Treesearch

Major ion chemistry (2000-2009) from 208 lakes (342 sample dates and 600 samples) in class I and II wilderness areas of the Sierra Nevada was used in the Steady-State Water Chemistry (SSWC) model to estimate critical loads for acid deposition and investigate the current vulnerability of high elevation lakes to acid deposition. The majority of the lakes were dilute (mean specific conductance = 8.0 µS cm−1) and characterized by low acid neutralizing capacity (ANC; mean = 56.8µeq L−1). Two variants of the SSWC model were employed: (1) one model used the F-factor and (2) the alternate model...

Air quality and air quality related values are important resources to the National Park Service (NPS) units and Wilderness areas in northern Southeast Alaska. Air quality monitoring was prioritized as a high-priority Vital Sign at the Southeast Alaska Network’s (SEAN) Inventory and Monitoring Program’s terrestrial scoping workshop (Derr and Fastie 2006). Air quality monitoring of fossil fuel combustion emission products and heavy metals was conducted at several sites in the Southeast Alaska Network (SEAN) parks, the Tongass National Forest’s Tracy Arm-Fords Terror Wilderness, and in the...

Sickleweed (Falcaria vulgaris), an introduced species native to Europe and Asia, grows as an aggressive weed in some areas of the upper Midwest in the United States. We are reporting genetic diversity and population structure of sickleweed populations using microsatellite markers and nuclear and chloroplast DNA sequences. Populations showed high genetic differentiation but did not show significant geographic structure, suggesting random establishment of different genotypes at different sites was likely due to human mediated multiple introductions. Three genetic clusters revealed by...

Families own 35% of US forestland and 67% of Vermont forestland. Sustainable management of their woodlots could provide social and economic benefits for generations. We examined sustainable forest management across four counties in Vermont by evaluating the use of silvicultural practices and best management practices on 59 recently harvested, family-owned properties with at least 25 acres of timberland. We explored relationships between management practices and Vermont's Use Value Appraisal Forestland Tax Program (UVA), one of Vermont's primary forest management policy instruments. We...

Interspecific hybridization is cited as one potential mechanism for increased invasiveness, particularly among some grass species. In the southeastern United States, the successful invasion of cogongrass (Imperata cylindrica) has sometimes been attributed to hybridization with the previously naturalized Imperata brasiliensis. This research aimed to determine whether genetic signals are consistent with these two species having experienced interspecific hybridization in Florida (USA), where it has been proposed that such an event facilitated cogongrass invasion across the region.

Detailed, accurate, efficient, and inexpensive methods of estimating basal area, trees, and aboveground biomass per acre across broad extents are needed to effectively manage forests. In this study we present such a methodology using readily available National Agriculture Imagery Program imagery, Forest Inventory Analysis samples, a two stage classification and estimation approach, .Net numeric libraries, Spatial Analyst, Function Datasets, and ArcObjects.

Raster modeling is an integral component of spatial analysis. However, conventional raster modeling techniques can require a substantial amount of processing time and storage space and have limited statistical functionality and machine learning algorithms. To address this issue, we developed a new modeling framework using C# and ArcObjects and integrated that framework with .Net numeric libraries. Our new framework streamlines raster modeling and facilitates predictive modeling and statistical inference.

Nitrogen (N) deposition is impacting a number of ecosystem types in California. Critical loads (CLs) for N deposition determined for mixed conifer forests and chaparral/oak woodlands in the Sierra Nevada Mountains of California and the San Bernardino Mountains in southern California using empirical and various modelling approaches were compared. Models used included the Simple Mass Balance (SMB) model for nutrient N and acidification (both site-specific and regional approaches) and the Daycent process-based biogeochemical simulation model. Empirical CLs reported herein were based on...

This Report provides a strategic approach for conservation of sagebrush ecosystems and Greater Sage- Grouse (sage-grouse) that focuses specifically on habitat threats caused by invasive annual grasses and altered fire regimes. It uses information on factors that influence (1) sagebrush ecosystem resilience to disturbance and resistance to invasive annual grasses and (2) distribution, relative abundance, and persistence of sage-grouse populations to develop management strategies at both landscape and site scales. A sage-grouse habitat matrix links relative resilience and resistance of...

Four years post-wildfire, we measured soil and plant properties on hillslopes treated with two different mulches (agricultural wheat straw and wood strands) and a control (unmulched, but burned). Soil total N was about 40% higher and microbial respiration of a standard wood substrate was nearly twice as high in the mulched plots compared to the unmulched plots. Greater respiration was tied to increased substrate moisture underneath mulch compared to bare soil. Nitrate reductase activity of a common forb (Arnica cordifolia) was about 30% higher on the wood strand plots than either the wheat...