| World natural heritage preserves and develops a large area of native vegetation and a variety of special ecosystem spatial pattern,carries important ecosystem service value and function,contains rich scientific value,economic value,aesthetic value and other multiple values,and is the precious wealth that nature presents to human beings.Lithologic basement is an important condition that affects the difference of regional ecological environment.The difference of soil and water resource allocation and nutrient geochemical cycle caused by lithology restricts the spatial and temporal pattern of regional vegetation.The spatial heterogeneity of soil in regional habitats is determined by rock types and geomorphic evolution stages,while the spatial heterogeneity of surface water and soil patches often determines the distribution pattern of communities.Therefore,the spatial combination structure of lithologic landforms has an obvious controlling effect on the spatial distribution and evolution of ecosystems.The three World Natural Heritage sites of Libo,Yuntai and Fanjingshan in Guizhou are not very different in terms of climate background,but they are very different in terms of lithology background and geomorphic environment.According to the lithology,the three heritage sites can be divided into three types: complex karst(Libo),single karst(Yuntai Mountain)and non-karst(Fanjing Mountain).It is of great practical significance to analyze the differences of the spatial and temporal patterns of the ecosystem in Libo,Yuntai and Fanjingshan heritage sites for understanding the differences of ecosystem functions,biodiversity and natural ecological restoration processes under the background of complex karst,single karst and non-karst rocks.Based on Landsat historical satellite remote sensing images,the spatial distribution data of the three heritage sites were obtained through human-computer interaction interpretation,and the basic geographical database of the ecosystem in the study area was established through the actual investigation and verification in the artificial field.Guided by the theories of geography and landscape ecology,Arc GIS and Fragstats software were used to analyze the spatial pattern of ecosystems in three heritage sites,Libo,Yuntai and Fanjing,from 2000 to 2018,and their differences were preliminarily explored.Through systematic analysis,the main conclusions of this study are as follows:(1)From 2000 to 2018,the proportion of the regional ecosystem in Libo World Natural Heritage Site changed significantly,and the proportion of arbor forest ecosystem increased the most.The ecosystem type with the largest increase in the net rate of change was wetland,and the ecosystem type with the largest decline was grassland.Ecosystem evolution was dominated by the forward transformation,but the reverse transformation was also significant.The number of heritage sites(NP),maximum patch index(LPI),landscape spread index(CONTAG)and dispersal and parallel index(IJI)all increased,while the Shannon diversity index(SHDI)decreased.The most obvious changes of landscape pattern index were shrub and grassland.The landscape index values in the dolomite area changed obviously,the interbedded area between limestone and clastic rock was relatively stable,the ecological environment quality in the core area was obviously better than the buffer area,and the overall stability of the ecosystem in the Libo natural heritage area showed an increasing trend.(2)From 2000 to 2018,arbor forests,wetlands and other types of ecosystems in the natural heritage site of Yuntai Mountain increased in area proportion,while shrubs and grasslands decreased in area proportion.The area of forward and reverse transformation of ecosystem is close to each other.The number of ecosystem patches(NP),the maximum patch index(LPI),the landscape spread index(CONTAG)and the dispersal and parallel index(IJI)of the heritage sites all increased,while the Shannon diversity index(SHDI)decreased.The landscape index values of each ecosystem in the heritage sites changed in different degrees,among which the landscape pattern changes of arbor forest,shrub forest and grassland ecosystem were more obvious.The high value areas of ecosystem stability were mainly distributed in the core areas of the heritage sites during the two periods,but there were significant differences in the specific distribution locations of landscape stability.On the whole,the ecosystem stability in the Yuntai Mountain Natural Heritage Site decreased significantly from 2000 to 2018.(3)From 2000 to 2018,arbor forest and shrub forest were the types of ecosystem that increased in the proportion of area in the natural heritage area of Fanjing Mountain.The types of ecosystem systems that showed a decrease in area ratio were grassland,wetland and others.Ecosystem evolution was mainly forward,but reverse transformation was also obvious.The number of ecosystem patches(NP),maximum patch index(LPI),landscape spread index(Con TAG)and dispersal and parallel index(IJI)all increased in the study area,while the Shannon diversity index(SHDI)decreased.The pattern indexes of arbor forest,shrub,grassland,wetland and other five ecosystems changed in different degrees,among which shrub and grassland showed the most dramatic increase.The high value areas of ecosystem stability in the two periods were mainly distributed in the core area of the heritage sites,but there were significant differences in the distribution locations and directions.From 2000 to 2018,the ecosystem stability of the natural heritage site of Fanjingshan increased significantly.(4)Comparing the quantitative structure of the ecosystem in the three heritage sites in two periods,we found that the arbor forest ecosystem tended to be distributed in the non-karst lithology area,while the grassland was mostly distributed in the complex karst lithology area.Compared with Yuntai Mountain and Fanjing Mountain,Libo has the highest overall sensitivity of the ecosystem,and the ecosystem structure was more likely to change.In terms of single type ecosystem,arbor forest and wetland are prone to change in complex karst lithology area,while shrub and grassland are more likely to change in non-karst lithology area.(5)From 2000 to 2018,the region with the largest area of ecosystem transformation was Libo,followed by Yuntai Mountain,and finally Fanjing Mountain.The forward conversion ratio of the three heritage sites was higher than the reverse conversion ratio,and the transformation level of the three heritage sites was Libo > Yuntai Mountain > Fanjing Mountain.According to the sequence of positive/prospective conversion rate of the three heritage sites,the positive conversion rate of arbor forest and shrub forest ecosystem is:Yuntai Mountain > Fanjingshan > Libo;Grassland ecosystem positive conversion rate: Libo > Yuntai Mountain > Fanjing Mountain.The reverse conversion rate of arbor forest ecosystem: Libo > Yuntai Mountain > Fanjing Mountain;The reverse conversion rate of shrub ecosystem: Yuntai Mountain > Libo > Fanjingshan;the inverse conversion rate of grassland ecosystem: > in Yuntai Mountain,> in Fanjing Mountain,Libo;reverse conversion rate of wetland ecosystem:Libo > Yuntai Mountain > Fanjing Mountain.(6)The degree of ecosystem landscape fragmentation in the three heritage sites from two periods: Libo > Fanjingshan > Yuntai Mountain;Ecosystem dominance: Fanjingshan > Yuntai Mountain >Libo;Patch connectivity: > in Fanjingshan,> in Yuntai Mountain,Libo;Natural condition restriction level: Libo > Yuntai Mountain,Fanjing Mountain;Landscape heterogeneity: Libo > Yuntai Mountain > Fanjing Mountain.In general,the landscape pattern of Libo natural heritage site has changed most obviously.Landscape pattern characteristics of single ecosystem in the region: the landscape fragmentation degree of arbor forest,shrub forest and grassland ecosystem in Libo was the highest,and the landscape fragmentation degree of wetland ecosystem in Fanjingshan was the highest.The grassland ecosystem patch density was the highest in Fanjing Mountain,and the wetland ecosystem patch density was the highest in Yuntai Mountain.The arbor forest,shrub forest and grassland ecosystem in Libo were the most disturbed by human activities,and the wetland and other ecosystems in fanjingshan were the most disturbed by human activities.In general,the ecosystem landscape stability of the natural heritage sites of Fanjing Mountain was obviously higher than that of Yuntai Mountain and Libo.In the karst lithologic area,the landscape stability of Libo ecosystem was slightly higher than that of Yuntai Mountain. |
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