凋落物输入对三江平原弃耕农田土壤基础呼吸和活性碳组分的影响

土壤有机碳的积累主要由土壤有机质的输入与输出间的净平衡决定的,植被的恢复和凋落物质的大量输入是土壤恢复的先决条件,凋落物的输入在土壤恢复过程中起着至关重要的作用.通过对不同类型凋落物输入到三江平原弃耕农田后土壤的基础呼吸、溶解有机碳(DOC)和土壤微生物量碳(MBC)的研究表明:相同种类凋落物输入后,输入到土壤总有机碳(TOC)背景值低的凋落物被微生物降解的速率大于TOC背景值高的土壤,TOC较低的土壤能够加快微生物对输入凋落物的分解,不利于有机质的积累;不同类型凋落物的输入使土壤基础呼吸、DOC和MBC等活性组分的生成和降解产生差异,改变了凋落物的降解速率,在三江平原研究的4种主要植被类型中,人工林凋落物最容易降解,小叶章、大豆的降解能力次之,玉米是最难降解的凋落物.

Influence of litter importation on basal respiration and labile carbon in restored farmland in Sanjiang Plain

The accumulation of soil organic carbon is determined by the net balance between soil organic matter importation and exportation. The vegetation restoration and litter importation are prerequisite factors, which could determine the nutrition restoration in soil, but the litter importation often been considered the fundermental factor determining the process of soil restoration. In this paper, we studied the reaction of soil basal respiration, microbial biomass carbon (MBC) and dissolved organic carbon (DOC) after organic litter importation. Under the condition of same litter importation, the decomposition rate of litter biomass showed the opposite tendency as the content of total organic matter in soil. The different kinds of litter imporation could influce the basal respiration, MBC and DOC in soil, which could also determine the ability of soil microbial decomposition. Our results indicated that the litter decomposition rate from easier to harder in Sanjiang Plain was: plantation> Deyeuxia angustifolia and soybean>maize.