Forest Dynamics
Project Investigators
Mike Saunders, Purdue University, msaunder@purdue.edu
Mike Jenkins, Purdue University, jenkinma@purdue.edu
In Indiana and across the Central Hardwood Region, many wild species depend on oak and hickory forests to survive. However, these forests have been allowed to grow for many years without controlled fires or tree harvesting. As a result, shade-loving trees like maples and beeches now fill the forest understory. Land managers must now decide how and when to step in using techniques like controlled burns and planned timber harvests.
Researchers set up sampling plots on a grid across the Hardwood Ecosystem Experiment (HEE) area. These plots help track long-term changes in the forest canopy and monitor how young oak trees grow into mature trees after forest management. The plots also help researchers model how oak regeneration responds to light, canopy cover, and the surrounding environment. This connects local seed spread to larger forest patterns.
Regeneration data is gathered at these same locations. The plots are set up on a 75-meter by 150-meter grid across all study sites, connecting them directly to bird survey locations and controlled fire grids.
Key Papers:
- Kellner, K.F. and R.K.Swihart. 2016. Timber harvest and drought interact to impact oak seedling growth and survival in the Central Hardwood Forest. Ecosphere 7(10): e01473
- Olson, M.G. and M.R. Saunders. 2017. Long-term research on managed hardwood forests in eastern North America. Forest Ecology and Management, 387: 1-2.
- Murray, B.D., J.D. Holand, K.S. Summerville, J.B. Dunning, M.R. Saunders, and M.A. Jenkins. 2017. Functional Diversity response to hardwood forest management varies across taxa and spatial scales. Ecological Applications 1002/eap.1532
- Kellner, K.F. and R.K. Swihart. 2017. Herbivory on planted oak seedlings across a habitat edge created by timber harvest. Plant Ecology, 218:213-223.
- Kellner, K.F. and R.K. Swihart. 2017. Simulation of oak early life history and interactions with disturbance via an individual-based model, SOEL. PLoS ONE 12(6): e0179643. https://doi.org/10.1371/journal.pone.0179643
Digital Forestry
Project Investigator
Songlin Fei, Purdue University, sfei@purdue.edu
https://ag.purdue.edu/digital-forestry/
Sustainable forest management depends on detailed counts of tree quantity and health. Accurate records help managers make decisions that balance both economic needs and environmental health. Currently, crews collect forest data by hand. Because this field sampling relies on human observers, it can introduce errors and lead to inconsistent results. New technologies offer faster, cheaper, and more reliable ways to measure trees accurately.
We plan to modernize how inventory is collected at the HEE site by using drone technology alongside existing ground data. Specifically, our goals are to:
(1) Test how accurately drone-based LiDAR and specialized cameras can automatically map individual trees and measure their sizes in natural hardwood forests.
(2) Test whether drones can effectively locate and map invasive plant species.
Acorn Production
Project Investigator
Robert K. Swihart (Retired), Purdue University, (765) 494-3575, rswihart@purdue.edu
Mike Saunders, Purdue University, msaunder@purdue.edu
Dr. Swihart is studying acorn production and how wildlife removes fallen acorns. His team wants to find out which forest animals benefit most from acorns, how acorn use changes based on food supply and animal population sizes, and whether timber harvesting alters these relationships.
Researchers placed acorn traps under more than 100 oak trees. They count the collected acorns regularly from August through December and X-ray a sample each year to check for acorn weevil larvae. Around each tree, special wire cages limit access to acorns based on animal size, ranging from large deer down to small mice.
Key Findings:
- Harvest Impacts: During the first 6 years after timber harvesting, logging had little effect on acorn production, except for a decrease in black oak acorns along forest edges.
- Pest & Animal Pressure: Removing midstory trees reduced insect infestations in shelterwood sites. However, acorn loss to insects and animals was highest during years when trees produced very few acorns (Kellner, Riegel, and Swihart 2014).
- Wildlife Populations: Large acorn crops were linked to higher numbers of white-footed mice and short-tailed shrews the following summer (Kellner, Urban, and Swihart. 2013).
- Modeling Regeneration: Acorn production and insect data were used to build a computer model simulating young oak survival. The model showed that oak survival depends most on total acorn production, how often rodents bury acorns, and seedling growth rates (Kellner and Swihart 2017).
- Seed Dispersal: In sites where midstory trees were removed, acorns were more likely to be eaten by animals and less likely to survive the winter. This led to a 67% drop in successful seed spread (Kellner, Lichti and Swihart 2016).
Key Paper:
- Kellner, K.F., J.R. Riegel and R.K. Swihart. 2014. Effects of silvicultural disturbance on acorn infestation and removal in the central hardwood forest region. New Forests, 45(2): 265-281.