A model for a population of trees structured by phenological traits

TL;DR

This paper develops a mathematical model to study how tree populations adapt to climate change through phenological traits like summer dormancy, revealing complex effects of environmental stresses on population dynamics.

Contribution

The paper introduces a detailed mathematical model linking phenological traits and population dynamics, simplifying it to coupled ODEs for analysis under climate change scenarios.

Findings

Water stress and temperature stress have contrasting impacts on populations.

Plasticity can have both beneficial and detrimental effects depending on conditions.

Model simulations show varied population responses to environmental shifts.

Abstract

In the context of global warming, tree populations rely on two primary mechanisms of adaptation: phenotypic plasticity, which enables individuals to adjust their behavior in response to environmental stress, and genetic evolution, driven by natural selection and genetic diversity within the population. Understanding the interplay between these mechanisms is crucial for assessing the impacts of climate change on forest ecosystems and for informing sustainable management strategies. In this manuscript, we focus on a specific phenological adaptation: the ability of trees to enter summer dormancy once a critical temperature threshold is exceeded. Individuals are characterized by this threshold temperature and by their seed production capacity. We first establish a detailed mathematical model describing the population dynamics under these traits, and progressively reduce it to a system of two coupled ordinary differential equations. This simpler macroscopic model is then analyzed numerically, to investigate how the population reacts to a shift in its environment: an temperature increase, a drop in precipitation levels, or a combination of the two. Our results highlight contrasting effects of water stress and temperature stress on population dynamics, as well as the ambivalent effect of the plasticity.