关键词: 天然植被, 人工植被, 凋落物, 土壤有机碳, 土壤可溶性碳

Abstract:

Litter plays an important role in carbon flow between above ground and the soil, however there is little knowledge of relationship between litters and soil organic C under vegetation types. The objective of the present study was to quantify litter accumulation, and soil organic C in artificial and natural vegetations in the hilly region of Loess Plateau, China. A sampling grid was established from arable land, grassland, shrubland, and woodland on the Huangmian soil at the Yangou watershed. Three soil cores were collected in each sampling site. Soil samples were analyzed for organic C, dissolved C. All surface litter in 1 m×1 m area was collected prior to soil sampling, dried, weighed, and analyzed for total C and N. The litter accumulation in the natural grassland, shrubland and woodland were 5.3, 12.1 and 32.4 t·hm^-2, respectively, and the litter accumulation of artificial shrubland and woodland were just 6.7 and 11.4 t·hm^-2.The natural vegetation's litter accumulation ranged from two to five times of artificial vegetation. Except pure Robinia crop, the C/N of natural vegetation is higher than that of the artificial vegetation. SOC content in grassland was as 3.1 times as that in arable land; natural shrubland and artificial shrubland were as 5.9 and 1.8 times as arable land, respectively; natural woodland and artificial woodland were as 8.0 and 4.0 times as arable land, respectively. In addition, there was a significant correlation between litter accumulation and SOC content of the soil layer from 0 to 20 cm, however not below 20. There was a significant correlation between litter accumulation and DOC content of the soil layer from 0 to 10 cm. The litter accumulation and SOC content of the soil layer from 10 to 60 cm was not significantly correlated. A negative significant correlation was found between litter accumulation and DOC content of the soil layer from 80 to 100 cm.

Key words: natural vegetation, replanted vegetation, litter, SOC, DOC