Treesearch

We describe assumed tiger habitat characteristics and attempt to identify potential tiger habitats in the Garo Hills region of Meghalaya, North East India. Conserving large forest tracts and protected wildlife habitats provides an opportunity for restoring populations of wide-ranging wildlife such as tigers and elephants. Based on limited field observations coupled with focused group discussion with local villagers and senior staff members of the wildlife wing of the State Forest Department of Megahlaya, we identified 20 localities in South Garo Hills, which if protected and managed for...

Two opposing hypotheses have been presented to explain reduced tree growth at the treeline, compared with growth in lower elevation or lower latitude forests: the carbon source and sink limitation hypotheses. The former states that treeline trees have an unfavorable carbon balance and cannot support growth of the magnitude observed at lower elevations or latitudes, while the latter argues that treeline trees have an adequate carbon supply, but that cold temperatures directly limit growth. In this study, we examined the relative importance of source and sink limitation in forest and...

Large, late-winter ptarmigan migrations heavily impact the shoot, plant, and patch architecture of shrubs that remain above the snow surface. Ptarmigan browsing on arctic shrubs was assessed in the vicinity of Toolik Lake, on the north side of the Brooks Range in Alaska. Data were collected in early May 2007, at maximum snow depth, after the bulk of the ptarmigan migration had passed through the area. In an area of tall shrubs, half of the buds on Salix alaxensis were browsed by ptarmigan. Three percent of the buds that were buried beneath the snow were browsed, 90% of the buds that were...

On the basis of projected losses of their essential sea-ice habitats, a United States Geological Survey research team concluded in 2007 that two-thirds of the world's polar bears (Ursus maritimus) could disappear by mid-century if business-as-usual greenhouse gas emissions continue. That projection, however, did not consider the possible benefits of greenhouse gas mitigation. A key question is whether temperature increases lead to proportional losses of sea-ice habitat, or whether sea-ice cover crosses a tipping point and irreversibly collapses when temperature reaches a critical threshold....

The boreal region stores a large proportion of the world's terrestrial carbon (C) and is subject to high-intensity, stand-replacing wildfires that release C and nitrogen (N) stored in biomass and soils through combustion. While severity and extent of fires drives overall emissions, methods for accurately estimating fire severity are poorly tested in this unique region where organic soil combustion is responsible for a large proportion of total emissions. We tested a method using adventitious roots on black spruce trees (Picea mariana) in combination with canopy allometry to reconstruct...

We used twelve Landsat scenes from the 1980s-2009 and regional 2000-2009 MODIS data to examine the long-term trend in the normalized difference vegetation index (NDVI) within unburned areas of the Alaskan boreal forest. Our analysis shows that there has been a declining trend in NDVI in this region, with the strongest "browning trend" occurring in eastern Alaska where the climate during the growing season is relatively dry and warm. Possible reasons for the "browning trend" are decreased vegetation due to temperature-induced drought stress and increased infestations of insect pests.

Observations indicate that over the past several decades, geomorphic processes in the Arctic have been changing or intensifying. Coastal erosion, which currently supplies most of the sediment and carbon to the Arctic Ocean, may have doubled since 1955. Further inland, expansion of channel networks and increased river bank erosion has been attributed to warming. Lakes, ponds, and wetlands appear to be more dynamic, growing in some areas, shrinking in others, and changing distribution across lowland regions. On the Arctic coastal plain, recent degradation of frozen ground previously stable...

Mechanisms involved in post-fire morel fructification remain unclear. A new undescribed belowground vegetative structure of Marchella tomentosa in a burned boreal forest was investigated north of Fairbanks, Alaska. The name "radiscisclerotium" is proposed to define this peculiar and elaborate belowground vegetative structure of M. tomentosa. Bayesian and maximum parsimony analyses based on ITS rRNA regions and nLSU gene strongly supported a new clade composed of M. tomentosa within the genus Morchella.

The scientific community has largely reached consensus that climate change is real, is exacerbated by human activities, and is causing detectable shifts in both living and non-living components of the biosphere. Yet, documenting and predicting the ecological, economic, social, and cultural consequences of climate change have not yet stimulated an appropriately strong and rapid societal response, especially in the US. Climate-change impacts, and the related environmental degradation and species extinctions, continue to increase at rates far steeper than the rate of social change. If this...

High-latitude regions store large amounts of organic carbon (OC) in active-layer soils and permafrost, accounting for nearly half of the global belowground OC pool. In the boreal region, recent warming has promoted changes in the fire regime, which may exacerbate rates of permafrost thaw and alter soil OC dynamics in both organic and mineral soil. We examined how interactions between fire and permafrost govern rates of soil OC accumulation in organic horizons, mineral soil of the active layer, and near-surface permafrost in a black spruce ecosystem of interior Alaska. To estimate OC...