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Abstract Both tree size and life history variation drive forest structure and dynamics, but little is known about how life history frequency changes with size. We used a scaling framework to quantify ontogenetic size variation and assessed patterns of abundance, richness, productivity and light interception across life history strategies from >114,000 trees in a primary, neotropical forest. We classified trees along two life history axes: afast–slowaxis characterized by a growth–survival trade‐off, and astature–recruitmentaxis with tall,long‐lived pioneersat one end and short,short‐lived recruitersat the other.Relative abundance, richness, productivity and light interception follow an approximate power law, systematically shifting over an order of magnitude with tree size.Slowsaplings dominate the understorey, butslowtrees decline to parity with rapidly growingfastandlong‐lived pioneerspecies in the canopy.Like the community as a whole,slowspecies are the closest to obeying the energy equivalence rule (EER)—with equal productivity per size class—but other life histories strongly increase productivity with tree size. Productivity is fuelled by resources, and the scaling of light interception corresponds to the scaling of productivity across life history strategies, withslowandallspecies near solar energy equivalence. This points towards a resource‐use corollary to the EER: the resource equivalence rule.Fitness trade‐offs associated with tree size and life history may promote coexistence in tropical forests by limiting niche overlap and reducing fitness differences.Synthesis. Tree life history strategies describe the different ways trees grow, survive and recruit in the understorey. We show that the proportion of trees with a pioneer life history strategy increases steadily with tree size, as pioneers become relatively more abundant, productive, diverse and capture more resources towards the canopy. Fitness trade‐offs associated with size and life history strategy offer a mechanism for coexistence in tropical forests.
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Plant carbohydrate storage: intra‐ and inter‐specific trade‐offs reveal a major life history trait
Summary Trade‐offs among carbon sinks constrain how trees physiologically, ecologically, and evolutionarily respond to their environments. These trade‐offs typically fall along a productive growth to conservative, bet‐hedging continuum. How nonstructural carbohydrates (NSCs) stored in living tree cells (known as carbon stores) fit in this trade‐off framework is not well understood.We examined relationships between growth and storage using both within species genetic variation from a common garden, and across species phenotypic variation from a global database.We demonstrate that storage is actively accumulated, as part of a conservative, bet‐hedging life history strategy. Storage accumulates at the expense of growth both within and across species. Within the speciesPopulus trichocarpa, genetic trade‐offs show that for each additional unit of wood area growth (in cm2 yr−1) that genotypes invest in, they lose 1.2 to 1.7 units (mg g−1NSC) of storage. Across species, for each additional unit of area growth (in cm2 yr−1), trees, on average, reduce their storage by 9.5% in stems and 10.4% in roots.Our findings impact our understanding of basic plant biology, fit storage into a widely used growth‐survival trade‐off spectrum describing life history strategy, and challenges the assumptions of passive storage made in ecosystem models today.
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- Award ID(s):
- 2010781
- PAR ID:
- 10369693
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 235
- Issue:
- 6
- ISSN:
- 0028-646X
- Format(s):
- Medium: X Size: p. 2211-2222
- Size(s):
- p. 2211-2222
- Sponsoring Org:
- National Science Foundation
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