Impacts of Climate Change and Human Activities on NDVI Change in North China

Abstract

The Normalized Differential Vegetation Index （NDVI） is an essential index of vegetation growth status and an indicator of terrestrial ecological conditions.North China is China's political and cultural center， with complex and diverse land cover types， and is a critical agriculture production region in China.Meanwhile， the vegetation ecology in North China has become very fragile under the influence of climate warming and drying and intensified human activities.Based on satellite data NOAA/AVHRR NDVI and meteorological data information， this study explores the spatial and temporal variability characteristics of NDVI in North China and the effects of climate change and human activities on NDVI from 1982 to 2019 using trend analysis， partial correlation analysis， and residual trend analysis.The results showed that （1） The vegetation NDVI in spring， summer， fall， and growing seasons in North China from 1982 to 2019 exhibited a significant upward trend with strong spatial heterogeneity， among which the fastest growth rate of 0.024 （10a）-1 was observed in the summer and growing seasons.The percentage of the area with significant increase was 57.35% and 58.10%， respectively.（2） NDVI in spring， summer， and growing seasons in North China displayed a significant positive correlation with precipitation， while NDVI in fall was mainly influenced by air temperature.NDVI in summer was positively affected by both air temperature， precipitation and relative humidity.（3） The effects of climate change and human activities on vegetation growth in North China have regional differences.In the vegetation increased areas， the relative role of climate change is 45.64%， and the relative role of human activities is 54.36%.In the vegetation decreased areas， the relative role of climate change is 32.66%， and the relative role of human activities is 67.34%.（4） Among different land use types， the vegetation growth of forest and farmland in North China is faster， and the vegetation improvement is mainly affected by human activities， the relative effect of human activities is 66.07% and 60.82%， respectively.The vegetation degradation of grassland is also mainly affected by human activities， the relative effect is 69.48%.Human activities have an essential influence on the vegetation NDVI in North China， which mainly stems from the construction of major human ecological projects such as the Three North Protective Forests and the influence of urban expansion and population surge in recent decades in China， and the research results also provide necessary theoretical support for the construction of ecological barriers as well as ecological， environmental protection in North China.

Keywords

• normalized differential vegetation index （ndvi）
• residual analysis
• trend analysis
• north china