Traits controlling shade tolerance in tropical montane trees

Tropical canopies are complex, with multiple canopy layers and pronounced gap dynamics contributing to their high species diversity and productivity. An important reason for this complexity is the large variation in shade tolerance among different tree species. At present, we lack a clear understand...

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Bibliographic Details
Published in:Tree physiology 2020-02, Vol.40 (2), p.183-197
Main Authors: Ntawuhiganayo, Elisée Bahati, Uwizeye, Félicien K, Zibera, Etienne, Dusenge, Mirindi E, Ziegler, Camille, Ntirugulirwa, Bonaventure, Nsabimana, Donat, Wallin, Göran, Uddling, Johan
Format: Article
Language:English
Subjects:
acclimation
biomass allocation
Environmental Sciences
Forestry
growth
importance
intolerance
leaf life-span
leaf temperature
Life Sciences
light
Miljövetenskap
ontogenic changes
photosynthetic capacity
plant traits
rain-forest trees
relative
Research Paper
Rwanda
seedlings
shade
shade tolerance
tropical montane forest
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Summary:Tropical canopies are complex, with multiple canopy layers and pronounced gap dynamics contributing to their high species diversity and productivity. An important reason for this complexity is the large variation in shade tolerance among different tree species. At present, we lack a clear understanding of which plant traits control this variation, e.g., regarding the relative contributions of whole-plant versus leaf traits or structural versus physiological traits. We investigated a broad range of traits in six tropical montane rainforest tree species with different degrees of shade tolerance, grown under three different radiation regimes (under the open sky or beneath sparse or dense canopies). The two distinct shade-tolerant species had higher fractional biomass in leaves and branches while shade-intolerant species invested more into stems, and these differences were greater under low radiation. Leaf respiration and photosynthetic light compensation point did not vary with species shade tolerance, regardless of radiation regime. Leaf temperatures in open plots were markedly higher in shade-tolerant species due to their low transpiration rates and large leaf sizes. Our results suggest that interspecific variation in shade tolerance of tropical montane trees is controlled by species differences in whole-plant biomass allocation strategy rather than by difference in physiological leaf traits determining leaf carbon balance at low radiation.
ISSN:1758-4469
0829-318X
1758-4469
DOI:10.1093/treephys/tpz119