Beta diversity of plant-insect food webs along an altitudinal gradient in the tropics

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Food webs describe the flow of resources through ecosystems from producers (plants) to primary consumers (herbivores) and on to secondary consumers (predators). Food webs are especially complex in diverse tropical rainforests where numerous species share common resources. Plant-insect food webs are a major component of Earth's biodiversity, but little is known about the interconnected webs of tropical rain forests because they are more difficult to study than simpler ecosystems. Slash-and-burn agricultural practices on the island of New Guinea provide a unique opportunity to disentangle complex food webs. Unlike ecological research in protected natural areas, scientists can extract living plants and insects from pristine forests for experimental purposes when New Guinea farmers expand their gardens. A previous project experimentally tested the feeding habits of insect pests attacking approximately 250 species of lowland tropical forest trees. The present project builds upon the earlier work by examining forests at higher elevations where predictions about the shape of complex food webs can be evaluated. This research aims to identify predators and parasites influencing the dietary limits of timber pests including bark beetles and caterpillars.

Recovery of managed forests from outbreaks of damaging insects can be informed by studies of plant-insect food webs. The recent mountain pine beetle outbreak in the western U.S. is ten times larger than any previously recorded in the region, with an economic impact that is measured in billions of dollars. Food webs of diverse forests, as on the island of New Guinea, offer unparalleled opportunities to understand the factors limiting the diet and range of timber pests. New Guinea is also home to the world's third largest remaining tropical forest wilderness and is under international consideration for markets in greenhouse gas mitigation. This project supports the training of young scientists including several graduate students and develops natural resource expertise in a region of global importance. In addition, species discovery and ecological information will establish a baseline for future monitoring of forest response to continuing global change.