放牧干扰对岷江上游山地森林/干旱河谷交错带土壤有机碳及其碳库管理指数的影响

Effect of Grazing Disturbance on Soil Carbon and Carbon Management Index in Mountain Forest-the Arid Valley Ecotone in Upper Reaches of Minjiang River

研究了岷江上游理县山地森林–干旱河谷交错带地区人工刺槐林、人工杨柳林、草地和锥花小檗灌丛4种植被类型土壤有机碳和碳库管理指数对放牧干扰的响应,以距牧道距离远近的不同设置了3种放牧干扰强度,分别对各植被类型3种放牧干扰强度的土壤进行分析。结果表明：在各植被类型下,随放牧干扰强度增加土壤总有机碳（TOC）和易氧化碳（LOC）降低。在人工刺槐林和人工杨柳林,随放牧强度增加,TOC和LOC大致为梯度降低;草地和灌丛表现为随放牧强度增加先降低再升高,这取决于各植被下牲畜的可进入性和植被对牲畜的可利用性。植被类型下表层土壤碳库管理指数（CPMI）值随放牧强度增加先下降后升高,轻度干扰值最高,下层土壤CPMI值随放牧强度增加梯度下降,下降幅度介于6.2%~70.41%之间。

Soil carbon and carbon management indices were studied under three different grazing strengths which were set by different distances between grazing-path and the sample points of four kinds of plantations, including artificial robinia, artificial poplar, grassland and berberis aggregate shrub in mountain forest-the arid valley of ecotone in Li County in the upper Minjiang River. The amount of TOC and LOC reduced with the increase of grazing strength in artificial robinia and poplar, but they reduced first and then increased in grassland and berberis aggregate shrub, which depended on the accessibility of livestock and the availability of vegetation under each plantations. With the grazing strength, CPMI decreased and then increased in surface soil, but decreased in 10-20 cm, which decreased by 6.2%-70.41%.