城镇化背景下河流生境评价——以深圳市为例

Abstract

城镇化背景下，河流生态系统退化趋势明显，有效评价河流生境状况是修复和保护河流生态系统健康的重要基础。深圳市作为全国经济发展的窗口城市，河流生境的调查研究十分匮乏。因此，为阐明深圳市不同城镇化程度的流域河流生境的差异与主要影响因素，对深圳市两个代表性流域的河流生境展开了研究。针对深圳市河流的生境特点，于2019年丰水期（8月）和枯水期（11月）对城镇化程度较高的深圳河流域的13个样点和城镇化程度较低的坪山河流域12个样点河段的生境状况进行定量调查与评价。采用综合评价法，从河床、河道和河岸带3个方面选取10个生境指标，构建深圳市河流生境评价指标体系和评价方法。结果表明：深圳河流域河流生境质量总体较差，生境评价等级为"良"、"中"、"差"的样点河段分别占7.7%、38.5%、53.8%；坪山河流域河流生境质量总体较好，生境评价等级为"优"、"良"、"中"、"差"的样点河段分别占8.3%、41.7%、41.7%、8.3%。方差分析结果表明两次调查河流生境状况无显著性差异，短时间跨度内河流生境状况变化较小；两个流域河流生境状况差异显著，城镇化程度较低的坪山河流域河流生境质量显著好于城镇化程度较高的深圳河流域。河流生境评估指标主成分分析结果表明人类活动强度、河岸稳定性、河道变化、底质、河岸土地利用及植被多样性是影响深圳市河流生境变化的主要因子。本文对河床、河道、河岸带3个方面分别提出针对性的修复建议，对深圳市河流的生境修复和保护具有重要的指导作用。;In the context of urbanization, the degradation of river ecosystems has become increasingly prominent. Consequently, effectively assessment of river habitat conditions is an important foundation for restoration and protection of river ecosystem health. Shenzhen, as a window or opening city of China’s economic development, has extremely limited research conducted related to river habitat conditions. Therefore, in order to accurately elucidate the differences and main influencing factors of river habitats in basins with different degrees of urbanization in Shenzhen, a habitat assessment study was conducted on streams and rivers in two representative basins in Shenzhen. Based on characteristics of river habitats in Shenzhen, quantitative investigation and assessment of habitat conditions were conducted in 13 sampling sites in the highly urbanized Shenzhen River Basin and 12 sampling sites in the less urbanized Pingshan River Basin, in both wet (August) and dry (November) seasons in 2019. We adopted a comprehensive evaluation method to select 10 key habitat indicators from three categories: river bed, river channel, and riparian zone, to construct the habitat assessment index system and assessment method for Shenzhen rivers. The results showed that the overall condition of river habitat in the Shenzhen River Basin was poor, and the habitat condition of river sections with good, fair and poor were 7.7%, 38.5%, and 53.8%, respectively. The overall condition of river habitat in the Pingshan River Basin was good, and the habitat condition of river sections with excellent, good, fair and poor were 8.3%, 41.7%, 41.7%, and 8.3%, respectively. The analysis of variance (ANOVA) results showed that there was no significant difference in river habitat conditions between the two seasons, which indicated that the overall river habitat conditions did not change too much in the short time period. There were significant differences in river habitat conditions between the two basins, and the overall river habitat condition of the less urbanized Pingshan River Basin was significantly better than that of the highly urbanized Shenzhen River Basin. Principal components analysis (PCA) results of river habitat assessment indices showed that human activity intensity, riparian stability, river channel modifications, substrate composition, riparian land use and vegetation diversity were the main factors driving river habitat conditions in Shenzhen. Based on the results of the river habitat assessment in Shenzhen, targeted restoration and management recommendations were proposed from three aspects: riverbed, river channel, and riparian zone, which have important implications for river habitat restoration and ecological conservation in Shenzhen.