Remotely Sensed Quantification For Effects Of Human Activities On Vegetation

Terrestrial ecosystem is the environmental foundation for human survival and development.Vegetation is a major component of terrestrial ecosystem,and is important for material flow and energy cycling in terrestrial ecosystem.Under effects of climate change and human activities,terrestrial ecosystem has suffered double interference,and how to distinguish and quantify effects of human activities on terrestrial ecosystem has become focus at present.Remotely sensed quantification methods,which are proposed to study effects of human activities on vegetation,aim to provide basis for the change of terrestrial ecosystem services,and are of great significance for rational use of terrestrial resources and sustainable development of terrestrial ecosystem.This part investigated the vegetation cover variations on the Shanxi Province based on MODIS normal difference vegetation index?NDVI?from2001 to 2013 using transition matrix,and liner regression method.Effects of human activities on vegetation cover variations were also analyzed from threeaspects: land use change,agricultural production and vegetation.Results showed that:?1?Average area of land use change was accounting for 15.8 percent of the total area on Shanxi Province.Average variations in NDVI caused by land use change accounted for 16.1 percent.?2?Contribution of agricultural production to NDVI was about 80 percent in the unchanged cropland area.Fertilization and irrigation played an important role in the output of crops,and contribution was82.1 percent.?3?Contributions of vegetation construction to NDVI were about87.4 and 85 percent in unchanged area of woodland and grassland,respectively.Contribution of vegetation construction to NDVI in unchanged woodland area increased with increasing altitude.Contribution of vegetation construction to NDVI in low altitude grassland area was larger than middle altitude area.Based on MODIS net primary productivity data?NPP?,meteorological data and statistical data,the temporal and spatial characteristics of NPPA and NPPP was analyzed,and their relationship with climatic factors in Xilingol grassland from 2001 to 2010.Effect of human activities on net primary productivity was quantitatively calculated,and the temporal and spatial characteristics of NPPH was analyzed.Results showed that :?1?NPPA?actual NPP?was influenced by climate change and human activities.Average value of NPPA was 150.78gC·m^-2·a^-1,and showed horizontal zonal feature and gradually decreased from east to west.There was a significant regional difference in spatial trend of NPPA.?2?NPPP?potential NPP?was influenced by climate change.Average value of NPPP was 185.57 g C·m^-2·a^-1,and showed horizontal zonal feature and graduallydecreased from east to west.There was a significant regional difference in spatial trend of NPPP.?3?Average value of NPPH?NPP affected by human activities?was-34.80 g C·m^-2·a^-1 in the Xilingol grassland.Negative effects of human activities accounted for 93.4% of study area.Average change rate of NPPH was 1.18 gC·m^-2·a^-1.?4?Effects of human activities on NPP mainly changed from negative to positive.Effects of human activities showed a boundary in Xilingol grassland.Negative effect strengthened in the South,and positive effect weakened in the North.In this study,Shanxi Province and Xilingol grassland were selected as the study area,and two remotely sensed quantification methods for effects of human activities on vegetation were proposed.Effect of human activities on net primary productivity of Xilingol grassland and vegetation cover of Shanxi Province was quantitatively evaluated.Effect of human activities on restoration and degradation of vegetation ecosystems in Shanxi Province and Xilingol grassland was discussed.