Biogeochemical Consequences of Arctic Climate Warming


High latitudes are a critical component of the global carbon cycle, because they store nearly half of the world’s soil carbon and are experiencing unprecedented rates of warming. A suite of stabilizing and destabilizing feedbacks among the plant community and the soil system complicates projecting the future carbon balance of warming arctic systems. Warming initially stimulates tundra decomposition, increasing plant productivity and woody-shrub dominance. These responses may be transitory, however, due to coupled abiotic-biotic feedbacks that alter seasonal soil temperature regimes (by increasing summertime shrub shading and wintertime shrub-trapped snow insulation), plant growth patterns, and decomposer activity. In collaboration with an array of researchers, I used an ecosystem warming experiment initiated in 1989 at Toolik, the NSF Arctic Long Term Ecological Research (LTER) site, to identify:

1. How these feedbacks are mediated though seasonal interactions among the plant community, decomposers, and abiotic conditions; and

2. The consequences of these feedbacks on sustained arctic carbon storage.

Read more about our work here and here.

Crowther, T., et al. Quantifying global soil carbon losses in response to warming.  Nature. 540, 104–108 doi:10.1038/nature20150  

Sistla, S., E. Rastetter, J. Schimel. Responses of a tundra system to warming using SCAMPS: A stoichiometrically coupled, acclimating microbe-plant-soil model. Ecological Monographs 84 (1): 151 – 170.

Sistla, S. and J. Schimel. Seasonal patterns of microbial extracellular enzyme activities in an arctic tundra soil: Identifying direct and indirect effects of long-term summer warming. Soil Biology & Biochemistry 66: 119 – 129.

Sistla, S., J. Moore, R. Simpson, L. Gough, G. Shaver, J. Schimel. Long-term warming restructures arctic tundra without changing net soil carbon storage. Nature 497 (7451): 615 – 18.

Sistla, S., S. Asao, J.P. Schimel. Microbial N-limitation in tundra soil and its detection: Implications for Arctic SOC cycling. Soil Biology & Biochemistry 55: 78 – 84.