模拟氮沉降对华西雨屏区光皮桦林土壤酶活性的影响

Effects of simulated nitrogen deposition on soil enzyme activities in a Betula luminifera plantation in Rainy Area of West China

在华西雨屏区光皮桦(Betula luminifera)人工林内设置不同氮沉降水平(0、5、15和30gN.m-2.a-1)的模拟氮沉降试验,研究氮沉降对林地土壤酶活性的影响.结果表明:模拟氮沉降促进了光皮桦人工林土壤中水解酶(蔗糖酶、纤维素酶、酸性磷酸酶和脲酶)活性,抑制了氧化酶(多酚氧化酶和过氧化物酶)活性.土壤水解酶活性的增强预示着在活性氮增加的情况下,光皮桦和土壤微生物对碳、磷元素的需求增加.外源无机氮的增加显著降低了土壤多酚氧化酶和过氧化物酶的活性,可能导致凋落物分解受到抑制,促进凋落物在土壤中的积累,并通过抑制土壤有机质的分解增加土壤中碳的贮存量.

From January 2008 to January 2009,a field experiment was conducted to investigate the effects of simulated nitrogen（N） deposition（0,5,15,and 30 g N·m-2·a-1） on the soil enzyme activities in a Betula luminifera plantation in Rainy Area of West China.As compared with the control（0 g N·m-2·a-1）,simulated N deposition stimulated the activities of soil hydrolases（β-fructofuranosidase,cellulase,acid phosphatase,and urease） significantly,but depressed the activities of soil oxidases（polyphenol oxidase and peroxidase）.These results suggested that the increased exogenous inorganic N could stimulate soil microbial activity and increase the demands of both B.luminifera and soil microbes for C and P,whereas the depress of soil polyphenol oxidase and peroxidase activities under N addition could inhibit the degradation of litter and promote its accumulation in soil,leading to the increase of soil C storage in the B.luminifera plantation ecosystem.