Environmental resource perspective on plant green-up and green-down

Global climate change has led to changes in plant phenology, potentially altering growing season length and the productivity of plants. Simulating phenological changes is fundamental to predicting changes in ecosystem function. However, the existing methods have not adequately represented the joint control of plant development by multiple environmental resources, including temperature, precipitation and photoperiod. In this study, we introduce the concept of an “environmental resource space” (ERS) and present generic algorithms for interpreting and predicting plant green-up and green-down. We found that the ERS-derived indices, including quantity (S) and synergistic efficiency (V) of resources, had a greater importance than other environmental variables in explaining variations in the green-up and green-down periods of natural ecosystems. Ground and satellite observations in the mid- and high latitudes of the Northern Hemisphere supported a significant positive relationship between phenological period length and the S:V ratio. An ERS-based model can predict the green-up and green-down periods of plants with an accuracy of 0.7-0.8 at a hemispheric scale. The ERS framework and algorithms could help predict the combined effects of multiple environmental changes on the phenology and function of natural ecosystems.