The Effects of Drought and the Recovery Phase of Two Tropical Epiphytic Ferns

The climate change scenario results in a reduction in rain precipitation in a large part of the tropical regions. This could be particularly severe for epiphytic species that rely entirely on rain or air humidity. Therefore, the knowledge of whether epiphytic plants can recover after a prolonged period of drought is pivotal in understanding their ecology, allowing us to better act for their conservation. In this study, drought stress was induced for 10 weeks in Asplenium nidus and Davallia denticulata, two tropical epiphytic ferns, by the exclusion of their water supply. Subsequently, they were rehydrated for 3 weeks. The aim was to test the effects of drought and the recovery rate of the fern species, and its relationship with stomatal conductance and chlorophyll content. In the prolonged drought stress period, D. denticulata showed a decline in both stomatal conductance and chlorophyll content values whilst A. nidus only showed a decline in stomatal conductance. In the rehydration interval, both species showed a steady recovery. The results indicated that the two species were negatively impacted by the 10 weeks of drought stress. However, A. nidus and D. denticulata recovered quickly in terms of stomatal conductance whereas for chlorophyll content, D. denticulata recovered at a slower rate compared to A. nidus. Therefore this study highlighted that A. nidus is better adapted to low precipitation and performed better in relation to future changes in precipitation. D. denticulata ranked second due to having more difficulty recovering from drought.