The Arctic Flux Study: A Regional View of Trace Gas Release

Weller, Gunter; Chapin, F. Stuart; Everett, KR; Hobbie, J. E.; Kane, D. L.; Oechel, W. C.; Ping, C. L.; Reeburgh, WS; Walker, Donald A.; Walsh, John E.

doi:10.2307/2845932

Cited by 87 publications

(87 citation statements)

References 19 publications

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“…If the effect of decomposition were to increase nutrient availability, there may be an additional uptake of CO 2 owing to higher rates of photosynthesis (Shaver & Chapin 1986;Shaver et al 1998;Johnson et al 2000), although as sink strength in vascular plants decreases, productivity may be offset by substrate-controlled or nutrient-limited CO 2 loss from soil respiration by microorganisms (Nadelhoffer et al 1991;Hobbie 1996;Jonasson et al 1999). Larger sinks of CO 2 are accordingly associated with lower respiration rates in wetter habitats (Vourtilis et al 2000), while short-term experiments designed to explain the net effect of climate warming on soil moisture and the C-balance of tundra plots (Johnson et al 1996) support observational data demonstrating that a shift from net C-input to C-output accompanies the recent drying of tundra habitats (Oechel et al 1993Weller et al 1995).…”

Section:      mentioning

confidence: 59%

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Ellis

Rochefort

2005

Journal of Ecology

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Summary 1The response of peat-rich permafrost soils to human-induced climate change may be especially important in modifying the global C-flux. We examined the Holocene developmental record of a High Arctic peat-forming wetland to investigate its sensitivity to past climate change and aid understanding of the likely effects of future climate warming on high-latitude ecosystems. 2 The microhabitat of mosses was quantified in the present-day polygon-complex at Bylot Island (73 ° N, 80 ° W) and used to interpret the radiocarbon-dated macrofossil record of three cores, comprising c. 3500 years of wetland development. Recurrent wet and dry phases in the reconstructed palaeohydrological record indicated pronounced temporal variability. Wet and dry phases were compared between cores and with palaeoclimatic proxy values, measured as percentage melt and δ 18 O in nearby ice cores. 3 Periodic wet and dry phases appear unrelated to past climate over c. 50% of the combined stratigraphic records, and are attributable instead to geomorphological mechanisms. At other times, association of wet and dry phases with significantly lower and higher values of percentage melt and δ 18 O indicate a possible effect of past climate change on polygon hydrology and vegetation, although inconsistencies between cores suggest that local geomorphological processes continued to modify a regional climatic effect. However, during a period incorporating the Little Ice Age ( c. 305-530 cal. years  ), reconstructed moisture and vegetation change is pronounced and consistent among all three cores. 4 The results provide strong evidence for the sensitivity of a High Arctic terrestrial ecosystem to past climate change during the Holocene. The estimated magnitude of changes in soil moisture between wet and dry phases is sufficient to imply recurrent shifts in wetland function, periodically impacted upon by pronounced climatic variability, although controlled principally by autogenic processes. The structure and function of such wetlands may therefore be susceptible to predicted, human-induced climate warming.

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Section:      mentioning

confidence: 59%

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Ellis

Rochefort

2005

Journal of Ecology

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“…This goal has proved more difficult than representing plant functional types or traits in models, because not all microbial taxonomic groups have ecologically coherent functions (Philippot et al, 2010). A fourth challenge is to simulate the lateral transport of dissolved and particulate biogeochemical variables that are necessary to better simulate the storage and transport of CH 4 within heterogeneous landscapes (Weller et al, 1995). A fifth challenge is modeling CH 4 flux across spatial scales.…”

Section: Modeling Challengesmentioning

confidence: 99%

Reviews and syntheses: Four decades of modeling methane cycling in terrestrial ecosystems

et al. 2016

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Abstract. Over the past 4 decades, a number of numerical models have been developed to quantify the magnitude, investigate the spatial and temporal variations, and understand the underlying mechanisms and environmental controls of methane (CH 4 ) fluxes within terrestrial ecosystems. These CH 4 models are also used for integrating multi-scale CH 4 data, such as laboratory-based incubation and molecular analysis, field observational experiments, remote sensing, and aircraft-based measurements across a variety of terrestrial ecosystems. Here we summarize 40 terrestrial CH 4 models to characterize their strengths and weaknesses and to suggest a roadmap for future model improvement and application. Our key findings are that (1) the focus of CH 4 models has shifted from theoretical to site-and regional-level applications over the past 4 decades, (2) large discrepancies exist among models in terms of representing CH 4 processes and their environmental controls, and (3) significant datamodel and model-model mismatches are partially attributed to different representations of landscape characterization and inundation dynamics. Three areas for future improvements and applications of terrestrial CH 4 models are that (1) CH 4 models should more explicitly represent the mechanisms underlying land-atmosphere CH 4 exchange, with an emphasis on improving and validating individual CH 4 processes over depth and horizontal space, (2) models should be developed that are capable of simulating CH 4 emissions across highly heterogeneous spatial and temporal scales, particularly hot moments and hotspots, and (3) efforts should be invested to develop model benchmarking frameworks that can easily be used for model improvement, evaluation, and integration with data from molecular to global scales. These improvements in CH 4 models would be beneficial for the Earth system models and further simulation of climate-carbon cycle feedbacks.

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“…The frost ecosystems are arguably among the most sensitive to the climate change because of the sensitivity of the permafrost environment to climate warming (Walker et al, 2003;Christensen et al, 2004). Changes in vegetation cover of these ecosystems lead to dramatic changes in the physical properties of the soil, the dynamics of the surface soil water, and the soil carbon cycle, which in turn exert a profound influence on the entire biosphere (Weller et al, 1995;Jorgenson et al, 2001;Christensen et al, 2004). Given the magnitudes of the heat sinks within frost regions, the terrestrial ecosystems of Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

Impacts of changes in vegetation cover on soil water heat coupling in an alpine meadow of the Qinghai-Tibet Plateau, China

Wang

Liu

et al. 2009

Hydrol. Earth Syst. Sci.

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Abstract. Alpine meadow is one of the most widespread grassland types in the permafrost regions of the QinghaiTibet Plateau, and the transmission of coupled soil water heat is one of the most crucial processes influencing cyclic variations in the hydrology of frozen soil regions, especially under different vegetation covers. The present study assesses the impact of changes in vegetation cover on the coupling of soil water and heat in a permafrost region. Soil moisture (θ v ), soil temperature (T s ), soil heat content, and differences in θ v -T s coupling were monitored on a seasonal and daily basis under three different vegetation covers (30, 65, and 93%) on both thawed and frozen soils. Regression analysis of θ v vs. T s plots under different levels of vegetation cover indicates that soil freeze-thaw processes were significantly affected by the changes in vegetation cover. The decrease in vegetation cover of an alpine meadow reduced the difference between air temperature and ground temperature ( T a−s ), and it also resulted in a decrease in T s at which soil froze, and an increase in the temperature at which it thawed. This was reflected in a greater response of soil temperature to changes in air temperature (T a ). For T a−s outside the range of −0.1 to 1.0 • C, root zone soil-water temperatures showed a significant increase with increasing T a−s ; however, the magnitude of this relationship was dampened with increasing vegetation cover. At the time of maximum water content in the thawing season, the soil temperature decreased with increasing vegetation. Changes in vegetation cover also led to variations in θ v -T s coupling. With the increase in vegetation cover, the surface heat flux decreased. Soil heat storage at 20 cm in depth increased with increasing vegetation cover, and the heat flux that was downwardly transmitted de-

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The Arctic Flux Study: A Regional View of Trace Gas Release

Cited by 87 publications

References 19 publications

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Long‐term sensitivity of a High Arctic wetland to Holocene climate change

Reviews and syntheses: Four decades of modeling methane cycling in terrestrial ecosystems

Impacts of changes in vegetation cover on soil water heat coupling in an alpine meadow of the Qinghai-Tibet Plateau, China

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