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Osteocephalus buckleyi, Tiputini Biodiversity Station, Rio Tiputini, Ecuador.


Vanzolinius discodactylus, Tiputini Biodiversity Station, Rio Tiputini, Ecuador.





Monitoring and modeling amphibian populations in lowland Ecuador:
A high priority case in light of planned natural resource extraction

The research site is the Tiputini Biodiversity Station (TBS), located at 00° 37’ 05” S 76° 10’ 19 “ W, on the north shore of the Tiputini River in the lowland rainforest of eastern Ecuador. The station consists of approximately 650 hectares in the buffer zone of Yasuni National Park, part of a 1.7 million hectare region designated as a Biosphere Reserve and World Natural Heritage Site by the United Nations. We have conducted amphibian quadrat (3 x 10m) surveys in five plots (3 x 1000m) during 2002, 2003 and 2004, for a total of 175 plots surveyed. In 2004 we also began bromeliad patch sampling surveys (5 bromeliads in each of 2 trees per plot, 40 bromeliads total) to document canopy species; these surveys resulted in the discovery of two new species of Eleutherodactylids which are the first of the newly discovered taxa for which we have submit complete descriptions. The alpha diversity of amphibians recorded at the site exceeds all other reported locations and exemplifies the region’s exceptional biodiversity.

In the past 15 years Yasuni has begun to experience significant petroleum development followed by subsequent colonization and illegal logging practices. The park lands are not protected from this exploitation. Under Ecuadorian law natural resources are property of the government and much of the park is leased as oil blocks to foreign multi-national petroleum companies. Most of the exploration phase for oil has been completed and rapid development of oil fields and infrastructure is occurring throughout the region.

The project focus is on population monitoring and GIS-based predictor modeling of amphibian species density and distribution correlated with environmental parameters. Over 40 different variables are recorded as pertain to the sites (temperature, humidity, soil pH, water pH, vegetation density, etc.) and specimens (snout-to-vent length, weight, vertical position, activity, etc.). For each sample location a differentially-corrected GPS control point is taken and geo-referenced. Photographs are taken of all specimens, quadrats, trees and bromeliads sampled. Blood and tissue samples are also collected for genetic analysis. Very few long-term monitoring initiatives have been established for amphibians within Amazonia, TBS has been established as one such site. Work at TBS is crucial to documenting the potential effects of development on amphibian populations in an area of such great diversity. Timing is critical, as current oil development in the area has been halted (due to pressure from environmental groups working in the area) pending a governmental inquiry.

Existing data is complemented by further data collection, having a cumulative affect on knowledge of amphibians in the region. Continued quadrat surveys in the existing five plots and bromeliad patch sampling will be conducted at the same spatial scale as existing data. These data will be utilized for the continued monitoring of density and distribution of amphibian species. These new data will be added to the current GIS model and include the incorporation of other environmental parameters as predictors. The value of such models is their ability to aid in analyzing areas that may be extremely remote and therefore focusing costs and time for surveys. Importantly, a baseline for amphibian populations prior to disturbance by oil extraction has been established. If oil extraction does occur around TBS, this could be useful in studying effects, if any, from this type of disturbance.


The primary objective of the project is to conduct research on the amphibians of the Amazon basin in order to establish data for conservation efforts. The Amazon basin is of particular interest because of its incredibly high biodiversity and the rapid rate of deforestation and consequent fragmentation occurring. The goal is to establish long-term monitoring sites and to create a comprehensive biological and Geographic Information System (GIS) of the amphibian species located in the Amazon basin. Toward this goal I began with a conceptual, and now digital, model of parameters likely influencing occupancy and diversity, collected field data, and applied that information to examine model validation. Those data are used collaboratively for the analysis of density, diversity and distribution of amphibians, and for the development of predictor models in GIS to aid amphibian research and monitoring efforts. Declines in amphibian populations and habitat ranges worldwide have been documented and rates of extinction have increased substantially within the last few decades. We seek to provide tools and raw data allowing our own efforts and those of other researchers to integrate GIS modeling within their efforts of amphibian population monitoring.

The project being conducted during the 2006 field season will gather additional data via quadrat surveys, bromeliad patch sampling surveys and environmental variable data collection to contribute to the GIS model. These data will increase the sample size and provide additional environmental parameters to be incorporated into the model to meet model development and validation requirements for both density and diversity estimates. The current model uses a topographical wetness index as a predictor for amphibian density and diversity. Regression analysis has shown soil pH to correlate well with amphibian density and diversity values, therefore, soil pH measurements will be collected in a systematic manner to create a GIS layer using interpolation methods for the research area.

During the 2004 field season, arboreal bromeliad patch sampling was conducted to make preliminary observations on the poorly studied amphibian communities occupying the epiphyte canopy strata. These surveys proved very successful in providing an insight into the amphibians utilizing the canopy habitat, including two currently undescribed species of Eleutherodactylids. Additional bromeliad patch sampling surveys during this project will contribute to more comprehensive surveys in order to fully document the amphibian fauna of this habitat. Integrating GPS positions of trees where communities are located into a GIS, we plan to create distribution maps for the canopy dwelling species and look at forest type occupation patterns.

Finally, Ecuadorian students will be sought as field assistants to provide education and field experience opportunities and promote awareness of amphibian declines globally. The goal is to instruct new students on techniques of study design, data collection and statistical analyses of these data for measuring and monitoring amphibian populations. With the empowerment of this knowledge and technical support it can be shared and applied by others at the local level to encourage further amphibian monitoring projects for the observation of greater ecosystem health status.








last updated: March 2006'



Eleutherodactylus sp., Tiputini Biodiversity Station, Rio Tiputini, Ecuador.


Phyllomedusa vaillantii, Tiputini Biodiversity Station, Rio Tiputini, Ecuador.

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