Predicting global vulnerability of forests to drought using plant functional trait evolution

Project Information

Plant-FATE

Grant agreement ID: 841283

DOI

10.3030/841283

Project closed

EC signature date 15 April 2019

Start date 1 August 2019

End date 31 July 2021

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 186 167,04

EU contribution

€ 186 167,04

Coordinated by

INTERNATIONALES INSTITUT FUER ANGEWANDTE SYSTEMANALYSE
Austria

Periodic Reporting for period 1 - Plant-FATE (Predicting global vulnerability of forests to drought using plant functional trait evolution)

Reporting period: 2019-08-01 to 2021-07-31

Summary of the context and overall objectives of the project

Forests across the globe are increasingly being threatened by various anthropogenic drivers, especially changes in climate. Climate variability is expected to increase in the future, leading to more frequent and more intense droughts. Yet, despite decades of research, understanding the drought vulnerability of forests has remained limited, primarily because of a lack of realism in vegetation models and, in particular, their lack of capacity to predict plant responses to unprecedented environmental conditions.

Thus, the Plant-FATE (Plant FunctionAl Trait Evolution) project has aimed to incorporate new and emerging paradigms in vegetation modelling centred on the principles of adaptation and evolution, to develop a new trait-based eco-evolutionary vegetation model and use it to predict global plant responses to drought and assess the vulnerability of forests to future changes in climate.

The two most important physiological processes determining the responses of individual plants to droughts are carbon uptake (photosynthesis) and water transport (hydraulics): accordingly, plants have evolved diverse photosynthetic and hydraulic strategies to respond to drought, addressing the fundamental tradeoff between their acquisition of CO2 and water and their survival from carbon starvation and hydraulic failure. With individual plant responses scaling up to the level of plant communities, these strategies influence emergent ecosystem properties in terms of community structure, ecosystem productivity, and biodiversity.

Through Plant-FATE Objectives 1 and 2, I have developed new optimality-based theory for the aforementioned fundamental physiological processes and embedded this theory into a trait-based eco-evolutionary vegetation model (Plant-FATE-EGVM) capable of representing competition for light, individual-level and community-level responses to drought, successional dynamics, and trait evolution. Through Plant-FATE Objective 3, I have calibrated the Plant-FATE-EGVM at both local and global scales, enabling predictions of the responses of current plant communities to future climate change.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The Plant-FATE project has achieved the following seven key innovations:
(1) We have created a new unified theory of plant photosynthesis and hydraulics, called P-hydro, to accurately predict the responses of individual plants to drought stress.
(2) We have developed new optimality-based theory to account for xylem hydraulics and to predict xylem hydraulic traits, both of which are especially important for predicting plant mortality due to hydraulic failure, and have successfully applied this theory to predict global and site-specific distributions of xylem hydraulic capacity.
(3) We have incorporated into the ‘Plant’ model the ‘perfect plasticity approximation’ (PPA), a spatially implicit yet accurate optimality-based theory to describe forest canopy structure, to model successional dynamics and account for the light-seeking behaviour of plants.
(4) We have implemented a generic numerical package for solving physiologically structured population models (PSPMs) with options to choose between four alternative numerical schemes to enable flexible model simulation with dynamic climate forcing.
(5) We have embedded the P-hydro model of photosynthesis and hydraulics into the Plant-FATE-EGVM and analysed the emergent vegetation under different drought regimes to investigate the evolution of plant hydraulic strategies under different regimes of drought and rainfall variability.
(6) We have calibrated the Plant-FATE-EGVM for sites along an elevational gradient in the Himalaya, India, with further calibrations for other regions of the world presently ongoing.
(7) We have developed an extended theory of oligomorphic dynamics to study evolution in size-structured populations, going beyond the originally stated Plant-FATE objectives.

This body of work has resulted in one published manuscript, two manuscripts that have already been submitted to journals and/or are available as preprints, and six forthcoming manuscripts in various stages of preparation. Research results have been presented, in addition, at two international conferences organized by the European Geosciences Union. Through this project, I have developed a collaborative network involving leading researchers in theoretical ecology, plant physiology, and vegetation modelling. Furthermore, scientific insights originating from this project have been disseminated to the general public via social media, and several blog articles are forthcoming. All code developed through the Plant-FATE project has been published on GitHub.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Through the Plant-FATE project, we have been able to make several fundamental contributions to the fields of plant ecology, theoretical ecology, and computational biology:
(1) Our optimality-based models for plant photosynthesis and xylem hydraulics can be plugged into many Earth system models and can therefore help improve predictions of global carbon and water cycles. I am already in touch with vegetation modelling groups across the world to explore opportunities for including our optimality-based models into existing vegetation models.
(2) Our numerical package for solving PSPMs provides several unique features that will make the powerful size-structured population modelling framework accessible to a wide spectrum of ecologists. These features include (i) the capacity to use different numerical methods by simply changing the name of the method while calling the solvers, (ii) the ability to simulate multispecies models, and (iii) high computational performance.
(3) Our ongoing work on the oligomorphic dynamics of size-structured populations is expected to advance a powerful theoretical framework to analyse evolutionary dynamics in size-structured populations.

Our modelling framework for vegetation dynamics, combining optimality principles and evolutionary dynamics, can account for the adaptative responses of plants to environmental change and thus has the potential to revolutionize vegetation modelling and climate-impact studies. It also enables addressing a myriad of questions in forest dynamics, biodiversity studies, and community ecology that were hitherto inaccessible.
Our efficient computational package for vegetation dynamics can pave a path for ecologists to harness the power of size-structured population modelling, stimulating research that has so far been stymied by a lack of flexible computational methods.
In the near future, the Plant-FATE project will make available planetary-scale vulnerability maps that will inform forest managers and policymakers of the differential vulnerability of global forest ecosystems to future climate change and help inform large-scale plantation programs to make climate-resilient management choices.

Plant-FATE-EGVM