Treesearch

Predicting ecosystem responses to global change is a major challenge in ecology. A critical step in that challenge is to understand how changing environmental conditions influence processes across levels of ecological organization. While direct scaling from individual to ecosystem dynamics can lead to robust and mechanistic predictions, new approaches are needed to appropriately translate questions through the community level. Species invasion, loss, and turnover all necessitate this scaling through community processes, but predicting how such changes may influence ecosystem function is...

Arctic coastal communities in the Bering Strait region of Alaska (USA) and Chukotka (Russia) share a close relationship with their natural environments that can be characterized as a social-ecological system. This system is complex, featuring changing ecosystem conditions, multiple jurisdictions, migratory animal populations, and several cultures. We argue that linkages between communities in both countries enhance the effectiveness of transborder polar bear and walrus conservation. We find that locally embedded bilateral institutions can provide effective management venues that persist...

Satellite remotely sensed data of fire disturbance offers important information; however, current methods to study fire severity may need modifications for boreal regions. We assessed the potential of the differenced Normalized Burn Ratio (dNBR) and other spectroscopic indices and image transforms derived from Landsat TM/ETM+ data for mapping fire severity in Alaskan black spruce forests (Picea mariana) using ground measures of severity from 55 plots located in two fire events. The analysis yielded low correlations between the satellite and field measures of severity, with the highest...

Lichen regeneration timelines are needed to establish sound fire management guidelines for caribou (Rangifer tarandus) winter range. Paired burned and unburned permanent vegetative cover transects were established after 1981, 1977, and 1972 tundra fires in northwestern Alaska to document regrowth of tundra vegetation including caribou forage lichens in the wintering range of Alaska's largest caribou herd. Following fire, lichen had recovered very little compared to unburned transects (1% cover vs.15% cover) after 14 years. After 24 or 25 years, lichen cover in the burns remained low...

Lesser Canada Geese (Brania canadensis parvipes) are widespread throughout interior regions of Alaska and Canada, yet there have been no published studies documenting basic aspects of their nesting biology. We conducted a study to determine reproductive parameters of Lesser Canada Geese nesting along the Tanana River near the city of Fairbanks, in interior Alaska. Fieldwork was conducted in May of 2003, and consisted of locating nests along the riparian corridor between Fairbanks and Northpole, Alaska. Nests were found on gravel islands and shore habitats along the Tanana River, and were...

Human activities now dominate most of the ice-free terrestrial surface. A recent article presents a classification and global map of human-influenced biomes of the world that provides a novel and potentially appropriate framework for projecting changes in earth-system dynamics.

The role of ungulates as contributors to establishment and spread of non-native invasive plants in natural areas is not well known. The objectives of this study were to document whether or not sulfur cinquefoil (Potentilia recta L.) is grazed by ungulates and to quantify the effects of ungulate herbivory on the density and demography of sulfur cinquefoil. Despite reports suggesting sulfur cinquefoil is minimally grazed, our results indicate that substantial grazing of sulfur cinquefoil occurs in a northeastern Oregon natural area. As sulfur cinquefoil reproduces only by seed and seeds...

The FIA BioSum model was used to simulate three fire-hazard-reduction policies in an area comprising northern California, southwestern Oregon, and the east slopes of the Cascade Mountains in Oregon. The policy scenarios, all subject to a stand-scale fire-hazard-reduction effectiveness constraint, included maximize torching index improvement (Max TI), maximize net revenue recovery (Max NR), and minimize merchantable timber removal (Min Merch). Differences in the area treated under each scenario were considerable, ranging from 15 to 96% of the area for which effective treatments are technical...

High throughput sequencing methods are widely used in analyses of microbial diversity but are generally applied to small numbers of samples, which precludes charaterization of patterns of microbial diversity across space and time. We have designed a primer-tagging approach that allows pooling and subsequent sorting of numerous samples, which is directed to amplification of a region spanning the nuclear ribosomal internal transcribed spacers and partial large subunit from fungi in environmental samples.

We studied the effect of epidermal mining on aspen growth and physiology during an outbreak of Phyllocnistis populiella in the boreal forest of interior Alaska. Experimental reduction of leaf miner density across two sites and 3 years significantly increased annual apsen growth rates relative to naturally mined controls. Leaf mining damage was negatively related to leaf longevity. Mining damage to the top and bottom surfaces of leaves had different effects on physiology. Mining damage to the bottom leaf surface, where stomata are located, had significant negative effects on net photosynthes...