David C. Chojnacky

Comprehensive database of diameter-based biomass regressions for North American tree species

A database consisting of 2,640 equations compiled from the literature for predicting the biomass of trees and tree components from diameter measurements of species found in North America. Bibliographic information, geographic locations, diameter limits, diameter and biomass units, equation forms, statistical errors, and coefficients are provided for each equation, along with examples of how to use the database. The CD-ROM included with the paper version of this publication contains the complete database (Table 3) in spreadsheet format (Microsoft Excel 2002© with Windows XP©). The database files can also be viewed in both spreadsheet and pdf formats by directing your browser to the Global Change page at http://www.fs.fed.us/ne/global/pubs/books/index.html

Estimating down deadwood from FIA forest inventory variables in Maine

Down deadwood (DDW) is a carbon component important in the function and structure of forest ecosystems, but estimating DDW is problematic because these data are not widely available in forest inventory databases. However, DDW data were collected on USDA Forest Service Forest Inventory and Analysis (FIA) plots during Maines 1995 inventory. This study examines ways to predict DDW biomass from other FIA variables so that DDW could be estimated without tedious measurement. Our results include a regression model that predicts DDW as a function of stand size class, basal area of dead and cut trees, and dummy variables for forest type and forest industry ownership. We also found DDW similar to FIAs standing-tree mortality at a statewide scale.

Down dead wood statistics for Maine timberlands, 1995

Down dead wood (DDW) is important for its role in carbon and nutrient cycling, carbon sequestration, wildfire behavior, plant reproduction, and wildlife habitat. DDW was measured for the first time during a forest inventory of Maine by the USDA Forest Service in 1994-1996. Pieces greater than 3 feet long and greater than 3 inches in diameter at point of intersection were measured on line transects located on standard forest inventory plots. Large piles of DDW were sampled using the standard circular plot. The amount of DDW is presented in terms of totals and per area estimates for volume, number of pieces, biomass, and carbon, summarized by attributes such as forest type group, owner group, species, and diameter class. This inventory indicates Maines timberlands contain approximately 7.2 billion cubic feet (=or- 28%) in piles of DDW. DDW in piles and pieces contains 68.9 billion pounds (=or- 8%) of carbon. This is equivalent to an average of 8,030 pounds of DDW biomass per acre.

Measuring Carbon in Shrubs

Although shrubs are a small component of the overall carbon budget, shrub lands and shrub cover within forested lands warrant monitoring with consistent procedures to account for carbon in shrubs and to track carbon accumulation as communities change from shrubs to trees and vice versa. Many different procedures have been used to sample and measure shrubs (Bonham 1989) but only three types are selected here, to represent a range from simple and subjective to more time-consuming but objective measurements. Although the goal is to measure shrub carbon, the methods outlined here estimate biomass—which is about 50% carbon. For sample design, we advocate compatibility with the USDA, Forest Service, Forest Inventory and Analysis (FIA) program by using transects, microplots, or quadrats arranged within or near FIA subplots. Three basic methods are suggested for measuring shrub biomass: (1) cover estimations along transects, including point-intercept and line-intercept; (2) visual cover estimates in fixed area units; and (3) diameter measurement within fixed-area sampling frames. The 3rd method for measurement of individual shrub stem-diameters provides the most robust data for estimating biomass (and by extension, carbon) but requires the most field time. The other two methods allow more rapid measurements of shrub cover along transects or within plots. Our summary provides a framework for collecting shrub measurements three different ways; however, more work will likely be needed to develop appropriate equations that equate cover or stem measurements with biomass for various species.