Research

Ecological Research Projects

Diversity of soil microbes and the function of beech-maple forests

The natural areas of The Holden Arboretum contain some of the finest examples of mature, intact beech-maple forest in Ohio. Holden is conducting research into the effects of soil physical and chemical properties on the diversity and function of soil microbes in these forests. In particular, we are interested in soil fungi that colonize plant roots (mycorrhizae) and how this symbiotic association controls the structure and function of these forests and how they respond to environmental variability and change. Holden scientists are using molecular techniques that extract and amplify DNA from environmental samples to determine the diversity and relative abundance of these important soil fungi, as well as measuring microbial processes using biogeochemical techniques.



Tree roots in soil	Mycorrhizal fungi on roots	Fungal fruiting body in the forest

Winter ecology and altered precipitation dynamics

Most studies of forest ecosystems and soil microbial communities at northern latitudes ignore functional processes that occur during cold months or under snow. Recent work by Holden scientists and others has suggested that these processes may be more important that previously thought and can represent a significant portion of annual carbon and nutrient cycling in many ecosystems. Moreover, altered precipitation and temperature patterns related to climate change might influence the magnitude and importance of winter processes in the Great Lakes region. Holden scientists are working to understand how forests and soils in Northeast Ohio function during our extended periods of cold temperatures and snow cover.
	Measuring soil respiration under snow

Measuring the effect of snow on soil temperature and soil freezing	Estimating leaf decomposition under snow

Acid precipitation and forest health

Acid precipitation resulting from burning fossil fuel is chronic problem in areas near population centers or near concentrations of industrial activity. The northern United States is one area that received high levels of acid rain. Ecosystem acidification can a variety of impacts on plants, soils and water. In hardwood forests, such as those common in Northeast Ohio, there is concern that long-term acidification of forests and can decrease the availably of the essential nutrient phosphorous in soil, which could result in decreased forest health and forest decline. Holden scientists (David Burke and Kurt Smemo), along with Professor J. L. DeForest at Ohio University, recently received a grant from the National Science Foundation (www.nsf.gov) to look at how forests and soil microbes respond to changes in acidity and soil phosphorous availability. They will be manipulating soil pH and fertility over the next several years using agricultural lime and phosphorous fertilizer, and watching how plants and soil microbes respond.



17 tons of lime	Getting lime into the forest	Applying lime 40 pounds at a time

Production and emission of greenhouse gases from soil

Soils are important source of atmospheric gases such as carbon dioxide, methane and nitrous oxide, which are important greenhouse gases associated with global warming. Because these gases are biologically produced, the processes controlling their production and emission to the atmosphere are sensitive to environmental change. It is uncertain how these soil processes will respond to current and future changes in climate and soil chemistry, and the potential exists for a variety of feedback mechanisms. Holden scientists are interested in three primary areas relating to the biogeochemistry of greenhouse gases:

Microbial control of methane dynamics in peat-forming wetlands
Methane and nitrous oxide dynamics in vernal pool ecosystems
Development of techniques and instruments to improve estimates of and controls on nitrous oxide production and emission from soils



Example of a Great Lakes peat bog	Collecting peat samples	Measuring methane emissions

Jennings woods complex ecosystem study

Ecologists in the field collecting leaf litter in Jenning's Woods

One teaspoon of soil contains millions of different microorganisms that perform functions important for forest health, soil fertility, climate and water quality.

Nevertheless, little is known about the rules governing the diversity, assembly, and distribution of soil microorganisms. Holden scientists (Kurt Smemo), along with collaborators at Kent State University (Christopher Blackwood and Mark Kershner) are using soil microbes to test ecological theories relating to the spatial and temporal distributions of diverse biological organisms. Specifically, they are working in a spatially complex forest ecosystem (Jenning's Woods) in Northeast Ohio and using manipulative experiments and rigorous statistical modeling to test theories related to microbial biogeography.

Collecting leaf litter at Jenning's Woods

Horticultural Research Projects