恢复状态下羊草（Leymus chinensis）草原植被根冠比动态及影响因子

利用内蒙古羊草草原围栏样地连续两年的地上、地下生物量数据和当地同时期的降水、气温资料，分析了退化羊草草原，在恢复过程中植被根冠比动态及与水热因子之间的关系。研究结果表明：（1）羊草草原植被地上、地下生物量季节变化均呈单峰型曲线，峰值出现在8月。（2）羊草草原植被根冠比具有明显的季节变化，生长季初和生长季末根冠比值较大，最低值出现在地上生物量最高的8月中下旬。（3）羊草草原植被月根冠比与上上月月降水量相关关系极显著，与七月平均气温相关关系显著；以根冠比为因变量，上上月月降水量、上月平均气温为自变量可分别建立线性回归方程。该方程可以较好地模拟羊草草原植被生长季内月根冠比的动态变化，这样在草地恢复过程中，可由上月的水热因子来指导下月的草地管理，并为更准确地估算草原生态系统生产力及碳储存动态提供重要参数。

The dynamics of root-shoot ratio and its environmental effective factors of recovering Leymus chinensis steppe vegetation in Inner Mongolia

A field study was conducted to examine the relationships between the root-shoot ratio dynamics and the precipitation and temperature of the typical Leymus chinensis steppe recovering from grazing in Inner Mongolia, China. A former piece of pasture land that had been fenced off for 2 years was selected for the study, and aboveground and belowground biomass was collected from the study site along with local precipitation and temperature observations during the study period and was used in the analysis. The results indicated that 1) the seasonal change in both aboveground and belowground biomass in Leymus chinensis steppe demonstrated a pattern with a single peak occurring in August. 2) The root-shoot ratio showed a seasonal variation, with relatively high values at the beginning and the end of the growing season. The minimum ratio occurred in late August when the aboveground bio-mass reached its maximum. 3) The monthly root-shoot ratio was significantly correlated (p < 0.05) with the monthly precipitation two months ago, and with the mean temperature in the previous month. A regression model was built with the root-shoot ratio as the dependent variable, and precipitation and temperature as the independent variables. This regression could be used to model the monthly root-shoot ratio dynamics of Leymus chinensis steppe during the growing season.