中文摘要：

本文对黄土丘陵区退耕地生物结皮影响下的土壤腐殖质分异特征进行了研究。结果表明，①该区生物结皮影响下的±壤腐殖质组分HA、FA和HM含量均有明显的分层特征，土层间均表现出：结皮层〉0～2cm土层〉2～5cm土层：不同年限生物结皮土壤腐殖质含量总体表现出：16年〉8年〉32年〉12年，表明退耕地生物结皮影响下的土壤腐殖质含量随时间变化呈非线性变化趋势：HA／FA平均值变化范围为0．34～0．70，低于1，该区生物结皮影响下的土壤腐殖质胡敏酸含量不高，腐殖酸以富啡酸为主；②结皮层土壤腐殖酸FA／E6值随时间变化总体上呈“抛物线”型变化趋势；而0～2cm和2～5cm土层土壤腐殖酸E4／E6值呈缓慢增长的趋势；③腐殖质组分与土壤养分因子的全N、NO3-N、NH4＋-N和有效Zn之间存在极显著的线性相关关系（p〈0．01）；④土壤腐殖质组分含量的变化与全N、NO3--N、NH4＋-N和有效Zn含量间存在满足二项式的函数回归关系（p〈0．01），表明生物结皮对土壤C素与N素和有效Zn的影响密切相关。

英文摘要：

This paper focuses on the characteristics of soil humus components and their changing tendency influenced by biological soil crusts in the rehabilitated grassland of the hilly loess region. The results showed that： 1） There was clear hierarchical characteristics of the distributions of humic acid, fulvic acid and humin content of the soil humus components influenced by biological soil crusts, all in the order of the crust layer〉 0- 2 cm layer〉2 - 5 cm layer. Humus contents of different years showed an overall order of 16a〉8a〉32a〉12a. Soil humus content changed non-linearly with the time. HA/FA changed in the average range of 0.34 - 0.70. Humic acid in the humus content was not high, influenced by biological soil crusts in this area. Fulvic acid is the main composition of soil humic acids. 2） In the crust layer, E4/E6 values of soil humic acids mainly performed as a ＂parabolic curve＂ type with the time, while in 0 - 2 cm and 2 - 5 cm layers, E4/E6 values of soil humic acids showed a slow increasing trend. 3） There was very significant linear correlations （p〈0.01） between soil humus components and soil nutrients, including total nitrogen, nitrate nitrogen, ammonium nitrogen and available zinc. 4） There was a very significant binomial function regression correlation between soil humus component content and total nitrogen content, nitrate nitrogen, ammonium nitrogen as well as available zinc. It showed the close relation among the influences on soil carbon, nitrogen or available zinc by biological soil crusts.