低温季节西南亚高山森林土壤多酚氧化酶动态研究

以亚高山针叶林均质化土壤为研究对象,采用裸露地表、凋落物覆盖、积雪覆盖、凋落物和积雪同时覆盖4个不同覆盖处理的原位培养实验,对各处理在低温季节(11月～5月)土壤表层(0~10cm)和下层(10～20 cm)多酚氧化酶(PPO)活性动态进行了分析,结果表明:(1)在低温季节,所有处理表层PPO活性在12~2月出现波动,差异不显著;下层土壤PPO活性逐渐升高,到低温季节结束前后活性达到最高,但是不同处理的升高幅度不同;(2)积雪和凋落物覆盖变化引起不同处理和不同深度土壤PPO活性动态的差异性响应。不论是表层还是下层土壤,在整个低温季节积雪对PPO活性的影响达到极显著水平,但凋落物覆盖能缓冲积雪对PPO活性的效应。(3)降雪时空格局变化对亚高山土壤PPO的影响主要体现在没有凋落物覆等盖层的裸露土壤,在有凋落物等覆盖情况下,全球变化可能导致的积雪减少甚至消失对土壤PPO活性的影响不大。

Dynamics of Soil Polyphenol Oxidase Activities During the Cold Season of Subalpine Forest in the Southwest of China

Subalpine coniferous forest in the southwest of China,with cold season more than 7 months,is one of the major forest and huge soil carbon pools of China.Changes in groundcover of difference soil surface such as snow and litter may impact enzymatic activities in the cold season from Oct.to May.The dynamics of activities of soil polyphenol oxidase(PPO) of 0-10 cm and 10-20 cm depth of the subalpine forest in the cold season was determined by incubation in situ under different surface covers(i.e.,bare soil without snowcover,bare soil with snowcover,litter without snowcover,and litter with snowcover).The results showed that:(1) the temporal dynamics of PPO in 0-10 cm depth was fluctuated in all treatments from Dec.to Feb.,and there was no significant difference.However,in the 10 20 cm layer,activities of PPO increased gradually,and reached a peak value by the end of cold season.(2) PPO activities of different sampling times and soil layers gave difference responses to surface with and without snow and/or litter covering,and PPO activities of treatment with snow were lower than that of bare soil.However,there was no significant difference when soil surface was covered with litter,which shows that litter cover buffered the effects of snowcover on PPO activities.(3) The results of temporal and vertical variation of subalpine soil PPO activities indicated that changes in snow pattern had mainly effects on the PPO activitied of bare soil.Reduction or disappearance of snowcover induced by global change could have little impacts on PPO activities if subalpine soil was covered by litter or other groundcover.