Storage and turnover of carbon in grassland soils along an elevation gradient in the Swiss Alps

Leifeld, Jens, Zimmermann, Michael, Fuhrer, Jürg, and Conen, Franz (2009) Storage and turnover of carbon in grassland soils along an elevation gradient in the Swiss Alps. Global Change Biology, 15 (3). pp. 668-679.

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Amount, composition, and rate of turnover of soil organic carbon (SOC) in mountainous cold regions is largely unknown, making predictions of future responses of this carbon (C) to changing environmental conditions uncertain. We hypothesized increasing amounts and declining turnover times of soil organic matter (SOM) under permanent grassland with increasing elevation and decreasing temperature. Samples from an irrigated transect in the Swiss Alps (880 to 2200 m elevation, mean annual temperatures +8.9 to +0.9 ˚C) were analyzed. Soil C stocks ranged from 49 to 96 t C ha−1 (0–20 cm) and were not related to elevation, though the highest site stored least C. Particulate organic carbon (POC) increased significantly with elevation and accounted for > 80% of the total soil C at 2200 m (0–5 cm). Mean residence times (MRTs) of POC computed by means of radiocarbon dating were in the order of years to decades and were positively related to elevation in the topsoil. At higher elevations, the estimated total C flux through the soil profile mainly depended on this fraction. MRT of mineral-associated matter ranged from decades to centuries and was not systematically related to elevation, but positively related to the soil mineral surface area and it increased with soil depth. Turnover rates from simulations with the soil C model RothC exceeded those from 14C measurements by a factor of 1.7–3.3 which suggests that C dynamics at these sites is overestimated by the model. Size of model pools and amount of C in soil fractions were only weakly correlated, thereby challenging previously postulated hypotheses concerning the correspondence of pools and fractions for grasslands at higher elevations.

Item ID: 17752
Item Type: Article (Research - C1)
ISSN: 1365-2486
Keywords: global warming; grassland; NaOCl; radiocarbon; RothC; soil carbon turnover; soil fractionation
Date Deposited: 15 Aug 2011 00:59
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050301 Carbon Sequestration Science @ 100%
SEO Codes: 96 ENVIRONMENT > 9614 Soils > 961405 Mountain and High Country Soils @ 100%
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