Evidence for a weakening relationship between interannual temperature variability and northern vegetation activity

Abstract

Satellite-derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. This relationship, however, may change over time following alternations in other environmental factors. Here we show that above 30°N, the strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient R NDVI-GT ) declined substantially between 1982 and 2011. This decrease in R NDVI-GT is mainly observed in temperate and arctic ecosystems, and is also partly reproduced by process-based ecosystem model results. In the temperate ecosystem, the decrease in R NDVI-GT coincides with an increase in drought. In the arctic ecosystem, it may be related to a nonlinear response of photosynthesis to temperature, increase of hot extreme days and shrub expansion over grass-dominated tundra. Our results caution the use of results from interannual time scales to constrain the decadal response of plants to ongoing warming.

Notable shifting in the responses of vegetation activity to climate change in China

“…The correlation of NDVI and climate variables can be influenced by general changes in background climate over a period of 15 years (Piao et al, 2014). For example, the correlations of NDVI with temperature and precipitation were calculated in the first 15-y window (1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996).…”

“…Then, we interpreted the time series of the residuals of NDVI, temperature, and precipitation, respectively (Piao et al, 2014). As vegetation variables are influenced by several factors (e.g., temperature, precipitation, cloud cover, solar radiation, anthropogenic activity, etc.…”

“…More precisely, both Pearson correlation and partial correlation analyses were performed to analyze the correlations of NDVI with mean growing season temperature and total growing season precipitation with a 15-y moving window (Piao et al, 2014). The correlation of NDVI and climate variables can be influenced by general changes in background climate over a period of 15 years (Piao et al, 2014).…”

“…Recent research has indicated a weakening relationship between inter-annual temperature variability and northern vegetation activity over the past three decades (Piao et al, 2014). However, how and to what extent the response of vegetation growth to climate variables has changed in China is still unclear.…”

“…The study of the response of vegetation growth to climate change on regional, continental, and global scales is receiving increasing attention (Myneni et al, 1997;Zhou et al, 2001;Lucht et al, 2002;Piao, 2003;Piao et al, 2006aPiao et al, , 2014Anderson et al, 2010;Peng et al, 2011;Wu et al, 2012). Recent research has indicated a weakening relationship between inter-annual temperature variability and northern vegetation activity over the past three decades (Piao et al, 2014).…”