人工防护林作用下风沙土成土过程的研究进展

人工防护林是防风固沙，有效防治沙漠化的重要措施之一。在沙漠地区建立人工防护林，可以有效防止土壤侵蚀，促进土壤有机质及粘粒积累，促使地表结皮形成，不仅对流沙起到了固定作用，而且促进了风沙土的成土过程。本文结合植物－土壤相互作用理论，分别从植物地上部分对养分的阻滞和聚集，以及减少土壤表面蒸发；地下部分的固沙和物质的分解与营养补给等方面综述了生物防护林在风沙土成土过程中的作用。同时，从以往的研究发现，在风沙土成土过程中，土壤机械组成变细，比重和容重减小；土壤剖面结构分异显著，分层增加；土壤含水量和养分显著聚集；土壤微生物数量和种类增加，活性增强，酶活性也大幅度提高。总之，随着沙漠生物防护林的建造，林下风沙土性质发生了明显的改良作用，逐渐发展成固定风沙土。这说明人工防护林和风沙土的成土过程是协同发展的，这不仅有利于沙漠防护林的可持续管护，也有利于沙漠化的防治和退化生态系统的恢复与重建。

Research progress of soil forming process of aeolian sandy soil under the effect of artificial shelter-belt

Artificial shelterbelt is an important and effective measure for checking winds and fixing drifting sands and hence for controlling desertification. To build up windbreak forest belts in desert areas can effectively control soil erosion and promote accumulation of organic matter and clay in the soil and formation of crust at soil surface, thus fixing drifting sands and accelerating formation of aeolian sandy soil. Based on the theory of plant-soil interaction theory, an overview is presented of the effects of artificial shelterbelt on formation of aeolian sandy soil, from the aspects of the function of the aboveground parts of plants intercepting and accumulating nutrients and reducing surface soil evaporation, and the function of the underground parts of plants fixing drifting sands, decomposing organic matter and supplying nutrients. It was found from the researches in the past that during the soil forming process of aeolian sandy soil, the soil became finer in mechanical composition, lighter in bulk density higher in soil porosity; more apparent in differentiation of soil profile structure, more in soil layer; more significant in nutrient enrichment, higher in population, species and activity of soil microbes, and higher in enzyme activity as well. In a word, with the establishment of artificial shelterbelts in desert, the aeolian sandy soil underneath altered significantly in soil properties, and developed gradually into fixed aeolian sandy soil, suggesting that windbreak forest belts and aeolian sandy soil develop synergically, which is beneficial not only to sustainable management of the forest belts, but also to control of desertification, and restoration and reestablishment of degraded ecosystems.