Trends in Plant Science
OpinionA Wood Biology Agenda to Support Global Vegetation Modelling
Section snippets
From One Big Leaf to Many Trees
Forests play a crucial role in the global carbon cycle and climate system [1]. Forest responses to climate change have direct implications for regional climate, carbon uptake, biodiversity, and society. Sound predictions of forest responses to climate change are therefore crucial. Since the 1990s, dynamic global vegetation models (DGVMs) (see Glossary) have been used to forecast forest responses to climate change and forest-climate feedbacks [2]. First-generation DGVMs treated forest canopies
Hungry Models
Next-generation DGVMs aim to accurately simulate carbon, nutrient, and water cycling in forests by scaling from tissue, through tree organ, individual tree, population, stand, and landscape to the grid cell (Box 1, Figure 1). At tissue, organ, and individual tree levels, the availability and fluxes of water, light and thermal energy, nutrients, and carbon co-determine rates of biomass growth and loss. These processes are driven by, and feedback upon, a number of environmental variables, and
How Wood Biology Can Contribute
Wood biology is well positioned to fill major data and knowledge gaps for next-generation models (Box 2, Figure 2). Wood biological studies deliver insights into individual tree performance [18] (the simulation unit of these models) and do so at the high temporal resolution at which trees respond to climatic variation (and extremes) and models simulate processes 19, 20. Wood biological studies are supremely flexible to yield insights for nearly any choice of forest type, location, tree species,
A Wood Biology Research Agenda
Our proposed research agenda is structured according to six interconnected knowledge gaps. To fill these gaps, we propose specific wood biological studies (Figure 2) and explicit collaboration with other disciplines, in particular for gaps 5 and 6.
1. Understand wood formation within the year.
Dendrochronologists have a reasonably good understanding about the climatic drivers of annual stem growth. Climate-growth analyses of tree-ring data have revealed the important roles of rainfall,
Implementing the Agenda: Strategy and Challenges
How can the proposed agenda be implemented? We propose a multipronged strategy that is also cognizant of several challenges.
1. Standardization of wood biological measurements and analyses.
Many of the wood biological methods shown in Figure 2 have a short application history, resulting in unstandardized procedures and measurements. For instance, different types of dendrometers exist (band or point dendrometers), that measure variations in tree diameter or circumference at different temporal
Concluding Remarks
The development of ‘big-leaf’ vegetation models benefited from ground-breaking theoretical and empirical research on leaf physiology and the increased availability of Earth observation data. In a similar fashion, the development of next-generation models could greatly benefit from improved theoretical and empirical understanding of tree water transport and limitation, tissue growth, dynamic biomass allocation, and the roles of source versus sink limitation in tree growth. We have argued that
Acknowledgements
We thank Frank Sterck, Rafael Oliveira, Kathy Steppe, and an anonymous reviewer for commenting on the manuscript and providing valuable comments and suggestions.
Glossary
- Benchmarking
- a procedure comparing model output with independent empirical observations of processes, structure, or development (of vegetation).
- Big-leaf models
- a class of DGVMs that simulates carbon, energy, and water fluxes of vegetation canopies based on a characteristic leaf in the top of canopy.
- Climate-growth analysis
- the study that relates temporal variation in tree growth (from a chronology) to that in climatic variables.
- Dendrochemistry
- the field that studies chemical composition and chemical
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