Climate and the biogeography of plant function and diversity
File(s)
Author(s)
Li, Jiaze
Type
Thesis
Abstract
Climate shapes terrestrial ecosystems by determining which species and functions can persist under given environmental conditions. Recent climate governs the large-scale distribution of contemporary ecosystems and their function; long-term climate dynamics explain why species and functions with distinct evolutionary histories are found in today’s environments. However, there is currently no framework that integrates these spatial and temporal dimensions to explain how ongoing climate change shapes terrestrial ecosystems.
Plants form the structural and trophic basis of ecosystems on land. They regulate community composition, biogeochemical cycles, and productivity by responding to climate. This thesis investigates how climate influences plant functional traits and diversity across space and time, using an analytical framework that integrates geographic and climate-defined multidimensional spaces. Firstly, I quantify the relationships among key plant functional traits and between these traits and contemporary climate across herbaceous, deciduous and evergreen woody plants. This generates the most comprehensive global trait maps to date based on a statistical upscaling approach. Secondly, by tracing the emergence, persistence, expansion, contraction, and movement of climatic conditions across the Earth’s surface over approximately the past 50 million years, I show that historical persistence and shifts in the geographic extent of climates are crucial for explaining contemporary patterns of global vascular plant diversity. Thirdly, I use C4 plants as a model functional group to reconstruct their biogeographic dynamics over the past 50 million years, based on C4 diversity data and eco-evolutionary optimality models. This analysis demonstrates how Cenozoic climate change drove the origin and spread of C4 photosynthesis.
Taken together, these findings imply that the functional and diversity patterns of modern ecosystems are the result of spatio-temporal variations in climate. This integrated explanatory framework provides an underpinning for better understanding of the resilience and adaptive capacity of the biosphere in an ever-changing world.
Plants form the structural and trophic basis of ecosystems on land. They regulate community composition, biogeochemical cycles, and productivity by responding to climate. This thesis investigates how climate influences plant functional traits and diversity across space and time, using an analytical framework that integrates geographic and climate-defined multidimensional spaces. Firstly, I quantify the relationships among key plant functional traits and between these traits and contemporary climate across herbaceous, deciduous and evergreen woody plants. This generates the most comprehensive global trait maps to date based on a statistical upscaling approach. Secondly, by tracing the emergence, persistence, expansion, contraction, and movement of climatic conditions across the Earth’s surface over approximately the past 50 million years, I show that historical persistence and shifts in the geographic extent of climates are crucial for explaining contemporary patterns of global vascular plant diversity. Thirdly, I use C4 plants as a model functional group to reconstruct their biogeographic dynamics over the past 50 million years, based on C4 diversity data and eco-evolutionary optimality models. This analysis demonstrates how Cenozoic climate change drove the origin and spread of C4 photosynthesis.
Taken together, these findings imply that the functional and diversity patterns of modern ecosystems are the result of spatio-temporal variations in climate. This integrated explanatory framework provides an underpinning for better understanding of the resilience and adaptive capacity of the biosphere in an ever-changing world.
Version
Open Access
Date Issued
2025-09-17
Date Awarded
2026-03-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Prentice, Iain Colin
Publisher Department
Department of Life Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)