Research: carbon stocks

Assessment of belowground carbon stocks in forest and steppe
Researchers: Dr. Brent Helliker, Dr. Alain Plante, Dr. Alain Plante, Anarmaa Sharkhuu

Northern Mongolia is a unique and important region where we can quantify soil carbon stocks in both steppe and boreal forest systems and determine how future carbon sequestration capacity might change with both an ecotonal shift and a warming climate. Shifts between wood-based and grass-based ecosystems are happening worldwide due to climate and human-induced changes, and shifts between forest and steppe ecosystems in Mongolia will have a large impact on the carbon balance of the region. Northern hemisphere forests, of which the boreal forests of Asia are a large fraction, represent a major carbon sink, and thus an expansion of the larch forests should enhance carbon sequestration in northern Mongolia. However, evidence suggests that conversion of grasslands to woody ecosystems can result in a net loss of carbon due to a large decrease in organic carbon storage in the soil or in SOM. Furthermore, warming over the last century should lead to decreased permafrost and increased SOM loss in both forests and steppe ecosystems due to increased microbial activity.

To elucidate belowground carbon stocks across the forest-steppe ecotone we take transects of soil cores in: (1) pure larch forests, (2) larch forest edge, (3) the ecotone boundary, (4) steppe edge and (5) pure steppe. Transects established during the GEF project are being used. Cores are 5 cm in diameter and 1 m in length. In 10 cm increments, we determine bulk soil density. Samples are then dried and sieved to remove and quantify root mass. Inorganics are removed by acidification and total organic carbon and nitrogen is then determined using an elemental analyzer.

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