Abstract:Vegetation is the most active component of natural ecosystems and is highly responsive to many factors such as atmospheric conditions, water availability, and soil factors; thus, vegetation is a sensitive indicator of environmental change in terrestrial ecosystems. With growing concerns on global change and global warming, more and more scholars are focusing their research on understanding how plants respond to environmental change.
Based on climate data collected from 1951 to 2000, NOAA/AVHRR NDVI data from 1982 to 2000 and flowering phenophase data for Prunus davidiana collected from 1951 to 2000 in Beijing, relationships between climatic factors and vegetation at different time scales were investigated. The purpose of the study was to assess the impacts of climate change on vegetation and feedbacks between land cover changes and climate to better understand the effects of global change. Time lag cross-correlation analyses were used to examine time lags in climatic factors and NDVI, and P． davidiana flowering phenophase.
Our statistical analyses indicated that at different temporal scales different relationships between climate factors and growing conditions of plants were found. On an annual scale, there were no differences between actual temperature or effective temperature and actual precipitation or effective precipitation and their relationship to vegetation. Relationships between effective temperature, effective precipitation and vegetation were the highest when examined at the scale of a month. The highest correlation between NDVI and temperature occurred when the time lag was zero. At the scale of a year, the influencing threshold was about one year while at the scale of a month it was about one month. Land surface temperature in Beijing had a statistically more meaningful relationship with NDVI and the flowering phenophase than with precipitation. At the scale of a year, the influencing threshold between climate factors and plant phenophase was two years, whereas at the scale of a month, the influencing threshold between actual temperature and plant phenophase was about one month.