Deciduous woody species have more conservative leaves when increased water is available in a dry tropical forest

Abstract

Species in dry environments may adjust their morphological and physiological behaviors by adopting safer or more efficient strategies. Thus, species distributed across a water availability gradient may possess different phenotypes depending on the specific environmental conditions to which they are subjected. Leaf and vascular tissues are plastic and may vary strongly in response to environmental changes, such as water-use strategies, affecting an individual’s fitness and species distribution. To identify whether and how legumes vary across a water availability gradient in a seasonally dry tropical forest, we quantified leaf construction costs and performed an anatomical study on the leaves of seven legume species. We evaluated seven species, which were divided into three categories of rainfall preference: wet species, which are more abundant in wetter areas; indifferent species, which are more abundant and occur indistinctly under both rainfall conditions; and dry species, which are more abundant in dryer areas. We observed two different behavioral patterns based on rainfall preference categories. Contrary to our expectations, wet and indifferent species changed traits in the sense of security when occupying lower rainfall areas, whereas dry species changed some traits when more water was available. Trischidium molle, the most plastic and wet species, exhibited similar behavior to the dry species. Generally, intraspecific variation did not occur in adopting relatively more conservative characteristics, at least at the foliar level, with reduced water availability. Our results corroborate the risks to vegetation under future climate change scenarios as stressed species and populations may not endure even more severe conditions.