Spatio-Temporal Variation Of Land-Use Intensity And Its Influence On Vegetation Cover From 1998 To 2018,Jiangsu Province,China

THESIS:Spatio-temporal Variation of Land-use Intensity and Its Influence onVegetation cover from 1998 to 2018,Jiangsu Province,China.SPECIALIZATION: Physical geography POSTGRADUATE: Shen Feixue MENTOR: Associate prof.Yang LinAbstractHumans are irreversibly changing the physical environment,with more intensive and diverse human activities,exerting greater pressures on terrestrial ecosystems both locally and globally.Land use is a good way for depicting the human activities,but we know very little about the impacts of intensive human activities within the same land use type on ecological environment change,such as the vegetation cover change influenced commonly by anthropogenic and natural factors.Moreover,quantification of land use intensity within a land use type has been referred as an important part of “GLP”,which is a proceeding after“LUCC”.Therefore,quantifying the intensity of land use over a long time and the knowledge about human-natural interaction of vegetation cover change is significant for better understanding the interactions between the earth environmental system on which human depend and the developing human society.Here,we take the Jiangsu Province,China as the study area.Firstly,we quantify the long-term land use intensity by connecting the remote sensing data of land use type including cropland,rural settlements and urban built-up land with 9 socio-economic statistics at county scale.Next,we refer to ecological environment change as vegetation cover change that directly and indirectly being impacted interactively by anthropogenic and natural drivers.Hence,we detect the interactions between NDVI change,and the land use intensity change,climate change and terrain conditions using the structural equation model.The results are: 1)the land use intensity in Jiangsu Province was mainly increased,accounting for 51% of the total change trends,while there were also about 25% linear and non-linear decreasing types,and the land use intensity gradually showed a "northwest to southeast" spatial differentiation pattern,which is consistent with the socio-economic gradient of the province.And the four basins of Jiangsu are disturbed by different type of land use intensity change from different land use type.2)Land use intensity change and annual precipitation change were the most important driving factors of vegetation change in Jiangsu Province,followed by annual mean temperature change,elevation.The slope had the least influence.In addition,the importance of the direct and total impacts of each factor is not exactly the same in different land use models.Therefore,the interaction between human factors and natural factors cannot be ignored in the simulation of vegetation change.3)Except for the intensity of agricultural management on cropland,the enhancement of land use intensity directly or indirectly leads to vegetation degradation.But the positive effects of increased agricultural management intensity are highly uncertain due to their intensive interaction with changes in meteorological factors.4)The increase of annual precipitation leads to vegetation degradation,and the increase of annual mean temperature is beneficial to the greening of vegetation as a whole,but has a negative effect on the urban construction land where human activities are the most complex.5)As for the topography,the direct and indirect effects of elevation on vegetation change are both positive,while the indirect negative effects of slope are greater than its direct positive effects.Therefore,for the trades off between social development and ecological environment protection,we provide the following suggestions: Firstly,Yishu River Basin and Huaihe River Basin should pay attention to the potential threat of climate drought caused by the agricultural intensification.Then it need to implement the sustainable and multi-functional agricultural managements for the food security,and narrow the gap between urban and rural residents.Secondly,the Yangtze River basin and the Taihu basin need to reduce the negative impact of land exploitation intensity,like the constructive lands expanding.In addition,the ecological environment governance should be performed both in rural and urban areas.At the same time,the cropland protection should be further strengthened to avoid waste of cropland resources.This study provides a framework for managing and controlling the ecological and environmental impacts of human activity intensity,as well as formulating relevant policies,by quantitatively simulating the complex relationship between natural and human factors behind ecological and environmental change.