延河流域不同立地条件下植物-枯落物-土壤生态化学计量学特征

Soil-plant-litter Stoichiometry under Different Site Conditions in Yanhe Catchment, China

通过对黄土高原延河流域不同立地条件的植物、枯落物和土壤进行调查、取样和分析,选取不同立地条件下的共有植物达乌里胡枝子,研究了不同立地条件下共有植物-枯落物-土壤的碳、氮、磷化学计量特征,以期探索不同立地条件中的元素迁移和转化。结果表明:1)土壤碳氮比的平均值为10.88,土壤碳磷比和氮磷比的平均值分别为23.14和2.13。2)土壤碳氮比表现为阳坡>阴坡、沟坡>峁坡,氮磷比无显著差异;共有植物碳氮比表现为阳坡>阴坡,峁坡>沟坡,碳磷比和氮磷比为阴坡>阳坡,峁坡>沟坡;枯落物碳氮比表现为阳坡>阴坡,峁坡>沟坡;氮磷比和碳磷比在不同立地条件中均表现为阴坡>阳坡,沟坡>峁坡。3)通过对不同立地条件下植物-枯落物-土壤化学计量特征的探讨,得知沟坡条件下土壤有机碳累积速率相对高于峁坡,阳坡土壤有机碳固定大于阴坡,各立地条件中土壤全磷含量相对一致;在植物生长后期以及枯落物分解过程中,阳坡和峁坡表现为氮素迁移转化相对强烈,阴坡和沟坡则有利于磷的迁移和转化。

Based on the investigation of the plant, litter and soil under different site conditions in Yanhe catchment, we selected Lespedeza davurica(Laxm.) Schindl as common plant, and studied the C, N, P stoichiometry of plant, litter and soils in this paper. We also discussed the migration, conversion and limition of the elements. The results showed that: 1) Soil C/N was10.88, and soil C/P and N/P ratios were 23.14 and 2.13. 2) Soil C/N and C/P decreased as follows: sunny slope>shady slope; gully slope > hill slope; there was no significant difference in soil N/P under different site conditions. Plant C/N decreased as follows: sunny slope > shady slope; hill slope > gully slope; whereas plant C/P and N/P decreased as follows: shady slope >sunny slope; hill slope > gully slope. Litter C/N decreased as follows: shady slope > sunny slope; hill slope > gully slope; litter C/P and N/P decreased as follows: shady slope > sunny slope, gully slope> hill slope. 3) The C, N, P stoichiometry of plant, litter and soil reflected higher rate of soil organic carbon accumulation in gully slope than in hill slope, and higher rate in sunny slope than in shady slope. Soil P was similar under different site conditions. In the later stage of plant growth and the decomposition of litter, the migration and conversion of N was observed in sunny slope and hill slope, whereas the migration and conversion of P were usually observed in shady slope and gully slope.