Methods and Equations for Estimating Aboveground Volume, Biomass, and Carbon for Trees in the U.S. Forest Inventory, PDF

Please download to get full document.

View again

of 34
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Information Report
Category:

Crosswords

Published:

Views: 5 | Pages: 34

Extension: PDF | Download: 0

Share
Related documents
Description
United States Department of Agriculture Forest Service Northern Research Station General Technical Report NRS-88 Methods and Equations for Estimating Aboveground Volume, Biomass, and Carbon for Trees in
Transcript
United States Department of Agriculture Forest Service Northern Research Station General Technical Report NRS-88 Methods and Equations for Estimating Aboveground Volume, Biomass, and Carbon for Trees in the U.S. Forest Inventory, 010 Christopher W. Woodall Linda S. Heath Grant M. Domke Michael C. Nichols VOLUME BIOMASS Abstract The U.S. Forest Service, Forest Inventory and Analysis (FIA) program uses numerous models and associated coefficients to estimate aboveground volume, biomass, and carbon for live and standing dead trees for most tree species in forests of the United States. The tree attribute models are coupled with FIA s national inventory of sampled trees to produce estimates of tree growing-stock volume, biomass, and carbon, which are available in the Forest Inventory and Analysis database (FIADB; To address an increasing need for accurate and easy-to-use documentation of relevant tree attribute models, needed individual tree gross volume, sound volume, biomass (including components), and carbon models for species in the United States are compiled and described in this publication with accompanying electronic files on a CD-ROM included with the publication. This report describes models currently in use as of 010. These models are subject to change as the FIADB and associated tree attribute models are improved. Cover and disk artwork courtesy of Suzy Stephens, U.S. Forest Service. Printed on Recycled Paper Manuscript received for publication 4 April 011 Published by: For additional copies: U.S. FOREST SERVICE U.S. Forest Service 11 CAMPUS BLVD SUITE 00 Publications Distribution NEWTOWN SQUARE PA Main Road Delaware, OH Fax: (740) October Visit our homepage at: INTRODUCTION The official annual U.S. greenhouse gas (GHG) inventories contain forest carbon and other greenhouse gas estimates (e.g., see U.S. Environmental Protection Agency 010) based on U.S. Forest Service s, Forest Inventory and Analysis (FIA) program survey data, coupled with other basic models (Heath et al. 010). The FIA program, through its regional units (Northern, Southern, Rocky Mountain, and Pacific Northwest; see USDA For Serv. 011), is the primary provider of state-, regional-, and national-scale forest population estimates such as forest land area, and tree volume, growth, mortality, and removals. U.S. forest carbon inventories have used biomass estimates based on equations from Jenkins et al. (003 and 004), due to previous inconsistencies in tree biomass estimates between FIA regions (pre-009). Estimates for a tree species in one region may have differed notably from estimates of the same species in another region. In 009, FIA adopted a process for estimating tree biomass (Heath et al. 009). This methodology is now consistently applied across the United States, with estimates reported in the publicly available Forest Inventory and Analysis database (FIADB; USDA For. Serv. 010a). With emerging carbon markets and growing interest in bioenergy at various scales across the United States, many individuals are interested not only in the models FIA uses for individual tree species, but also in adjusting models and associated coefficients for their own population estimates. The purpose of this report is to present in an accessible format the methodology and requisite equations for estimating attributes for most of the tree species in the United States. Until publication of this report, similar information had been only available for the southern (Oswalt and Conner 011) and northern (Miles and Hill 010) regions of the eastern United States. The volume and biomass attributes described in this paper and the conditions under which they are computed are described in the following tabulation. Carbon estimates follow directly from biomass estimates based on the assumption that biomass is 50 percent carbon (Birdsey 199). The process of tree attribute estimation for all sample trees 5 inches in diameter and larger begins with the estimation of tree gross volume (VOLCFGRS) and tree sound volume (VOLCFSND). For the majority of tree species (nonwoodland trees where diameter is measured at 4.5 feet above ground; refer to REF_SPECIES.xlsx for woodland species designation) biomass and carbon by component (stump, bole and tops) are also estimated (Table 1). For all woodland trees (trees where diameter is measured at the root collar) biomass and carbon are estimated but are not broken down by component. For all sample trees between 1 to 4.9 inches in diameter only total biomass and carbon are estimated. Estimates of volume (VOLCFGRS and VOLCFSND) and breakdowns of total biomass and carbon into components are not made for trees 5.0 inches in diameter. No estimates of volume, biomass, or carbon are made for sample trees where diameter is 1.0 inch. The Authors CHRISTOPHER W. WOODALL is a research forester with the Forest Inventory and Analysis program of the U.S. Forest Service, St. Paul, MN. LINDA S. HEATH is a research forester, U.S. Forest Service, Forest Inventory and Analysis, Durham, NH; currently on detail as Senior Forest Climate Change Specialist at the Global Environment Facility, Washington, DC. GRANT M. DOMKE is a postdoctoral research forester with the Forest Inventory and Analysis program of the U.S. Forest Service, St. Paul, MN. MICHAEL C. NICHOLS is a scientific programmer with the Forest Inventory and Analysis program of the U.S. Forest Service, Durham, NH. 1 Table 1. Volume and biomass components estimated by FIA for live and standing dead trees Non-woodland species: Diameter is measured at 4.5 feet above ground Woodland species: Diameter is measured at root collar Less than 1.0 inches in diameter No estimates of volume or biomass 1.0 to 4.9 inches in diameter No estimate of volume Sapling biomass = Total aboveground biomass 5.0 inches in diameter and larger Gross volume Sound volume (Stump wood biomass + Stump bark biomass + Bole wood biomass + Bole bark biomass + Top and branch biomass) = Total aboveground biomass Biomass of woodland species = Total aboveground biomass Gross volume Sound volume Biomass of woodland species = Total aboveground biomass Biomass for woodland species 5.0 inches in diameter and saplings (non-woodland species between 1.0 to 4.9 inches in diameter) are estimated directly from the biomass equation in Jenkins et al. (003 and 004) using the observed diameter and a sapling adjustment factor. Biomass for woodland species 5.0 inches diameter is based on volume estimates for the entire aboveground portion of the sample tree with no component breakdown. Volume, biomass, and carbon models for tropical trees (e.g., species in Puerto Rico or Hawaii) are not included in this report. This compilation does not necessarily reflect the ideal system for estimating an array of tree attributes (e.g., volume and carbon) that are additive among individual tree components (i.e., scalable tree attributes from components to whole tree) and consistent across diverse forest conditions at a national scale (i.e., do not arbitrarily change at political boundaries). Rather, this system reflects an effort to meld localized tree volume/ biomass information into a consistent, national approach. We suggest that future research focus on consistent national-scale individual tree volume/biomass/carbon equations that accommodate the diversity of tree habitats (e.g., woodlands or tropics) and conditions (e.g., sound or rotten). METHODS FOR BIOMASS ESTIMATION The approach used for nationally consistent biomass estimation of non-sapling and nonwoodland trees in the FIADB is called the component ratio method (CRM; Heath et al. 009). CRM entails 1) measuring attributes of the tree in the field; ) applying those tree measurements to the applicable volume model to compute both gross cubic-foot volume (VOLCFGRS) and sound cubic-foot volume (VOLCFSND) of wood in the bole; 3) converting the sound cubic-foot volume (VOLCFSND) of wood in the bole to mass and estimating bark biomass using compiled sets of specific gravity (Miles and Smith 009); 4) calculating the biomass of tops and limbs as a proportion of the bole based on component proportions from Jenkins et al. (003); 5) calculating stump volume based on equations in Raile (198) and converting to biomass, and 6) summing all aboveground components for a total aboveground biomass estimate. The use of CRM requires the calculation of VOLCFSND. Because VOLCFSND is based on gross cubic-foot volume (VOLCFGRS) for many areas of the country, VOLCFGRS must also be calculated. It should be noted that FIA calculates many types of volumes of interest to a range of user groups including: total stem volumes (calculated for all trees 1.0-inch d.b.h.), cubic-foot volumes up to various top diameters (e.g., 4-, 6-, or 8-inch tops), and board-foot volumes using Scribner or International ¼ inch volume rules (for definitions see Helms 1998). The CRM is based on VOLCFGRS and VOLCFSND; only those volume equations are compiled in this study (Appendix A). The five general steps for calculation of tree (d.b.h. 5.0 inches) oven-dry mass (lb) are: 1) Obtain needed tree and plot or condition measurements using FIA protocols (e.g., tree diameter, rotten and missing cull, site index, height, basal area) ) Calculate VOLCFGRS 3) Calculate VOLCFSND (i.e., subtract rotten or missing from VOLCFGRS) 4) Convert VOLCFSND to bole biomass 5) Calculate additional biomass components (e.g., tops and limbs, stump) that are summed for total biomass Note that estimation procedures are different for saplings (d.b.h. 1.0 inch and 5.0 inches). Sapling biomass is based on biomass computed from Jenkins et al. (004) using the observed diameter and an adjustment factor computed as a national average ratio of the CRM total biomass divided by the Jenkins et al. (003 and 004) total biomass for all 5.0-inch trees, which is the size at which biomass based on volume begins (Heath et al. 009). At this time estimation procedures are not different for standing dead trees. Users of this documentation should consider adopting decay and structural reduction factors for standing dead trees such as those currently under development by FIA (Domke et al. in press). Such information could reduce any potential upward bias of estimating standing dead wood volume/biomass using live tree procedures. The steps for biomass calculation are described for each component separately in the Biomass Calculations section of this report. We also provide example calculations for a live growing- 3 stock tree, a live rough cull tree, a standing dead tree, and a small diameter tree for comparison and reference. The text refers to appendices where volume equations are presented; coefficients for the equations and species-specific information can be found in the companion spreadsheets (volcfgrs_eqn_coefs.xlsx, volcfsnd_eqn_coefs.xlsx, and REF_SPECIES.xlsx) on the CD included in this report. Tree Measurements Field protocols for FIA are found in USDA For. Serv. (010b). The diameter of most tree species is measured at d.b.h., except in the case of woodland tree species where it is measured at d.r.c. Species information, including species names, codes, diameter type, wood and bark specific gravity, bark percentage, sapling adjustment factors, Jenkins et al. (004) biomass coefficients, and Raile (198) stump volume coefficients can be found in the REF_SPECIES table in FIADB, the original publications cited in this document, or on the CD included with this report. Models may differ by state or ecoregion within a state, thus location of the tree is important. See Figure 1 for definition of areas for model determination. Other information that may be needed includes site index, height, bole height, percent of cubic-foot volume rotten or missing, percent of sound dead cull as a percentage of merchantable bole, and number of stems (for trees measured at d.r.c.). For standing dead trees, a decay class is determined for each tree, but is not currently used in estimation procedures (USDA For. Serv. 010b). Gross Volume Estimation Gross cubic-foot volume is defined as the total volume inside bark of the central stem of a tree 5.0 inches d.b.h. from a 1-foot stump to a minimum 4-inch top diameter outside bark (d.o.b.), or to where the central stem breaks into limbs all of which are less than 4.0 inches d.o.b. (Woudenberg et al. 010). Gross volume includes rotten and missing parts and form cull. Rotten and missing cubic-foot cull volume is estimated to the nearest 1 percent in the field. This estimate does not include any cull deduction above actual length so volume lost from a broken top is not included. Form cull is the percent of the cubic-foot volume that is cull due to form defect, and is only collected at some locations. Gross volume is set to null (not available) if d.b.h. is not available. Usually, if d.b.h. is 5.0 inches, gross volume is set to null, with the possible exception of woodland tree species (i.e., d.r.c.) in Rocky Mountain and Southern States. The form of the models to calculate VOLCFGRS are listed by FIA unit (i.e., Northern or Southern) and sub-unit model region (i.e., eastern MT or western MT; Fig. 1) in Appendices A and B (see CD for model coefficients), along with the reference for each model. Unless otherwise noted, the b values in these tables are regression parameter estimates and the x values are the observed attributes. The bold text indicates conditions that should be met regarding the observed attributes. The values for the coefficients are given in the VOLCFGRS spreadsheet provided on a CD in this report. To find the appropriate model and coefficients for the tree species and location, use the following steps: 1) To calculate VOLCFGRS, locate the species-specific equation for the region of interest found in Tables 1-4 of Appendix A and Table 6 of Appendix B. ) Find species-specific coefficients (denoted by the letter b, as in b 1, b, etc.) in the spreadsheet volcfgrs_eqn_coefs.xlsx. 4 Figure 1. Delineated areas for identifi cation of gross cubic-foot growing stock volume models and coefficients from the spreadsheet file. Further description is given in U.S. Forest Service (010b; Appendix c). 3) In the volcfgrs_eqn_coefs spreadsheet, locate the regional config worksheet for the area of interest. They are designated as follows: NCCS North Central Central States; NCLS North Central Lake States; NCPS North Central Plains States; NE Northeastern States; AZ_N_NM_N northern Arizona and northern New Mexico; AZ_S_NM_S southern Arizona and southern New Mexico; CO_E_WY_E eastern Colorado and eastern Wyoming; CO_W_WY_W western Colorado and western Wyoming; ID_MTW Idaho and western Montana; MT_E eastern Montana; NV Nevada; UT_NE northern and eastern Utah; UT_SW southern and western Utah; S Southern States; CA California (except mixed conifer forest type); CA_MC California mixed conifer forest type; OR_E eastern Oregon; OR_WA western Oregon; OR_JJ Oregon (Jackson and Josephine Counties); WA_E eastern Washington; WA_W western Washington; and WA_CF Washington (highelevation silver fir region). 4) Find the row corresponding to the particular species; the sheet is ordered by species number (Column C). For a list of all species with common and scientific names, refer to the worksheet ref_species_reduced. The column COEF_TABLE contains the name 5 of the table which has the coefficients for this species. The column COEF_TBL_SP contains the species number you should look for in the table. 5) Insert the appropriate coefficients and the tree-specific variables into the equation from step 1 to estimate VOLCFGRS. Sound Volume Estimation Sound cubic-foot volume is the volume of sound wood in the central stem of a tree 5.0 inches diameter from a 1-foot stump to a minimum 4-inch top d.o.b., or to where the central stem breaks into limbs, all of which are less than 4.0 inches d.o.b. Note that in some instances VOLCFSND may be 0 or null and the VOLCFGRS is 0 in FIADB. In those cases, biomass is calculated using VOLCFGRS adjusted for the percentage sound. When both VOLCFSND and VOLCFGRS are 0 or null, biomass is calculated using net cubic-foot volume (VOLCFNET) adjusted for the percentage sound (Woudenberg et al. 010). The form of the models to calculate VOLCFSND from VOLCFGRS are listed by FIA region in Table 5 of Appendix A (see CD for model coefficients; see Appendix C for Alaska VOLCFSND algorithm), along with the reference for the model. Unless noted, the b values in these tables are regression parameter estimates and the x values are the observed attributes. The bold text indicates conditions that should be met regarding the observed attributes. To find the appropriate model and coefficients for the tree species and location, use the following steps: 1) To calculate VOLCFSND, locate the appropriate equation in Appendix A, Table 5 (see Appendix C for Alaska VOLCFSND algorithm). Only a few of the equations use species-specific coefficients (denoted by the letter b, as in b 1, b, etc.). If the applicable volume equation you want to use contains these coefficients, they may be found in the Excel spreadsheet volcfsnd_eqn_coefs.xlsx ) In the volcfsnd_eqn_coefs spreadsheet, locate the regional config worksheet for the area of interest. They are designated as follows: NCCS North Central Central States; NCLS North Central Lake States; and NCPS North Central Plains States. The column COEF_TABLE contains the name of the table containing the coefficients for this species. The column COEF_TBL_SP contains the species number you should look for in the table 3) Insert the appropriate coefficients (if present), the tree-specific variables and the VOLCFGRS (calculated in step 5 under Gross Volume Estimation) into the equation from step 1 in this section to estimate VOLCFSND. Biomass Calculations Biomass of bole Biomass in the bole of a species is calculated by multiplying the VOLCFSND by weight of 1 cubic foot of water (6.4 lb) to convert volume to mass, and then multiplying by the specific gravity of wood and bark, separately for the species listed in Miles and Smith (009). For a complete list of specific gravities for all tre species in FIADB, please refer to REF_SPECIES.xlsx included in this publications s CD-ROM. The specific gravities of bark and wood are different. 6 The bark component includes an additional term, bark as a proportion of wood volume, so the two components must be calculated separately and then summed. Bole wood biomass: B odw = V gw * SG gw * W (eq. 1) where B odw = oven-dry biomass (lb) of wood V gw = VOLCFSND of green wood in the central stem SG gw = basic specific gravity of wood (oven-dry mass of green volume) W = weight of ft 3 of water (6.4 lb) Bark biomass: B odb = V gw * BV% * SG gb * W (eq. ) where B odb = oven-dry biomass (lb) of bark V gw = VOLCFSND of green wood in the central stem BV% = bark as a percentage of wood volume SG gb = basic specific gravity of bark (oven-dry mass of green volume) W = weight of ft 3 of water (6.4 lb) Total bole (bole and bark) biomass (DRYBIO_BOLE): B odt = B odw + B odb (eq. 3) where B odw = oven-dry biomass (lb) of wood B odb = oven-dry biomass (lb) of bark B odt = total oven-dry bole biomass (lb) in wood and bark Biomass of tree components Biomass in the stumps and tops and limbs of trees 5.0 inches d.b.h. is estimated as a proportion of CRM bole biomass (eq. 3) using component ratios from Jenkins et al. (004) and Raile (198). All tree components derived from Jenkins et al. (004) and Raile (198) must be multiplied by an adjustment factor to estimate CRM biomass. CRM adjustment factor: CRM AdjFac = B odt /MST (eq. 4) where CRM AdjFac = component ratio method adjustment factor for tree components derived from Jenkins et al. (003) and Raile (198) B odt = total oven-dry biomass (lb) (eq. 3) MST = merchantable oven-dry bole biomass (lb) (Jenkins et al. 004) Biomass in the stump of a species is estimated using volume equations developed by Raile (198), con
Recommended
View more...
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks