DYNAMICS OF LANDSCAPE PATTERNS AND THEIR IMPACTS ON URBAN THERMAL AND BIOMASS ENVIRONMENTS IN THE kUNMING METROPOLITAN AREA

Abstract

Urban expansion is occurring at an unprecedented rate in most countries worldwide with no exception in China. The conversion of natural land into impervious areas has resulted in many environmental consequences. Having realized the important role of green space in urban ecosystems, many municipal governments in China have set out a series of policies to introduce green elements into urban areas. Insights into how urban landscape pattern changes in response to urbanization and greening policies and to what extent land use transformation affects local environment are essential for guiding sustainable urban development. This study investigated urban landscape pattern change in response to the rapid urbanization and greening policies in the Kunming metropolitan areas, China. Urban thermal environment and green biomass were investigated in the context of landscape pattern change. The concentric and directional landscape analyses along with landscape metrics were first used to characterize landscape patterns. Change intensities of the landscape patterns were then calculated for the study area as a whole, the concentric belts, and the directional transects to examine the variation of the green space change rate in the city. Next, the study used land surface temperature (LST), derived from remotely sensed images, to characterize the thermal environment of the study area and to associate the LST with the changing landscape patterns. Global and local models were performed to explore the impacts of different land use types on LST variations. Urban green biomass was represented by vegetation density (VD) to evaluate the urban green space conditions and wildlife habitats. VD was derived from remote sensing indices and its spatial change was analyzed using Geographical Information Systems. Results revealed that both rapid urbanization and greening policies accounted for the process of landscape pattern change. Among different green space types, agriculture land was largely encroached and fragmented by urban sprawl, especially in the outer belts of the city. Forest land was also impacted but encountered a relatively moderate loss rate compared to agriculture land. Conversely, greening policies contributed to the recovery of grass land in the last decade. Land use transformation largely altered the local thermal environment and green biomass. A remarkable LST increase was detected in the urban fringe when natural land cover was replaced by impervious surface. Green space was confirmed to be important in mitigating urban heat. As for green biomass, low vegetated areas encountered a substantial biomass loss, mainly due to the rapid shrinkage of the agriculture land. Densely vegetated areas maintained a relatively stable biomass status, suggesting forest areas remained less impacted by human disturbances. This study unveiled the processes of landscape pattern change in the presence of two seemingly contradicting driving forces, i.e. urbanization and greening policies, providing insights into the mechanisms of urban land use change and the subsequent environmental implications. Based on the results, several planning strategies were put forward to ensure a sustainable urban development.