Will leaf phenology keep pace with climate warming?

Introduction

Leaf phenology, the study of the seasonal timing and drivers of budburst, leaf unfolding, maturation, and senescence, is the starting point of land carbon (C) cycle models. It drives C allocation between organs, thus largely controlling C budget estimates. It is often cited as one of the largest uncertainties in future climate predictions.

Research Gaps

Despite centuries of research, the environmental control of leaf phenology is still not fully understood. State-of-the-art approaches empirically relate phenophases to macroclimatic air temperature, which are unable to capture conditions sensed by the tree (microclimate) or species-specific variability. This translates into models that are unable to accurately reproduce forest response to climate change. Understanding why trees grow or shed their leaves is thus key to assessing the resilience of forests.

Project Proposal

This project proposes a new paradigm for exploring the biophysical and ecophysiological controls of leaf phenology across scales, based on a unified theory linking phenology to species strategy and the coordination of physiological processes in a limiting environment.

Key Innovations

Key innovations are:

1. New insight into the microclimatic control of phenology through unprecedented monitoring of the bud/leaf energy budget.
2. The identification of the key links between phenology and species strategy.
3. The quantification of the colimiting factors of leaf phenology across scales, accounting for environmental and physiological processes.
4. The application of a new generation of models incorporating the biophysical and ecophysiological controls of phenology.

Importance of Insights

These insights are urgently needed to reduce uncertainties in C cycle estimates and to assess the response of forests to climate within the context of the IPCC.

Future Applications

These innovations will unlock several domains to which phenology is central, such as forestry and agriculture, and open a realm of untapped research questions and applications that require robust forecasting of forest dynamics (drought, fire).