呼伦贝尔草甸草原土壤呼吸及其影响因子对不同放牧强度的响应

摘要

From June to September in 2010, soil respiration was measured at six different grazing intensities in experimental plots in Hulunber meadow steppe using a LI-6400-09 Soil Chamber to understand the influence of different grazing intensities on soil respiration of grassland. The controlling factors of soil respiration were taken into account under different grazing intensities. 1) Soil water content, root biomass, above ground bio-mass, and litter accumulation decreased with an increase of grazing intensity. However, soil temperature had an irregular change pattern with an increase of grazing intensity. 2) The dynamic changes in soil respiration rate have a double peak curve from different grazing intensities during the whole experimental period, while the varied mode of the mean value of soil respiration rate can be expressed as R1>R0>R2>R3>R4>R5. There was no significant difference between R0 and R1. The soil respiration rate was higher in R0 and R1 treatments than in the R5 treatment except on September 30th. Soil respiration rate was dramatically influenced by grazing intensity, with a more intense response under the R4 and R5 grazing intensities. 3) The effect of grazing intens-iy on soil respiration changed with variation of grazing season or date showing there was an interaction between them. The partial correlation of time analysis has shown that soil temperature, soil water content, root biomass, above ground biomass, litter accumulation had significantly positive correlations with soil respiration under different grazing intensities but there was a significantly negative correlation with grazing intensities. The lower grazing intensity (R1) had no adverse effect on soil respiration rate and its controlling factors, while the higher grazing intensities (R4 and R5) have obviously influenced them.%于2010年6-9月期间,采用LI-6400-09 Soil Chamber对呼伦贝尔草甸草原6个不同放牧强度处理下的土壤呼吸速率及其影响因子进行研究.结果表明,1)除R1外,土壤含水量、根系生物量、地上生物量和枯落物等影响因子随着放牧强度增大而下降,而土壤温度却无统一的变化规律.2)试验期内,不同放牧强度下土壤呼吸速率的动态变化呈双峰型；土壤呼吸速率均值变化为:R1＞R0＞R2＞R3＞R4＞R5,R0和R1间的差异不显著(P＞0.05)；除9月30日外,其余测试日下R0和R1的土壤呼吸速率均显著(P＜0.05)高于R5.土壤呼吸速率随着放牧强度的增大,放牧效应加剧,以R4和R5最为强烈.3)放牧强度因素对土壤呼吸的作用随着放牧季节(日期)的变化而变化,且二者存在互作效应.控制时间的偏相关分析表明,土壤呼吸速率与土壤温度、土壤含水量、根系生物量、地上生物量、枯落物呈显著正相关；而与放牧强度之间呈极显著负相关.研究表明,在呼伦贝尔草甸草原,较低的放牧强度(R1)对土壤呼吸速率及其影响因子无不利影响,而较高的放牧强度(R4和R5)显著影响土壤呼吸速率及其影响因子的变化.