漓江水陆交错带植被与土壤空间分异规律

面对近年来漓江出现水资源短缺、植被退化等生态问题,研究漓江流域水陆交错带植被、土壤特性空间分异规律,旨在为漓江水陆交错带植被恢复、景观美化、典型湿地的保护管理及其可持续利用等方面提供科学依据。该研究以喀斯特地貌漓江流域水陆交错带为研究区域,通过对水陆交错带4个典型梯度带植被与土壤调查,分析其分布及两者相关关系,结果表明:随着河岸梯度高程增加,植被丰富度、多样性、均匀度、优势度和覆盖度呈现递增趋势,分别由0递增至9.500、1.742、0.774、0.786、0.673;土壤容重由1.065g/cm3先增加至1.352g/cm3,后下降至1.257g/cm3,呈现先增后减趋势;砂粒含量明显下降,粉黏粒含量显著增加;土壤有机质质量分数由25.522mg/kg先下降至15.634mg/kg,后增加至26.148mg/kg,呈现先减后增趋势;全氮质量分数由0.399g/kg增至0.556g/kg;有效磷质量分数由13.930mg/kg降低至4.685mg/kg。漓江水陆交错带喀斯特碱性土壤pH值与全氮含量相关系数为0.628,呈显著负相关;与有效磷含量相关系数为0.942,呈极显著正相关。植被丰富度、多样性、均匀度、优势度和覆盖度与土壤粉粒含量、黏粒含量、全氮含量以及有机质含量呈现正相关关系,与砂粒含量、土壤容重、pH值、有效磷含量呈现负相关;研究结果还显示,全氮含量是对植被生长影响最大的土壤因子。规范漓江沿岸居民行为和充分利用砾石河滩现有条件进行适当开发均有助于漓江水陆交错带的植被恢复。

Spatial distribution of vegetation and soil in aquatic-terrestrial ecotone, Li River

Abstract: In the face of ecological problems such as the shortage of water and vegetation degeneration occurred in the Li River in recent years. Research on the spatial distribution of vegetation and soil in aquatic-terrestrial ecotones in Li River aims to provide a scientific basis to vegetation restoration, landscaping, wetland protection and management and its sustainable use in aquatic-terrestrial ecotones of the Li River. This paper mainly studies aquatic-terrestrial ecotones in the Li River, which belongs to a Karst landform. According to the elevation and vegetation types of aquatic-terrestrial ecotones, we divided the study area into four gradient zones including gravel beach, grassland, shrub-grass land, and open forestland. By investigating the spatial distribution of soil and vegetation in four typical gradient zones and analyzing their distribution and correlation, the results showed that with the increase of riverbank gradient elevation, vegetation abundance, diversity trend (Shannon-Wiener plant diversity), evenness (Pielou index), dominance (Simpson index) and coverage presented an increasing trend, the number of species had become increasingly diverse, and species composition structure had become complicated. Soil bulk density increased initially and then decreased. Sand content declined significantly. Silt and clay content increased significantly, which was related to the improvement effect of vegetation. Soil organic matter decreased initially and then increased. Total nitrogen content continuously increased. Available phosphorus content presented a reducing trend that was unnatural, related to non-point source pollution on the shore of Li River, and regulating the residents' behavior is necessary. The alkaline soil pH of Karst ecotone was negatively correlated with total nitrogen content while it was positive correlated with available phosphorus content. Soil properties influence vegetation diversity. The results showed that vegetation abundance, diversity trend, evenness, dominance and coverage were positively correlated with the content of silt, clay, total nitrogen and soil organic matter, but negatively with sand content, soil bulk density, soil pH and available phosphorus content. Furthermore, the results demonstrated that the total nitrogen content was one soil factor that had the largest influence on vegetation growth. Having higher soil-nutrient content, gravel beach had considerable potential for vegetation restoration, and it was a key area in the aquatic-terrestrial ecotones. Making full use of gravel beach can be helpful to the vegetation restoration in aquatic-terrestrial ecotones in the Li River.