重度放牧对短花针茅根系分解的影响

Effects of Heavy Grazing on the Root Decomposition of Stipa breviflora

基于2004年在内蒙古短花针茅荒漠草原采用随机区组设计建立的放牧控制试验平台,在对照区和重度放牧区进行18个月的短花针茅根系分解试验,探讨重度放牧及其环境变化对短花针茅根系分解的影响。结果表明:放牧和分解时间对短花针茅根系分解均有显著影响,在分解前期(第1个月和第5个月)对照区的分解速率高于放牧区(P<0.05)。Olson负指数衰退模型在该地区有很好的适用性,对照区和放牧区短花针茅根系的半分解时间分别为2.15a和2.41a。对于气象指标而言,累计空气温度(r^2=0.790,P<0.0001)和累计降水量(r^2=0.796,P<0.0001)对根系分解都有很好的预测性;对于土壤环境指标而言,累计土壤含水量(对照:r^2=0.856,P<0.0001,放牧:r^2=0.783,P<0.0001)和累计土壤温度(对照:r^2=0.823,P<0.0001,放牧:r^2=0.751,P<0.0001)对短花针茅根系分解的预测性均很高。

A root decomposition experiment of Stipa breviflora was conducted in the control area and heavy grazing area for 18 months by using the random block designed, which based on the grazing control experiment in S. breviflora desert steppe of Inner Mongolia in 2004, and the effects of environmental changes by heavy grazing on the root decomposition of S. breviflora were evaluated. Results showed that grazing and decomposition duration had significant effects on the root decomposition of S. breviflora. The decomposition rate in the control area was higher(P<0.05) than that in the grazing area in early decomposition period(1 st and 5 th month);the Olson negative index regression model had a good applicability in this area. The half decomposition time of S. breviflora roots in the control and heavy grazing was 2.15 a and 2.41 a, respectively. The accumulated air temperature and precipitation had a good predictors for the root decomposition, accumulative soil moisture content was the best soil index for predicting the root decomposition of S. breviflora in the desert steppe.