东祁连山高寒草地牧草返青期土壤酶活性特征

Characteristics of Soil Enzymatic Activity during Forage Green-up Period of Alpine Grasslands in the Eastern Qilian Mountain Areas

对东祁连山7种高寒草地型土壤过氧化氢酶、脲酶、中性磷酸酶活性及其与土壤理化性质的相关性等进行了研究,以期明确土壤酶活性的生态分布及其与土壤理化性质的相关性特征。结果表明,土壤过氧化氢酶、脲酶和中性磷酸酶的活性分别介于0.37-0.49 mL.g-1.min-1、0.24-0.42 mg.g-1.24 h-1和1.14-3.03 mg.g-1,且脲酶和中性磷酸酶活性上层高于下层;样地间土壤酶活性差异明显,其中过氧化氢酶和中性磷酸酶活性多为草本草地高于灌丛草地,但脲酶多为灌丛草地高于草本草地;土壤酶与土壤含水量、容重、pH值、微生物量碳、氮和磷的相关性在不同草地型也有差异,如土壤脲酶与土壤含水量、pH值在珠芽蓼（Polygonum viviparumL.）草地、沼泽草地和嵩草（Kobresiasp.）草地呈显著（P〈0.05）或极显著（P〈0.01）负相关,但在其他样地相关性不显著,且在土壤肥力较一致的金露梅（Dasiphora fruticosa）灌丛和沼泽草地相关性并不一致。因此,用土壤脲酶活性作为土壤肥力指标具有一定局限性。

Soil enzymatic activities have drawn a lot attentions from researchers worldwide because they can serve as the assessing measure on soil quality,agrotechnical efficiency,and changing index of soil quality.In this experiment,the activities of soil enzymes（including catalase,urease,and neutral phosphatase） and their correlations with soil physical-chemical properties were studied of seven alpine grassland types,e.g.Rhododendrons simsii Planch.brushland（DJ）,Salix cupularis Rehd.brushland（GL）,Dasiphora fruticosa（L.） Rydb.brushland（JL）,Polygonum viviparum L.grassland（ZY）,gramineous steppe（HC）,swamp grassland（ZZ）,and Kobresia capillifolia（Decne.） C.B.Clarke grassland（SC）,in the Eastern Qilian Mountains areas of the Qinghai-Tibetan Plateau in order to understand their ecological distribution characteristics and its relationship to soil properties.The results show that the activities of soil catalase,urease and neutral phosphatase were different among sampling sites and varied from 0.37 to 0.49 mL·g-1 min-1、0.24 to 0.42 mg·g-1 24 h-1,and 1.14 to 3.03 mg·g-1,espectively.The urease activity and neutral phosphatase activity at upper soil layer were higher than those at the lower layer.Soil catalase activity and neutral phosphatase activity at grassland were higher than those at brushland,but the soil urease activity was opposite.Soil enzymatic activity showed differently significant correlation with soil water content,bulk density,pH value,microbial biomass carbon,microbial biomass nitrogen,and microbial biomass phosphorus at different sampling sites.For example,soil urease activity had significantly negative correlation with soil water content and pH value at 0.05 or 0.01 levels at ZY,ZZ and SC,but no significant correlation at other grassland types with disagreement between JL and ZZ which had approximate quantity of soil organic matter.Therefore,taking soil urease activity as the soil fertility index has its limitation.