Effects Of Landscape Dynamics On Landscape Connectivity

With the influence of human activities,landscape changes often affect the number and area of patches in the habitat of species,thus providing resistance to the survival and reproduction of species,resulting in the survival of species highly dependent on the connectivity between patches in the habitat.In the current studies on landscape change and its impact on the ecosystem,many studies are conducted based on virtual species,that is,different distance thresholds are assumed to simulate the diffusion capacity of different species.The purpose of this study was to study the impact of landscape wholeness and type change on the real multi-species habitat patch connectivity.This study mainly explores the following issues:(1)Taking the agricultural area in the middle reaches of the Yellow River in Gongyi city,Henan province as an example,the positive or negative effects of landscape changes and various types of changes on landscape connectivity of multiple species under different ecological demands of species are analyzed.(2)How to spatially map the impact of landscape changes on functional connectivity,and dynamically change according to functional connectivity,so as to provide a basis for determining species priority reserves.With Mustela sibirica,Lepus tolai and Martes flavigula as the study objects,the diffusion distances of three species were determined,which were 3000 m,7000m and 7000m respectively.Moreover,remote sensing technology of geographic information system was used to comprehensively analyze the changes and transfers of landscape types in the research area from 1990 to 2002,from 2002 to 2011,and from 1990 to 2011.The changes of landscape types were decomposed into 95,124 and 121 types of changes,and the movement of landscape types in and out was analyzed by using the transfer matrix.Two indexes of landscape connectivity are calculated:probability connectivity index(PC)and patch significance value(dPC).Then,based on Fragstats 4.2 software,inverse function of distance weight is used to form spatial distribution map of landscape patch connectivity.The research results show that:(1)From 1990 to 2011,all landscape types in the study area had great changes,and the suitable habitat of species had great changes.From 1990 to 2002,from 2002 to 2011 and from 1990 to 2011,the largest areas were cultivated land,with the areas of 5036.04 hm~2,16060.10 hm~2 and 16360.07 hm~2.The second type is grassland,forest land and construction land,from 1990 to 2011,the total transferred area accounted for 50.36%,45.29%and 28.80%of grassland,forest land and construction land in 1990,and63.78%(2210.81hm~2)of shrub.From the perspective of area transfer of various landscape types,47.73%(9058.39 hm~2)of construction land has been transformed from other types,ranking the first in area transfer.Secondly,7680.80 hm~2,7677.90 hm~2 and 7188.55 hm~2 of cultivated land,grassland and forested land were transferred from other landscape types,accounting for 16.53%,57.28%and 54.11%of the total area of cultivated land,grassland and forested land in 2011.76.57%(4102.97 hm~2)of shrub forest area from other types of transformation.(2)From 1990 to 2011,for the three target species of Mustela sibirica,Lepus tolai and Martes flavigula,the PC value showed an increasing trend.Detailed analysis is made from different time periods.For the target species,the overall landscape connectivity(PC)in the two time periods from 1990 to 2002and from 2002 to 2011 is increasing.For Lepus tolai,PC values in the two periods also showed a gradually increasing trend.For Martes flavigula,the PC value decreased slightly from 1990 to 2002,and increased significantly from 2002 to 2011,which may be due to the fact that the habitat selection of the Martes flavigula is more rigorous than that of the other two species,and the species spread over a large distance,so they are more sensitive to shrub changes within the research area in the past 20 years.Overall,from 1990 to2011,the overall,landscape connectivity of the Mustela sibirica,Lepus tolai and Martes flavigula increased by 22.22%,25.64%and 45.46%,respectively.(3)There are differences in the sum of PC values obtained by changing the overall landscape connectivity and by changing the landscape types.The increase or decrease of landscape connectivity is closely related to the increase or decrease of habitat patch area.Location and spatial variation of non-habitat patches can also affect landscape connectivity,including positive and negative effects.From the spatial distribution map of multi-species landscape connectivity the key areas of species habitat protection can be well identified.Species habitat area and habitat connectivity are of great significance to biological protection.Spatial analysis of the impact of landscape changes on landscape connectivity of multiple species can provide reference for species protection planning and landscape rational development and management.