Results/Conclusions In deciduous broadleaf forests, there was significant negative correlation between NEE and ecosystem respiration. However, spatial pattern of NEE appears more related to GPP than to ecosystem respiration in evergreen needleleaf forests. The absolute IAV of NEE had a significant positive correlation with both absolute IAV of GPP and ecosystem respiration in deciduous broadleaf forests, and the relative IAV of NEE correlated significantly with relative IAV of GPP and ecosystem respiration.

Correlation analyses showed mean annual ecosystem respiration in deciduous broadleaf forests correlated negatively and significantly with the mean annual air temperature, while gross primary production tends to be constant, inducing to positive correlation of NEE along the temperature gradient. In evergreen needleleaf forests, GPP, ecosystem respiration and NEE increased significantly with air temperature, and GPP and ecosystem respiration also showed significantly negative correlation with annual precipitation. Annual precipitation was major cause for spatial patterns of GPP and ecosystem respiration in grasslands, however, no significant correlation was found about NEE.

In deciduous broadleaf forests, relative IAV of air temperature had significant correlation with relative IAV in GPP, Re and NEE, except for the two sites in Europe. Changes of precipitation were the reason for interannual variability in GPP and ecosystem respiration in grasslands. Absolute IAV of Precipitation explained 40% and 63% variables of absolute IAV in GPP and ecosystem respiration respectively in grasslands, and also relative IAV was a reason for 41% and 56% variables of relative IAV in GPP and ecosystem respiration.