Scenarios of Biodiversity Changes in Arctic and Alpine Tundra

Walker, Marilyn D.; Gould, William A.; ChapinIII, F. Stuart

doi:10.1007/978-1-4613-0157-8_5

Cited by 23 publications

(20 citation statements)

References 62 publications

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“…The transition between High and Low Arctic is primarily controlled by climate (Bliss, 1995; Walker, 2000), as the filtering effect of reduced summer warmth in the north constrains the pool of available species and alters vegetation composition and biological activity (Rannie, 1986; Walker, 1995; Callaghan et al. , 2001; Walker et al. , 2001a,b).…”

Section: Comparison Of Ecosystem Properties Between the Low (Subzonesmentioning

confidence: 99%

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The nature of spatial transitions in the Arctic

Epstein

Beringer

Gould

et al. 2004

Journal of Biogeography

111

113

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Aim Describe the spatial and temporal properties of transitions in the Arctic and develop a conceptual understanding of the nature of these spatial transitions in the face of directional environmental change.Location Arctic tundra ecosystems of the North Slope of Alaska and the tundraforest region of the Seward Peninsula, AlaskaMethods We synthesize information from numerous studies on tundra and treeline ecosystems in an effort to document the spatial changes that occur across four arctic transitions. These transitions are: (i) the transition between High-Arctic and Low-Arctic systems, (ii) the transition between moist non-acidic tundra (MNT) and moist acidic tundra (MAT, also referred to as tussock tundra), (iii) the transition between tussock tundra and shrub tundra, (iv) the transition between tundra and forested systems. By documenting the nature of these spatial transitions, in terms of their environmental controls and vegetation patterns, we develop a conceptual model of temporal dynamics of arctic ecotones in response to environmental change.Results Our observations suggest that each transition is sensitive to a unique combination of controlling factors. The transition between High and Low Arctic is sensitive primarily to climate, whereas the MNT/MAT transition is also controlled by soil parent material, permafrost and hydrology. The tussock/shrub tundra transition appears to be responsive to several factors, including climate, topography and hydrology. Finally, the tundra/forest boundary responds primarily to climate and to climatically associated changes in permafrost. There were also important differences in the demography and distribution of the dominant plant species across the four vegetation transitions. The shrubs that characterize the tussock/shrub transition can achieve dominance potentially within a decade, whereas spruce trees often require several decades to centuries to achieve dominance within tundra, and Sphagnum moss colonization of non-acidic sites at the MNT/MAT boundary may require centuries to millennia of soil development.Main conclusions We suggest that vegetation will respond most rapidly to climatic change when (i) the vegetation transition correlates more strongly with climate than with other environmental variables, (ii) dominant species exhibit gradual changes in abundance across spatial transitions, and/or (iii) the dominant species have demographic properties that allow rapid increases in abundance following climatic shifts. All three of these properties characterize the transition between tussock tundra and low shrub tundra. It is therefore not surprising that of the four transitions studied this is the one that appears to be responding most rapidly to climatic warming.

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Section: Comparison Of Ecosystem Properties Between the Low (Subzonesmentioning

confidence: 99%

“…are absent) (Walker et al, 2001a;Hobbie & Gough, 2002). Although MNT has greater species diversity (Walker et al, 1994) with twice the number of species per 100 m 2 in northern Alaska (Walker et al, 2001b), the biomass of MAT is 25-35% greater than that of MNT (Walker et al, 1994(Walker et al, , 2003a. Soils.…”

Section: Ecosystem Properties Of the Transitionmentioning

confidence: 99%

The nature of spatial transitions in the Arctic

Epstein

Beringer

Gould

et al. 2004

Journal of Biogeography

111

113

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“…Recent decades have witnessed strong effects of climatic warming as this region has been experiencing three times the average global warming rate since 1960 (Li and Tang, 1988). It is predicted that the Tibetan alpine tundra could decrease to 20% of its current level with further climate warming (Walker et al, 2001). These observations and in silico modeling render Tibet as one of the most threatened regions by climate warming.…”

Section: Introductionmentioning

confidence: 99%

The microbial gene diversity along an elevation gradient of the Tibetan grassland

et al. 2013

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Tibet is one of the most threatened regions by climate warming, thus understanding how its microbial communities function may be of high importance for predicting microbial responses to climate changes. Here, we report a study to profile soil microbial structural genes, which infers functional roles of microbial communities, along four sites/elevations of a Tibetan mountainous grassland, aiming to explore the potential microbial responses to climate changes via a strategy of space-for-time substitution. Using a microarray-based metagenomics tool named GeoChip 4.0, we showed that microbial communities were distinct for most but not all of the sites. Substantial variations were apparent in stress, N and C-cycling genes, but they were in line with the functional roles of these genes. Cold shock genes were more abundant at higher elevations. Also, gdh converting ammonium into urea was more abundant at higher elevations, whereas ureC converting urea into ammonium was less abundant, which was consistent with soil ammonium contents. Significant correlations were observed between N-cycling genes (ureC, gdh and amoA) and nitrous oxide flux, suggesting that they contributed to community metabolism. Lastly, we found by Canonical correspondence analysis, Mantel tests and the similarity tests that soil pH, temperature, NH 4 þ -N and vegetation diversity accounted for the majority (81.4%) of microbial community variations, suggesting that these four attributes were major factors affecting soil microbial communities. On the basis of these observations, we predict that climate changes in the Tibetan grasslands are very likely to change soil microbial community functional structure, with particular impacts on microbial N-cycling genes and consequently microbe-mediated soil N dynamics.

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“…Alpine meadows, like high-latitude and cold regions generally, are especially sensitive to global warming (Walker et al 2001). Many experiments conducted in these cold regions have demonstrated that increased temperature tends to directly enhance plant productivity (e.g., Kudo and Suzuki 2003).…”

Section: Introductionmentioning

confidence: 99%

A brown-world cascade in the dung decomposer food web of an alpine meadow: effects of predator interactions and warming

Duffy

Reich

et al. 2011

Ecological Monographs

107

113

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Abstract. Top-down control has been extensively documented in food webs based on living plants, where predator limitation of herbivores can cascade to facilitate plant growth (the green-world hypothesis), particularly in grasslands and aquatic systems. Yet the ecosystem role of predators in detrital food webs is less explored, as is the potential effect of climate warming on detritus-based communities. We here show that predators have a ''brown-world'' role in decomposer communities via a cascading top-down control on plant growth, based on the results of an experiment that factorially manipulated presence and size of two predator species as well as temperature (warmed vs. unwarmed). The inclusion of predatory beetles significantly decreased abundance of coprophagous beetles and thus the rate of dung decomposition and productivity of plants growing surrounding the dung. Moreover, the magnitude of these decreases differed between predator species and, for dung loss, was temperature dependent. At ambient temperature, the larger predators tended to more strongly influence the dung loss rate than did the smaller predators; when both predators were present, the dung loss rate was higher relative to the treatments with the smaller predators but comparable to those with the larger ones, suggesting an antagonistic effect of predator interaction. However, warming substantially reduced dung decomposition rates and eliminated the effects of predation on dung decomposition. Although warming substantially decreased dung loss rates, warming only modestly reduced primary productivity. Consistent with these results, a second experiment exploring the influence of the two predator species and warming on dung loss over time revealed that predatory beetles significantly decreased the abundance of coprophagous beetles, which was positively correlated with dung loss rates. Moreover, experimental warming decreased the water content of dung and hence the survival of coprophagous beetles. These results confirm that the ''brown-world'' effect of predator beetles was due to cascading top-down control through coprophagous beetles to nutrient cycling and primary productivity. Our results also highlight potentially counterintuitive effects of climate warming. For example, global warming might significantly decrease animalmediated decomposition of organic matter and recycling of nutrients in a future warmed world.

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Scenarios of Biodiversity Changes in Arctic and Alpine Tundra

Cited by 23 publications

References 62 publications

The nature of spatial transitions in the Arctic

The nature of spatial transitions in the Arctic

The microbial gene diversity along an elevation gradient of the Tibetan grassland

A brown-world cascade in the dung decomposer food web of an alpine meadow: effects of predator interactions and warming

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