黄土区人工与天然植被对凋落物量和土壤有机碳变化的影响

在黄土丘陵区选择从耕地、草地、灌木林到乔木林样地,不同样地内设立1m×1m(乔木10m×10m)的样方,分析样方内凋落物积累量、碳氮含量、土壤有机碳(SOC)和可溶性碳(DOC)含量变化。结果表明:天然草地、灌木林、乔木林凋落物积累量依次为5.3,12.1和32.4t.hm-2;但人工灌木林和乔木林的凋落物积累量分别为6.7和11.4t.hm-2,分别是天然灌木林和乔木林的1/2和1/3。随着植被的恢复,天然植被凋落物的C/N高于人工植被(刺槐林除外)。与耕地SOC(4.67g·kg-1)相比,天然灌木林地SOC提高5.9倍,人工灌木林地提高1.8倍;天然乔木林地提高8.0倍,而人工乔木林地仅提高4.0倍。凋落物积累量与0～20cm土层土壤有机碳存在显著线性相关关系(R2>0.83),但20cm以下线性相关关系不显著。凋落物积累量与0～10cm土壤可溶性碳含量存在显著线性相关关系(R2>0.893),与10～60cm土层线性相关关系不显著,与80～100cm土壤可溶性碳存在显著线性负相关关系。

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 col...