In the Shade
Sunlight drives plant growth, making both light and its absence equally powerful factors in the survival of trees and understory plants. In August, the Northern Research Station’s web features shine a light on shade with stories about a scientist studying oak regeneration, research on how non-native Japanese stiltgrass is adapting to new environments, and identifying conditions favorable to a tree that almost disappeared.
Project Learning Tree’s Focus on Forests curriculum was developed with the USDA Forest Service to guide high school students through an in-depth look at forested lands in America.
Patrick Brose has been interested in nature as long as he can remember. Born and raised on a small farm in rural western Pennsylvania, his playground was the creeks, fields, and woods of the farm and surrounding area. He was very active in Boy Scouts of America (attaining the rank of Eagle Scout) as a teenager and twice attended Philmont Scout Ranch in the Sangre de Cristo Mountains of New Mexico.
After high school, Brose studied park management at a local community college then went out west for a job as a seasonal forest technician on the Sitgreaves National Forest of Arizona. While working there he fell in love with firefighting, which he engaged in for many summers in California, Utah, and Wyoming.
Brose learned about the problems with oak regeneration in a forestry course at Utah State University. “This struck me as odd because oaks of all species and sizes abounded in the woods around the family farm due to periodic fires,” he said.
Brose earned a Master’s degree from Penn State University then worked for 3 years as a forester in the Black Hills of South Dakota. He earned his Ph.D. on the role of fire in oak regeneration from Clemson University. After graduation Brose worked on fire behavior and fire ecology of southern pine ecosystems at the Southern Research Station. He was hired by the Northern Research Station in 2000 as a research forester in Irvine, Pennsylvania.
Currently, Brose is finishing an oak regeneration study begun in the early 2000s in collaboration with two Northern Research Station colleagues. The study follows the survival and growth of thousands of oak seedlings and stump sprouts from the final harvest of mature oak stands until canopy closure of the new stands. The results will help foresters predict how new oak stands will develop over time. In addition, this information will make the SILVAH (short for Silviculture of Allegheny Hardwoods) decision-support system even more applicable in mixed-oak forests of the Mid-Atlantic region.
Brose finds that teaching practicing natural resource managers how to regenerate mixed-oak forests via the SILVAH workshops and field tours the most rewarding part of his job. “A close second would be mentoring young forestry students through field trips, invited lectures, and summer jobs,” he said.
More about Pat Brose >>
Japanese Stiltgrass and Adaptation
In collaboration with partners at West Virginia University, Research Botanist Cindy Huebner of the Northern Research Station is launching a new study that aims to answer a critical question for land managers: how do some invasive plants adapt so rapidly to new conditions?
Huebner is working with Craig Barrett of West Virginia University on a recently funded National Science Foundation grant focused on evaluating the role of genetic variation in the spread of invasive plants. Their research will focus on Japanese stiltgrass (Microstegium vimineum), a poster plant when it comes to invasion and adaptation.
Japanese stiltgrass was introduced to the United States in 1919 via packing material in a shipment of porcelain from Asia. In just over a century, it has spread across 24 Eastern and Midwestern states, invading such diverse landscapes as agricultural areas, forests, riparian areas, and dry, open habitats. Because it is shade-tolerant, the invasive grass can spread to sunny and shady environments, where it crowds out native vegetation, reduces biodiversity, and changes ecosystem function by changing soil conditions.
“A fundamental question in invasive species biology is: how do species rapidly adapt to new environments, especially when they arrive with relatively low genetic diversity?” Huebner said. “While we are using Japanese stiltgrass to explore the question, our research will be relevant to all of the non-native plants affecting forests, agricultural crops, and prairie ecosystems.”
One of the initial targets of the study is to explore the role of something called “transposable elements” in a plant’s genome and associated epigenetic variation in how quickly they adapt and invade in a novel environment. Transposable elements are believed to be involved in environmental stress responses; they are described as mobile genetic elements that can alter gene expression and genome structure. Huebner, Barrett and several other partners are focusing on Japanese stiltgrass for this research because while it has low genetic variation, Japanese stiltgrass’ growth rates and reproduction differ among plants collected from different geographic regions in the United States.
Research will use ecological niche modeling to determine parameters important in predicting the success of Japanese stiltgrass invasion and genome-wide association to link genotypes, phenotypes, and environmental parameters. “Our goal is to build an integrative framework for studying adaptation in an emerging model for invasive species,” Huebner said.
The American Chestnut: Growing Trees through Strong Collaborations
"Now is the time for chestnuts." Penned by Henry David Thoreau in 1855, these words hold new meaning today.
The American chestnut (Castanea dentata) once dominated forests throughout much of the Eastern United States. Chestnut was ecologically important as a food source for wildlife and was economically valuable for its rot- and weather-resistant lumber, high tannin content, and edible nuts. Culturally important as well, the Iroquois and Cherokee used the chestnut for food, fiber, fuel, and medicine.
Prior to 1900, in some locations in the native range, 1 out of every 4 trees was an American chestnut. Following the unintended introduction of the Chestnut blight fungus (Cryphonectria parasitica) and the subsequent decimation of the native chestnut population, this tree has become functionally extinct across the East. Occasional large survivors and sprouts are found, although most die of blight before bearing fruit.
Researchers with the Northern Research Station (NRS), The American Chestnut Foundation (TACF), the University of Tennessee, and others, are using traditional breeding techniques to develop an American chestnut hybrid that is resistant to blight in efforts to reintroduce this iconic species back into forests across the East. Along with traditional breeding methods, TACF and partners, are also combining modern biotechnology and biocontrol techniques together in a process they call “3BUR: Breeding, Biocontrol, and Biotechnology United for Restoration”.
Sara Fitzsimmons, Director of Restoration with TACF, is dedicated to restoring the chestnut tree to its native range. “Our goal is to develop a disease-resistant American chestnut tree to restore this species to its natural niche in the forest,” said Fitzsimmons. “No one organization could succeed alone in such a monumental project. TACF is dependent upon many partners, collaborators, and citizen scientists to drive research and education to get the work done.”
Developing a disease-resistant American chestnut is a major step, and so too is the science of determining what growing conditions provide the greatest chance for long-term survival. Leila Pinchot, Research Ecologist with NRS is focused on discovering what growing conditions and silvicultural practices will allow a future generation of chestnuts to survive and thrive. “Once disease-resistant American chestnuts are available, planting them into managed forests will be the next step toward restoring the species,” said Pinchot. “Understanding how site characteristics, such as soil moisture and nutrient availability, impact chestnut performance will inform appropriate site selection.”
Researchers and land managers are working together to determine how to get the chestnut back in the forest to survive, compete, and disperse on its own. With dedicated partners working toward a common goal, now is the time for the successful reintroduction of the American chestnut.