不同植被带生态恢复过程土壤团聚体及其稳定性——以黄土高原为例

Soil aggregates and stability in the ecological restoration process under different vegetation zones on loess plateau

为分析黄土高原不同植被带植被恢复对土壤团聚体分布特征及其稳定性的影响,以黄土高原从北到南不同纬度梯度分布的3个典型植被类型区域(草原带、森林草原带和森林带)为研究对象,对不同植被类型和恢复年限下的土壤团聚体分布及其稳定性进行了研究.结果表明:不同植被带对土壤团聚体分布及其稳定性影响显著,大于0.25mm团聚体含量(WR0.25)、水稳性团聚体平均重量直径(EWMD)、水稳性团聚体几何平均直径(EGMD)和有机质含量(SOM)整体上均表现为:森林带>森林草原带>草原带.不同植被带下不同恢复类型对土壤团聚体及其稳定性影响不一,森林草原带表现为灌木>草地>乔木,森林带则表现为乔木>草地.随植被恢复年限增大,各种恢复类型WR0.25、EGMD、SOM整体呈逐渐增加趋势,团聚体结构破坏率(PAD)和可蚀性因子(K)呈现相反的变化趋势;分形维数(D)无显著差异.冗余分析表明,植被带对土壤团聚体及其稳定性的影响最大,其次是恢复年限,恢复类型与植被带和恢复年限具有较强的交互作用.本研究有利于加强对区域生态恢复过程机理的认识.

With the aim to analyze the effects of vegetation restoration on soil aggregates on the Loess Plateau, various categories of the distribution and stability of soil aggregates in different restoration ages of vegetation zones were studied. With three typical restoration zones including the steppe zone, the forest-steppe zone and the forest zone at different latitude on the Loess Plateau as the object of this research. The results showed that the distribution and stability of soil aggregates were significantly influenced by vegetation zones. For the five indexes including 〉0.25 mm soil water-stable aggregates（WR0.25）, mean weight diameter（EWMD）, geometric mean diameter（EGMD） and soil organic matter（SOM）, these indexes in the forest zone were the highest, followed by the forest-steppe zone, and these in the steppe zone were the lowest. Different vegetation restoration condition and vegetation zone had different impacts on soil aggregates and their stability, with the trend of shrubs〉 grasslands〉 trees in the forest-steppe zone and trees 〉 grasslands in the forest zone. pectively, indexes including WR0.25、EGMD and SOM in different restoration conditions increased with restoration ages, but other indexes including percentage of aggregate destruction（PAD） and soil erodibility（K） decreased. No significant difference has been found in the fractal dimension（D）. The redundancy analysis showed that the distribution and stability of soil aggregates were mostly effected by the vegetation zones, and the restoration ages as following. The type of the restoration had a significant interaction with the vegetation zones and the restoration ages. This research is conducive to better understand the mechanism of regional ecological restoration process.