The main goal of my studies is to understand how tropical biodiversity is being impacted by anthropogenic perturbations such as habitat degradation (i.e., deforestation and fragmentation) and hunting. I am particularly interested in the ecological impacts anthropogenic perturbation has on plant-mammal interactions and how this, by affecting ecological processes such as: seed predation, seed dispersal and herbivory, ultimately alters plant community diversity. I am developing research in complementary areas with the aim of developing expertise and a comprehensive approach to addressing this issue.
In collaboration with Dr. Rodolfo Dirzo (Stanford University) we set up in January 2008 a group of 25 triplets of experimental plots (3x6 m) in the vicinity of the Field Station Chajul. This field station is located in the southern limit of the Montes Azules Biosphere Reserve (RBMA) in the state of Chiapas, Mexico. The RBMA (331, 200 ha) constitutes one of the largest remnants of tropical rain forests in México. Each triplet consists of a free access plot, a partially excluded plot (fenced with chicken wire but open at the base) and an excluded plot (fenced with chicken wire and galvanized sheet metal). Treatments are aimed to mimic different degrees of terrestrial mammal defaunation. Within each plot a central area of 1x4 m was marked and all the plants between 30 cm and 1.5 m in height were identified to species or genus, mapped and measured (height). Annual censuses will allow us to quantify plant mortality, growth and recruitment patterns under the different treatments.
With the collaboration of a group of students, postdocs, staff and volunteers, leaded by Dr. Rodolfo Dirzo, we carried out a two-year and a half survey (2006-2008) of the mammalian community present at the Jasper Ridge Biological Preserve operated by Stanford University. Our sampling design consisted in a regular array of 12 stations aimed to cover the entire preserve (481 ha). Each station had two film cameras 10 m apart connected to an active infrared animal detection system. Over the course of this survey we collected almost 16 000 pictures of animals including: deer, bobcat, raccoon, rabbits, coyotes, foxes, squirrels, skunks and opossums. We are currently analyzing this dataset looking at the patterns of spatial and temporal variation in the occurrence of the different species in relationship to climatic and vegetation variables. In addition, for bobcats we are testing different approaches to estimate species abundance.
Currently, with the support of Dr. Thomas B. Smith and researchers and postdocs from the CTR at UCLA, I am developing an approach to generate more accurate information about the current conservation status of the last mega-herbivore occurring in Neotropical forests: the tapir. The aim of this project is to use DNA analyses of fecal samples and spatial modeling to generate demographic and genetic information that helps to assess the conservation status of this species in Southeast México.
Mendoza, E., Fuller, T., Thomassen, H. A., Buermann, W. and Smith, T. B. Submitted. Effectiveness of the Mesoamerican Biological Corridor to protect biodiversity: the case of tapirs in southern Mexico.
Mendoza, E., Martineau, P., Brenner, E. and Dirzo, R. In review. A novel method to improve animal individual identification based on camera-trapping data. Journal of Wildlife Management.
Mendoza, E. and Dirzo, R. 2009. Seed tolerance to predation: evidence from the toxic seeds of the buckeye tree (Aesculus californica; Sapindaceae). American Journal of Botany 96: 1255-1261.
Mendoza, E. and Dirzo, R. 2007. Does interspecific seed-size variation determine differential predation by mammals? An experimental test in a Neotropical rain forest. Oikos 116: 1841-1852.
Dirzo, R., Mendoza, E. and Ortíz, P. 2007. Effects of differential mammalian defaunation on seed predation patterns in a Mexican tropical rain forest. Biotropica 39: 355-362.
Mendoza, E., J. Fay and Dirzo, R. 2005. A quantitative analysis of forest fragmentation in Los Tuxtlas, southeast Mexico: patterns and implications for conservation. Revista Chilena de Historia Natural 78: 451-467.
Mendoza, E. and Dirzo, R. 1999. Deforestation in Lacandonia (southeast Mexico): evidence for the declaration of the northernmost tropical hot-spot. Biodiversity and Conservation 8:1621-1641.