闽三角林地景观结构与功能连接度的空间耦合关系

Spatial coupling analysis of forest landscape structure and functional connectivity in Min River Delta

以闽三角地区为例,为探讨景观连接度不同评价方法的科学性,提出一种基于最小耗费距离模型的成本距离指数表征景观功能连接度,并与传统的基于景观格局指数的景观结构连接度度量指标进行比较,揭示两者的空间耦合关系,为景观连接度的有效评价提供支持。结果表明:(1)2000—2020年,林地与其他土地利用类型之间发生不同程度的转化,林地转为建设用地370.72km2,占总转出面积的77.28%;草地和耕地转为林地80.45km2,占总转入面积的90.53%。(2)20年间,林地景观结构与功能连接度总体呈减小趋势,其中,湖里区林地景观结构与功能连接度降幅均最大,斑块密度、最大斑块指数、聚合度指数和斑块结合度指数分别下降了76.47%、51.33%、68.13%和68.40%,成本距离指数增加了178.56%。(3)成本距离指数与斑块密度、最大斑块指数、聚合度指数、斑块结合度指数和景观结构连接度综合指数均为负相关。(4)在研究期间,双变量局部空间自相关聚集类型由低⁃高转化为高⁃高,结构连接度无变化时,景观功能连接度降低;由高⁃高转化为低⁃高,结构连接度无变化时,景观功能连接度增加,表明运用成本距离指数表征景观功能连接度,比景观格局指数表征的景观结构连接度更为敏感。因此,成本距离指数在度量快速城市化地区的景观连接度时具有优势;而在海拔较高、地形复杂以及受人为干扰少的地区,景观格局指数和成本距离指数的适用性相近。研究结果可为闽三角地区生物多样性保护工作提供科学参考依据,为研究不同方法对景观连接度评价的影响提供新思路。

Taking Min River delta as an example,in order to explore the scientificity of different evaluation methods for landscape connectivity,a cost distance index based on the minimum cost distance model was proposed to characterize landscape functional connectivity,and compared with the traditional landscape structure connectivity index based on landscape pattern index.The aim is to reveal the spatial coupling relationship between the two,and provide support for effective evaluation of landscape connectivity.The results showed that:(1)From 2000 to 2020,the conversion of forest land to construction land was 370.72 km2,accounting for 77.28%of the total conversion area.The conversion of grassland and cultivated land into forest land was 80.45 km2,accounting for 90.53%of the total conversion area.(2)During the past 20 years,the structure and functional connectivity of forest land showed a decreasing trend in general.Among which,the decrease of the structure and functional connectivity of forest land in Huli area was the largest,and the patch density,the largest patch index,aggregation index and patch cohesion index decreased by 76.47%,51.33%,68.13%,and 68.40%,respectively.The cost distance index increased by 178.56%.(3)The cost distance index was negatively correlated with patch density,the largest patch index,aggregation index,patch cohesion index,and integrated index of landscape structure connectivity.(4)During the study period,the bivariate local spatial autocorrelation aggregation type changed from low⁃high to high⁃high,and the landscape functional connectivity decreased when the structural connectivity did not change.From high⁃high to low⁃high,the landscape functional connectivity increased when the structural connectivity did not change.The results showed that the cost distance index was more sensitive to landscape functional connectivity than the landscape structure connectivity index.Therefore,cost distance index has advantages in measuring landscape connectivity in rapidly urbanized areas.However,the applicability of landscape pattern index and cost distance index is similar in areas with higher elevation,complex terrain and less human disturbance.The research results can provide a scientific reference for biodiversity conservation in Min River Delta,and provide a new way to study the impact of different methods on landscape connectivity evaluation.