Comparative drought-resistance of seedlings of 28 species of co-occurring tropical woody plants

Abstract

Quantifying plant drought resistance is important for understanding plant species' association to microhabitats with different soil moisture availability and their distribution along rainfall gradients, as well as for understanding the role of underlying morphological and physiological mechanisms. The effect of dry season drought on survival and leaf-area change of first year seedlings of 28 species of co-occurring woody tropical plants was experimentally quantified in the understory of a tropical moist forest. The seedlings were subjected to a drought or an irrigation treatment in the forest for 22 weeks during the dry season. Drought decreased survival and growth (assessed as leaf-area change) in almost all of the species. Both survival and leaf-area change in the dry treatment ranged fairly evenly from 0% to about 100% of that in the irrigated treatment. In 43% of the species the difference between treatments in survival was not significant even after 22 weeks. In contrast, only three species showed no significant effect of drought on leaf-area change. The effects of drought on species' survival and growth were not correlated with each other, reflecting different strategies in response to drought. Seedling size at the onset of the dry season had no significant effect on species' drought response. Our study is the first to comparatively assess seedling drought resistance in the habitat for a large number of tropical species, and underlines the importance of drought for plant population dynamics in tropical forests.

SWAPDT: A method for Short-time Withering Assessment of Probability for Drought Tolerance in Camellia sinensis validated by targeted metabolomics

“…The above metabolite results confirm that the five-hour withering of tea leaves has similar metabolite modulation patterns as seen in other plant species over longer times 5-12 days growing in soil (Engelbrecht and Kursar, 2003). This may be due to the absence of roots in the tea shoots that cause the metabolites to change in a short time.…”

“…The trend observed ( Figure 5) is the same as what has been documented in other plants that have been exposed to drought stress over longer times (Engelbrecht and Kursar, 2003). The cross validation results show that the model developed on the t = 5 data works equally well on the t = 0 and t = 5 data, namely 85% and 83% correct classification respectively.…”

Quantifying the effects of seed arrival and environmental conditions on tropical seedling community structure

“…Looking at the entire seedling layer, seedling species composition was more tightly correlated with sown species composition than with environmental variables (Mantel's r^^: 0.23-0.28, Mantel's r^i^n^: 0.04-0.08). Discussion other hand, decades of research in tropical forests have supported the view that recruitment patterns are primarily generated by environmental conditions, including-among other factors-the availability of light, water, and nutrients, competition and seed predation (Nicotra et al 1999;Lewis and Tanner 2000;Montgomery and Chazdon 2002;Engelbrecht and Kursar 2003;Paine and Beck 2007). With effects on density, diversity and species composition, seed arrival also affects the community structure of the seedling layer.…”

“…Much effort has been dedicated to elucidating the myriad environmental conditions in tropical forests that affect the structure of the seedling layer. They include, among others, soil moisture (Engelbrecht and Kursar 2003), light availability (Nicotra et al 1999, Montgomery and, competition (Lewis and Tanner 2000) and seed predation (Paine and Beck 2007). By contrast, the role of seed arrival in generating seedling community structure has received less attention, directed primarily towards its effects on seedling density and diversity (Harms et al 2000;Norden et al 2007).…”

Habitat partitioning among neotropical pioneers: a consequence of differential susceptibility to browsing herbivores?

“…In contrast, deterministic models of community organisation have emphasised the importance of limiting similarity in determining the trait composition of tree communities, with species diVerentiated according to their resource requirements (e.g. Engelbrecht and Kursar 2003;John et al 2007), or through interactions with mutualists, herbivores and predators (Fine et al 2004). When communities contain closely related species, then potential niche overlap might be expected to be especially high, and divergent responses to habitat conditions may be necessary to prevent competitive exclusion.…”