QUANTIFYING THE FOOTPRINT OF A DOMINANT ORGANISM: IMPACTS OF LEAF CUTTER ANTS ON BIOGEOCHEMICAL CYCLING IN TROPICAL FORESTS
One of the most conspicuous features of a tropical forest is the abundance of leaf cutter ants. Their networks of trails extend throughout the forest and workers walk single-file, carrying pieces of leaves into their nests, where special fungi break down the plant material and produce hyphae, on which the ants feed. Leaf cutter ant nests are massive in size and during nest construction and maintenance, ants mix soil particles and alter soil chemistry. Leaf cutters are also the dominant herbivores in tropical forest ecosystems, bringing 10-50 % of all surrounding vegetation into the nest, fertilizing nest soils, and promoting the release of carbon dioxide into the atmosphere. Leaf cutter ant activities can therefore influence ecosystem carbon dynamics, though their influence remains unquantified. To address this knowledge gap, carbon dynamics inside leaf cutter ant nests will be compared to areas without ants. This information will be used to model how leaf cutter nests influence soil and atmospheric carbon dynamics across a range of tropical ecosystems. Leaf cutting ants are increasing in abundance in tropical and subtropical ecosystems that cover 17% of the Earth’s land mass and store approximately 40% of all carbon, much of it in soil. The global climate is changing and of particular concern is the potential influence of climate change on soil carbon dynamics. Understanding the contribution of an ecologically important ant species helps address a critical knowledge gap in the global carbon cycle and improve predictions of future carbon dynamics.
Past Projects
Propogating Climate-Driven Changes in Hydrologic Processes and Ecosystem Functions across Extreme Biophysical and Anthropogenic Gradients
In many arid and semi-arid regions of the world, including much of Western U.S., water resources management plans are predicated on the assumption that the snow pack holds the majority of the water, gradually melting to replenish the reservoirs as their supplies are metered out to satisfy human water and power demands, and environmental flow mandates. Nowhere is this more evident than in the Sierra Nevada Mountains in California, the remote and sparsely populated mountain range providing the water and power for millions of people. While it is known that this mountain range’s steep gradients in elevation, soils and vegetation render it extremely sensitive to climate change, the connection between the underlying hydrologic processes and the water sustainability issues in these regions is not well understood. This project will clarify the connection between likely climate change scenarios, stream flows, reservoir storage and releases, and groundwater storage and extractions for snow-dependent river basins. Furthermore, through engagement with key river basin stakeholders, the project will result in practical guidelines to how best to adapt policy to the changing hydrologic conditions in order to sustain water supply, energy and aquatic ecosystem needs in the future. The San Joaquin River basin was selected as the subject of study because it embodies water and sustainability issues in the semi-arid West given (1) its vulnerability to climatic variation due to its reliance on snow pack and a network of reservoirs for hydropower, flood control, and water supply; and (2) its massive lowland river salmon restoration effort, which was initiated in Fall 2009.
Sensing the Americas’ Freshwater Ecosystem Risks (SAFER) from Climate Change
SAFER is a major international research initiative with the following objectives: 1) To employ freshwater ecosystems as sentinels or sensors of climate variability and watershed processes and investigate their interaction with other multiple stressors to assess risks to ecosystem services in the Americas, and 2) To identify management and mitigation strategies which are both technically and economically feasible as well as culturally acceptable.