My research includes topics related to the conservation, ecology, and evolutionary relationships of species inhabiting the high canopy of tropical rainforests; with a focus on amphibians and reptiles. I am particularly interested in the animal communities utilizing tank bromeliads as microhabitat and the role of bromeliads as a keystone resource in the canopy.
My conservation interests concentrate on the effects of deforestation, fragmentation and climate change to canopy inhabiting herpetofauna and canopy microclimate in Amazonia using tank bromeliads as focal species. I also work on the effects of anthropogenic distrubance to herpetofauna of Texas.
Research interests pertaining to ecology include the abiotic and biotic factors driving species diversity and abundance, niche partitioning, and food web structure and dynamics. Naturally, canopy ecology is a particular interest to me with many questions remaining in this emerging field of science.
I am also interested in systematics of amphibians and the evolutionary relationships within food web structures of bromeliads.
Currently, I am studying the effects of natural (streams/rivers) and anthropogenic semi-linear forest clearings (roads/pipline ROW’s) on the internal and adjacent microclimate of canopy tank bromeliads. I am applying molecular techniques to examine for ecological diversification (vertical niche partitioning) in the direct-developing anuran genus Pristimantis. I am working on different ecological aspects of the endangered Houston toad (Bufo (Anaxayrus) houstonensis); including anthropogenic and catastrophic wildfire impacts to disjunct populations as well as range-wide automated call surveys to evaluate detection probability and population size. Finally, I am investigating habitat-suitability for the Texas tortoise (Gopherus berlandieri) throughout its historic range in Texas.
Environmental quality effects and the ecological context of a rainforest canopy bromeliad fauna
The forest canopy is one of the least explored terrestrial ecosystems, particularly those of Neotropical rainforests. The effects of rapid deforestation in Amazonian rainforests have been sparsely reported for large mammals, birds, plants, and few other organisms. General knowledge of Amazonian canopy biota is limited and effects of forest disturbance on this stratum are primarily based on remote sensing studies and tree community dynamics. Large phytotelm tank bromeliads found in the lowland rainforests of Amazonian Ecuador are canopy obligate epiphytes with a high water holding capacity. Tank bromeliads forms a structurally discrete habitat and maintains an aquatic environment in the canopy supporting a taxonomically rich fauna. These features allow their use as a model organism for inquiries of environmental quality effects and ecological processes in the rainforest canopy.
Observations on the herpetofauna and arthropod communities living within high canopy tank bromeliads and associated microclimate factors are used to address three major objectives. The first is to evaluate the effects of anthropogenic forest disturbance, in the form of roads with low or high levels of deforestation driven by agricultural colonization, on these complete species assemblages occupying tank bromeliads. Bromeliads collected at an undisturbed site and a road site with low-colonization-associated deforestation in the Ecuadorian Amazon showed trends of lower amphibian diversity and significantly reduced abundance at the road site, and the introduction of a ‘pest’ anuran species near petroleum installations. The inclusion of a heavily impacted road site will allow for a complete picture of colonization driven deforestation effects on this ecologically distinct community. The second objective is to test for differences in microclimate conditions (e.g. relative humidity) of bromeliads among forest disturbance levels. Microclimate observations of bromeliads will directly complement the species diversity and abundance observations; these environmental data will assist in explaining any observed differences due to increased wind and temperatures in the canopy, and potential decreases in rain due to deforestation and climate change. The third objective is to quantify the microclimate of bromeliads allowing them to support a diverse and abundant fauna. The unique physical structure of tank bromeliads may provide a more stable internal microclimate, enabling a greater diversity of organisms to reside in the upper canopy now and under predicted models of climate change. Initial data indicate that the internal microclimate of Aechmea zebrina bromeliads is moderated for extremes of temperature and humidity compared to the external canopy environment. Knowledge on these potentially moderated climatic parameters within A. zebrina is a first step to understanding their influence on the surrounding canopy microclimate.
These objectives will generate a comprehensive dataset on the diversity, ecology, and environmental habitat quality of canopy tank bromeliad-dwelling Amazonian herpetofauna and arthropods. The dataset provides an opportunity to explain the influence of anthropogenic disturbances, including climate change, on abiotic and biotic factors driving the ecological processes that support a diverse and abundant faunal community in the epiphytic canopy tank bromeliad community. Quantitative knowledge of climatic conditions within large tank bromeliads, as compared to adjacent and surrounding parameters, contributes to a better understanding of their internal microclimatic features providing a climate moderated sanctuary for its inhabitants at the harsh interface with the atmosphere in a lowland Neotropical rainforest.
Expanding on my previous work, I am pursuing the causative effects on the decline of canopy bromeliads and their inhabitants at quantified levels of deforestation and forest disturbance type. First, an unmanned aerial vehicle fitted with RGB and multispectral sensors will be used to acquire ultra-high resolution aerial imagery for large-scale canopy bromeliad detection and mapping. With the ability to better quantify forest change and detect bromeliads in trees we can assess forest management regimes on a larger scale with finer resolution. Second, experiments will be designed to assess canopy and bromeliad microclimate factors across identified forest disturbance levels and types. While disruption of canopy microclimate is hypothesized to be the primary component negatively impacting bromeliad communities, other factors related to anthropogenic input into the system are to be tested. For example, the abundance of gas and oil extraction facilities in the western Amazon necessitate the need for testing tank bromeliad water for a range of petroleum pollutants, including Benzene, Toluene, Ethylbenzene, Xylenes (BTEX), and sulfates. Third, effects on functional diversity will be characterized using stable isotopes to identify changes in trophic levels due to environmental disturbance and predict thresholds at which hypothesized biodiversity loss due to habitat disturbance are triggered. Finally, the application of molecular techniques will be used to answer questions about the effects of forest disturbance and climate change to population size and structure, genetic diversity, and dispersal in both bromeliads and their inhabitants. The molecular work will include metagenomic profiling of the aquatic microbial community to assess overall diversity and contrast communities between forest disturbance regimes and across the vertical strata.