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 Research Activities

Detailed descriptions of the pre-treatment conditions for each of the communities being studied can be found in The Hardwood Ecosystem Experiment: A Framework for Studying Responses to Forest Management.

Vegetation: Forest Dynamics and Acorn Production

Birds: Breeding birds, Cerulean warbler, Owls

Mammals: Bats, Small mammals, White-tailed deer

Reptiles & Amphibians: Salamanders, Eastern box turtle, Timber rattlesnake

Insects: Wood-boring beetles and Moths (Lepidoptera)

Human Dimensions


Forest Dynamics


Wildlife managers face a conundrum when asked to manage a species that requires a specific type of sub-climax habitat. If you remove the habitat, you lose the animal. Conversely, if you leave the habitat alone, it will become over-mature and eventually cause a decline of the species. This is the issue facing wildlife biologists and timber managers in Indiana where many of our species are dependent on Oak/Hickory forests. For many years, these forests have been allowed to grow without harvest or fire, and the result is that the understory of these woods is now filled with species such as maples and beeches that are the true local climax habitat.

Inventory plots are being installed to characterize the long-term, landscape-level changes in forest canopy structure and overstory recruitment by oak and other highly valued tree species in response to forest management. These plots will also allow spatial modeling of oak regeneration in response to overstory canopy and other environmental valuables, thereby linking local, seed dispersal mechanisms to the landscape pattern. Data concerning herbaceous plants and seedlings is also recorded at these same plots. Plots are installed across all treatment types on a 75 meter by 75 meter grid, linking them to avian inventories and, eventually, an associated dead wood inventory.

Project Investigators
Mike Saunders, Purdue University,
Mike Jenkins, Purdue University,

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Acorn Production


Dr. Swihart is also studying the removal of fallen acorns to determine which consumers in the forest community are benefiting from this important food supply, how use varies with food availability and consumer density, and whether differences occur due to tree harvesting. A series of semi-permeable enclosures is used to restrict access to acorns by vertebrates of different size, from deer to mice. Future work may study the dispersal of acorns into harvest openings to improve our understanding of forest regeneration processes.

Project Investigators
Robert K. Swihart, Purdue University, (765) 494-3590,

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Breeding Birds


Many species of songbirds that nest in mature forests of the eastern United States are declining, and it is thought that forest management activities may be part of the cause for the declines, but also may be part of the solution. For the past two years, field technicians under the direction of Dr. John Dunning of the Department of Forestry and Natural Resources have conducted surveys of breeding birds at the HEE study areas to establish the distribution and abundances of species across the sites.

As timber is harvested on the sites in the coming years, we will be looking at how birds respond, not only at the specific sites where timber management is conducted but also across the larger spatial scales of the HEE project. With Melissa Malloy, a Master's student within the FNR department, Dr. Dunning will focus initially on predicted changes in the distribution of common breeders across the study regions, but future study may also look at impacts on breeding success. Birds are surveyed with 10-minute point counts, during which field technicians record all birds seen and heard within 100 meters of permanently marked locations.

While all birds are surveyed, some species are of management or conservation concern, and therefore are of special interest. These include migratory songbirds such as the Wood Thrush and Acadian Flycatcher, resident species such as Blue Jays that play important ecological roles as nest predators and acorn dispersers, and unusual birds such as the Worm-eating Warbler, a habitat specialist that breeds in the steep forested slopes of southern Indiana.

Project Investigator
John B. Dunning, Purdue University, (765) 494-3565,

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Cerulean Warbler

Cerulean warbler

Dr. Kamal Islam and his students at Ball State University have been studying the Cerulean Warbler in southern Indiana for the past 7 years. This tiny migratory songbird of conservation concern has experienced long-term population declines on its breeding grounds during the past 40 years. We are trying to understand factors responsible for the decline of this species in Indiana. Although Cerulean Warblers are generally associated with mature forests, their territories are often characterized by canopy gaps. The presence of Cerulean Warblers in selectively-cut stands suggests that canopy gaps are likely an important habitat variable. Our main goal is to monitor response of Cerulean Warbler populations to silvicultural treatments. During 2007, we conducted bird surveys using fixed-radius point counts in all 9 management units with over 90 detections of Cerulean Warblers. In addition, we calculated territory sizes and measured vegetation characteristics both within and outside of the territory boundaries. We intend to sample again in 2008 before harvest, and then monitor response of Cerulean Warbler populations to various silvicultural treatments beginning in 2009.

Project Investigator
Kamal Islam, Ball State University, (765) 285-8847,

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A new project was initiated during the winter of 2009-2010 that will continue for the next few years. In order to get a better study on how different parts of the overall forest community interact in response to timber management, we were interested in examining owl populations in and around the HEE study region.

Owls are top predators in the regional food webs, feeding on species groups that are already under study in the HEE project, namely small mammals (the prey of Great Horned Owls and Barred Owls) and forest insects (Eastern Screech-Owls). All three of these species are permanent residents (e.g., they are non-migratory). In addition to different prey, the three species have different territory sizes. Thus we were interested in conducting focused studies on population sizes and territory placement in the region surrounding the HEE study areas. Surveys are conducted in each of the nine HEE research areas, throughout Morgan-Monroe and Yellowwood State Forests, in Brown County State Park, and in parts of the Hoosier National Forest including the Deam Wilderness area.

Due to the wide-ranging area we wanted to survey, we recruited volunteers from the local birding community to conduct surveys of forest night birds (primarily owls, but also Whip-poor-wills and their relatives in the summer). We got an excellent response from birders throughout the region. Surveys are done in mid-winter because most of the owls breed from January – March and are most responsive to recordings of their calls at this time. The surveys targeting Barred Owls are repeated in May-July to attempt to detect family groups and therefore get an impression of reproductive success.

We expect to continue the winter and summer surveys for at least two more years. If funding becomes available, we would also like to conduct a radio-telemetry study to examine how the owls use harvest and edge areas for foraging habitat. If you are interested in volunteering with this project, please contact the HEE Project Coordinator.

Project Investigators
John B. Dunning, Purdue University, (765) 494-3565,
Robert K. Swihart, Purdue University, (765) 494-3590,

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Bat in human hand

For many species of wildlife, particularly game animals such as deer and turkey, we have enough scientific knowledge to predict the results of timber harvest on local populations. Such is not the case for the endangered Indiana bat (Myotis sodalis). Part of the problem is that these bats spend their summers in old dead or dying trees with loose bark. In these snags the females form large colonies (often with 100+ individuals) and raise their young. So biologists are very concerned that timber harvest will either remove the roost trees or the next generation of roost trees.

Although Indiana bats will use almost any large tree with sloughing bark and substantial solar exposure, oaks and hickories seem to be some of the better roosts because one dead tree will hold onto its bark for many years. Maples are rarely used and seem not to form high quality roosts, while no one has ever recorded an Indiana bat using a beech. Thus, we also face a situation that as oak-hickory forests become beech maple forests, they may become less valuable to bats. One way of turning back the clock on succession is by using timber harvest—the overall goal of Hardwoods Ecosystem Experiment is to determine the impact of harvest on a wide variety of wildlife.

To determine the impact of timber harvest on bats we are "trapping" bats in 2 ways. First, we are using mist-nets to capture them as they fly through an opening in the forest. This allows us to directly handle the bats and determine their age, sex, reproductive state, even if they have been captured before. Unfortunately, mist-nets are only effective when placed in an area, such as a roadway or stream, where bats are funneled into the net. Thus, they are not very good for detecting bats that are simply flying through, or over a forest. To "trap" these bats we are using a device called an Anabat® Detector that converts the echolocation calls of bats into an electronic file. Once these data are stored, we can go back and identify many of the calls to species. This technique allows us to "capture" many more bats, but we do not have the detailed information about the individuals such as we get from netting.

Project Investigators
Joy O'Keefe, Indiana State University, (812) 237-4520, joy.o'
Tim Carter, Ball State University, (765) 285-8847,

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Small Mammals


Small mammals are important but seldom-seen components of forest ecosystems. They play important roles as seed dispersers, seed predators, and food for larger animals. The Hardwood Ecosystem Experiment is studying the effect of forest management on small mammal populations and communities. Dr. Robert Swihart designed a study in which livetrapping grids were established at 32 sites during summer of 2007, and trapping will continue in summer 2008 to establish baseline population levels. Attributes of habitat also are being measured around each trap, in the area scheduled for harvest, and in each of the 900-acre management units, to enable us to assess whether certain attributes are consistently associated with use by small mammals. Beginning in 2009 we will evaluate the response of small mammal populations and communities to forest harvest and post-harvest silvicultural treatments.

Project Investigator
Robert K. Swihart, Purdue University, (765) 494-3590,

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White-tailed Deer

When examining oak regeneration in Indiana, one must not underestimate the power of the white-tailed deer. Although the deer in the study forests do not appear to be having as much of a devastating impact as they did in nearby Brown County State Park in the 1980s and 1990s, excluding deer from regeneration sites may have a positive impact on growing oak seedlings.

Thirty-two deer exclosures were erected in and around many of the harvest areas during 2009. These exclosures are 72 ft by 72 ft and 8 ft tall. The exclosure placement is relative to the edge of the harvest opening. In four 3-acre group selections, an exclosure is placed near the center of the opening, one is along the edge, and one is outside the 3-acre opening in the single-tree harvested matrix. In four of the six 10-acre clearcuts, a center, edge, and matrix exclosure is supplemented by an additional exclosure within the opening between the center exclosure and the edge. The four 10-acre shelterwood areas will only have a single center exclosure until the second shelterwood entry removes some of the overstory trees.

Each fenced exclosure has an unfenced reference plot associated with it to compare vegetation response to deer browsing. Researchers will be looking at the effects of deer (and other herbivores like rabbits) on hardwood growth and survival and how these effects vary among the different harvest types (clearcut, shelterwood, group selection) and in relation to the distance from the harvest boundary.

Project Investigators
Scott Haulton, DNR Division of Forestry, (317) 234-5725,
Mike Saunders, Purdue University, (765) 494-2155,
Robert K. Swihart, Purdue University, (765) 494-3590,

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Reptiles & Amphibians



Terrestrial plethodontid salamanders are an ideal group of species to monitor forest ecosystem integrity and biodiversity across the eastern United States. They play a significant role in nutrient recycling by consuming vast quantities of invertebrates and in turn serve as prey items for other forest species. They are sensitive to environmental stresses, and they are often the most abundant vertebrates in deciduous forests.

However, our current knowledge of the effects of timber harvesting on salamander populations is incomplete. Most studies suffer from a lack of replication among various silvicultural treatments and focus solely on immediate post-treatment responses. The terrestrial salamander portion of the Hardwood Ecosystem Project is designed to evaluate the effects of timber harvesting on the diversity, abundance, and demographics of woodland salamanders. Beginning in May 2007, we placed a total of 66 coverboard grids (30 boards per grid) within the 9 study areas. The coverboard grids were checked every other week from September through November. A second year of pre-harvest data will begin in the spring of 2008 and will include nearly 2000 quadrat surveys (1x1m plots) in addition to the coverboard sampling. Beginning in 2009 and continuing through 2011, we will evaluate the immediate response of plethodontid salamander populations in regenerating forests < 5 years old. Planning is currently underway for the evaluation of long-term harvest effects (7-10 years post-harvest) on terrestrial salamander populations among the various harvest treatments.

Project Investigator
Rob Chapman, Purdue University, (812) 458-6978,

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Eastern Box Turtle

Eastern box turtle

Recent research indicates that previously unnoticed declines in box turtle populations have become apparent across the country. What were often regarded as 'good numbers' in box turtle density, have been determined to be insufficient for healthy population growth and survival. Although Indiana does have a few healthy populations, these populations are widely scattered. Timber harvesting is a major land use activity throughout the range of this forest species that could impact turtle populations.

Our research is designed to evaluate the responses of box turtle home range and habitat use to even- and uneven-aged timber harvesting. Beginning in May 2007, we located box turtles in 6 research core areas (2 control, 2 uneven-age, 2 even-age) and subsequently tracked individuals 2-3 times per week through October 2007. Vegetation characteristics collected at a subset of turtle locations will be used to assess box turtle habitat use and selection.

Relatively high population densities of box turtles are required for successful reproduction. In 2007, we established two, 20-acre search plots within the each core area. Plots were searched for turtles 6 times to estimate local population densities within each plot. All data collected in 2007 and part of 2008 will serve as the baseline to compare to post-harvest responses.

Project Investigator
Brian MacGowan, Purdue University, (765) 647-3538,
Rod Williams, Purdue University, (765) 494-3568,

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Timber Rattlesnake

Timber rattlesnake

Timber rattlesnakes have experienced population declines throughout most of their range. These population declines have been attributed to habitat loss, habitat fragmentation, and human persecution. Within Indiana, timber rattlesnakes have been listed as endangered due to extensive population declines. Although previous work has been performed on the spatial ecology of this species within Brown County, no information exists on the effects of timber harvesting. This study will attempt to quantify the effects of timber management practices on rattlesnake movement patterns and habitat selection.

Beginning in May of 2007, surveys for timber rattlesnakes were preformed within core units where previous observations occurred. Nineteen snakes were observed as part of these surveys. A subset of captured rattlesnakes (6M:5F) were implanted with a radio transmitter and tracked 3 times a week throughout their active season. Radioed snakes are currently located on control and even-aged management units. All snakes were tracked to their respective hibernacula. The habitat selected by study individuals was quantified and will be compared to paired random habitat measurements. Data collected from 2007 will be used for comparison against post harvest snake radiolocations and habitat selection.

Project Investigator
Brian MacGowan, Purdue University, (765) 494-7739, macgowan@purdue.eduBack to Top


Wood-boring beetles

Wood-boring beetle

Dr. Jeffrey Holland of Purdue's Department of Entomology and his graduate students are studying the influence of different types of forestry management on assemblages of longhorned beetles. Some of these beetles are devastating pests of forest trees, while many others play important ecological roles by decomposing rotting wood, acting as natural thinning agents, and reducing fire fuel load.

Understanding how the assemblages of species changes over time under different management techniques will allow us to both promote the biodiversity of those native species providing ecosystem services and limit economic losses from the few pest species. The beetles are sampled using arrays of four different types of traps that each has characteristics to attract certain types of beetle. Thirty-six of these arrays were used to sample the longhorned beetles for about one and a half months in 2006 and three months in 2007. The sampling arrays will continue to sample after the harvests to detect changes in the assemblages of beetles. This is a diverse beetle family and they have found 70 longhorned beetle species during this project so far.

Project Investigator
Jeff Holland, Purdue University, (765) 647-3538, jdhollan@purdue.eduBack to Top

Moths (Lepidoptera)

Lepidoptera moth

Dr. Keith Summerville's goal for the first five years of the Hardwood Ecosystem Experiment is to test for the relative importance of direct and indirect effects of timber harvest on the moth species. While species that rely on oak species may be directly affected by removal of their host by logging, the broader impacts of timber harvest remain unclear. After the first year, Keith has identified upwards of 350 species and 5000 individuals of moths in Morgan-Monroe State Forest. To sample these species, he uses a battery-powered light that draws the moths in and traps them in a funnel capped bucket. Twenty of these traps were set for five different nights in the summer of 2007.

Project Investigator
Keith Summerville, Drake University, (515) 271-2265,

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Human Dimensions

Project Investigators
Shannon Amberg, Purdue University,
Bill Hoover, Purdue University, (765) 494-3580,

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