放牧对新疆天山山地草甸土壤团聚体和土壤呼吸潜力的影响

Effects of Grazing on Soil Aggregates and Soil Respiration Potential in Tianshan Mountain Grassland,Xinjiang

放牧是新疆山地草甸重要的利用方式,探明放牧对草地土壤呼吸的影响机制,可为深入了解草地碳汇功能,合理的利用草地提供参考依据。本研究在天山北坡中段山地草甸开展,以长期放牧和围封草地(CK)的土壤为研究对象,采用干筛法将土壤筛分为<0.25 mm,0.25~1 mm,1~2 mm,2~4 mm粒径的土壤团聚体,并测定了各粒径团聚体的比例、土壤β-葡萄糖苷酶、土壤β-木糖苷酶、土壤N-乙酰-β-D葡萄糖苷酶活性及其21天的CO_(2)释放量。研究结果表明:放牧显著增加了<0.25 mm粒径的团聚体比例,降低了<0.25 mm,1~2 mm土壤团聚体的CO_(2)释放量;<0.25 mm粒径土壤团聚体CO_(2)释放量均显著高于其他粒径;三种土壤酶活性在<0.25 mm,1~2 mm粒径的土壤团聚体中与土壤呼吸表现出显著的正相关。综合分析表明,在天山北坡中段山地草甸,放牧会抑制<0.25 mm,1~2 mm团聚体酶活性,降低土壤呼吸,使得草地整体代谢速率降低。

Grazing is an important way of grassland utilization in mountain meadows in Xinjiang,Exploring the influence mechanism of grazing on grassland soil respiration can provide a reference for an in-depth understanding of grassland carbon sink function,rational management,and utilization of grassland.In this study,the soil of long-term grazing and enclosed grassland(CK)were collected in Xiejiagou,Urumqi county,the middle part of the northern slope of Tianshan Mountain.The soil was screened into four kinds of soil aggregates with different particle sizes of<0.25 mm,0.25~1 mm,1~2 mm,and 2~4 mm by dry screening method,And the proportion of each particle size aggregate,S-β-GC,S-β-XYS,S-NAG activity and the 21 days CO2 release of soil aggregates with various particle sizes were measured.The results showed that grazing significantly increased the proportion of aggregates with particle size less than 0.25 mm,and reduced the CO2 emission of soil aggregates with particle size less than 0.25 mm and 1~2 mm.The CO2 emission of soil aggregates with 0.25 mm particle size was significantly higher than that of other particle sizes;The three soil enzyme activities showed a significant positive correlation with soil respiration in soil aggregates with particle sizes of<0.25 mm and 1~2 mm.Comprehensive analysis showed that heavy grazing would inhibit the enzyme activity of aggregates<0.25 mm,1~2 mm,reduce the soil respiration of mountain meadows and reduce the overall metabolic rate of grassland.