三峡库区消落带植物多样性变化规律及其驱动因子研究

The patterns and driving factors of vegetation diversity in the riparian zone of the Three Gorges Reservoir

反季水位涨落导致三峡库区消落带植物发生显著变化。但是关于植物多样性变化及其驱动因子的研究还比较匮乏。通过对三峡库区消落带13个监测点3个海拔高程近10 a植物多样性长期定点调查,发现其多样性指数变化区间小,库区中游多样性指数较大。不同海拔高程对植物多样性有显著影响,海拔越高,多样性越大。此外,干流监测点的植物多样性比支流监测点高。虽然植被恢复方式对植物多样性影响不显著,但是对植被均匀度有增加的趋势。土壤理化性质是这些多样性指数和均匀度指数变化的重要驱动因子,并且海拔高程不同,驱动因子不同。低海拔区(高程145~155 m)土壤中的锰、可利用钾、汞以及土壤粒度(>0.25 mm)是主要驱动因子;中海拔区(高程155~165 m)土壤中的锰、铁、可利用磷、粒度(0.01~0.05 mm)以及含水率是主要驱动因子;高海拔区(高程165~175 m)土壤中的汞、锰以及氨态氮是主要驱动因子。所涉及的时空尺度较大,可为三峡库区消落带植被恢复提供科学依据,为后续消落带的保护策略提供参考。

The vegetation in the riparian zone of the Three Gorges Reservoir have undergone significant change due to the water level fluctuations.However,research on vegetation diversity and its driving factors is scarce.Here,we conducts a long-term survey of vegetation diversity in 13 monitoring points at the riparian zone of the Three Gorges Reservoir.It is found that the range of the diversity index is narrow,but in the middle section of the reservoir,the diversity index is relatively large.Altitude variation also has a significant impact on vegetation diversity.The higher altitude,the greater diversity.In addition,the vegetation diversity near the mainstream is higher than that near the tributary.Although the effect of restoration approaches on vegetation diversity is not statistically significant,there is a tendency to increase the vegetation evenness.These changes in diversity index and evenness index can be attributed to the soil physicochemical properties.Interestingly,driving factors are different for different altitudes.In low altitude(EL.145~155 m),the main driving factors are manganese,available potassium,mercury and soil particle size(>0.25 mm).In the middle altitude(EL.155~165 m),the main driving factors are manganese,iron,available phosphorus,grain size(0.01~0.05 mm)and soil water content.At high altitudes(EL.165~175 m),the main driving factors are mercury,manganese,and ammonia nitrogen.The larger temporal and spatial scales involved in this study could help to develop the vegetation restoration and protection strategies in the riparian zone of the Three Gorges Reservoir.