1063	1074
Pl	1	2	41	28	255

******** CWD Model ***************

CWD Woody Debris Recruitment Simulator

Authors

Don C. Bragg

School of Natural Resources and Environment, University of Michigan, 430 East University (Dana Building), Ann Arbor, MI 48109-1115. Tel: (734) 615-2215. E-mail: DonCBragg@netscape.net

Jeffrey L. Kershner

USDA Forest Service Fish Ecology Unit, Department of Fisheries and Wildlife, Utah State University, Logan, UT 84322-5215. Tel: (435) 797-2500. E-mail: kershner@cc.usu.edu

Availability

CWD version 1.4 is currently available only for the Utah and Teton variants of FVS. Plans are in the works for the development of a generic version of CWD to work with any variant of FVS. Species are limited to those found in the Utah and Teton variants. Also, CWD version 1.4 ONLY works with FVS version 6.1 (future versions will work with the newer variants of FVS).

Brief Description

CWD is a riparian large woody debris (LWD) recruitment simulator that acts as a post-processor to dead tree output provided by the Forest Vegetation Simulator (FVS). All live stand dynamics and disturbances occur within FVS, which produces a dead tree list file that CWD processes into cyclic (10 yr) recruitment patterns. CWD is responsible for snag dynamics, including snag longevity, direction of fall, fragmentation, and channel recruitment.

Documentation and Publications Available

Documentation on the assumptions and operation of CWD is in the final publication stages with the USFS Rocky Mountain Experiment Station. General release of this information (both in paper and over the web) will probably happen in the next few months. Once available, the USFS Fish Ecology Unit home page will likely have a section dedicated to CWD. Numerous journal and technical publications displaying simulation results are already in print (or in press). Contact Don C. Bragg (DonCBragg@netscape.net) for reprints.

Software Requirements

Operating system: Version 1.4 runs in a DOS console application, so it will run in DOS (preferably version 6 or higher) or a DOS window sponsored by Windows 3.x, Windows 9x, or Windows NT.
Specific software: Written in FORTRAN as a stand-alone application.

Input

Input requirements are minimal. The FVS dead tree list file (minus text headers) is entered into CWD, then processed. There are a number of subroutines that allow for some customization of CWD.

Output

Several files are created detailing model processing, recruitment patterns, and recruited LWD demographics. These are ASCII files that can be further analyzed using spreadsheets or statistical packages.

Data Used for Model Parameterization

Data used in the parameterization of CWD came from a 1995 field inventory of old- growth spruce-fir conditions on the Bridger-Teton National Forest. These data are described in the soon-to-be-released user's guide.

Models: Down Dead Tree Models

******************** SRS ********************

******** TASS CWD ***************

TASS CWD Model

Authors

Jeff Stone

Southern Interior Forest Region
B.C. Ministry of Forests

515 Columbia Street

Kamlops BC V2C 2T7 Canada

jeff.stone@gems7.gov.bc.ca

Availability

The TASS model is not distributed.

Brief Description

TASS tracks individual trees from live to a down dead state. A simple exponential decay model provides some stand level decay dynamics ability for down dead trees.

TASS is a growth and yield model that simulates the growth of individual trees within a stand. The growth of a tree (i.e., the stem) is based on the development of the tree’s crown in response to internal growth regulation, the physical restrictions imposed by neighbouring trees, stochastic environmental factors, and imposed silvicultural treatments. Because of its individual tree and crown structure, many silvicultural practices (e.g., planting patterns, thinning) can be simulated.

Documentation and Publications

Currently, there is no published documentation of the down dead tree model.

Input

TASS requires a variety of start up information (e.g., initial planting density and distribution, species, site index). The down dead tree model enables the user to override the default decay rates.

Output

For each time step in the stand's development, the down dead tree summary table provides information on the trees that became down dead trees in that period. The information includes stems per ha, the mean time since their death, mean quadratic diameter at 1.3 m height, mean total length, basal area, total volume, a dbh size class distribution in stems per ha. A total accumulated volume is provided at each step. This amount is the sum of volume of inputs from stand initiation less an amount for decay calculated with a simple exponential decay function. Coarse woody debris from the previous stand is not counted.

Species and Geographic Applicability

TASS has been parameterized for many of the commercial tree species of British Columbia. The CWD model default parameters are expert-derived estimates of the decay rate for the commerically important species.

Data Used for Model Parameterization

No data were used to parameterize the model.

******** TIPSY CWD Model ***************

TIPSY Snag Model

Authors

Jeff Stone

Southern Interior Forest Region
B.C. Ministry of Forests

515 Columbia Street

Kamlops BC V2C 2T7 Canada

jeff.stone@gems7.gov.bc.ca

Ramsoft Ltd.

Victoria, BC

ramsoft@islandnet.com

Availability

TIPSY is available free of charge at the following web site http://www.for.gov.bc.ca/hre/gymodels/Tipsy/ The CWD option is available in the current version of TIPSY that will be released shortly.

Brief Description

TIPSY (Table Interpolation Program for Stand Yields) is a growth and yield model used in silvicultural decisions and timber supply analysis in British Columbia. TIPSY is based upon the interpolation of a set of yield tables from TASS, a British Columbia Ministry of Forests individual tree growth and yield model. Additional features such as economic analysis have been developed specifically for TIPSY.

The coarse woody debris model option of TIPSY provides information on the number and size distribution of dead trees that have fallen. It provides an accumulated volume summary of CWD that can include an exponential decay model.

Software Requirements

Windows-based personal computer.

Documentation and Publications

The CWD model within TIPSY is described in the Help files contained with TIPSY.

Input

In additon to standard TIPSY input, the CWD model enables you to input the coefficients for a simple exponential decay model. Default coefficients are provided.

Output

A table of the number of snags per hectare by diameter class for each age step is provided.

Species and Geographic Applicability

TIPSY provides yields for most of the commerically important coniferous species in coastal and interior British Columbia forests. The CWD model default parameters are expert derived estimates of the decay rate for the commerically important species.

Data Used for Model Parameterization

No data were used to parameterize the model.