高寒灌丛与珠芽蓼草地土壤有机碳的稳定性

Differences in biological stability of soil organic carbon pools between shrub and Polygonum viviparum grassland at alpine site

在高山草原带选择了以珠芽蓼为主要群落组成的草地、以金露梅为主要群落组成的灌丛和以柳＋金露梅为主要群落组成的灌丛,研究土壤有机碳的生物稳定性.研究结果表明,在0~30 cm土层,金露梅灌丛平均土壤总有机碳含量显著低于珠芽蓼草地,但是与柳＋金露梅灌丛之间差异不显著.金露梅灌丛和柳＋金露梅灌丛土壤粗有机碳、热水溶性有机碳在土壤总有机碳中的比例以及矿化有机碳与微生物量有机碳的比值显著高于珠芽蓼草地.这些结果说明灌丛土壤有机碳的生物稳定性显著低于草本珠茅蓼草地,意味着在过度放牧、砍伐和开垦等人为干扰下灌丛土壤有机碳将更加容易降低.

Polygonum viviparum grassland,Dasiphora fruticosa shrub and Salisc cupulalis plus Dasiphora fruticosa shrub were selected to examine the differences in the bio-stability of soil organic carbon at an alpine site in the Eastern Qilian mountains. The results showed that in depth 0~30 cm,total soil organic carbon concentration was averagely significantly lower under Dasiphora fruticosa than under Polygonum viviparunl, but it was identical under Dasiphora fruticosa and under Salix cupulalis plus Dasiphora fruticosa. The proportions of coarse organic carbon and hot-water extracted carbohydrate carbon in total soil organic carbon, and the ratio of mineralized-carbon to microbial biomass carbon were significantly higher in soils under the two shrub fruticetas, i. e. ,Dasiphora fruticosa and Salix cupulalis plus Dasiphora fruticosa, than under herbosa, i. e. , Polygonum viviparum. These results might mean that the biological stability of soil organic carbon in shrub were lower than that in herbosa pasturelands,and that soil organic carbon level in shrub soils were more easily prone to recede than in herbosa pastureland soils in case pastu- relands be exposed to unsustainable management.