Research Overview

Research in the Fisk lab explores decomposition and nutrient cycling processes and the soil organisms that carry out these processes. Our general goal is to better understand how feedbacks between plants and decomposer organisms influence ecosystem response to environmental change. We are currently involved in the following general projects.



Invasion of north temperate forests by exotic earthworms

earthworm picture earthworm casts We are collaborating with a diverse group of ecologists to test the effects of invasion by exotic earthworms on forest ecosystem function. One component of the project follows the fate of C from 13C-labelled leaf litter in mesocosms located in areas without earthworms, and areas with two different types of earthworm communities (transitional and well-established). Work in our lab focuses on the flow of C through the detrital food web and on soil P dynamics.





Characterization of fungal communities in northern hardwood forests of New Hampshire

fungal hyphae
We are using molecular genetic approaches to learn about the distribution of different fungi in forest litter (roots and leaves), organic horizons, and mineral soil, at the Hubbard Brook Experimental Forest (HBEF) and the Bartlett Experimental Forest in NH. We are building upon this work to answer questions regarding fungal responses to environmental change (acidic and nitrogen deposition, and forest harvest) and the implications for decay and nutrient mineralization processes.




Microbial processes and plant nutrient acquisition in changing nutrient environments

This project examines the implications of increased N availability and reduced cation availability (Ca in particular) for plant and microbial processes in northeastern hardwood forests of different successional stages. We are quantifying root and microbial responses to different combinations of nutrient and mineral additions at the HBEF, and will elaborate upon this work in a larger-scale factorial fertilization experiment in collaboration with a number of other scientists at the HBEF.