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Coupled whole-tree optimality and xylem hydraulics explain dynamic biomass partitioning
Aaron Potkay1, Anna T Trugman2, Yujie Wang3,4
1Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, 08854, USA.
The New Phytologist
|February 1, 2021
Summary
This study introduces the Tree Hydraulics and Optimal Resource Partitioning (THORP) model, explaining how trees allocate biomass to optimize fitness. The model successfully predicts tree allometry and root growth based on hydraulic factors and resource availability.
Area of Science:
- Plant physiology
- Ecology
- Biophysics
Background:
- Trees allocate biomass based on resource availability and physiological needs, likely to optimize fitness.
- Allometry, the study of size-related biological traits, can potentially be modeled from first principles if optimization criteria are defined.
Purpose of the Study:
- To present the Tree Hydraulics and Optimal Resource Partitioning (THORP) model for predicting tree allometry.
- To estimate organ allocation fractions based on the ratio of marginal gain to marginal cost.
Main Methods:
- Developed the THORP model to optimize allometry by estimating biomass allocation.
- Used net canopy photosynthesis rate as gain and senescence rates as cost.
- Employed a numerically efficient analytical solution for optimal partitioning.
Main Results:
- THORP model predictions align with observed tree biomass partitioning across various conditions (size, water stress, elevated CO2, pruning).
- Root biomass and profile shape were predicted simultaneously and accurately.
- Roots extended to groundwater, which buffered water stress and stabilized allometry and root profiles up to 30m depth.
Conclusions:
- Hydraulic considerations are key drivers of plant allometry.
- While nutrient limitations are relevant, hydrological factors significantly influence below-ground biomass distribution and overall tree architecture.
- The THORP model provides a unified approach to understanding tree biomass partitioning and allometry.
Keywords:
CO2 enrichmentcarbon allocationgroundwaterhydraulic limitationsoptimalitystomatal controltree allometrytree drought responsesMore Related Videos
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