Research

BOB CAT

Assessing demography and genetic variation in Bobcat (Lynx rufus) using non-invasive DNA analysis and comparing with population size estimates obtained by camera-trapping in Jasper Ridge Biological Preserve

Research by on June 30, 2016
Felids, as mammalian carnivores in general, are inherently difficult to survey because of large home ranges, small sized populations, nocturnal activity, and wariness resulting from persecution by humans. Due to their elusive nature, wild cats are remarkably difficult to monitor and study, and thus, demographic data are often insufficient to guide appropriate conservation action or… Read more Assessing demography and genetic variation in Bobcat (Lynx rufus) using non-invasive DNA analysis and comparing with population size estimates obtained by camera-trapping in Jasper Ridge Biological Preserve
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Effects of “primatization” on the population dynamics of a palm tree that is vulnerable to extinction

Research by on June 29, 2016
Changes caused by habitat fragmentation are expected to lead to a decrease in the recruitment of plant seedlings, changing their population dynamics and thus jeopardizing the persistence of populations. The high density of a predator can therefore be predicted to cause a drastic decrease in the density of the plant on which it feeds. The… Read more
Jomar Barbosa using a GPS unit to draw borders around a mistletoe-infected tree at Jasper Ridge.

Incidence and dynamics of mistletoe infestation on the oaks of Jasper Ridge

Research by on June 10, 2016
The project examines spatial variation in the degree of mistletoe infestation at Stanford’s Jasper Ridge Biological Preserve. We are establishing a baseline for monitoring the progress of mistletoe infestation and its impacts on individual oak trees. Collaborator: Jomar Barbosa (CAO laboratory at the Institute of Pacific Islands Forestry, Hilo, Hawaii. USA) Funding: Jasper Ridge Biological… Read more Incidence and dynamics of mistletoe infestation on the oaks of Jasper Ridge
Rodolfo demonstrates the difference in the intensity of herbivore damage between caged oak saplings (left), which are protected from large herbivores such as deer, and uncaged saplings (right).

Ecology of oak regeneration at Jasper Ridge

Research by on June 10, 2016
In this project, we are monitoring 75 pairs of individually caged saplings for three predominant oak species at Jasper Ridge: coast live oak, valley oak, and blue oak. The saplings are monitored for growth and survival, as well as invertebrate herbivory. We are documenting dramatic contrasts in mortality, and found that growth was lower in… Read more

Osa-Golfito Initiative in Southern Costa Rica (INOGO)

Research by on June 10, 2016
The central question being addressed with this project is: How can we make human well-being and the well-being of the natural environment compatible? One of the main projects in this program (LAPA) is the experimental enrichment of oil palm plantations, via addition of bananas, cacao, and timber trees, to address risks of fungal pathogens, secure… Read more Osa-Golfito Initiative in Southern Costa Rica (INOGO)
Rodolfo Dirzo with an elephant, one of the species of large herbivore experimentally removed from the study plots in Kenya.

Linkages between wildlife defaunation, savannah ecosystem structure and composition, and consequences for small mammal abundance in the context of risks for human health

Research by on June 10, 2016
This study combines experimental manipulations of wildlife together with “real life” pairwise comparisons (intact vs. defaunated landscapes) in the context of landscape heterogeneity and land use change. As an example of the cascading consequences of defaunation, we found that when large herbivores are experimentally removed, the abundance of rodents increases dramatically, along with the abundance… Read more Linkages between wildlife defaunation, savannah ecosystem structure and composition, and consequences for small mammal abundance in the context of risks for human health
Rodolfo and field assistant measure plant characteristics in a control plot.

Consequences of defaunation on the structure and diversity of the understory in neotropical forests

Research by on June 10, 2016
This study compares two tropical rainforest sites in Mexico with contrasting levels of defaunation: Los Tuxtlas (defaunated) and Montes Azules (intact). In addition, we have established exclosure experiments in both sites to look at mammalian herbivory, seed predation and structure and composition of the understory vegetation. Collaborator: Dr. Eduardo Mendoza (Universidad de Michoacán, Mexico) Funding:… Read more Consequences of defaunation on the structure and diversity of the understory in neotropical forests
Palmyra Atoll in the Central Pacific.

Ecological consequences of rat eradication on the Palmyra Atoll (Central Pacific)

Research by on June 10, 2016
For this project, we are able to draw on extensive and detailed baseline data on the structure, composition, and diversity of the native vegetation and the islets dominated by the invasive coconut palm, as well as information about the food chain length and dynamics and soil, foliage, and runoff nutrients on the Palmyra Atoll in… Read more Ecological consequences of rat eradication on the Palmyra Atoll (Central Pacific)
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A new paradigm for the conservation of turtles

Research by on March 11, 2016
Turtles are more highly threatened with extinction than many other vertebrate groups, and numerous species will likely become extinct in the next decades.  Failure to conserve the world’s remaining turtle populations is partially due to the ineffectiveness of current conservation strategies.  A new paradigm is needed for the conservation of turtles, one which maintains the… Read more A new paradigm for the conservation of turtles

The effects of deforestation on a tropical mutualistic interaction network

Research by on March 11, 2016
I have been investigating the effects of gradual habitat change on mutualistic interaction networks using plant-hummingbird interaction data from along a deforestation gradient in a Costa Rican coffee plantation landscape. I am studying changes in the structure of the entire network as well as changes in the feeding behavior of individual hummingbird species. I hope… Read more The effects of deforestation on a tropical mutualistic interaction network