Biomass, and carbon and nitrogen pools in a subtropical evergreen broad-leaved forest in eastern China.

摘要

Subtropical evergreen broad-leaved forest is the most widely distributed land-cover type in eastern China. As the rate of land-use change accelerates worldwide, it is becoming increasingly important to quantify ecosystem biomass and carbon (C) and nitrogen (N) pools. Above and below-ground biomass and ecosystem pools of N and C in a subtropical secondary forest were investigated at Laoshan Mountain Natural Reserve, eastern China. Total biomass was 142.9 Mg ha-1 for a young stand (18 years) and 421.9 Mg ha-1 for a premature stand (ca. 60 years); of this, root biomass was from 26.9 (18.8% of the total) to 100.3 Mg ha-1 (23.8%). Total biomass C and N pools were, respectively, 71.4 Mg ha-1 and 641.6 kg ha-1 in the young stand, and 217.0 Mg ha-1 and 1387.4 kg ha-1 in the premature stand. The tree layer comprised 91.8 and 89.4% of the total biomass C and N pools in the young stand, and 98.0 and 95.6% in the premature stand. Total ecosystem C and N pools were, respectively, 101.4 and 4.6 Mg ha-1 for the young stand, and 260.2 and 6.6 Mg ha-1 for the premature stand. Soil C comprised 23.8-29.6% of total ecosystem C whereas soil N comprised 76.9-84.4% of the total. Our results suggest that a very high percentage of N in this subtropical forest ecosystem is stored in the mineral soil, whereas the proportion of organic C in the soil pool is more variable. The subtropical forest in eastern China seems to rapidly accumulate biomass during secondary succession, which makes it a potentially rapid accumulator of, and large sink for, atmospheric C.