模拟降水对内蒙古短花针茅荒漠草原土壤酶活性的影响

Effect of Simulated Precipitation on Soil Enzyme Activity of Stipa breviflora Desert Steppe in Inner Mongolia

为探究模拟降水处理下土壤酶(脲酶、碱性磷酸酶和蔗糖酶)活性变化与土壤养分供应状况的内在联系机制。以内蒙古荒漠草原为研究对象,根据多年降水平均量设置了4个梯度:减少自然降水的50%(P-50%)、对照(P CK)、增加自然降水的50%(P+50%)和增加自然降水的100%(P+100%)。结果表明:内蒙古荒漠草原中脲酶、碱性磷酸酶和蔗糖酶活性对水分敏感度有较大差异;10~20 cm土层增水下显著增加了脲酶(17.36%)、碱性磷酸酶(9.9%)、蔗糖酶(34.85%)活性;3种土壤酶均与速效磷、全氮有显著相关关系(P<0.05),而速效磷的增加会降低全钾含量。综上,减水处理极显著抑制了碱性磷酸酶活性(P<0.01),蔗糖酶活性随增水梯度的增加表现为先显著升高后显著降低(P<0.05),脲酶活性表现为平稳升高,土壤酶活性改变对土壤养分含量起到促进作用,过量养分之间又产生抑制作用。

The intrinsic mechanism underlying the changes in soil enzyme activities(urease,alkaline phosphatase,and sucrase)in response to simulated precipitation alterations and their relationship with soil nutrient supply conditions were investigated in the desert grassland of Inner Mongolia.Four precipitation gradients were set based on the average precipitation levels over several years:a 50%reduction in natural precipitation(P-50%),a control group(P CK),a 50%increase in natural precipitation(P+50%),and a 100%increase in natural precipitation(P+100%).Results indicated significant differences in the sensitivity of urease,alkaline phosphatase,and sucrase activities to water availability in the desert grassland of Inner Mongolia.Increasing precipitation significantly enhanced the activities of urease(17.36%),alkaline phosphatase(9.9%),and sucrase(34.85%)in the soil layer at a depth of 10~20 cm,while decreased precipitation only significantly reduced alkaline phosphatase activity.All three soil enzymes are significantly correlated with available phosphorus and total nitrogen(P<0.05),while an increase in available phosphorus decreased the total potassium content.Overall,decreased precipitation significantly reduced alkaline phosphatase activity(P<0.01),while sucrase activity exhibited a significant increase followed by a significant decrease with increasing precipitation gradients(P<0.05),and urease activity showed a steady increase.Soil enzymes indirectly promoted soil nutrient content,the excessive nutrients exert an inhibitory effect on each other.