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MODULE RESPONSES IN A TROPICAL FOREST TREE ANALYZED WITH A MATRIX MODEL
Author(s) -
Sterck F. J.,
Bongers F.,
During H. J.,
MartÍnez-Ramos M.,
De Kroon H.
Publication year - 2003
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1890/02-0335
Subject(s) - biology , apical dominance , dormancy , tree (set theory) , canopy , ecology , growth rate , branching (polymer chemistry) , botany , mathematics , shoot , combinatorics , geometry , chemistry , germination , organic chemistry
Module dynamics were studied for the shade‐tolerant canopy tree species Vouacapoua americana in a French Guiana rain forest. A module life cycle graph was constructed, including all the possible transitions between four module states: apically growing (G), apically dormant (D), apically arrested (A), and branching (J). Transitions (module level) were translated to the module population growth rate λ (tree level) and related to the variance in λ among 18 different trees. This variance was also related to light availability (1–60% of ambient PAR) and tree height (5–30 m). Three module life cycle pathways (or loops) were dominant in their contributions to λ: persistent apical dormancy (D→D), biannual apical growth (G→D→G), and biannual branching by dormant modules (J→D→J). This suggests that biannual or even slower module production rates predominate in the module life cycle. The positive covariance between biannual loops seems the result of synchronization in apical and axillary activity. Slow production rates and synchronization allow trees to accumulate carbon, flush massively, and escape from herbivore attacks, and at the same time allow the tree to replace its leaves. The variance in λ ( V (λ)) among trees was low. Apical trade‐offs, which occur as one apical fate excludes other apical fates by definition, lead to negative covariances between apical growth and apical dormancy, and thus reduced the net contributions of the apical transitions to the variance in λ among trees. Branching (D→J) was independent of such trade‐offs, was highly variable, increased with light availability, and almost fully accounted for V (λ). Module fates and V (λ) were unaffected by tree height. The module mechanisms underlie the rather invariable module population growth rate λ in the shade, as well as the increasing λ during higher light episodes, enabling shade‐tolerant canopy trees to grow up and survive in a heterogeneous forest light environment.