Treesearch

In addition to long-standing concerns about sustaining forest productivity, maintaining forest ecosystems under changing conditions and emerging threats has become increasingly important when planning forest management. With the aim of understanding effects of management on both productivity and recovery, we quantified the 25-year impact of varying degrees of organic matter (OM) removal and soil compaction on above-ground biomass, soil carbon and nutrients, soil bulk density, and stand development in aspen-dominated forests in the upper Lake States region of the US. Treatment impacts were...

Spatial capture–recapture (SCR) models have become the preferred tool for estimating densities of carnivores. Within this family of models are variants requiring identification of all individuals in each encounter (SCR), a subset of individuals only (generalized spatial mark–resight, gSMR), or no individual identification (spatial count or spatial presence–absence). Although each technique has been shown through simulation to yield unbiased results, the consistency and relative precision of estimates across methods in real‐world settings are seldom considered. We tested a suite of models...

This report reviews existing research and datasets from 17 U.S. Forest Service-affiliated experimental forests and ranges (EFRs) that are relevant to science needs of state and federal water quality regulatory agencies. A focus group of regulatory personnel chose “biological responses to stream nutrients” as the focus for this synthesis, and identified a broader array of science topics that could be of regulatory interest. Additional research needs of regulators that could potentially be filled by future studies at these sites were identified as (1) the composition of biotic communities...

In 1994, an executive order on environmental justice directed federal agencies to identify and address any disproportionately high adverse effects their actions and policies may have on the health and environment of minority and low-income populations.Until recently, a suitable procedure did not exist for assessing natural resource management activities through the lens of environmental justice at the implementation scale. Researchers Mark Adams and Susan Charnley with the USDA Forest Service, Pacific Northwest Research Station developed an analytical method to do this. The method facilitat...

This report assesses recent forest disturbance in the Western United States and discusses implications for sustainability. Individual chapters focus on fire, drought, insects, disease, invasive plants, and socioeconomic impacts. Disturbance data came from a variety of sources, including the Forest Inventory and Analysis program, Forest Health Protection, and the National Interagency Fire Center. Disturbance trends with the potential to affect forest sustainability include alterations in fire regimes, periods of drought in some parts of the region, and increases in invasive plants, insects,...

The 2010 “National Report on Sustainable Forests” (USDA FS 2011) identified forest disturbance as the most immediate threat to forest sustainability in the United States, based on increased levels of insect activity and fire activity relative to levels reported in the 2003 edition of that report. This concern, combined with the prominent role that western forests play in national statistics, was the motivating factor behind this report. Key questions for this project were, are forest disturbances increasing, and will they affect forest sustainability in the Western United States? A simple...

Nonnative invasive plants are a potential threat to the sustainability of Western U.S. forests. In the implementation of the Montréal Process Criteria and Indicators, invasive plants are recognized as affecting native species diversity (indicator 1.6), the status of endangered species (indicator 1.7), and the area of forest outside the range of natural variation (indicator 3.15) (Robertson et al. 2011).2 Invasive plants can affect forest ecosystems by reducing the abundance and functions of native species, and they can affect nutrient cycling and the fitness of native plants and animals...

Experimental forests and ranges (EFRs) are a network of long-term, dedicated research sites that have been established nationwide by the U.S. Department of Agriculture, Forest Service (USFS), and include several collaborating research sites managed by other federal and state land management agencies (Adams et al. 2008, Lugo et al. 2006). Most were originally established to investigate the environmental effects of forest management practices, but, over time, many have become venues for long-term environmental monitoring and for investigations of fundamental ecological processes in these...

Height-to-crown-base (HTCB) measurements are frequently used as inputs for growth and yield models. They are essential for reliable projections of stand structure over time required for sustainable forest management. Often, HTCB is measured alongside total height (HT) for only a subsample of trees and must be imputed for unobserved measurements in the sample. Typically, HTCB models require HT as a covariate, requiring a “double” imputation for missing HTCB measurements, leading to potentially substantial error propagation issues. We compared the effects of subsample size, imputation...

The estimation of the sampling variance of point estimators under two-dimensional systematic sampling designs remains a challenge, and several alternative variance estimators have been proposed in the past few decades. In this work, we compared six alternative variance estimators under Horvitz-Thompson (HT) and post-stratification (PS) point estimation regimes. We subsampled a multitude of species-specific forest attributes from a large, spatially balanced national forest inventory to compare the variance estimators. A variance estimator that assumes a simple random sampling design...