Current Research Projects Print

A variety of research projects are currently being conducted at Palo Verde by senior researchers and students, quite a few of them new to the station this year. A brief description of these projects follows:

Countryside Biogeography of Bird Communities In Costa Rica. PIs: James Zook, Gretchen C. Daily, Paul R. Ehrlich, G. Arturo Sánchez-Azofeifa, Stanford University. Financial source: Stanford University. In this study, we investigate the relationship between bird diversity and agricultural intensity in four distinct biogeographic and agricultural regions of Costa Rica (in the vicinity of Palo Verde, La Selva, Las Cruces, and San Isidro del General). Our aim is to determine (i) whether this relationship is similar among biogeographic regions; and (ii) the extent to which patterns of bird diversity can be determined from remotely-sensed information. Within each of the four study circles (15-km radius), a census is taken of bird fauna at 12 sites (3 of low, 3 intermediate, and 3 of high intensity land use, as well as 3 in relatively undisturbed native forests). We are assessing land-use intensity on the basis of measures taken at each site as well as remotely sensed measures from Landsat TM images. We hope that the patterns we find will be useful for assessing and predicting changes in biodiversity in other parts of the tropics.

Diversidad Y Conservación De Humedades Dominados Por Palmas (Arecaceae) En Zonas Protegidas De Costa Rica Y Nicaragua. PIs: Mahmood Sasa, Instituto Clodomiro Picado, Universidad de Costa Rica y Estación Biológica Palo Verde, OET; Juan Salvador Monrós, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Universidad de Valencia; Ricardo Rueda, Herbario Nacional, Universidad Autónoma de Nicaragua en León, Nicaragua. Financial source: Agencia Española de Cooperación Internacional, Vicerrectoría de Investigación, Universidad de Costa Rica. Along the Nicaraguan-Costa Rican border, the palm genera Raphia, Mauritia, and Attalea form huge monospecific forests on soils that are waterlogged most of the year. Due to its impenetrability, and to the low diversity in plant diversity that can survive such extreme environments, research in palm dominated swamps has been extremely scarce, and little is known about animal species and ecological interactions occurring in them. Furthermore, palm swamps in this region are being rapidly drained, destroyed and converted in to agricultural land. This project is aimed to understand the importance of wetlands dominated by palms in the biology and conservation of vertebrate species. We conduct our study in areas of the conservation system of Costa Rica and Nicaragua: Reserva Guatuso, Reserva Indio Maiz, Parque Nacional Tortuguero, and Parque Nacional Palo Verde.

Environmental History of Palo Verde National Park. PI: Eben Kirksey. Center For Cultural Studies, University Of California. Financial Source: NSF Post-Doc. Dr. Kirksey continued his investigations about the environmental history of Palo Verde, building on a field project he began as student on the OTS Tropical Ecology Fundamentals course in 2006. He interviewed key sources associated with the National Park and read key archival documents. His project treats non-human species as actors and agents of history.

Amphibian Productivity in Costa Rica´S Dry Forest: Implications for Wetlands Protection as Reproductive Sites. PIs: Rafe Brown, Collection of Herpetology, Natural History Museum, KU; Ivan Gómez-Mestre, Estación Biológica Doñana, CSIC, España; Mahmood Sasa, Instituto Clodomiro Picado, Universidad de Costa Rica y Estación Biológica Palo Verde, OET. Financial Source: CRUSA, CSIC, Vicerrectoría de Investigación, Universidad de Costa Rica, Kansas University. Wetlands are the major reproductive sites for many species of amphibian and reptile populations, and in the case of dry forest environments, the only breeding sites for the majority of anurans. In tropical dry forest, anurans constitute a unique ecological assemblage, with many species endemic to that ecosystem. Most of those species use seasonal ponds and lagoons to reproduce, so the amphibian biomass produced there eventually repopulate the near forested areas. This implies that the protection of ponds and lagoons is indispensable if the objective is the correct conservation of terrestrial natural environments. Unfortunately, most wetlands located in Tropical dry forests have been destroyed or modified, a situation that has severely affected populations of amphibians (and other organisms), that are also in severe decline for other causes. In an effort to overcome wetland destruction, Costa Rica has made several efforts to protect those habitats, including many of them within protected wild land. No evaluation however, has been conducted in determining the effects of wetlands disturbance on amphibian productivity. This is an indirect way of assess the resilience of amphibian to modifications of their reproductive environment. In this study, we are determining the productivity of anurans and some reptiles in several wetlands along the Río Tempisque basin. As some of those wetlands are located within the protected Palo Verde National Park, we will compare anuran and reptile productivity in protected versus disturbed wetlands. Our study will provide a new way of recording the potential contribution of reptiles and amphibian to the matter and energy transfer between aquatic and terrestrial ecosystems. In this way, we will assess the effect of wetlands disturbance in a tangible effect of the ecosystem: mass productivity.

Monitoring and Surveillance of Highly Pathogenic Avian Influenza in Wetlands in Costa Rica. PIs: Mario Baldí, Tropical Disease Research Program, Escuela de Veterinaria (PIET), Universidad Nacional de Costa Rica, Servicio Nacional de Salud Animal, Ministerio de Agricultura y Ganadería (MAG) Tropical Disease Research Program, Veterinary School (PIET); Randall Arguedas, Zoológico Nacional Simón Bolivar, Ministerio de Recursos Naturales Energía, Minas y Telecomunicaciones (MINAET). Financial Source: Universidad Nacional de Costa Rica. Wetlands in northwestern Costa Rica are important migratory paths to birds from North, Central and South America. This generates the risk that infectious diseases carried by birds could spread into other locations. One such disease, avian influenza, might be potentially dangerous to public heath and animals, and could impact the extensive poultry industry of Costa Rica. In order to understand avian influenza dynamics and to assess the risk of epidemic in the country, it is necessary to understand the incidence in wild bird populations, and to monitor and identify virus strains present. Unfortunately, Costa Rica lacks a national surveillance system, and thus potential pathogens that could be present in wildlife populations can not be assessed. The goal of this study is to determine presence of Avian Influenza virus in migratory and resident population of wild birds (orders Anseniformes and Charadriiformes) in the wetlands in northwestern Costa Rica; and to assess potential effects in economic, conservation, and public health system.

Genetic diversity of the cherimoya in Costa Rica: implications for its conservation. Federico Albertazzi, Centro de Investigaciones en Biología Celular y Molecular, Universidad de Costa Rica, José Ignacio Homaza Urroz, Consejo Superios de Investigaciones Cientificas, España. Financial source: CRUSA, CSIC. This project addresses the genetic diversity in Costa Rica for two species within the Annonaceae family (Annona cherimoya and A. purpurea). Both species are native to America and the goals of the study are to optimize conservation strategies to protect their genetic resources. A. cherimoya (custard apple) is a species already domesticated and cultivated commercially, especially in Spain, although it is still an underutilized species with clear potential in countries of Central and South America. A. purpurea (Soncoya) is not grown commercially yet but may be of interest under some conditions. Because the greatest diversity in A. cherimoya is located in the Andean valleys of southern Ecuador and northern Peru, this region is considered its center of origin (Popenoe, 1921, Van Damme et al., 2000). However, other sources (Pozorski and Pozorski, 1997) debate that the center of origin of this species is still unclear(Bonavia et al., 2004).It is therefore necessary to analyze the distribution of genetic diversity of cherimoya in other countries, primarily Central American, looking for its protection and the sustainable use of genetic resources of the species. On the other hand, the Soncoya requirements is a more tropical species, that is distributed in lowlands of Central and northern South America. Therefore, both species represent an interesting alternative to fruit production in both inland areas (cherimoya) and coastal lowlands (Soncoya) in Costa Rica ($ 10300).

Study of the impact on water resources generated by the installation of municipal open dumps in Tempisque River Basin, Province of Guanacaste. Juan Serrano Sandí (OTS, Estación Biológica Palo Verde). Financial source: Estación Biológica Palo Verde. The Tempisque River is one of the major basins in northwestern Costa Rica, and includes an important component of the rich biodiversity of the country. This research aims to describe the environmental impacts generated by the development of landfills and waste dumps in Tempisque River Basin including the Bebedero river system. A very important element to consider in this research is the application and use of GIS to describe the physiographic features of the current landfill sites and waste dumps. Another aim is to use these tools to generally locate suitable sites for installation of a sanitary landfill, considering physiographic features such as slope, land use, hydrology apparent, and city or nearby villages, roads, soil type, and rock structures, among others.

Systematization and analysis of the contributions of National Parks and Biological reserves to the Economic and social development in Costa Rica, Benin, and Bhutan. Mary Luz Moreno Diaz, Centro Internacional de Politica Económica (CINPE-UNA). Financial Source: Fundecooperación. Program South- South. The national parks and biological reserves are vital in the social, economic and environmental develop of the three countries. Around the national parks there are economic activities and communities that have a close relationship in the economic, social and cultural aspects with them. Benin and Bhutan don´t have quantifiable studies to assess the real social and economic benefits of protected areas to the country since their establishment. Costa Rica has an innovative methodology created for CINPE and INBIO two years ago for made this kind of quantification; nevertheless only in three of the 27 national parks have been apply this methodology. The project will analyze the relationships between national parks and economic activities and communities in Benin, Bhutan and Costa Rica, through a methodological approach created in Costa Rica two years ago. This methodology will be adapted to Benin and Bhutan with the support from the Costa Rican Team.

Symbiotic relationships between legumes and bacteria in Costa Rica. Joan Abrams, Rindge School of Technical Arts – MA. There are 12.000 to 14.000 species in the legume family Fabaceae, that includes alfalfa, clover, and soybeans. The roots of the legumes produced chemicals (flavonoids) that attract Rhizobia (Bacteria), and it is known that different flavonoids produced attract different rhizobia. Thus, the interaction between Rhizobia and Leguminosae is very specific, although little is known about the symbiotic interactions between legumes and bacteria in the tropical forest. The main goal of this research is to further investigate the diversity and phylogenetic relationships of root nodule bacteria associated with various species of legumes located in Guanacaste Province, Costa Rica. Samples will be taken in the Palo Verde Biological Station, operated by the Organization for Tropical Studies. Be collected and analyzed nodules of 4 species in order to answer the following questions: (1) are symbiotic bacteria shared among several species of legumes? (2) What are the phylogenetic relationships of the root nodule bacteria in several species of legumes? The main importance of this study is to provide a better understanding of symbiotic interactions with several root nodules of legumes in Costa Rica.

Impact of pesticides in water resources in the Tempisque Basin. Elba de la Cruz Malavassi (Instituto Regional de Estudios en Sustancias Tóxicas, Universidad Nacional) and Carlos Barata Martí (Consejo Superios de Investigaciones Cientificas, España). This project attempts to develop a comprehensive field monitoring to evaluate the quality of water resources influenced by agricultural crops such as rice, sugar cane, and melon in the Lower Tempisque Basin, Costa Rica. To do that, we employ a similar methodology to one used in the Ebro basin, implemented in three steps: 1– Assessing the exposure of aquatic ecosystems at Palo Verde National Park, to pesticides used in agricultural systems in the area. 2 – A comprehensive assessment of the effects that pollutants have on the habitat of fish and invertebrate communities of the wetland and water quality. To do this, we will account pollution levels in the water column, the sediment and organisms, which include specific toxicity responses, their relationships with ecological processes and their effects on planktonic and benthic communities. There will be field bioassays to assess effects on the consumption of plant biomass and detritus by planktonic species and macro-invertebrates, as a measure of altered river ecosystem function. These bioassays will be contrasted and complemented by toxicity tests in the laboratory and changes in species diversity tolerant and sensitive to pollutants. 3 - The third step is modeling, predicting and managing aquatic ecosystem quality. The information obtained will contribute decisively to improve predictive capability, the diagnosis of environmental problems, and improvement of natural resource protection of ecological significance.

Anfibios y Reptiles comunes de Costa Rica. PIs: Alejandro Solórzano, Serpentario Nacional, Museo de Zoología Universidad de Costa Rica. Mahmood Sasa, Instituto Clodomiro Picado, Universidad de Costa Rica y Estación Biológica Palo Verde, OET. Financial Source: Vicerrectoría de Investigación, Universidad de Costa Rica, Serpentario Nacional. Costa Rica’s herpetofauna currently consists of 420 species (189 amphibians, 231 reptiles), of which 75 species are endemic to the country. Considering the size of its surface area, Costa Rica has more herpetofaunal species than any other country in Mesoamerica. Costa Rica’s extreme species richness results from ecological and historical factors that have allowed different patterns of colonization, dispersal, and in situ speciation. The distribution and natural history of most amphibian and reptile species in Costa Rica is relatively well documented, because of the extensive amount of field research conducted in the country for over a century. This work is aimed to popularize some of the current knowledge on Costa Rican herpetofauna. Photographs and field data of common species are being retrieved from several national parks in the country, including Palo Verde. A final product of these efforts should be a popular book on the common species of the country, aimed to general public.

Functional Trait Differences and Tree Species Co-Existence in Palo Verde. PI: Catherine M. Hulshof, University of Arizona. Financial Source: NSF-IRES. Despite over a century of intensive study, the mechanisms underlying patterns of species coexistence and diversity in plant communities remains a topic of debate. It is often thought that the co-existence of plant species is constrained by the ability of individuals to function in different abiotic and biotic environments. Testing this prediction therefore requires functional differences to be quantified between individuals of different species and individuals of the same species. The present study quantifies the degree of functional trait variation within and across species and individuals for tree species in Palo Verde National Park, Costa Rica across a soil moisture gradient from inundated forests to those situated on limestone outcrops. Additionally, by comparing trait variation within and across populations arrayed along a soil moisture gradient, this study tests the hypothesis that underlying drivers of plant trait variation can be predicted on the basis of biotic and abiotic factors. Results from this study show that several emergent patterns of trait variability were found across the soil moisture gradient, which suggest that the rarity of a species, on a local scale, may be a result of a plasticity constraint within particular leaf traits. In order to further understand the underlying drivers of variation as well as patterns of species coexistence and diversity, it will be necessary to quantify both genetic and phenotypic components of plant trait variation.

Testing Dear Enemies Hypothesis in Termites. Timothy K. O´Connor, University of Illinois at Urbana-Champaign. Financial Source: NSF-IRES. My project concerned aggressive interactions among colonies of the termite Nasutitermes corniger. Their lumpy globular nests and networks of foraging trails are a ubiquitous sight on the trees of Palo Verde, where this species is the principal decomposer of woody material. Because colonies occur in such high density and compete for resources, I was curious about the interactions among neighboring colonies. In particular, I wondered how aggressive interactions were influenced by frequent contact between colonies, genetic relatedness among colonies, and genetic diversity within nests determine intensity of competition and aggression in the field. Because aggressive behaviors limit energetic investment in other colony-building activities and limit nest density, investment in aggressive activity has direct consequences for efficiency of both the colony and the population, which in turn impacts the broader forest ecology. In another light, this research has implications for social evolution in termites and may explain N. corniger’s dominance in a range of Neotropical habitat.

Decomposition Effects of Exotic Plant Competition in Wetland Floodplain Justin Montemarano, Kent State University. Financial Source: NSF-IRES. Eichhornia crassipes (water hyacinth), a floating-mat species native to Brazil, has established worldwide as an invasive species.  Moreover, establishment of E. crassipes in dense beds can lead to alterations in native plant and animal communities. Given differences between macroinvertebrate communities and the physicochemical environment associated with E. crassipes and native floating-mat vegetation (i.e., pennywort Hydrocotyle umbellate [Toft et al., 2003] and garden puff Neptunia prostrata [de Szalay, personal communication]) are substantial, decomposition dynamics (i.e., leaching rates, overall mass loss rates, and productivity of detritivore communities) within mats dominated by E. crassipes relative to native plant species may differ. Decomposition of plant material can be an important source of energy and nutrients in freshwater wetlands and understanding factors controlling detrital dynamics in these systems is crucial, particularly in managed freshwater wetlands. E. crassipes establishment in new areas may be facilitated by the plants’ growth patterns and ability to outcompete native vegetation. A floating-mat species native to Palo Verde that may compete with E. crassipes is the legume Neptunia prostrata (syn. - N. natans and N. oleracea [James et al., 2001]). The first goal of this study is to examine whether competitive interactions between E. crassipes and N. prostrata exist when space is limiting and, if so, which plant species tends to be the competitive dominate. Additionally, to evaluate effects of floating-mat species on decomposition, the decomposition of plant material within floating-mat vegetation beds that differ in proportions of E. crassipes and N. prostrata will be examined. These two goals will be examined simultaneously using a de Wit replacement series (de Wit, 1960) to vary proportions of E. crassipes and N. prostrata within enclosures. Given that the Palo Verde wetland (a RAMSAR site) is managed for waterfowl, E. crassipes can influence wetland invertebrate communities, and these invertebrate communities may be an important food source for waterfowl at PV, understanding E. crassipes competitive relationship with native flora and its effects on decomposition dynamics is important in considering future management strategies at PV.

Spatial Patterns and Habitat Preference in Black Spiny-Tailed Iguana. Vincent Farallo (Texas State University) and Dennis Wasko (University of Miami). Financial Source: NSF-IRES. Having an extensive knowledge of a species ecology can help us better manage habitat to prevent the spread of invasive species. One such species, the black spiny-tailed iguana (Ctenosaura similis) has established colonies in Florida (Krysko et al., 2003). The black iguana is native to Mexico and Central America, where it is an important species as a source of food for many people and as a top predator in natural ecosystems (Fitch et al., 1982). Several aspects of the behavior, natural history, and ecology of Ctenosaura similis has been addressed (Fitch and Henderson, 1978; Fitch and Hackforth-Jones, 1983; Van Devender, 1982), but little information exist on the spatial ecology of the species. We plan to determine habitat characteristics of Ctenosaura similis home ranges for both dominate and lesser males, and determine habitat preference in both groups. This information will benefit management of populations which are heavily harvested. Additionally, increased knowledge of native habitat requirements may help to successfully manage for the reduction of increasing invasive populations in southwest Florida.

Phylogeography of Hamadryas butterflies. Ivonne Garzon, Department of Biological Sciences, University of New Orleans. This project is aimed to understand the phylogenetic relationships of a small group of butterflies included in the Neotropical genus Hamadryas. Morphological and molecular characters will be examined to reconstruct the evolutive relationships within the genus, and to infer their position regarding putative related taxa.

Role of municipal governments in environmental policies in the Tempisque River Basin, Costa Rica. Ashley Ross, Department of Political Sciences, Texas A&M University. Financial Source: NSF-IRES. Due to its long history of conservation and its diverse system of environmentally-protected areas, Costa Rica offers an excellent case to study the role of municipal governments in environmental policy. To assess the role of Costa Rican municipal governments in the environmental policy process, I plan to conduct a survey of local government officials at the municipalities within the Tempisque River Basin. The survey will assess the implementation of policy by examining municipal capacity and coordination with higher government agencies and the motivations to promote environmental policy by evaluating the political and economic pressures municipal governments confront. To measure municipal capacity I will include questions that record the education and experience of officials in addition to municipal fiscal resources. To evaluate municipal coordination with upper tiers of government, questions will investigate local government involvement and interaction with the national and provincial government as well as the Area of Conservation (AC) regional administration overseen by SINAC. The survey will also explore the economic and political pressures on municipal government officials related to environmental policy, including questions about eco-tourism, sustainable agriculture industries, voter preferences, and political party pressures. These economic and political factors provide mixed incentives to municipal governments in the promotion of the environmental preservation and ecologically-sustainable activities. The survey, interviews, and archival data will give me the information needed to construct a measure of the environmental orientation of local governments based on their motivations to promote and their ability to implement environmental policy. This research will enhance our understanding of the role of municipal governments in ecological preservation and will identify institutions and policies that may be changed to ease the implementation of and to provide incentives for environmental policy on the local level.

Great-tailed Grackle Quiscalus mexicanus habitat use in Palo Verde National Park and the surrounding anthropogenically modified landscape. Jeffrey Norris, Department of Biology, University of Missouri at St. Louis. Financial Source: NSF-IRES. The Great-tailed Grackle (Quiscalus mexicanus) has greatly expanded its range throughout Costa Rica, Central America, and well-into North America as humans have greatly altered the natural environment over the past few hundred years. Great-tailed Grackles along with other Icterids are often classified as agricultural pests or as nuisance species for their damage to crops and for fouling anthropogenic environments due to the copious excrement beneath roosting trees or structures. Species like Q. mexicanus, as well as others that dominate anthropogenic habitats are often exotic or species that have moved from their native, natural range to fill the novel habitats created by humans. In many cases the full ecological and social impact of these species are poorly understood and needs to be studied to facilitate management decisions in the future. The objective of this project is to map the distribution, habitat associations, and movement of the Great-tailed Grackle (Q. mexicanus) within Palo Verde National Park, and the surrounding anthropogenically modified habitats to determine the extent Q. mexicanus still uses natural areas or if it is more dependent upon the relatively novel human modified habitats. The results of this initial project will increase our knowledge and understanding of Costa Rica’s most abundant avian synanthrope, and should be an important tool for the future management of this nuisance species.

Effect of invasive dominant species on tropical plant and associated animal communities. Jennifer Bufford, Department of Biology, University of Hawaii. Financial Source: NSF-IRES. The invasion of non-native plants is a serious, rapidly-growing threat to biodiversity, especially in natural areas. Species introduced to an area outside of their natural range by human activity are usually defined as “invasive” when the species begins to spread widely from non-cultivated reproducing populations. Invasive species can alter community composition and fundamental ecosystem functions, such as fire regime, further disrupting native communities and creating positive feedback cycles that promote further invasion. Though invasive species are widely assumed to have negative impacts on native communities, their specific effects are often poorly documented. Understanding the effects of invasive species is crucial to prioritization, management and conservation. The impact of invasion on species diversity and on the survival and reproduction of threatened native flora and fauna is especially important. The proposed research would examine community composition in vegetation stands dominated by invasive Typha domingensis (or Hyparrhenia rufa depending on site availability) and in stands in which the invasive species has been controlled or is not present. Plant community characteristics, including composition and functional diversity would be measured in addition to the type and diversity of plant-animal interactions in each patch.  Where possible, this data will be compared to previous years to assess the impact of the current drought on plant and animal communities.

Assessing the impact of land management on native bees and plant-pollinator interactions: marsh management in Palo Verde, Costa Rica. Zak Gezon, Dartmouth College. Financial Source: NSF-IRES. Land-use change is a leading component of global environmental change and can have a dramatic effect on biodiversity, species interactions, and ecosystem function. While the effects of land-use change on the diversity and abundance of native and introduced plants is well documented, the effects of land-use change and subsequent species invasions on native insects and plant-insect interactions is less well known. For example, land management decisions could lead to a change in plant community structure, which in turn could affect the diversity of native pollinators and native plant-pollinator interactions. Over 75% of flowering plants require insects or other animals for pollination, making pollination an important ecosystem service (Committee on the Status of Pollinators in North America 2007). Understanding the effects of land-use change and management on native pollinators and plant-pollinator interactions has important implications for biodiversity, pollination of native and agricultural plants, and feedbacks to other organisms that rely on flowering plants for forage, habitat, and protection. The goal of this study is to understand how land-use management of invasive aquatic plants affects native pollinator (bee) diversity and subsequent native plant-pollinator interactions. The purpose of the study is to determine the degree to which the dominant plant community in the marsh (non-native Eichhornia vs. Typha) affects the species richness, evenness, and abundance of native bees in the adjacent forest as well as to determine which plants the bees in the forest and marsh are pollinating. This research is important because it will assess how land-use management of the marsh affects native bees and plant-pollinator interactions, important features in the functioning of native ecosystems.

Last Updated ( 02/21/10 )
Organization for Tropical Studies
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