川西亚高山冷杉林和白桦林土壤酶活性季节动态

SEASONAL VARIATIONS OF SOIL ENZYME ACTIVITIES IN FIR AND BIRCH FORESTS IN SUBALPINE AREA OF WESTERN SICHUAN*

研究了川西亚高山冷杉林和白桦林中与土壤碳氮元素循环有关的土壤脲酶、蛋白酶、转化酶、过氧化氢酶、多酚氧化酶和脱氢酶活性的季节变化规律 .结果表明 :(1)在两个群落中 ,腐殖质层 (A)中 6种土壤酶活性均高于淀积层(B)和母质层 (C)中的酶活性 ;(2 )白桦林A层土壤酶活性显著高于冷杉林A层土壤 ,而C层的脲酶和过氧化氢酶活性以冷杉林明显高于白桦林 ,但C层的其它 4种酶活性没有明显差异 ;(3)土壤酶活性的高峰期主要出现在温度较高的7、8月份 (冷杉林A层土壤中的蛋白酶、过氧化氢酶和脱氢酶 ,白桦林A层土壤中的蛋白酶、蔗糖酶和脱氢酶 ) ,或是凋落物高峰期的 10月份 (冷杉林A层土壤中的脲酶、多酚氧化酶和蔗糖酶 ,白桦林A层土壤中的多酚氧化酶 ) .可见 ,不同土壤酶的活性对温度的敏感程度是不一样的 ,有一些土壤酶的活性 (如多酚氧化酶 )明显受凋落物动态的影响 .图 1表 2参

Soil enzymes play an important role in mass cycle in forest soil ecosystem. Seasonal variations of the activities of soil urease, protease, invertase, catalase, polyphenol oxidase and dehydrogenase, which are related to soil carbon and nitrogen cycle, were analyzed in birch (Betula platyphylla) and fir (Abies faxoniana) forests. The results indicated: (1) The activities of all six soil enzymes decreased with increasing depth of soil; (2) The activities of the soil enzymes of layer A in birch forest were higher than those in fir forest, while there were no significant difference in layer C between the two forests except that the activities of urease and catalase in fir forest were significantly higher than those in birch forest; (3) The maximum enzyme activities occurred mainly during July～August due to higher soil temperature, or in October when litterfall was the maximum. These illustrated that according to the types of soil enzymes, temperature could have different influences on the activities of soil enzymes, and the activities of some soil enzymes, for example polyphenol oxidase was obviously affected by the litterfall dynamics. Fig 1, Tab 2, Ref 18