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Filters: Tags: P2-Changes in Plant and Animal Species Due to Climate Change (X) > Extensions: Citation (X)

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1. ?Most current climate?carbon cycle models that include the terrestrial carbon (C) cycle are based on a model developed 40 years ago by Woodwell & Whittaker (1968) and omit advances in biogeochemical understanding since that time. Their model treats net C emissions from ecosystems as the balance between net primary production (NPP) and heterotrophic respiration (HR, i.e. primarily decomposition). 2. ?Under conditions near steady state, geographic patterns of decomposition closely match those of NPP, and net C emissions are adequately described as a simple balance of NPP and HR (the Woodwell-Whittaker model). This close coupling between NPP and HR occurs largely because of tight coupling between C and N (nitrogen)...
High-latitude northern ecosystems are experiencing rapid climate changes, and represent a large potential climate feedback because of their high soil carbon densities and shifting disturbance regimes. A significant carbon flow from these ecosystems is soil respiration (RS, the flow of carbon dioxide, generated by plant roots and soil fauna, from the soil surface to atmosphere), and any change in the high-latitude carbon cycle might thus be reflected in RS observed in the field. This study used two variants of a machine-learning algorithm and least squares regression to examine how remotely-sensed canopy greenness (NDVI), climate, and other variables are coupled to annual RS based on 105 observations from 64 circumpolar...
We present an analysis of ozone (O-3) photochemistry observed by aircraft measurements of boreal biomass burning plumes over eastern Canada in the summer of 2011. Measurements of O-3 and a number of key chemical species associated with O-3 photochemistry, including non-methane hydrocarbons (NMHCs), nitrogen oxides (NOx) and total nitrogen containing species (NOy), were made from the UK FAAM BAe-146 research aircraft as part of the "quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites" (BORTAS) experiment between 12 July and 3 August 2011. The location and timing of the aircraft measurements put BORTAS into a unique position to sample biomass burning...
We evaluated the potential for grazers to regulate benthic algal biomass and taxonomic composition in an Alaskan marsh after enrichment with nutrients that are expected to increase in the region with ongoing climate change. We nested caged and uncaged substrates together inside mesocosm enclosures with natural abundances of snails or no snails and with or without nutrient enrichment (NO3 + PO4 + Si). Algal biomass was greater in all nutrient-enriched enclosures than in controls. Algal biomass was greater in enclosures where grazers were present but excluded by a cage than in enclosures where grazers were allowed to graze or where grazers were absent. In the presence of nutrients, grazed communities were dominated...
Research on impacts of human activity and infrastructure development on reindeer and caribou (Rangifer tarandus) is reviewed in the context of spatial (m to many km) and temporal (min to decades) scales. Before the 1980s, most disturbance studies were behavioral studies of individual animals at local scales, reporting few and short-term (min to h) impacts within 0-2 km from human activity. Around the mid 1980s, focus shifted to regional-scale landscape studies, reporting that Rangifer reduced the use of areas within 5 km from infrastructure and human activity by 50-95% for weeks, months or even years and increased use of remaining undisturbed habitat far beyond those distances. The extent could vary with type of...
Mast-seeding conifers such as Picea glauca exhibit synchronous production of large seed crops over wide areas, suggesting climate factors as possible triggers for episodic high seed production. Rapidly changing climatic conditions may thus alter the tempo and spatial pattern of masting of dominant species with potentially far-reaching ecological consequences. Understanding the future reproductive dynamics of ecosystems including boreal forests, which may be dominated by mast-seeding species, requires identifying the specific cues that drive variation in reproductive output across landscape gradients and among years. Here we used annual data collected at three sites spanning an elevation gradient in interior Alaska,...
map background search result map search result map Is Alaska's Boreal Forest Now Crossing a Major Ecological Threshold? Late-glacial alpine glacier advance and early Holocene tephras, northern British Columbia Examining barriers and opportunities for sustainable adaptation to climate change in Interior Alaska A 200-year perspective of climate variability and the response of white spruce in interior Alaska Late-glacial alpine glacier advance and early Holocene tephras, northern British Columbia Examining barriers and opportunities for sustainable adaptation to climate change in Interior Alaska A 200-year perspective of climate variability and the response of white spruce in interior Alaska Is Alaska's Boreal Forest Now Crossing a Major Ecological Threshold?