基于多光谱数据的湿地景观格局变化对越冬候鸟生境影响

Impact of Water Level Fluctuations on Habitats of Wintering Migratory Birds Based on Multispectral Data

安徽升金湖是典型的长江中下游自然通江湖泊湿地,是越冬候鸟尤其是珍稀鹤类的理想越冬地,水利设施的修建改变了升金湖的自然连通状况,使湖泊水位变化受人为控制,继而引起景观格局变化,从而影响越冬候鸟生境。为探究水位波动对越冬候鸟生境影响规律,基于Landsat-8(OLI)多光谱遥感影像对升金湖土地利用类型进行分类,结合水位数据和候鸟种群特征数据,选取景观斑块谱特征指数并对其分级,分析不同水文期升金湖湿地水位变化规律,探索湿地景观斑块谱特征时空变化特征,探究不同水文时期自然湿地景观格局和越冬候鸟生境变化规律。结果表明:空间上该区域丰水期大斑块面积占优,枯水期中等斑块面积达到峰值,在退水期和枯水期景观格局分布良好,景观整体表现出大斑块面积占优、数量较少且形状复杂,小斑块分布分散、数量巨大且形状规则,中小型斑块面积均匀,形状各异。时间上景观格局随水位变化,斑块总数随水位升高先增后降,小斑块数量变化最大且稳定性差易受水位波动影响;水位对大斑块形状指数影响较大,水位升高大斑块形状趋于复杂化,涨水期和丰水期大斑块形状指数最大,趋于狭长式分布,景观边缘效应趋于明显,内部结构异质性降低;四个水文期香浓多样性指数分别为1.7542(涨水期)、1.5717(丰水期)、1.7623(退水期)、1.7901(枯水期),香浓多样性指数减小,景观类型多样性趋于单一。越冬候鸟生境面积与水位高低呈负相关,草滩地、泥滩地和芦苇滩地三种类型面积此消彼长并长期处于平衡状态,草滩地面积在生境面积中占比最高起主导作用(68.01%),总体生境面积在候鸟越冬末期(枯水期)达到峰值,利于越冬候鸟觅食等行为活动。基于此,建议在越冬候鸟前期(8月—翌年1月)通过控水闸人为调控升金湖水位,使各生境类型面积增加,为越冬候鸟提供优质生境。

Shengjin Lake wetland in Anhui Provinceis a typical lake wetland which located in the middle and lower reaches of the Yangtze River in China.It is an ideal wintering place for wintering migratory birds,especially rare cranes.The construction of water conservancy facilities has changed the natural connection of Shengjin Lake,and the lake water level has been affected by changes.Human-made control,which in turn causes changes in the landscape pattern,affects the habitat of over wintering migratory birds.In order to explore the influence of water level fluctuations on overwintering migratory birds,in this paper land use types in Shengjin Lake were classified based on Landsat-8(OLI)multispectral remotesensing images,water level data were combined and migratory bird population characteristics data were selected,the landscape patch spectral feature index was ranked,the water level change law of the Shengjin Lake wetland in different hydrological periods was analyzed,the spatiotemporal change characteristics of wetland landscape patch spectral characteristics were explored,the natural wetland landscape pattern and the habitat change pattern of overwintering migratory birds were explored.The results showed that spatially the large patches areas were dominant in the wet season,and the medium patches areas have reached the peak in the dry season.The landscape patterns were well distributed in the ebb and dry season.The overall landscape showed that the large patches areaswere dominant,small and complex;the small patches distribution were scattered,huge and regular;and the small and medium patches areas were uniform and different.In terms of time,the landscape patterns were changed with the water level,the total numbers of patches were increased firstly and then decreased with the rising of water level,while the numbers of small patches were changed mostly and their stability was poor,which were easily affected by the fluctuation of water level.The shape indexes of large patches were influenced greatly by the water level,which the shape index of large patches was tended to be complicated when the water level raised.The shape indexes of large patches werethe largest in the flood period,and were tended to be long and narrow.The effects of landscape edge were tended to be obvious,and the heterogeneity of internal structure was decreased;the fragrance diversity index in the four hydrological periods were 1.7542(Flood Period),1.5717(Wet Period),1.7623(Ebb Period),and 1.7901(Dry Period)respectively.The indexes of fragrance diversity were decreased,and the diversity of landscape types were tended to be single.Winter migratory birds habitat areas were negative correlation with the water level,the areas of three types including grass land,mudflats and reed shoal were tradeoffs and long-term equilibrium.The grass land areas were accounted for the highest in the habitat area which played a leading role(68.01%),the overall habitat areaswere peaked in the late migratory birds wintering(in the dry season),which were benefited by wintering birds for foraging behavior activities.Based on this conclusion,it is suggested that artificially regulating the water level of Shengjin lake by controlling sluice during the dry season of over wintering(August to January of the following year)could increase the area of each habitat type and provide excellent habitat for over wintering migratory birds.