Gas exchange and phenotypic plasticity in three tree species in preserved and anthropized areas in a Tropical Dry Forest

Caatinga, the Brazilian tropical dry forest and source of endemic species, suffers anthropic disturbances that are responsible for affecting plants and their functional traits. Therefore, we aimed to evaluate the plasticity woody species’ leaf traits due to abiotic conditions of preserved and anthropized areas in Caatinga. The study took place in Vale do Riacho São José, in the municipality of Caetés, Pernambuco, Brazil. The selected species were Mimosa tenuiflora, Mimosa arenosa and Senna sp., all belonging to the Fabaceae family. We measured gas exchange, water content, specific leaf area and phenotypic plasticity index of all selected species in both areas. For all species, stomatal conductance was higher in preserved areas, but photosynthesis followed this pattern only for Senna sp. which also showed lower water use efficiency among all species. Furthermore, Senna sp. presented the highest relative water content in preserved areas, and showed no differences in specific leaf area between preserved and anthropized areas. The plasticity index showed that Senna sp. were the most plastic species, mainly adjusting water content and gas exchange parameters according to the area. The less plastic species was Mimosa arenosa. A principal component analysis showed a group formation due to anthropization, for all species. However, Senna sp. showed the largest distance among species. We conclude that all analyzed species respond to environmental conditions of preserved and anthropized areas, but this pattern cannot be related to the characteristics of the botanical family due to species-specific leaf traits’ variations.