Tropical Forestry


The challenges that tropical forestry faces in the 21st century are very well known. In the early 1990s, the total area of deforested and degraded tropical land surpassed the area of mature tropical forests due to unsustainable forestry, illegal logging, overgrazing and agriculture. Similar trends persist in the current century. Tropical forestry is confronted with the task of finding strategies to alleviate pressure on remaining forests and techniques to enhance forest regeneration and restore abandoned lands, using productive alternatives that can be attractive to local communities. In addition, sustainable forestry in tropical countries must be supported by adequate policies to promote and maintain specific activities at local and regional scales.

La Selva Biological Station, Costa Rica, where some of Professor Montagnini's
research plots are located. (photo by Tania Ellersick)

Program Mission

The mission of the Program in Tropical Forestry is to promote collaborative research in sustainable forestry, the conservation of biological diversity and forest environmental services, and the restoration of degraded tropical ecosystems to alleviate pressure on remaining forests and provide economic and environmental benefits for local communities. The Program in Tropical Forestry seeks to expand and share the work of Yale faculty, students and staff by conducting research, offering relevant courses, seminars and workshops, and promoting cooperation among faculty and students from Yale FES and collaborating institutions worldwide.

The Program in Tropical Forestry works with local communities and institutions from developing countries to promote sustainable land use practices that facilitate the conservation of biological diversity and natural resources. At the local level, the Program aims to increase the technical skills of individuals in order to benefit communities and conserve natural resources.

Core Activities

Conservation of Native Tree Species
Research is ongoing on the rescue, propagation, conservation and use of highly endangered species and populations of forest trees in Central America in collaboration with colleagues from CATIE (Tropical Agriculture Research and Higher Education Center, Costa Rica).

Plantation Silviculture
We are studying the silviculture and environmental services of mixed and pure plantations of native species for sustainable development in rural areas of the humid tropics (Costa Rica, Nicaragua, Honduras).

Strategies are being developed for the recovery of biodiversity in degraded ecosystems through natural regeneration in mixed and pure plantations of native species in humid tropical lowlands (Costa Rica).

Education Exchange
Faculty at the Yale School of Forestry and Environmental Studies teach courses in tropical forestry, agroforestry, tropical ecology and silviculture. Forum and roundtable discussions in this arena are part of the program’s information outreach.

It is becoming widely accepted that the conservation of biodiversity has to take place in managed landscapes as well as in protected areas. In many regions of the tropical world, the landscape consists of a complex mosaic of forest patches, pastures and agricultural fields and is heavily influenced by human activity. Any efforts to conserve biodiversity within this managed landscape must be compatible with local livelihood needs and offer sustainable and economically attractive alternatives to local farmers. Strategies that provide various ecosystem services and fulfill local human needs, in addition to promoting the conservation of biodiversity, will have a higher chance of success.

In many tropical countries, large portions of natural forests have been cleared for agriculture and grazing, yet the productivity of cleared lands is often short-lived. Forest regeneration on abandoned pasturelands is desirable to restore soil fertility, reduce erosion, reduce fire hazard, and restore biological productivity. However, on abandoned lands in advanced stages of degradation, native forests often cannot regenerate naturally. Selective planting and management of woody species can jump-start successional processes to restore native forests.

The existence of tree species in the tropics is under threat mainly because of irrational use and the absence of effective policies that could guarantee their sustainable management. Several tree species may have medicinal, ornamental or timber values yet to be discovered. The rescue and protection of forest species can be achieved by developing strategies for propagation and conservation and the promotion of plantations and agroforestry systems involving these species.

Tropical Field Botany students at La Selva Biological Station, Costa Rica
(photo by Tania Ellersick)

Research Agenda

Research by faculty of the Global Institute of Sustainable Forestry and collaborators in tropical countries includes sustainable management of natural forests and their biodiversity, and the identification and quantification of ecological services provided by forests (biodiversity conservation, carbon fixing and storage). The design of systems of diversified forest management also involves studies on the ecology and management of non-timber species used for medicinal, insecticidal, ornamental, craft and construction purposes. There are also projects on reforestation of degraded lands with native species, including mixed-species designs. These systems can encourage natural regeneration in their understories, contributing to the recovery of biodiversity of the surrounding landscape. Some of the subjects covered in this program are:

  • Sustainable forest management, criteria and indicators, forest certification
  • Reforestation with native and exotic species
  • Plantation silviculture
  • Ecosystem restoration
  • Recovery and conservation of biodiversity
  • Carbon sequestration by tropical forests and plantations
  • Conservation and management of non-timber forest products

The overall research objective of the PTF is to design restoration strategies for degraded forest landscapes in tropical regions, focusing on tree plantations and agroforestry systems, with special emphasis on Latin America.  We are currently conducting research in Costa Rica, Panama, Argentina, Brazil, and Mexico, thus covering a whole range of tropical ecosystems including lowland tropical rainforests, dry forests and savannas, and montane tropical and subtropical forests. 

We are collaborating with local academic/research institutions in each country, such as CATIE (Tropical Agriculture Research and Higher Education Center), and the Organization for Tropical Studies (OTS) in Costa Rica; the Center for Tropical Forest Science (CTFS) of the Smithsonian Tropical Research Institution (STRI), and the Panama Canal Authority (ACP) in Panama; the School of Forest Science in Misiones, Argentina; local Universities, CEPLAC (Center for Cacao Promotion and Research), and the Center for Environmental Studies of the Michelin Company in Bahia, Brazil; and the National University of Hidalgo in Mexico.

In Costa Rica, I am continuing long term research on the role of native tree species in plantations and agroforestry ecosystems in reclaiming degraded areas with species of economic value. Our most recent studies involve tree measurements at a mature age of the plantations, 15-16 years of age. We have estimated biomass, carbon sequestration, harvestable volume; and calculated economic returns of these systems (article recently published in New Forests). We have also found that species richness and abundance was greatest in mixed plantation plots, followed by the pure species plantations, and it was the lowest in the control plots (no trees planted) (article in press in Journal of Sustainable Forestry).  These results show that these systems can be profitable alternatives for restoration of degraded pasturelands, providing useful economic returns as well as environmental services: carbon sequestration and biodiversity.

Also in Costa Rica, I am collaborating with CATIE in research on organic coffee with diversified shade trees: relationship between biodiversity and productivity (book chapter in press: Rossi et al. 2010). 

In Panama, I am part of the steering committee of PRORENA, the Native Species Reforestation Project, advising the project on the scientific aspects of reforestation with native species, and reclamation of lands of the Panama Canal watershed which are invaded by aggressive grasses. Two of my Yale MS students (Gillian Paul, Adriane Cromer) did their masters project as part of the new Agua Salud Project; Gillian is already submitting an article on herbivory on young saplings of 5 tree species that were planted as part of the research. Our current project in Panama, The Native Timber Species Plantation Experiment (NTSP), which is part of the “Agua Salud” (Water/Health) project that studies the ecosystem services provided by forests within the Panama Canal Watershed, is now well underway. One of my masters students will be conducting research in the site as part of his masters, in summer 2010.

In Misiones, NE Argentina, in collaboration with the School of Forest Science of the University of Misiones (UNAM), we maintain several experimental settings since the early 1990s, consisting of pure and mixed plantations with native timber species on degraded land; and native trees in agroforestry combinations with commercial crops.  The Misiones forests are part of the Interior Atlantic Forests, an expanse of the highly threatened Atlantic forest of Brazil, where we are also engaged in ecosystem restoration projects as explained below.

We are using the results of our long-term experiences in establishing new projects that investigate the use of native tree species to ameliorate environmental conditions in terms of soil and water quality, in various locations and in collaboration with several partners. For example, in 2008-2009 we established native tree plantations in local municipalities, as part of community forestry projects for obtaining tree products and improving local environmental conditions.

In 2008-2009 we started collaboration with local farms to integrate native tree species in organic farming including yerba mate, Ilex paraguariensis, a product that is sold as certified organic tea in the USA (EcoTeas), and other countries.  We are studying soils and productivity in the organic farms, comparing with conventional monocultures of the yerba mate crop. In 2009, we assessed long-terms impacts on soils in our experimental agroforestry settings including yerba mate and native trees, in comparison with adjacent areas of degraded land and mature forest as controls. A book chapter reporting these results is in press (Day et al. 2010). In addition we are collaborating with local tobacco companies to encourage farmers to plant native trees in the tobacco farms, to improve water yield and quality.

In March 16, 2010, with colleagues from the School of Forest Science of the National University of Misiones, Argentina, we had an important meeting with colleagues from INTA (National Institute for Agricultural Technology) in Eldorado, Misiones, Argentina.The INTA is launching a new “Program on domestication of native tree species for plantations and ecosystem restoration”. To initiate collaboration among the institutions, and to define priorities in terms of species for their domestication program, they held a “Workshop on exchange of information and interest on planting native tree species in Misiones, Argentina”. This meeting marks the start of a new era in collaboration among the institutions, and ensures the formal incorporation of long term research results in a program that will promote their dissemination in Misiones. Since INTA is of national scope the program will also be carried on throughout the country as well, at each of the regional INTA experiment stations.

With personnel from the Argentine Ministry of the Environment, we are using one of our research areas, which is part of a network of Model Forests worldwide, as a model for a system of Payment for Environmental Services, focusing on water yield and water quality: grant proposal submitted May, 2010.

Together in collaboration with six colleagues from the Facultad de Ciencias Forestales, Universidad Nacional de Misiones, Argentina, we just got a multi million dollar grant from PNUD ARG (United Nations Development Program, Argentina). The proposal was entitled: Manejo Sustentable De Recursos Naturales – Componentes Bosque Nativo Y Su Biodiversidad. (Sustainable Management of Natural Resources; Component: Natural Forests and their Biodiversity). Within this large project, F. Montagnini, along with colleagues from the National Univ. of Misiones and Yela FES students, is working on developing guidelines and models for the implementation of a Program for Payment of Environmental Services (PES) for Argentina. They report directly to the Ministry of the Environment of Argentina, thus their research will have direct applications on environmental policy at the national level.

In Bahia, Brazil, in collaboration with local Universities, CEPLAC (Center for Cacao Promotion and Research), and the Center for Environmental Studies of the Michelin Tire Company, we are examining alternatives for restoration of the highly endangered Atlantic Forest, using different strategies according to the degree of degradation found in the landscape. We are following up the regeneration of secondary forests as it may happen naturally, when degradation conditions are not extremely harsh; encouraging or accelerating regeneration of secondary forests using enrichment planting techniques, when degradation level is intermediate; and, in the more drastic cases when restoration thresholds are too large, we are reforesting the lands with mixed plantations of native species. The Michelin Tire Company is funding our research on their 10,000 hectares land in Itubera, Bahia, where we are contributing to restore old rubber plantations by enriching the groves with native species; and restoring part of the native secondary forests and abandoned pastures wit mixed plantations of native species. Our experiments were started in 2008, planting valuable native tree species under old rubber groves to test the hypothesis that valuable native tree species grow better using the rubber as nurse trees for the seedlings, in enrichment plantings with different intensities of illumination. In 2009-2010 we are measuring the experiments that are already in place.

Also the Atlantic Forest region of Brazil, in 2008-2009 we have started experiments with the Aracruz Company, to replace eucalyptus plantations with native species. We are using eucalypts to serve as nurses for encouraging growth of valuable native tree species, planting native tree seedlings in contrasting environments: under the canopy of eucalypts, in association with eucalypts, and in the open. In 2009-2010 we are measuring the experiments that are already in place.  

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