Harvard Forest On-Going Research Projects

Harvard Forest Research

Impacts of elevated temperature on ant species, communities, and ecological roles at two temperate forests in eastern North America

Principal Investigator: Aaron Ellison
Harvard Forest: Jan 01 2008 - Dec 31 2011:

Abstract:
Experimental field studies are needed to understand the consequences of global climatic change for local community structure and associated ecosystem processes. We propose to use large open-top environmental chambers to simultaneously manipulate air and soil temperatures using a
statistically powerful and cost-efficient response-surface (regression) design at two field sites situated in northern and southern temperate mixed hardwood forests in eastern North America (Massachusetts, North Carolina). The proposed field manipulations will reveal the effects of temperature increases on the populations, communities, and associated ecosystem services of assemblages of ground-foraging ants. Ants are a model taxon for studying effects of global climatic change because they comprise the dominant fraction of animal biomass in many terrestrial communities and because they provide essential ecosystem services, including soil turnover, decomposition, and seed dispersal. The experiment is designed to test three predictions:
1. Projected atmospheric warming will lead to declines in ant species’ abundances at the warmer, southern extent of their ranges in the US. Conversely, projected atmospheric warming will lead to increases in abundance or range extensions of ant species at the cooler, northern extent of their ranges in the US.
2. Warming will change the relative abundance and composition of ant
communities, and will lead to the loss of ant biodiversity.
3. Warming will potentially diminish ecosystem processes and services provided by ants, particularly with respect to the dispersal of seeds. Ten open-top chambers at each site which will each be exposed to one of ten levels of air temperature increases, ranging from no change (ambient conditions) to 5 °C (commensurate with best-case IPCC climate model forecasts for the year 2100); soil temperatures will be increased
simultaneously from 0 to ~ 2 °C. After an initial year of pre-intervention measurements, the experiment will run for 3 consecutive years of continuous warming. The response variables measured will include ant activity, population densities and colony sizes of focal species, ant community diversity and species composition, and rates of seed dispersal and predation as mediated by ants. This study will provide an experimental test of the hypothesis that species at the northern and southern boundaries of their ranges will respond predictably to climatic change. In addition, this research will further establish ants as a model taxon for the study of climatic change.

Our work will address PER’s core mission to "deliver improved scientific data and models about the potential response of the Earth's climate and terrestrial biosphere to increased greenhouse gas levels for policy makers to determine safe levels of greenhouse gases in the atmosphere,” while focusing on one aspect of greenhouse gas emissions: temperature. Our response-surface experimental design with many levels of temperature, unlike more conventional ANOVA designs that examine only 2 or 3 “extreme” cases, makes our study more likely to “identify safe levels of emissions,” and to reveal potential nonlinearities and threshold effects in the
relationship between temperature, animal community structure and associated ecosystem function.

Update 2009
1. Shannon Pelini has joined the project as a post-doc. She is supported by a DOE subcontract to University of Vermont, which will be billed quarterly for her housing, office space, computer, and other expenses.

2. Israel del Toro is joining the project in May as a graduate student. His work will be supported by the DOE subcontract to HF.

3. Chambers should be up and running by June 2009.

4. Woods crew to construct boardwalks over conduit.

5. Data collection begins in earnest this summer; pre-treatment micromet data collected beginning mid-February 2009.:

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Faculty of Arts and Sciences of Harvard University
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	Harvard Forest Research Impacts of elevated temperature on ant species, communities, and ecological roles at two temperate forests in eastern North America Principal Investigator: Aaron Ellison Harvard Forest: Jan 01 2008 - Dec 31 2011: Abstract: Experimental field studies are needed to understand the consequences of global climatic change for local community structure and associated ecosystem processes. We propose to use large open-top environmental chambers to simultaneously manipulate air and soil temperatures using a statistically powerful and cost-efficient response-surface (regression) design at two field sites situated in northern and southern temperate mixed hardwood forests in eastern North America (Massachusetts, North Carolina). The proposed field manipulations will reveal the effects of temperature increases on the populations, communities, and associated ecosystem services of assemblages of ground-foraging ants. Ants are a model taxon for studying effects of global climatic change because they comprise the dominant fraction of animal biomass in many terrestrial communities and because they provide essential ecosystem services, including soil turnover, decomposition, and seed dispersal. The experiment is designed to test three predictions: 1. Projected atmospheric warming will lead to declines in ant species’ abundances at the warmer, southern extent of their ranges in the US. Conversely, projected atmospheric warming will lead to increases in abundance or range extensions of ant species at the cooler, northern extent of their ranges in the US. 2. Warming will change the relative abundance and composition of ant communities, and will lead to the loss of ant biodiversity. 3. Warming will potentially diminish ecosystem processes and services provided by ants, particularly with respect to the dispersal of seeds. Ten open-top chambers at each site which will each be exposed to one of ten levels of air temperature increases, ranging from no change (ambient conditions) to 5 °C (commensurate with best-case IPCC climate model forecasts for the year 2100); soil temperatures will be increased simultaneously from 0 to ~ 2 °C. After an initial year of pre-intervention measurements, the experiment will run for 3 consecutive years of continuous warming. The response variables measured will include ant activity, population densities and colony sizes of focal species, ant community diversity and species composition, and rates of seed dispersal and predation as mediated by ants. This study will provide an experimental test of the hypothesis that species at the northern and southern boundaries of their ranges will respond predictably to climatic change. In addition, this research will further establish ants as a model taxon for the study of climatic change. Our work will address PER’s core mission to "deliver improved scientific data and models about the potential response of the Earth's climate and terrestrial biosphere to increased greenhouse gas levels for policy makers to determine safe levels of greenhouse gases in the atmosphere,” while focusing on one aspect of greenhouse gas emissions: temperature. Our response-surface experimental design with many levels of temperature, unlike more conventional ANOVA designs that examine only 2 or 3 “extreme” cases, makes our study more likely to “identify safe levels of emissions,” and to reveal potential nonlinearities and threshold effects in the relationship between temperature, animal community structure and associated ecosystem function. Update 2009 1. Shannon Pelini has joined the project as a post-doc. She is supported by a DOE subcontract to University of Vermont, which will be billed quarterly for her housing, office space, computer, and other expenses. 2. Israel del Toro is joining the project in May as a graduate student. His work will be supported by the DOE subcontract to HF. 3. Chambers should be up and running by June 2009. 4. Woods crew to construct boardwalks over conduit. 5. Data collection begins in earnest this summer; pre-treatment micromet data collected beginning mid-February 2009.:
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