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Published on: June 24, 2019
Allometric growth and allocation in forests: a perspective from FLUXNET
Adam Wolf1, Christopher B Field, Joseph A Berry
1Department of Global Ecology, Carnegie Institution for Science, Stanford, California 94305, USA. adamwolf@princeton.edu
Summary
Forest biomass allocation is primarily driven by total productivity, not site conditions. Trees prioritize wood growth over leaves due to light competition, impacting carbon cycle models.
Area of Science:
- Ecology
- Forest Science
- Biogeochemistry
Background:
- Land-surface models require accurate schemes for partitioning photosynthetic products into biomass components.
- Understanding biomass allocation is crucial for predicting forest carbon cycling and accumulation.
- FLUXNET data provides valuable insights into ecosystem productivity and tree growth.
Purpose of the Study:
- To develop an allocation scheme for land-surface models based on observed allometric patterns.
- To investigate the relationship between total net primary productivity (NPP) and biomass partitioning in trees.
- To identify key drivers of biomass allocation trade-offs in forest ecosystems.
Main Methods:
- Analyzed a database of component mass and NPP from FLUXNET sites.
- Determined allometric scaling relationships between total NPP per individual (G) and NPP allocated to foliage (Gfol), stem (Gstem), and roots (Gcroot, Gfroot).
- Examined the influence of stand biomass, resource availability, and environmental factors on allocation patterns.
Main Results:
- NPP allocation to foliage, stem, and roots is strongly explained by total individual NPP (r2 = 67-91%).
- Foliage represents a constant fraction (approx. 25%) of total NPP, scaling isometrically.
- Root-shoot trade-offs show declining fine root allocation with increasing stand biomass, compensated by increased stem and coarse root allocation.
Conclusions:
- Forest biomass allocation is primarily governed by total productivity (stand biomass) rather than site-specific resource availability.
- Strong light competition drives trees to allocate more resources to wood growth, limiting allocational plasticity.
- The findings provide a basis for an improved algorithm for biomass partitioning in land-surface models, enhancing carbon cycle predictions.
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