Epiphyte establishment in an increasingly impacted environment

Vascular epiphytes provide important ecosystem services in tropical forests, including habitat and resources for birds and other biota and nutrient cycling in the canopy. However, epiphytes are characterized by slow growth and sensitivity to climatic conditions, so their stability is precarious, especially when subject to anthropogenic disturbances. The purpose of this study is to increase our understanding of factors that are critical for epiphyte establishment with the hope that the information generated can be used to inform policy makers and land-use managers in decisions regarding the restoration of tropical ecosystems. Naturally occurring epiphyte populations in the Yucatan Peninsula were quantified two months prior to and two months following Hurricane Wilma in five different ares of El Eden Ecological Reserve. Six of the seven most common wetland epiphyte species experienced extensive losses (>25% of population), and overall epiphyte loss as a result of the hurricane was greater than 25% in both the mature forest and the tintal wetland areas. Hygrochron™ temperature/ relative humidity iButton sensors were deployed in different forest types and successional stages to allow correlations of epiphyte presence or absence with temperature and humidity fluctuations. Although the average humidity varied less than 8% across all forest types, the minimum relative humidity in the tintal was 21% whereas it did not drop below 41% in an adjacent secondary forest (17 years since disturbance). Given these data, epiphyte seeds collected in the Yucatan Peninsula were germinated in growth chambers under varying humidity levels. Generally, greater germination occurred at higher humidity levels. However, days to germination and maximum germination varied between species and treatments. These data suggest there may be prohibitive limits on the types of forests epiphytes can be restored into.