Scott A. Mori, Ph.D., Nathaniel Lord Britton Curator of Botany, has been studying New World rain forests for The New York Botanical Garden for over 35 years. He has witnessed an unrelenting reduction in their extent and, as a result, is concerned about their survival.

Deforestation followed by fires for creating agricultural fields and pasture releases carbon dioxide into the atmosphere at such an accelerated rate in the tropics that it is a major contributor to global warming. Photo by Scott Mori

There are many different types of vegetation in the New World tropics. But rather than being a homogeneous whole, what grows where and when in these tropics is determined to a large extent by water availability and temperature variation. Climate change could potentially have a drastic impact on this region, especially on the rain forests. Liebig’s Law of the Minimum states that plant or animal growth is controlled by the scarcest resource in the environment; this is known as a limiting factor. For example, if a soil possesses all nutrients needed for plant growth except potassium, then the paucity of that nutrient will limit the potential growth of all plants except those that can grow in potassium-poor soils. Potassium is therefore a limiting factor for that soil.

More on the application of Liebig’s Law to the destruction of Amazonian rainforests below.

Garden Researchers Try to Understand, Address Challenge

Karl Lauby, Vice President for Communications, interviewed Christine Padoch, Ph.D., Matthew Calbraith Perry Curator of Economic Botany, who works with her team in Amazonia to combat agricultural fires that now regularly devastate both forests and farms in the region.

What’s going on with fires in Amazonia?
Fire has been used in tropical agriculture for millennia. In the past, fires rarely escaped the fields where they were used to clear brush, control pests, and fertilize soils. Large fires escaping from burning fields and pastures have recently become common events, ravaging forests, farms, and settlements in much of Amazonia. Such destructive fires have become a major problem along the upper Ucayali River in the lowland Peruvian Amazon.

Why are today’s fires in the Amazon Basin different and so destructive?
Extensive clearing of humid forests for cultivation and pasture, especially along the eastern slope of the Andes, has increased the vulnerability of the region to escaped fires. A major drought in 2005 set in motion conflagrations that burned more than 300,000 hectares (about 741,000 acres) of forests in the neighboring Brazilian state of Acre, producing economic losses of more than $50 million in Acre alone. Although the 2005 drought was indeed an exceptional one, droughts of similar magnitude have occurred in the western Amazon in 1926, 1983, and 1998, with far lesser impacts on forests and people. An observer of the 2005 fires in Acre concluded they were “a disaster never previously experienced by modern societies in this part of Amazonia.”

What does your research involve?
The premise of the project is that fire results from an integration of social, ecological, and climatic changes that are occurring in the region. Controlling fire damage and anticipating future fire depend on understanding these changes and how they are linked. The project, funded by the Tinker Foundation, is exploring the increasing fire danger inherent in landscapes in transition, e.g., ones that combine small- and large-scale uses, traditional communities with plantations operated by urban-based companies. The work will produce insights that will have implications not only for much of Amazonia but also for developing regions around the tropics.

How is your research and the Botanical Garden’s work bringing about change?
Project results are helping policymakers, communities, and farmers avert even more fire catastrophes as global climate change affects the region. The project has developed activities specifically designed to inform policymakers, local scientists and technicians, students, and members of the area’s communities of the increased danger as well as of ways to use fire safely. Our methods include informal meetings, illustrated lectures, and training courses. We are working closely with the regional government in all our outreach programs.

Please help support the important botanical research, education, and programs that are integral to the mission of The New York Botanical Garden.

Jim Miller is Dean and Vice President for Science.

Herison de Oliveira (left) and Fabián Michelangeli look for plants as they descend the Jordao River by canoe.
All photos by Fabián A. Michelangeli, Ph.D.

The Amazon basin, which spans nine South American countries, is the largest connected block of tropical rain forest in the world. Despite the efforts of explorers over several centuries, large parts of Amazonia remain completely unexplored, and some of these places where scientists have never been are thousands of square miles in extent.

In early February, Fabián Michelangeli, Ph.D., of The New York Botanical Garden and his Brazilian collaborator, Renato Goldenberg, Ph.D., from the Universidad Federal do Paraná, coordinated a 16-day trip into one of these unexplored regions, and their results tell us how very much remains to be discovered in one of the world’s most important ecosystems.

Edilson de Oliveira collects a liana in the Bignoniaceae family growing on a tree on the river bank.

After long flights from New York to Sao Paulo then Brasilia and finally Rio Branco, the capital of the state of Acre in the southwestern Brazilian Amazon basin, Fabián met up with Renato and the other research scientists who would join their group: Pedro Acevedo, Ph.D., from the Smithsonian Institution and C. Flavio Obermuller, Edilson de Oliveira, and undergraduate student Herison de Oliveira, all from the Universidade Federal do Acre. A two-hour flight in a small plane brought them to Foz de Jordao, the capital of a 2,100-square-mile municipality from which no plant collections had ever been made.

With the gracious provision of logistical support from the Mayor of Foz de Jordao, numerous short trips were made traveling upstream on the Taruaca and Jordao rivers, penetrating unexplored areas and hiking deep into the forests for four days. The expedition concluded with a seven-day trip down the Jordao river for about 185 miles, with daily incursions into the forests. Although this region had never been explored scientifically, about 6,000 people live in the municipality, mostly on small farms and cattle ranches that punctuate the forest, and they have established forest trails for rubber tapping. The botanical expedition members benefited from this trail network, which allowed them to use the boat on the river as a base—where they could establish a camp but then penetrate the forests for significant distances to collect plants during the day, and return to their river camp in the evening and process the day’s collections before collapsing into their hammocks at night.

Read more about the trip… read more »