贡湖湾退圩还湖区水位高程下植被分布格局与土壤特征

为揭示水陆交错带水位高程下植被分布格局、多样性指数和土壤特征的变化,于2015年10月对贡湖湾湿地北部生态修复区不同水位高程下植物群落组成和土壤特征进行调查,结果表明:整个研究区有165种植物,隶属65科、142属,多为多年生植物且受人为影响严重;随水位高程增加,植物群落R、H、D、J呈现逐渐递增趋势,具体表现为常年水淹区G1季节性水淹区G2水淹区G3;土壤容重及机械组成中粉、黏粒含量随水位高程升高而增加;随土壤营养物渐增其植物群落多样性增加,多样性和优势度指数与土壤全氮(TN和有机质(OM)负相关。OM含量呈"V"型先减后增分布;TN呈逐渐增多的趋势;速效钾(EP)含量无明显波动,约为13.50 mg/kg;有效磷(AP)含量先减少后基本不变;4个多样性指数间正相关;TN与OM显著正相关(R~2=0.533);OM与EP负相关(R~2=-0.144;TN与丰富度、多样性、优势度正相关;AP与4个多样性指数均正相关;pH值与4个多样性指数负相关;回归分析可见,TN和OM是影响植物群落多样性的关键因子。科学的植被管理、全面调控土壤营养盐含量有助于水陆交错带植被恢复。

Plant diversity and soil property changes in the restored Land/Water Ecotones of Gonghu bay

The aim of the present study was to determine the variation in vegetation distribution patterns, diversity indices, and soil characteristics under water level elevations in land and water ecotones, in the northern part of Gonghu Bay in October 2015. Observing and records of phytocoenosium formations and soil features showed that the majority of all 165 species, subordinated to 142 categories and 65 families, were perennial plants that were seriously affected by human activities. The higher the water levels, the higher the abundance of plant communities (R, H, D, J) and were affected by the duration of submergence. The particle and silt proportions in soil bulk density and its formation increased with increasing water levels. The soil total nitrogen level and community richness also indicated a positive relationship. In contrast, the diversity and dominance of plant communities showed a negative relation with TN and organic matter (OM). The OM content in soil decreased from 12.69 to 9.14 mg/kg initially and then increased to 14.78 mg/kg, showing a "V" type distribution. The total nitrogen content in soil increased linearly from 0.45 to 0.684 g/kg^-1. However, no obvious fluctuation was found in the available potassium (EP) content since it remained at 13.50 mg/kg, and the available phosphorus (AP) content decreased from 21.28 to 18.70 mg/kg and then remained unchanged. There was a positive correlation among the four diversity indices. Total nitrogen had a significantly positive relation with OM (R² = 0.533); OM had a negative correlation with EP (R² = -0.144), soil total nitrogen had a positive relationship with community richness, diversity, and dominance; available phosphorus had a positive relationship with the four diversity indices. The pH value had a negative relationship with the four diversity indices. The results of the regression analysis indicated that total nitrogen and OM are the key factors of vegetation diversity. Therefore, scientific vegetation management and comprehensive adjustment of nutrient salts are necessary to enhance the vegetation of the land/inland water ecotone.