Treesearch

Permafrost soils are a significant global store of carbon (C) with the potential to become a large C source to the atmosphere. Climate change is causing permafrost to thaw, which can affect primary production and decomposition, therefore affecting ecosystem C balance. We modeled decadal and millennial soil C inputs, decomposition constants, and C accumulation rates by plotting cumulative C inventories against C ages based on radiocarbon dating of surface and deep soils, respectively, in subarctic tundra soils undergoing minimal, moderate, and extensive permafrost thaw near Eight Mile Lake...

To compensate for losses in overwintering habitat, elk are fed hay in winter at approximately 37 locations throughout the western United States. These winter feeding programs concentrate elk activity, and there is concern that such concentrations could degrade plant communities. Except for one study focused exclusively on aspen (Populus tremuloides), ours is the first to quantify vegetation responses to supplemental winter feeding of elk. The western Wyoming feedground we studied was established in winter 1981-1982, and supplemental feeding occurred every winter through 2006. Transects...

Research on the degree to which carbon (C) availability limits growth in trees, as well as recent trends in climate change and concurrent increases in drought related tree mortality, have led to a renewed focus on the physiological mechanisms associated with tree growth responses to current and future climate. This has led to some dispute over the role of stored nonstructural C compounds as indicators of a tree's current demands for photosynthate. Much of the uncertainty surrounding this issue could be resolved by developing a better understanding of the potential functions of non-structura...

Port-Orford-cedar is of interest to ecologists and foresters, but little information is available on its growth, its genetic variation, or the field performance of families selected for resistance to root disease. Survival, damaging agents, and growth were evaluated for nine families at three outplanting sites in south coastal Oregon. Survival was excellent on two sites. Family differences were observed in growth rates, foliage dieback, and tendency to form multiple stems after browsing. Mean tree height 8 growing seasons after planting was 2.6 m; the heights of the tallest trees on one...

During the 21st century, climate-driven changes in fire regimes will be a key agent of change in forests of the U.S. Pacific Northwest (PNW). Understanding the response of forest carbon (C) dynamics to increases in fire will help quantify limits on the contribution of forest C storage to climate change mitigation and prioritize forest types for monitoring C storage and fire management to minimize C loss. In this study, we used projections of 21st century area burned to explore the consequences of changes in fire regimes on C dynamics in forests of Washington State. We used a novel empirical...

Lidar is currently the most accurate method for remote estimation of forest structure, but it has limited spatial and temporal coverage. Conversely, Landsat data are more widely available, but exhibit a weaker relationship with structure under medium to high leaf area conditions. One potentially valuable means of enhancing the relationship between Landsat reflectance and forest structure is to incorporate Landsat spectral trends prior to a date of interest. Because the condition of a forest stand at any point in time is linked to the stand's disturbance history, an approach that directly...

Fuel treatment effectiveness in Southern forests has been demonstrated using fire behavior modeling and observations of reduced wildfire area and tree damage. However, assessments of treatment effectiveness may be improved with a more rigorous accounting of the fuel characteristics. We present two case studies to introduce a relatively new approach to characterizing fuels and predicting potential fire behavior, fuel consumption, and emissions in Southern forests using the Fuel Characteristic Classification System (FCCS) and Consume. The first case study provides fine-scale (

Many aspects of forest structure are thought to contribute to the presence, abundance, and diversity of forest-floor bryophytes. To what extent easily measured characteristics of local environment (overstory structure or substrate availability) explain patterns of abundance and diversity remains unclear in most forest ecosystems. We explore these relationships in four mature, Douglas-fir dominated forests in southwestern Washington (U.S.A.). At each site, six 13-ha stands were sampled systematically (787 total plots) to capture variation in physical environment, forest overstory and...

The Northwest Forest Plan (NWFP), which aims to conserve late-successional and old-growth forests (older forests) and associated species, established new policies on federal lands in the Pacific Northwest USA. As part of monitoring for the NWFP, we tested nearest-neighbor imputation for mapping change in older forest, defined by threshold values for forest attributes that vary with forest succession. We mapped forest conditions on > 19 million ha of forest for the beginning (Time 1) and end (Time 2) of a 13-year period using gradient nearest neighbor (GNN) imputation. Reference data were...

Growing emphasis on ecosystem and landscape-level forest management across North America has spurred an examination of alternative management strategies which focus on emulating dynamic natural disturbance processes, particularly those associated with forest fire regimes. This topic is the cornerstone of research in the Blue River Landscape Study (BRLS) on the Willamette National Forest in the McKenzie River watershed of western Oregon. As scientists and managers work to unravel the ecological and economic implications of disturbance-based forest management, they must also consider public...