David C. Chojnacky's research while affiliated with Virginia Tech (Virginia Polytechnic Institute and State University) and other places

Publications (24)

Article
Full-text available
Lebanon’s Ministry of Environment initiated a project in 2009 to determine low-cost reforestation techniques for stone pine (Pinus pinea) and Lebanon cedar (Cedrus libani) for large-scale land rehabilitation activities in the arid Middle East. Irrigation (several techniques vs. no water), planting (8- to 18-month-old seedlings), seeding, and soil p...
Article
Historically, tree biomass at large scales has been estimated by applying dimensional analysis techniques and field measurements such as diameter at breast height (dbh) in allometric regression equations. Equations often have been developed using differing methods and applied only to certain species or isolated areas. We previously had compiled and...
Article
Accurate assessments of down woody materials (DWM)-soil duff and litter, dead and downed fine and coarse woody detritus, and live and dead understory vegetation-are important because of their roles in forest floor carbon storage, organism habitat, nutrient cycling, and fuel loading. The USDA Forest Service's Forest Inventory and Analysis Program (F...
Article
Stem circumference at breast height (1.4 m above ground), tree height, distance from the ground to the base of the crown, and crown radii from the stem to the average drip line were measured for fourteen blue oak (Quercus douglasii) trees from a California site. The trees were felled, and we determined mass of stems, branches, twigs, and foliage; a...
Chapter
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Dead fuel loads were measured on six distinct forest management compartments in North Carolina’s Uwharrie national forest, Croatan national forest and the Alligator River National Wildlife Refuge. Average 1-, 10-, 100- and 1000-hour fuels loads were analyzed within and between each of the three research areas and compared to National Fire Danger Ra...
Article
Using data from the USDA Forest Service's Forest Inventory and Analysis (FIA) program, we developed a mapping tool for displaying statistical forestland information. To develop this technique, we used data from Nevada's pinyon‐juniper dryland forests, a major component of Nevada's forest cover important for food and wood sources, wildlife cover, an...
Conference Paper
Background/Question/Methods Ground-based forest inventories often tabulate population statistics for geographic areas, land ownerships, or ecological classifications. Frequently, users also desire maps of inventory information. However, map-based technologies generally start with remote-sensing information independent of land-based inventories or...
Article
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Forest management can have large impacts on the production and yield of coarse woody debris (CWD) in terrestrial ecosystems, yet few modeling tools exist to inform such efforts. The goal here was to develop a set of prediction equations for use in conjunction with loblolly pine (Pinus taeda L.) modeling and inventory systems to estimate CWD yields...
Article
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Mass and carbon load estimates, such as those from forest soil organic matter (duff and litter), inform forestry decisions. The US Forest Inventory and Analysis (FIA) Program systematically collects data nationwide: a down woody material protocol specifies discrete duff and litter depth measurements, and a soils protocol specifies mass and carbon o...
Chapter
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...
Article
Full-text available
Methodology is lacking to easily map Forest Inventory and Analysis (FIA) inventory statistics for all attribute variables without having to develop separate models and methods for each variable. We developed a mapping method that can directly transfer tabular data to a map on which pixels can be added any way desired to estimate carbon (or any othe...
Article
Full-text available
Down woody materials (DWMs) are an important part of forest ecosystems for wildlife habitat, carbon storage, structural diversity, wildfire hazard, and other large-scale ecosystem processes. To better manage forests for DWMs, available and easily accessible data on DWM components are needed. We examined data on DWMs, collected in 2001 by the US Dep...
Article
Full-text available
Fallen or down dead wood is a key element in healthy forest ecosystems. Although the amount of down wood and shrubs can provide critical information to forest resource managers for assessing fire fuel build up, data on biomass of down woody materials (DWM) are not readily accessible using existing databases. We summarized data collected by the USDA...
Article
Full-text available
Estimates of national-scale forest carbon (C) stocks and fluxes are typically based on allometric regression equations developed using dimensional analysis techniques. However, the literature is inconsistent and incomplete with respect to large-scale forest C estimation. We compiled all available diameter-based allometric regression equations for e...
Article
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 Maine's 1995 inventory. This stu...
Article
Tree biomass estimates in the Forest Inventory and Analysis (FIA) database are derived from numerous methodologies whose abundance and complexity raise questions about consistent results throughout the U.S. A new model based on allometric scaling theory ("WBE") offers simplified methodology and a theoretically sound basis for improving the reliabil...
Article
Full-text available
Down dead wood (DDW) is important for its role in carbon and nutrient cycling, carbon sequestration, wildfire behavior, plant reproduction, and wildlife habitat. Down dead wood was measured for the first time during a forest survey of Maine by the USDA Forest Service in 1994-1996. Pieces greater than 3 feet long and greater than 3 inches in diamete...
Article
The habitat of the Mexican spotted owl must be monitored because of the owl's “threatened” status under the Endangered Species Act of 1973. A possible data source for habitat monitoring is the network of permanent plots maintained by Forest Inventory and Analysis (FIA), USDA Forest Service, Rocky Mountain Research Station. This article demonstrates...
Article
Since 1928, the Forest Inventory and Analysis (FIA) group within the Forest Service, U.S. Department of Agriculture (USDA 1992) has inventoried the nation's forests. Fundamental to current FIA inventories is a two-phase design using double sampling for stratification (Cochran 1977). In FIA's use of double sampling for stratification, a large first-...
Article
An individual-tree model has been developed to estimate diameter growth of pinyon and juniper trees in dryland forests throughout New Mexico, USA. The model was built from radial growth data on 917 trees sampled from 82 plots. Individual-tree growth can be predicted from measurements of tree diameter at the root collar, from the number of basal ste...
Article
Full-text available
Thousands of published equations purport to estimate biomass of individual trees. These equations are often based on very small samples, however, and can provide widely different estimates for trees of the same species. We addressed this issue in a previous study by devising 10 new equations that estimated total aboveground biomass for all species...

Citations

... The forests of Lebanon have been exploited for the last 5000 years, since the time of the Pharaohs [1,2] and later by Phoenicians, Assyrians, Babylonians, Kings of Israel, Romans, and more recently, by the Turkish Ottoman Empire until World War I [1]. At that time, forests covered up to 70% of Lebanon, but today they are highly fragmented due to urban expansion, sustainable timber use, grazing, and tourism [3,4] and have shrunk to 13.6% [5]. ...
... Generalized, regional biomass allometric equations were developed for the nine most abundant species at HWF using a modified metaanalysis approach (Table 2: See Pastor et al., 1984& Ter-Mikaelian & Korzukhin, 1997 for methods). These equations were developed using simulated biomass data from species-specific biomass allometric equations developed in the northeastern United States or southeastern Canada (Jenkins et al., 2004). New generalized models were fit to natural log transformed simulated data using OLS regression. ...
... modeled DWM based on FIA Phase 2 plots in the eastern United States and validated it against FIA Phase 3 plots. Chojnacky et al. (2013) then estimated DWM across the entire United States and made the resulting map available as an online web tool. Keane et al. (2013) looked at the accuracy of fuel classification systems, using two established systems and one new classification developed in their study from over 13 000 FIA plots. ...
... The TRW-based stem diameter 507 was converted into diameter at the breath height (DBH) using the model from508 Lockwood et al45 . Then DBH was converted into AABIper_tree using species-specific 509 allometric relationships from Jenkins46 and Chojnacky et al.47 , and then was averaged 510 to a site-level dataset using bi-weighted robust mean. Where the species-specific 511 equations were not available, more general equations at the biome level were used.512 ...
... To date, most carbon accounting in these woodland and shrubland systems has focused on calculating aboveground biomass and carbon at the organismal or plot scale (e.g., Rickard 1985, Rau et al. 2010). While mapping carbon storage in pinyon-juniper woodlands using remote sensing rather than field population estimates can provide the combined benefits of high spatial detail and regionalscale estimates (Chojnacky et al. 2012), most remote sensing-based studies of carbon in the Great Basin have focused on estimating expansion rates of pinyon-juniper woodlands over relatively small areas (Sankey and Germino 2008, Strand et al. 2008, Huang et al. 2009). As a result, regional estimates of aboveground carbon are lacking. ...
... Наконец, в некоторых работах пытаются получить обобщённые модели фитомассы, основанные на ранее опубликованных уравнениях и выведенных из них псевдоданных или псевдо-наблюдений. Подобный анализ предыдущих анализов и результатов независимых исследований относят к категории мета-анализа (Glass, 1976;Pastor et al., 1984;Iyengar, 1991;Jenkins et al., 2003;Zianis, Mencuccini, 2003;Muukkonen, 2007;Chojnacky et al., 2008;De-Miguel et al., 2014;Forrester et al., 2017). Соответственно модели, выведенные на основании опубликованных ранее уравнений, можно назвать мета-моделями (Urban et al., 1999). ...
... Most of these efforts have involved on the ground sampling campaigns, though some of these ground data have also been incorporated in spatial models to identify more detailed ecosystem function such as soil dynamics (D. A. Robinson et al., 2010). While most of these efforts focus on oak savanna habitat, they often rely on ground sampled data (Karlik & Chojnacky, 2014) or spectrally calibrated in situ data (Colgan et al., 2012). That is why efforts have focused on satellite based modeling methods for oak savanna classification (Wolter et al., 2014), allowing researchers to map larger areal extents at different temporal intervals. ...
... It is not only important for energy production and consumption but also crucial for understanding climate change, forest health, biodiversity, and ecosystem cycling of carbon, water, energy, and nutrients (Choi et al. 2002, Goodale et al. 2002, Houghton 2005, Houghton et al. 2009, Shao et al. 2011. Over the last several decades, Ͼ2,600 biomass models have been developed for Ͼ100 species around the world (Bond-Lamberty et al. 2002, Chojnacky 2002, Jenkins et al. 2003, Zianis et al. 2005. Most biomass models have been created to estimate aboveground biomass (e.g., Brown 1997, Chave et al. 2005, Wang 2006, Zianis 2008, Woodall et al. 2011, Alvarez et al. 2012, Li and Zhao 2013, whereas only few models are available for belowground or root biomass because of the difficulty and expense of excavating tree roots (Brown 2002, Wang 2006. ...
... TPSS has been applied by many authors to estimate the parameters of some concerned population parameters. Chojnacky ( [Cho98] ) made software characteristics comparison and concluded that FOSS is efficient over PS. However, this conclusion neither took into account the users feedback experience nor was the conclusion based on statistical analysis. ...
... The relative percentage of each class of woody debris in extant forests varies based on forest type and biome (González and Luce 2013). In temperate mixed-oak forests studied in the east-central United States by Chojnacky and Schuler (2004), Coarse Woody Debris (CWD -maximum diameter ≥ 10 cm) comprised about 37% of the total woody debris by volume. Although volume of CWD can be a substantial component of the total forest debris, the frequency of downed CWD as compared to FWD is low. ...