No abstract

Tropical dry forests are environmentally complex ecosystems with highly heterogeneous water availability, such that distinctive plant communities are found in contrasting habitats in close proximity to each other. This leads to the question of how resource heterogeneity has led to functional heterogeneity among communities. One hypothesis is that the main trade-offs and the size of the functional space should diverge between communities that differ in their most limiting resource. To test this, we compared aboveground and belowground traits of saplings of 33 dominant species from the dry forest plant communities of two locations that differ in water and also in light availability. In the drier community, the major functional dimension described a tradeoff between drought tolerance and drought avoidance strategies. This dimension was also evident in the wetter community; however, traits related to the efficiency of resource capture were decoupled from the drought tolerance-drought avoidance tradeoff. Trees from the wetter community tended to develop more efficient fine roots for resource capture. The functional space of the drier and more heterogenous forest was larger than the wetter forest, and plant strategies to deal with drought accounted for a much larger portion of trait variation. Overall, functional differentiation may occur between systems that are close in proximity but differ in the availability of resources such as water and light. These environmental differences cause plant communities to differ in functional properties both aboveground and belowground, likely promoting heterogeneous responses to anthropogenic and natural disturbances at the landscape scale.