模拟降雨变化对古尔班通古特沙漠土壤养分及酶活性的影响

土壤酶参与土壤系统的养分循环过程，是联系植物和土壤养分的关键纽带。土壤酶活性对降水格局变化响应敏感，这种响应对于缺水且养分贫瘠的荒漠生态系统显得尤为重要。然而，早春积雪完全融化后首次降雨时间及降雨量如何影响土壤养分及土壤酶活性还鲜见相关报道。以新疆古尔班通古特沙漠为研究区，在早春积雪完全融化后，设置3个首次降雨时间(积雪完全融化后第10天、20天和30天)和3个降雨梯度(5 mm、10 mm和15 mm),于植物生长旺季采集土壤样品，研究土壤养分含量和土壤酶活性的响应特征。结果表明：积雪完全融化后不同首次降雨时间下5mm降雨处理以及积雪完全融化后第30天下各降雨量处理对土壤养分和酶活性影响不显著。积雪完全融化后第10天，随降雨量增加，土壤全碳呈显著先下降后增加趋势，全钾呈显著增加趋势，而土壤微生物量碳呈显著降低趋势；积雪完全融化后第20天，随降雨量增加，速效氮、土壤蔗糖酶活性、土壤微生物量碳氮呈先下降后增加趋势，土壤全碳和多酚氧化酶活性显著下降，土壤全钾和碱性磷酸酶活性显著增加。模拟10 mm降雨，随首次降雨时间推迟，土壤全氮、速效氮、速效磷、土壤蔗糖酶活性和土壤微生物量碳呈增加趋势；...

Effects of simulated rainfall on soil nutrient contents and enzyme activities in the Gurbantunggut Desert, China

Soil enzymes actively participate in the nutrient transformation of soil system and are the key link between plants and soil nutrients. Soil enzyme activity is sensitive to the changes in rainfall patterns, particularly in deserts where rainfall is generally low and highly spatially and temporally variable. Little is known about how the timing and amount of rainfall affect soil nutrient contents and soil enzyme activity in areas where soil moisture is driven by snowmelt, particularly in early spring following complete snowmelt. We examined soil nutrient contents and enzyme activity at three times (Days 10, 20 and 30) and three rainfall amounts (5 mm, 10 mm, 15 mm) after complete snow melt, the period of maximum plant growth in the Gurbantunggut Desert in western China. We found no response under the lowest rainfall treatment (5 mm) at any times. The addition of 10 mm of rainfall stimulated a positive response in soil nutrients (e.g., nitrogen, phosphorus) but the 15 mm addition of rainfall had the greatest promotion effect on most soil indices such oxidase, phosphatase, and peroxidase activity, particularly 10 and 20 days after complete snow melt. Our results show that delaying of first rainfall time and addition of 15 mm rainfall after snowmelt can significantly increase soil microbial activity and nutrient transformation. These treatments can compensate for the inhibition effect of drought on nutrient transformation for a certain time period and enhance soil nutrients supply capacity in the growth period of desert ephemeral plants in early spring.