呼伦贝尔草原退化对植被碳库的影响

Impacts of Grassland Degradation on Vegetation Carbon Pool in Hulun Buir

植被碳库如何响应草原退化是草原生态学的重要研究内容。在呼伦贝尔典型草原上选取40个样地,获取植被地上、凋落物以及不同深度根系的生物量,在区域尺度上阐明草原退化对植被碳库影响。结果表明:植被地上碳库、凋落物碳库以及0~50 cm根系碳库之和通常占据植被总碳库的80.0%之上,草原群落根系碳库在50 cm土层以下无显著变化;随着退化程度的加剧,植被地上碳库、凋落物碳库的占比呈现下降的趋势,而植被地下碳库占比则呈现上升的趋势;随着退化程度的加剧,根系分布呈现明显的浅层化趋势,主要体现在0~10 cm土层根系碳库的占比提高,并且0~10 cm土层根冠比对退化强度具有良好的指示作用。研究结果对于深刻认识草原退化对植被碳库的生态效应具有重要意义,为草原生态系统增汇途径提供科学依据。

How the vegetation carbon pool will respond to grassland degradation is an important topic in grassland ecology.In order to clarify the impact of grassland degradation on vegetation carbon pool at regional scale, above-ground biomass, litter biomass and roots biomass of 40 plots in Hulun Buir typical steppe were measured in this research.The results showed that: the sum of the above-ground carbon pool, the litter carbon pool and the root carbon pool in the 0-50 cm soil layer usually accounted for more than 80.0% of the total vegetation carbon pool.The root carbon pool of grassland community at depths below 50 cm did not change significantly.With the aggravation of grassland degradation, the proportion of above-ground carbon pool and litter carbon pool showed a decreasing trend, while the proportion of belowground carbon pool showed an increasing trend.The proportion of roots biomass in the 0-10 cm soil layer tended to increase with degradation intensity, indicating a shallow-distribution trend of the root system.Moreover, the root-shoot ratio in 0-10 cm soil layer was found to be a good indicator for the degradation intensities.Our findings are of great significance for deepening understanding of the ecological effects of grassland degradation on vegetation carbon pools, and provide a scientific basis for the ways to increase the carbon sink of grassland ecosystem.