放牧与围栏羊草草原生态系统土壤呼吸作用比较

采用静态箱式法，比较分析了内蒙古典型羊草草原放牧与围栏生态系统土壤呼吸作用及其与环境因子的关系．结果表明，围栏和放牧样地的土壤呼吸作用日动态均呈单峰型曲线，高峰值一般出现在13：00～15：00，围栏样地土壤呼吸作用日动态与地表温度相关性最好，而放牧样地与地下5cm温度相关性最好．在整个观测期内，6、7月份是植物生长的旺盛期，围栏样地土壤呼吸作用明显大于放牧样地约2．7倍；到植物生长后期的8、9月份，二者差异不大，与地下生物量的变化相似，可能与牲畜的采食对不同物候期的植物影响不同及周围环境因子的改变有关，说明人类活动的干扰不一定增加土壤呼吸作用．围栏样地和放牧样地土壤呼吸作用季节动态都与0～10cm的土壤含水量相关性最好，相关系数分别是0．853和0．741，而围栏样地土壤含水量与土壤呼吸作用季节动态的相关性大于放牧样地；围栏和放牧样地不同层次土温、土壤含水量与土壤呼吸作用日、季动态的关系均表现出浅层的相关性普遍大于深层．

A comparative study on soil respiration between grazing and fenced typical Leymus chinensis steppe, Inner Mongolia

With enclosed chamber Method, this paper studied the soil respiration in grazing and fenced typical Leymus chinensis steppes, Inner Mongolia, and its relationships with environmental factors. The results showed that the daily pattern of soil respiration could be expressed as a one-humped curve, and the highest values appeared at 13:00-15:00 in the fenced and grazing plots. The diurnal dynamics of soil respiration mainly depended on the surface temperature at the fenced plots and the soil temperature at 5 cm depth at the grazing plots. In June and July, the average soil respiration rate was 2.7 times greater at the fenced plots than that at the grazing plots, while the difference was not distinct in August and September, which was similar with the change of the belowground biomass. The reason was probably that the plant was influenced differently in different phenological phases by grazing and the change of environmental factors. It showed that human activity may not result in the increase of soil respiration rate. The seasonal dynamics of soil respiration was closely correlated with soil water content at the 0-10 cm depth at the fenced and grazing sites, and the maximum R2 was 0.853 and 0.741, respectively. The difference was that the correlation of soil respiration seasonal dynamics with soil water content was larger at the fenced plots than at the grazing plots. The correlations of soil respiration diurnal and seasonal dynamics with temperature and soil water content at lower profiles were larger than those at deeper profiles at the fenced and grazing sites.