::UPR-RP Facultad de Ciencias Naturales-Departamento de Biología::

Research Areas
Landslides and the Organization of Tropical Mountainscapes "The hills are shadows and they flow from form to form, and nothing stands; they melt like mist, the solid lands, like clouds they shape themselves and go." In Memoriam (A. Tennyson 1850) Lord Tennyson beautifully captured the constant state of change exhibited by mountains in his 1850 poem In Memoriam, yet it took almost a century before scientists began the formal study of a broad class of systems with similarly complex dynamics. These systems are driven by a continuous supply of energy that is dissipated abruptly in the form of avalanches once a threshold is reached. In mountains the continuous accumulation of biomass and soil coupled with geomorphic thresholds leads to landsliding, a process that resets ecosystems to a state of quasi-primary succession that has been postulated to underlie the enormous diversity and productivity of montane tropical ecosystems. Although landsliding is likely to play a pivotal role in mountainscapes, our knowledge about ecosystem responses to the formation of landslides and in turn, about the influence of ecosystem on this process is very limited. This is unfortunate given the enormous contribution that ecologists can make to understand a large-scale process with evolutionary, ecological, environmental, and societal implications. We are interested in the landscape-level causes and consequences of landslides in tropical mountainscapes. In particular we have been quantifying the contribution of landsliding to local and regional carbon budgets. In July 2006 we organized the I International Symposium on Landslide Ecology as part of ATBC annual meeting in China.		This research is a collaboration with Anne Carey at Ohio State University and is currently funded through two NSF awards National Science Foundation, DEB: Collaborative Research-Landsliding, land-use change, and carbon dynamics in a Central American mountainscape.2009-2012.Summary National Science Foundation, GEO-EAR, SGER: Development of a landscape approach for understanding the contribution of landsliding to carbon budgets: Using the Rio Jones of the Sierra de Las Minas, Guatemala as a test watershed. 2009-2010. Summary.
Landscapes, Water, and the Sustainable Management of Tropical Watersheds Water is not only one of our basic needs, but also a resource that is critical for the sustainable development of our society. This research is aimed at developing a framework that incorporates ideas of sustainability and resilience for watershed management. Specifically we want to understand how interactions between spatially explicit natural and social networks may contribute to the resilience, and ultimately the sustainability of tropical watersheds. We are using the Rio Grande de Arecibo watershed of Puert Rico watershed as a model system for the island, and more broadly speaking for other tropical regions. This watershed became a key player for the provision of potable water in the island when a complex system of pipes was built to transfer water across the island to serve the Metropolitan area of San Juan. The RFP that originated this work called for the establishment of interdisciplinary research groups at UPR-RP.		xx ccc This research is in collaboration with Rafel Arce-Nazario, Maritza Barreto, Jorge Ortiz, Maria Eglee Perez, Ileana Quintero, Rafael Rios, Luis Santiago, and Gary Toranzos and is funded through an institutional award Resilience thinking for the sustainable management of the Rio Grande de Arecibo watershed: The use of a spatially explicit framework for understanding responses to perturbations. 2008-2010
Multimodal Distribution in Body Size "there may be more than one solution for one given ecological problem, we need not expect all individuals within a population to overcome such problems in he same way." (Maynard Smith 1982) Landscape heterogeneity strongly influences the number and distribution of organisms and therefore, the structure of populations and species assemblages. One process transforming landscape heterogeneity is deforestation, and many studies have documented the extinction of numerous species and the reorganization of entire assemblages in response to it. Yet, it is still unclear how resilient these assemblages are and what may be the driving mechanisms underlying the observed changes. To explore these two questions we focus on body size, a universal currency not only reflecting a fascinating dimension of diversity but also one related to a variety of physiological, morphological, behavioral, life-history, and ecological attributes of organisms. Unlike most studies, however, we have been interested in the multimodal distribution of body sizes and how these modes may reflect functional groups, in our case organisms sharing a similar body size. Moreover, we have been exploring the connection between developmental processes operating at the level of individuals with ecological process operating at the level of communities to understand the emergence of multimodal distributions in body size. In particular, we have explored the degree to which habitat loss may have altered developmental stability, and whether certain body sizes are more likely to exhibit higher levels of fluctuating asymmetry or morphological variation that may make them less likely to persist in altered environments. These questions are been addressed at a variety of scales and using different approaches including field and laboratory work, the compilation of large databases, photographing or x-raying preserved specimens, and using GIS. We have focused on birds, amphibians, and butterflies to accommodate students' interests. In March 2003 we organized the symposium "Multimodality in Body Size:An Ecological Puzzle and a Statistical Challenge".

Department of Biology
PO Box 70377
University of Puerto Rico-Rio Piedras
San Juan, Puerto Rico 00936-8377