Chi Chen and Taejin Park publish on photosynthetic activity in Global Change Biology

PhD students Chi Chen and Taejin Park recently published “Changes in the timing of peak photosynthetic activity in northern ecosystems” in Global Change Biology. The authors use the “laws of minimum” as a basis and introduce a new framework where the timing (day of year) of peak photosynthetic activity (DOYPmax) acts as a proxy for plant’s adaptive state to climatic constraints on its growth. They report a widespread warming‐induced advance in DOYPmax (−1.66 ± 0.30 days/decade, p < 0.001) across northern lands, indicating a spatiotemporal dynamism of climatic constraints to plant growth.

They show that the observed changes in DOYPmax are associated with an increase in total gross primary productivity through enhanced carbon assimilation early in the growing season, which leads to an earlier phase shift in land‐atmosphere carbon fluxes and an increase in their amplitude. Such changes are expected to continue in the future based on analysis of earth system model projections. The study provides a simplified, yet realistic framework based on first principles for the complex mechanisms by which various climatic factors constrain plant growth in northern ecosystems.

Chen and Park are members of the Myneni-Knyazikhin group.