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Title: | The Effects of Drought and Shade on the Performance, Morphology and Physiology of Ghanaian Tree Species |
Authors: | Amissah, Lucy Mohren, Godefridus M. J. Kyereh, Boateng Poorter, Lourens |
Issue Date: | 2015 |
Publisher: | PLOS ONE |
Abstract: | In tropical forests light and water availability are the most important factors for seedling
growth and survival but an increasing frequency of drought may affect tree regeneration.
One central question is whether drought and shade have interactive effects on seedling
growth and survival. Here, we present results of a greenhouse experiment, in which seedlings
of 10 Ghanaian tree species were exposed to combinations of strong seasonal
drought (continuous watering versus withholding water for nine weeks) and shade (5% irradiance
versus 20% irradiance). We evaluated the effects of drought and shade on seedling
survival and growth and plasticity of 11 underlying traits related to biomass allocation, morphology
and physiology. Seedling survival under dry conditions was higher in shade than in
high light, thus providing support for the “facilitation hypothesis” that shade enhances plant
performance through improved microclimatic conditions, and rejecting the trade-off hypothesis
that drought should have stronger impact in shade because of reduced root investment.
Shaded plants had low biomass fraction in roots, in line with the trade-off hypothesis, but
they compensated for this with a higher specific root length (i.e., root length per unit root
mass), resulting in a similar root length per plant mass and, hence, similar water uptake capacity
as high-light plants. The majority (60%) of traits studied responded independently to
drought and shade, indicating that within species shade- and drought tolerances are not in
trade-off, but largely uncoupled. When individual species responses were analysed, then
for most of the traits only one to three species showed significant interactive effects between
drought and shade. The uncoupled response of most species to drought and shade should
provide ample opportunity for niche differentiation and species coexistence under a range
of water and light conditions. Overall our greenhouse results suggest that, in the absence of
root competition shaded tropical forest tree seedlings may be able to survive prolonged
drought. |
Description: | This article is published in Plose One DOI:10.1371/journal.pone.0121004 |
URI: | 10.1371/journal.pone.0121004 http://hdl.handle.net/123456789/13507 |
Appears in Collections: | College of Agric and Natural Resources
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