Scale Effect Research On Land Use Change In Yunmeng Lake Watershed

Relationship between landscape pattern and ecological process has now becomethe frontal of land use change and one of the hotspots in recent years. Problems suchas land model and ecological environment can be reflected by assessing landscapepattern change analysis, which would give hint to the landscape optimization andecological environment protection. As the comprehensive performance ofheterogeneity in space, the landscape pattern has the characteristic of scaledependency. Through analysing characteristics and change rules of the samelandscape pattern under different scales, we found scale effect and real situation ofthe landscape. Based on the theory of landscape ecology and landscape indices, thispaper took the Yunmeng lake watershed as an example and made a quantitativeanalysis of the scale effect of the land use change. TM remote sensing image of1986,1995,2005,2010and the documents were used. The indices of patches type leveland landscape level were selected with variety of methods.The main conclusions are as followed:(1) At the scale of landscape types, the landscape indices were changing withdifferent scales except patch size percentage, and different land use types haddifferent scale effect. Cultivated land created stronger response to area/edge fractaldimension and more effective mesh size than other types, but reacted more weakly topatch density, patch size percentage and cohesion. The scale effect of area/edgefractal dimension and cohesion had greatest differences between residential land andcultivated land. Although the indices had difference in different years, the responsetendencies of changing size were similar. In addition to patch size percentage andeffective mesh size, mathematic models were used to fit the changeful curves ofdifferent land use types, which had a high accuracy. (2) At the scale of landscape, there are four type of grain effect, that is, monotonicdecrease, anomalistic changing, undulatory changing and amplitude-accreting.Monotonic decrease is characterized by monotonically decreasing indices withincreasing grain size and showed a power-law decay scaling relation, including patchdensity and landscape shape index. The indices of anomalistic changing effect haveone or more obvious inflection, including the maximum patches indices. The indexof undulatory changing rise or fall with increasing grain size, including the cohesion,area/edge fractal dimension. The changing trend of amplitude-accreting grain effectwere relatively stable, including Shannon diversity index and Shannon EvennessIndex. Among them, patch density and landscape shape index were the relativelysensitive indices. Patch density, landscape shape index, cohesion and area fractaldimension had extremely good fitting degree.(3)The suitable granularity range of various landscape type landscape indexcalculation in Yunmeng lake watershed are as followed: cultivated land90m,forestland90-120m and that of grassland, waters area, residential land is60-90m.Therefore, the suitable granularity of landscape pattern in Yunmeng lake watershedis90m.