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Aaron M. Ellison
- Current research topics:
- Food webs in dynamic habitats
- Spatial
dimension of species interactions
- Nutrient limitation and stoichiometry of carnivorous plants
- Frank
Morton Jones and carnivorous plant research in the early 20th century
- Foundation
species in forests -
In
many forested ecosystems, the architecture and functional ecology of certain tree
species define forest structure and their species-specific traits control ecosystem
dynamics (see Ellison
et al. 2005 for a review and summary of the conceptual ideas underlying this
research thrust). Such foundation tree species are declining throughout the world
due to introductions and outbreaks of pests and pathogens, selective removal of
individual taxa, and over-harvesting. The ongoing decline of many foundation species
provides a set of important, albeit unfortunate, opportunities to develop the
research tools, models, and metrics needed to identify foundation species, anticipate
the cascade of immediate, short- and long-term changes in ecosystem structure
and function that will follow from their loss, and provide options for remedial
conservation and management. A large-scale, long-term experiment on the loss of
a foundation species was initiated in 2003 at the Harvard
Forest Long-Term Ecological
Research site. This experiment - the Hemlock Removal Experiment - examines
the response of a late-successional forest ecosystem to the removal of its foundation
species - Eastern hemlock (Tsuga canadensis). Throughout the eastern United
States, hemlock is declining as it is killed by an exotic, invasive insect, the
hemlock woolly adelgid (Adelges tsugae). In many areas, human activities
are contributing substantially to this decline, directly through pre-emptive salvage
logging, and indirectly through continued inaction to prevent regional climate
change (warming) which will favor the expansion of the adelgid. The Hemlock Removal
Experiment includes replicate 90 x 90 m hardwood and hemlock control treatment
plots; replicate 90 x 90 m commercial preemptive salvage logging plots; and replicate
90 x 90 m plots in which all hemlocks were girdled in 2005 to kill them in place,
simulating the slow death by the adelgid. Response variables include environmental
variables (currently air and soil temperature, and light levels); population and
community dynamics of seeds, seedlings, understory and overstory vegetation, arthropods,
and salamanders; and carbon and nitrogen cycling; Two years of data were collected
prior to the imposition of treatments in 2005. If you would like to measure additional
response variables and you want to participate in this project, please see the
Guidelines
for Conducting Research at the Harvard Forest.
Parallel experiments on
the loss of foundation species are being conducted at the Coweeta
Hydrological Laboratory's Long-Term
Ecological Research site (hemlock removal) and the Black
Rock Experimental Forest (oak removal).
This project is a core experiment
of the Harvard
Forest Long-Term Ecological
Research site supported by the U.S. National
Science Foundation through grant 0620443. It is also a major focus of the
Harvard Forest Summer
Research Program in Forest Ecology, a Research Experience for Undergraduate
(REU) site supported by the U.S. National
Science Foundation through grant 0452254.
- Arthropods
of the Harvard Forest
- Statistics
for ecologists
- Cyberinfrastructure
tools for ecological synthesis
- Full
cv (PDF)
- Opportunities
for students, post-docs, and senior researchers
- Publications
- Software
- Favorite
links
- Home
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