模拟酸雨与凋落物对柳杉幼苗根际土壤酶活性的影响

Enzyme activity in rhizosphere soil of Cryptomeria fortunei seedlings with simulated acid rain and litter

为了探讨酸雨和凋落物对柳杉Cryptomeria fortunei林地土壤酶活性的影响,以柳杉幼苗根际土壤为材料,采用酸雨(pH 4.0),凋落物(500 g·m-2)和酸雨与凋落物复合等3种处理,测定了短时间(30 d)和长时间(90 d)处理后土壤氧化还原酶和水解酶活性的变化。结果表明:酸雨和凋落物处理对土壤氧化还原酶活性具有不同的影响,酸雨对土壤硝酸还原酶活性无显著影响,凋落物极显著地提高其酶活性,复合处理极显著地降低其酶活性(P<0.01);3种处理均显著提高了土壤多酚氧化酶活性(P<0.05);复合处理对土壤过氧化物酶活性无显著影响,短时间酸雨和凋落物处理均对其具有抑制作用,长时间处理具有促进作用(P<0.05);凋落物处理对土壤过氧化氢酶活性表现为抑制作用,复合处理对其具有极显著促进作用(P<0.01)。在水解酶中,短时间3种处理和长时间复合处理均对土壤脲酶活性具有极显著促进作用(P<0.01);酸雨、长时间凋落物和复合处理对土壤酸性磷酸酶活性具有显著地抑制作用(P<0.05);酸雨和凋落物处理以及长时间复合处理均使土壤蛋白酶活性降低(P<0.05);长时间酸雨处理对土壤蔗糖酶活性具有显著抑制作用,复合处理和短时间凋落物处理具有促进作用(P<0.05)。酸雨和凋落物复合处理柳杉幼苗根际土壤,显著改变了两者对土壤酶活性的影响,说明酸雨和林地凋落物长时间并存,能够缓解两者对除土壤蛋白酶外其他土壤酶活性的不利影响,有助于改善土壤条件。

To determine the effects of acid rain and litter on enzyme activities of Cryptomeria forestry soils on Mount Tianmu,rhizosphere soil from Cryptomeriafortunei seedlings was treated with Tr1：simulated acid rain （pH 4.0）,Tr2：litter （500 g·m-2）,and Tr3：Tr1 and Tr2 combined,to determine soil oxidoreductase and hydrolase activities in rhizosphere soil after short-term（30 d） and a long-term（90 d） processing.Results showed that for soil nitrate reductase activity,Tr1 had no significant effect,but Tr2 significantly increased（P＜0.01） and Tr3 significantly reduced （P＜0.01）activity.All three treatments significantly improved soil polyphenol oxidase activity （P＜0.05）.For soil peroxidase activity,Tr3 had no significant effect,but Tr1 and Tr2 were inhibited after 30 d and promoted after 90 d （P＜0.05）.For soil catalase enzyme activity,Tr2 inhibited and Tr3 promoted activity（P＜0.01）.Soil urease activity after 30 d was highly significant（P＜ 0.01） for all three treatments.Soil acid phosphatase activity significantly decreased （P＜0.05） with Tr1 as well as with Tr2 and Tr3 over 90 d（P＜0.05）.Soil protease activity was inhibited with Tr3 for 90 d（P＜ 0.05） and with Tr1 and Tr2 （P＜0.05）.Tr1 after 90 d inhibited （P＜0.05） soil invertase activity,but after 30 d Tr2 and Tr3 had a catalytic role on soil invertase activity （P＜0.05）.Thus,long term coexistence of acid rain and woodland litter were able to mitigate,except for protease,the adverse effects of each other on soil enzyme activities,and contributed to improved soil conditions.