Metabolic and phenological response of vegetation to temperature gradient: Evidence derived from avhrr data

Abstract

We studied the metabolic and phenological response of vegetation to the change in temperature using the latitudinal gradient to represent the temperature gradient. By comparing the seasonal curves of normalized difference vegetation index (NDVI) of northern latitudinal zones, we found that the annual peak value of the zonal NDVI average (MNDVI) increases as the latitude decreases from 75–56°N, with the greatest peak value occurring at 56°N. In the same latitude range, the arriving time (TNDVI) of the peak as measured by the Julian days when the MNDVI is reached decreases with latitude. These results imply that temperature increase in the high latitudes of the northern Hemisphere may increase the MNDVI and decrease TNDVI for the vegetation above 56°N, and therefore lower the trough of the seasonal curve of the atmospheric CO2 and make the trough arrive earlier. Because of the matching of spatial distribution of warming from 1965 to 1995 with the vegetation zone where the vegetation is sensitive to temperature, we conclude that the warming may have caused the metabolic enhancement and phenological shift for the vegetation in the high latitude region and which in turn causes the increase of seasonal amplitude of CO2 and its phase shift. © 1996 Taylor & Francis Group, LLC.