Structural complexity and land-surface energy exchange along a gradient from arctic tundra to boreal forest

Thompson, C.D.C.; Beringer, Jason; Chapin, F. S.; McGuire, A. D.

doi:10.1658/1100-9233(2004)015[0397:scalee]2.0.co;2

Cited by 20 publications

(35 citation statements)

References 37 publications

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“…Changes in microenvironment following thaw slumping likely also lead to slump reinitiation on multidecadal time scales. Because vegetation exerts strong controls on regional ecosystem processes Thompson et al, 2004;Chapin et al, 2005), understanding the effects of disturbance on short-term and long-term successional trajectories is also a critical component of efforts to understand the effects of climate change on the Arctic.…”

Section: Discussionmentioning

confidence: 99%

Relative impacts of disturbance and temperature: persistent changes in microenvironment and vegetation in retrogressive thaw slumps

Lantz

Kokelj

Gergel

et al. 2009

Global Change Biology

164

195

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In the Low Arctic, a warming climate is increasing rates of permafrost degradation and altering vegetation. Disturbance associated with warming permafrost can change microclimate and expose areas of ion-rich mineral substrate for colonization by plants. Consequently, the response of vegetation to warming air temperatures may differ significantly from disturbed to undisturbed tundra. Across a latitudinal air temperature gradient, we tested the hypothesis that the microenvironment in thaw slumps would be warmer and more nutrient rich than undisturbed tundra, resulting in altered plant community composition and increased green alder (Alnus viridis subsp. fruticosa) growth and reproduction. Our results show increased nutrient availability, soil pH, snow pack, ground temperatures, and active layer thickness in disturbed terrain and suggest that these variables are important drivers of plant community structure. We also found increased productivity, catkin production, and seed viability of green alder at disturbed sites. Altered community composition and enhancement of alder growth and reproduction show that disturbances exert a strong influence on deciduous shrubs that make slumps potential seed sources for undisturbed tundra. Overall, these results indicate that accelerated disturbance regimes have the potential to magnify the effects of warming temperature on vegetation. Consequently, understanding the relative effects of temperature and disturbance on Arctic plant communities is critical to predicting feedbacks between northern ecosystems and global climate change.

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Section: Discussionmentioning

confidence: 99%

Relative impacts of disturbance and temperature: persistent changes in microenvironment and vegetation in retrogressive thaw slumps

Lantz

Kokelj

Gergel

et al. 2009

Global Change Biology

164

195

View full text Add to dashboard Cite

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“…Beringer et al, unpubl. data;Thompson et al, 2004). The boundary between the two tundra types involves increases in the abundance and biomass of deciduous dwarf birch (Betula nana L.) and willow (Salix pulchra Cham.)…”

Section: Tussock Tundra-shrub Tundra Transitionmentioning

confidence: 99%

The nature of spatial transitions in the Arctic

Epstein

Beringer

Gould

et al. 2004

Journal of Biogeography

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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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“…The high resolution a regional climate model provides makes it a useful tool for this analysis, as a high resolution is necessary to investigate land surface processes (e.g. Thompson et al 2004;McGuire et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of high-resolution Arctic regional climate model projections to different implementations of land surface processes

et al. 2011

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This paper discusses the effects of vegetation cover and soil parameters on the climate change projections of a regional climate model over the Arctic domain. Different setups of the land surface model of the regional climate model HIRHAM were realized to analyze differences in the atmospheric circulation caused by (1) the incorporation of freezing/thawing of soil moisture, (2) the consideration of top organic soil horizons typical for the Arctic and (3) a vegetation shift due to a changing climate. The largest direct thermal effect in 2 m air temperature was found for the vegetation shift, which ranged between −1.5 K and 3 K. The inclusion of a freeze/thaw scheme for soil moisture shows equally large sensitivities in spring over cool areas with high soil moisture content. Although the sensitivity signal in 2 m air temperature for the experiments differs in amplitude, all experiments show changes in mean sea level pressure (mslp) and geopotential height (z) throughout the troposphere of similar magnitude (mslp: −2 hPa to 1.5 hPa, z: −15 gpm to 5 gpm). This points to the importance of dynamical feedbacks within the atmosphere-land system. Land and soil processes have a distinct remote influence on large scale atmospheric circulation patterns in addition to their direct, regional effects. The assessment of induced uncertainties due to the changed implementations of land surface processes discussed in this study demonstrates the need to take all those processes for future Arctic climate projections into account, and demonstrates a clear need to include similar implementations in regional and global climate models.

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Structural complexity and land-surface energy exchange along a gradient from arctic tundra to boreal forest

Cited by 20 publications

References 37 publications

Relative impacts of disturbance and temperature: persistent changes in microenvironment and vegetation in retrogressive thaw slumps

Relative impacts of disturbance and temperature: persistent changes in microenvironment and vegetation in retrogressive thaw slumps

The nature of spatial transitions in the Arctic

Sensitivity of high-resolution Arctic regional climate model projections to different implementations of land surface processes

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