Fine root growth and contribution to soil carbon in a mixed mature Pinus koraiensis forest

Abstract

Forest fine roots contribute substantially to carbon cycling, and old growth forests have an important role in the global carbon budget. We, hence, studied temporal variation in fine root production and turnover in an old forest. Fine root dynamics were investigated, using sequential soil cores for 6 years, and related to rainfall and air temperature in a mixed mature broad-leaved Pinus koraiensis forest in northeastern China. The mass, production, mortality, and disappearance of fine roots showed intra-annual variation. Monthly live and dead fine root mass were significantly positively correlated with meteorological conditions of the previous month. Monthly fine root production was associated with air temperature of the current month. The intra-annual pattern of fine root production was similar to that of net primary production and opposite to that of leaf litterfall. Total fine root production accounted for 25 % of net primary production, and the fine root input to soil carbon was 1.2 times larger than the leaf litterfall. Our results indicate tight linkages between fine roots and meteorological conditions. The important role of fine roots in forest carbon budget suggests that forest carbon flux estimations need to take fine root dynamics into account.