无锡市小微湿地演变特征及影响因素分析

Changing features and influencing factors of small and micro wetlands in Wuxi City

【目的】开展小微湿地时空演变特征及影响因素分析,可为湿地生态修复与保护提供数据基础和理论依据。【方法】基于2000、2010和2020年Landsat系列卫星影像,利用支持向量机分类等方法,提取无锡市小微湿地斑块信息,结合气象、土地利用等数据,对无锡市小微湿地的时空演变特征及其影响因素进行分析。【结果】(1)近20年来无锡市湿地总面积呈下降趋势,由2000年的17.8万hm^(2)减少至2020年的10.4万hm^(2),其中小微湿地总面积从2000年的1.9万hm^(2)减少到2020年的1.5万hm^(2)。(2)从空间分布来看,无锡市小微湿地主要分布在宜兴市,其面积占无锡市湿地面积的40.0%;从湿地类型来看,以自然湿地为主,比例高达61.0%;无锡市小微湿地具有明显的季节变化特征,2020年季节性小微湿地占小微湿地总面积的比例高达73.8%。(3)无锡市小微湿地受自然因素及人类活动影响,其动态变化与气温、降水呈正相关;人类活动对小微湿地面积下降影响显著,湿地和其他地类间的转化加速了湿地面积萎缩。【结论】无锡市小微湿地资源丰富,但受季节和土地利用变化等影响,小微湿地的萎缩较为严重,亟须加强小微湿地的保护和修复工作。

[Objective]Small and micro wetlands provide several important ecological functions,such as habitat support for key species,biological transfer,hydrological regulation and water purification,education and rest.Wuxi City in China contains numerous wetlands,of which most over 8 hm have been protected in recent years.However,not all small and micro wetlands have been protected in Wuxi City,and research regarding spatiotemporal changes in these habitats under yarious factors is lacking.Thus,analyzing the temporal and spatial characteristics and driving forces of small and micro wetlands can provide a theoretical basis for wetland ecological restoration and protection construction.[Method]Based on Landsat satellite images in 2000,2010 and 2020,patch information of small and micro wetlands in Wuxi City were extracted using support vector machine classification and other methods.Combined with meteorological and land use data,the spatiotemporal evolution of small and micro wetlands in Wuxi City and its influencing factors were analyzed.[Result](1)Within the past two decades,the total wetland area in Wuxi City has decreased from 178000 hm^(2)in 2000 to 104000 hm^(2)in 2020.Among them,the total area of small and micro wetlands has decreased from 19000 hm^(2)in 2000 to 15000 hm^(2)in 2020.(2)In terms of spatial distribution,small and micro wetlands in Wuxi were mainly distributed in the county-level city Yixing,which accounted for 40.0%of the area of Wuxi City.Small and micro wetlands in Wuxi City predominantly consisted of natural wetlands,accounting for up to 61.0%and displayed marked seasonal variation characteristics.In 2020,the proportion of seasonal small and micro wetlands in the total area of small and micro wetlands was as high as 73.8%.(3)The dynamic of small and micro wetlands in Wuxi City were positively correlated with temperature and precipitation due to natural factors and human activities.Specifically,human activities had a significant impact on the decline of small and micro wetland areas,and the transformation between wetland and other land types accelerated the decline of wetlands.[Conclusion]Wuxi City is rich in small and micro wetland resources,which are in rapid decline due to seasonal and land use changes.Thus,the protection and restoration of small and micro wetlands must be enhanced to mitigate the negative impacts imposed by different factors.