九寨沟和黄龙自然保护区原始林与次生林土壤物理性质比较

森林土壤的结构和贮水保水能力是决定土壤水分及其时空分布的关键,九寨沟和黄龙自然保护区均是以水为灵魂,其水量的多少及时空分布格局对景区景点的视觉观赏效果具有十分重要的作用.通过对几寨沟和黄龙核心景区原始林与次生林土壤容重、持水性能和孔隙度等指标的监测,探讨了不同植被类型下土壤结构及持水能力状况.结果表明:(1)由于较早地得到保护,九寨沟景区原始林、桦槭次生林土壤物理性质均优于四川西部其它同类犁植被,与此相反,人工云杉纯林土壤物理性质明显劣于其它植被类型,可能主要与云杉平根系统对土壤膨胀挤压和单优势乔木群落所形成的不利微气候影响有机物分解归还土壤有关;(2)在黄龙核心景区的原始云、冷杉林,发育于坡积母质的土壤物理性质明显优于发育于钙华母质卜的土壤物理性质.图3表1参31

Comparison of Soil Physical Properties under Primary and Secondary Forests in Jiuzhaigou and Huanglong Nature Reserves, Sichuan, China

Forest soil structure and water-holding capacity are key factors controlling soil water, and its temporal and spatial distribution. The Jiuzhaigou and Huanglong nature reserves in Sichuan, China are famous for their wonderful water areas. Therefore, water quantity and its pattern of temporal and spatial distribution there are quite important to attract visitors' eyes. The soil bulk density, water-holding capacity and soil porosity were investigated to study the structure and water-holding status of soil in main vegetation types of core areas of the Jiuzhaigou and Huanglong natural reserves. The results showed that: (1) Due to early protection in Jiuzhaigou, soil physical properties in primary forest and birch-maple secondary forest were better than those in the same vegetation types in other regions of western Sichuan, while the soil under pure spruce plantation was compacted and had lower water-holding capacity, which was perhaps caused by the flat root system extruding soil and unfavorable microclimate condition inhibiting the decomposition of organic matter in soil; (2) Under primary spruce and fir forest, soil physical properties were better in parent material of slope deposits than in parent material of calcified deposits in the Huanglong Nature Reserve. Fig 3, Tab 1, Ref 31