Pleistocene Park experiment: Effect of grazing on the accumulation of soil carbon in the Arctic.
Abstract
In the late Pleistocene Mammoth Steppe was the world largest ecosystem. It was a highly productive steppe ecosystem with numerous herbivores that maintained the dominance of grasslands. Over tens of thousands of years this ecosystem was accumulating carbon in the soil. Portion of this storage still persist in the permafrost of Siberia and Alaska. With the end of the Pleistocene, and human expansion this ecosystem vanished. Mosses, shrubs and larch forest soon replaced grasses and herbs.
Pleistocene Park is an experiment conducted in the far north of Siberia; its main goal is to restore the high productive steppe ecosystems in the Arctic similar to the Mammoth Steppe. This would increase the richness of the northern ecosystems and bioproductivity, and through a series of ecological mechanisms help to mitigate climate change. To conduct the experiment, we fenced 2000 hectares of land, and continue the ongoing process of introducing animals that either lived on this territory in the past or that can adapt to the modern northern environment. Through grazing, animals slowly transform the vegetation, replacing mosses, shrubs, and trees with grasses and herbs. Here we present detailed carbon inventory map of the Pleistocene Park territory, which been the subject of the active grazing in the last 20 years. Analyses are based on 300 frozen soil cores drilled in April-May 2018 within the oldest fenced area and territories outside of the Pleistocene Park with no grazing effect. Data indicates substantially higher carbon storage within entire soil profile (0 to 1 meter) for the grazed pastures. Based on 1200 samples taken at various depths average carbon content within the fenced area is 7.7% from dry weight. We attribute higher carbon soil content at the actively grazed pastures to the following mechanisms - Increased turnover of nutrients on the pastures compared with the modern Arctic ecosystems. - Grasses root system is penetrating to the deeper soil horizons where decomposition of organic matter is very slow. - More active photosynthesis dries soil through evapotranspiration and creates a more developed root system is required. - Grasses adapt to high grazing pressure by dedicating a higher portion of productivity to the root system. Restoration of high productive steppes will create a soil carbon sink in the Arctic.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B33B..08Z
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0486 Soils/pedology;
- BIOGEOSCIENCESDE: 1630 Impacts of global change;
- GLOBAL CHANGE