Water, Energy, and Carbon Dioxide Circulation in Eastern Siberian Larch Forests: GAME, CREST and RIHN Results

Abstract

 During 1998-2013, water, energy, and carbon (WEC) cycles in larch forests of the Lena River Basin of eastern Siberia were investigated using plot and watershed scales. Plot scale studies of Spasskaya Pad (SPA) near Yakutsk clarified complex relations among diverse environmental variables and the WEC cycles in warm seasons. The WEC cycle characteristics in Elgeeii (ELG) forest, approximately 300 km southeast of Yakutsk, which has similar climate but different species composition, differed from those at SPA. The annual maximum active layer depths of permafrost increased by 10⁰ cm year^-1 in the major tributaries of the Lena River Basin. A significant increasing trend was found for the annual maximum active layer depth. The WEC cycle model indicated that the estimated evapotranspiration was in the same range as that observed using eddy correlation. Using the hydrological model, almost 30 % of the total runoff in the Lena River discharged extremely slowly; this result agreed with observed amounts. Next we must ascertain how the WEC cycles of the Siberian boreal forest adapt to expected environmental changes caused by global warming. Waterlogging in eastern Siberia expanded to a watershed scale suggests that the WEC cycles will affect environmental variables. Therefore, discussion of WEC cycles in high-latitude forests should emphasize not only drought, but also waterlogging.