尕海湿地不同退化梯度土壤脲酶与蛋白酶活性时空分布特征

Temporal and Spatial Distribution Characteristics of Soil Urease and Protease Activities in Different Degraded Gradients of Gahai Wetland

为探讨高寒湿地退化对土壤酶活性的影响,本文以青藏高原东缘尕海湿地未退化、轻度退化、中度退化和重度退化4种不同退化梯度的0~10、10~20和20~40 cm层土壤为研究对象,研究不同退化梯度土壤脲酶与蛋白酶活性时空变化特征。结果表明:随退化梯度加剧,土壤含水量降低,温度升高;土壤脲酶活性在0~40 cm土层中表现为随退化加剧而逐渐降低,而蛋白酶活性趋势恰好相反;除重度退化外,其他退化梯度土壤两种酶活性均随土层加深而降低;0~40 cm土层中脲酶与蛋白酶活性分别在7、8月和6、7月最高;相关性分析表明土壤脲酶活性与蛋白酶活性和温度极显著正相关(P<0.01);土壤蛋白酶活性与微生物生物量氮极显著正相关(P<0.01),与含水量和温度显著正相关(P<0.05),与硝态氮显著负相关(P<0.05)。沼泽化草甸退化显著增加土壤表层脲酶活性而降低蛋白酶活性;温度对土壤脲酶与蛋白酶活性起促进作用,含水量、微生物生物量氮对土壤蛋白酶活性具有促进作用。

In order to investigate the effect of alpine wetland degradation on soil enzyme activities,this paper investigated the spatial and temporal characteristics of soil urease and protease activities in 0–10,10–20 and 20–40 cm layers in Gahai wetlands on the eastern edge of the Qinghai-Tibetan Plateau with four different degraded gradients:not degraded,slightly degraded,moderately degraded and severely degraded.The results showed that soil water content decreased but temperature increased with the increase of the degradation.Soil urease activity decreased but protease activity increased gradually with the increase of degradation in the 0–40 cm layer;Except for severely degraded,the two enzyme activities decreased with the increase of soil depth.The activity was the highest in the 0–40 cm layer in July and August for urease and in June and July for protease,respectively;Soil urease activity was positively correlated with protease activity and temperature(P<0.01),while soil protease activity was positively correlated with microbial nitrogen(P<0.01),water content and temperature(P<0.05),and negatively correlated with nitrate nitrogen(P<0.05).The degradation of marshy meadows significantly increased urease activity but decreased protease activity in topsoil;temperature promoted soil urease and protease activities,and water content and microbial nitrogen promoted soil protease activity.