| Determining the optimal spatial and temporal scales for the relationship between plant diversity and landscape is essential for better understanding the relationship between urban landscape pattern and plant diversity and for species conservation.In order to analyze the relationship between landscape pattern and plant diversity in karst mountainous cities and its scale effect,a typical karst mountainous city,the central urban area of Guiyang City(CUAG),was taken as the research object,and high-resolution remote sensing images from 2010,2015 and 2020 were used as the basic data source,use software platforms such as Arc GIS and Fragstats,based on the analysis of spatial and temporal evolution characteristics of landscape pattern in CUAG,27 karst remnant mountains were selected.Through the investigation of different types of mountain vegetation,the composition and structure of different life-type plant species were analyzed to reveal the plant diversity distribution pattern of urban mosaic mountain in CUAG.Furthermore,eight buffers were set with each mountain as the center and 500 m as the step length.Using random forest model and spatial econometric regression model to analyze the coupling relationship between landscape pattern and mountain plant diversity within different buffer radius.To investigate the effects of landscape patterns on plant diversity of different life types at different spatial and temporal scales.The main research results are as follows:(1)The landscape pattern in CUAG changed dramatically from 2010 to 2020.Except for grassland and cultivated land,the area of all other eight landscape types showed an increasing trend,and mountain greenspace was the dominant landscape type in the study area.The landscape fragmentation at landscape level was relatively high but a trend of slowing down was appearing,the internal connectivity of the landscape was enhanced and the uniformity of the landscape was reduced.At the class level,the fragmentation degree of each landscape type was high,and the shape of patches tended to be regular.(2)The composition of plant species in CUAG was abundant,with a total of 674 species recorded in 27 karst remnant mountains,belonging to 140 families and 428 genera.Among them,148 species of arbor belong to 105 genera in 50 families,320 species of shrub belong to 202 genera in 76 families,and 350 species of grass belong to 249 genera in 86 families.The species diversity indices of different life types differed significantly,with the overall expression of shrub layer > grass layer > arbor layer.Shannon-Wiener index,Simpson index and Margalef index of arbor layer and shrub layer,arbor layer and grass layer differed significantly.The Pielou indices of different life types were significantly different from each other.(3)The spatial distribution pattern of species diversity in karst remnant mountains showed strong spatial autocorrelation,and the spatial heterogeneity of landscape significantly affected the spatial distribution characteristics of plant species diversity.Shannon-Wiener index and Pielou index of arbor layer,Pielou index and Margalef index of shrub layer and grass layer showed "high-high" and "low-low" aggregation.The spatial differentiation of plant diversity in arbor layer was affected by the shape of water body and mountain greenspace landscape.The spatial distribution characteristics of plant diversity in shrub layer were affected by the shape of cultivated land and unused land.The shape of industrial and mining land was the main factor limiting the spatial distribution of grass plant diversity.(4)The spatial and temporal scales of plant diversity response to landscape pattern in karst remnant mountains were different.At the spatial scale,the best interpretation rates of arbor layer plants,shrub layer plants,grass layer plants and landscape pattern were in the range of 500-3500 m,1500-4000 m and 500-4000 m,respectively.At the temporal scale,there was a time-delay effect in arbor layer,and the explanation rate of species diversity was the highest with landscape pattern in2015.Shannon-Wiener index and Simpson index of shrub layer plants had no time-delay effect,and the Pielou index and Margalef index could be represented by the landscape pattern in 2010 and 2015,respectively.Grass layer plants had no time-delay effect.(5)The interpretive rate of landscape pattern to plant diversity of mountain ranged from 10.50 to 64.25%.The fragmentation degree and patch shape complexity of forestland,grassland and mountain greenspace were the key landscape factors reflecting the relationship between landscape pattern and plant species diversity. |
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