Current Research

• Influence of nitrogen deposition changes on black cherry seed production and seedling development in a changing environment following the reduced nitrate and sulfate emissions and deposition.
• Recognizing silvicultural problems and opportunities during the early stem exclusion phase of stand development including competition and use of treatments such as herbicides and fertilizers to enhance seedling development.
• Long term changes in old growth forests of the Allegheny Plateau region with focus on Hearts Content, Cook Forest and Tionesta Natural Area.
• Enhancement of regeneration guidelines for northern hardwood forests, especially as related to herbicide and fertilizer use.

Research Interests

• I am interested in how both woody and herbaceous plant communities respond to disturbances.
• I am interested in understanding the conditions that result in monoculture following overstory removal and how to apply existing or novel silvicultural techniques to prevent monoculture and promote mixed species regeneration.
• I am interested in how unmanaged old growth forests differ from or are similar to managed second growth forests in terms of  both woody and herbaceous species composition following disturbances.
• I work to develop guidelines for forest management that are used in the SILVAH system of stand inventory, analysis and prescription used by many foresters in the northcentral and northeastern states use as a tool for forest management.

Why This Research is Important

Our mission is to enhance the basic understanding of Allegheny Plateau forest ecosystems while developing resource management guidelines. Understanding how management activities alter the herbaceous plant community in stands under a variety of management strategies is critical to the practice of ecosystem management. Understanding the competitive ability of species like black birch, black cherry, and pin cherry are important. Understanding establishment requirements and creating conditions favorable for a variety of species to become established where they are best suited is critical to achieving our mission goals.

Education

• The State University of New York, College of Env. Sci. and For., Ph.D. Plant Ecology 2010
• The Pennsylvania State University, M.S. Forest Science 1997
• Houghton College, B.S. Biology 1991

Professional Organizations

• Ecological Society of America (1995 - Present)
• Torrey Botanical Society (1998 - Present)
• Society of American Foresters (SAF) (1995 - Present)

Featured Publications & Products

• Ristau, Todd . 2019. Using herbicides to control interfering understories in the Allegheny hardwood stands, 2. Sharpening the tools in the toolbox.
• Ristau, Todd E. 2017. Control of hay-scented and New York ferns with Oust Xp herbicide: Revisiting rate and timing required in mixed oak and northern hardwood stands.
• Ristau, Todd E.; Stoleson, Scott H.; Horsley, Stephen B.; deCalesta, David S. 2011. Ten-year response of the herbaceous layer to an operational herbicide-shelterwood treatment in a northern hardwood forest.
• McWilliams, William H.; Westfall, James A.; Brose, Patrick H.; Dey, Daniel C.; D'Amato, Anthony W.; Dickinson, Yvette L.; Fajvan, Mary Ann; Kenefic, Laura S.; Kern, Christel C.; Laustsen, Kenneth M.; Lehman, Shawn L.; Morin, Randall S.; Ristau, Todd E.; Royo, Alejandro A.; Stoltman, Andrew M.; Stout, Susan L. 2018. Subcontinental-scale patterns of large-ungulate herbivory and synoptic review of restoration management implications for midwestern and northeastern forests.
• Stoleson, Scott H.; Ristau, Todd E.; deCalesta, David S.; Horsley, Stephen B. 2011. Ten-year response of a forest bird community to an operational herbicide-shelterwood treatment in Allegheny hardwoods.
• Horsley, Stephen B.; Bailey, Scott W.; Ristau, Todd E.; Long, Robert P.; Hallett, Richard A. 2008. Linking environmental gradients, species composition, and vegetation indicators of sugar maple health in the northeastern United States.
• Nuttle, Tim; Yerger, Ellen H.; Stoleson, Scott H.; Ristau, Todd E. 2011. Legacy of top-down herbivore pressure ricochets back up multiple trophic levels in forest canopies over 30 years.
• Royo, Alejandro A.; Ristau, Todd E. 2013. Stochastic and deterministic processes regulate spatio-temporal variation in seed bank diversity.
• Ristau, Todd E.; Horsley, Stephen B. 2006. When is pin cherry (Prunus pensylvanica L.) a problem in Allegheny hardwoods.
• Ristau, Todd E.; Horsley, Stephen B. 1999. Pin cherry effects on Allegheny hardwood stand development.

Publications

• Royo, Alejandro ; Vickers, Lance ; Long, Robert ; Ristau, Todd ; Stoleson, Scott ; Stout, Susan L. 2021. The Forest of Unintended Consequences: Anthropogenic Actions Trigger the Rise and Fall of Black Cherry.
• Long, Robert P.; Ristau, Todd E. 2020. Changes in Black Cherry Seed Production: Is Stand Age a Factor.
• Ristau, Todd E.; Royo, Alejandro A. 2020. Influence of stand age, soil attributes, and cover type on Rubus (Rosaceae) seed bank abundance.
• Stout, Susan L.; Brose, Patrick H.; Cleveland, Helene ; Long, Robert P.; McGuinness, Barbara ; Peters, Matthew P.; Rebbeck, Joanne ; Ristau, Todd ; Royo, Alejandro A.; Stoleson, Scott H.; Thomasma, Scott ; Twery, Mark J.; Wurzbacher, Sarah . 2019. Fifty years of science-management cooperation from the SILVAH community of practice.
• McWilliams, William H.; Westfall, James A.; Brose, Patrick H.; Lehman, Shawn L.; Morin, Randall S.; Ristau, Todd E.; Royo, Alejandro A.; Stout, Susan L. 2017. After 25 years, what does the Pennsylvania Regeneration Study tell us about oak/hickory forests under stress.
• McWilliams, William H.; Westfall, James A.; Brose, Patrick H.; Dey, Daniel C.; Hatfield, Mark; Johnson, Katherine; Laustsen, Kenneth M.; Lehman, Shawn L.; Morin, Randall S.; Nelson, Mark D.; Ristau, Todd E.; Royo, Alejandro A.; Stout, Susan L.; Willard, Thomas; Woodall, Christopher W. 2015. A regeneration indicator for Forest Inventory and Analysis: history, sampling, estimation, analytics, and potential use in the midwest and northeast United States.
• Ristau, Todd E.; Stout, Susan L. 2014. Can cover data be used as a surrogate for seedling counts in regeneration stocking evaluations in northern hardwood forests.
• Nuttle, Tim; Ristau, Todd E.; Royo, Alejandro A. 2014. Long-term biological legacies of herbivore density in a landscape-scale experiment: forest understories reflect past deer density treatments for at least 20 years.
• Huebner, Cynthia D.; Steinman, Jim; Hutchinson, Todd F.; Ristau, Todd E.; Royo, Alejandro A. 2014. The distribution of a non-native (Rosa multiflora) and native (Kalmia latifolia) shrub in mature closed-canopy forests across soil fertility gradients.
• Trager, Matthew D.; Ristau, Todd E.; Stoleson, Scott H.; Davidson, Robert L.; Acciavatti, Robert E. 2013. Carabid beetle responses to herbicide application, shelterwood seed cut and insect defoliator outbreaks.
• Huebner, Cynthia D.; Hutchinson, Todd; Ristau, Todd; Royo, Alejandro; Steinman, James. 2012. Documenting the Regional and local distribution of Kalmia latifolia and Rosa multiflora in West Virginia, Ohio, and Pennsylvania Forests along a soil fertility gradient.
• Goetsch, Chandra ; Wigg, Jennifer ; Royo, Alejandro A.; Ristau, Todd ; Carson, Walter P. 2011. Chronic over browsing and biodiversity collapse in a forest understory in Pennsylvania: Results from a 60 year-old deer exclusion plot.
• Brose, Patrick H.; Gottschalk, Kurt W.; Horsley, Stephen B.; Knopp, Peter D.; Kochenderfer, James N.; McGuinness, Barbara J.; Miller, Gary W.; Ristau, Todd E.; Stoleson, Scott H.; Stout, Susan L. 2008. Prescribing regeneration treatments for mixed-oak forests in the Mid-Atlantic region.
• Morin, Randall S.; Liebhold, Andrew M; Gottschalk, K.W.; Woodall, Chris W.; Twardus, Daniel B.; White, Robert L.; Horsley, Stephen B.; Ristau, Todd E. 2006. Analysis of forest health monitoring surveys on the Allegheny National Forest (1998-2001).
• Stout, Susan L.; Hoover, Coeli M.; Ristau, Todd E. 2006. Listening to old beech and young cherry trees - long-term research in the Alleghenies.
• Stout, Susan L.; Ristau, Todd E. 2005. Long-term Research on the USFS Kane Experimental Forest in Northwestern Pennsylvania.
• Ristau, Todd E.; Horsley, Stephen B.; McCormick, Larry H. 2001. Sampling to assess species diversity of herbaceous layer vegetation in Allegheny hardwood forests.
• McCormick, Larry H.; Groninger, John W.; Penrod, Kathy A.; Ristau, Todd E. 1993. Deer exclusion effects on understory development following partial cutting in a Pennsylvania oak stand.

Research Highlights

Highlight	Title	Year
NRS-2017-57	Black cherry regeneration difficulties: Are They Related to Stand Age or Something Else? Forest managers report that black cherry regeneration is impeded by poor and erratic seed production. Tree stand age has been suggested as one o ...	2017
NRS-2016-130	Changes in Black Cherry on the Allegheny Plateau Increased tree mortality, decreased seed production, and seedling growth. Managers and scientists have been observing these changes in black che ...	2016
NRS-2016-145	Fine-tuning Herbicide Prescriptions in Northern Hardwood Forests Fine-tuning existing herbicide prescriptions leads to better results for forest managers and landowners.	2016
NRS-2011-02	Long-Term Differences in Forests With Different Deer Densities Thirty years after a study on the effects of deer on forest ecosystems established new forest stands at deer densities ranging from 10 to 64 dee ...	2011
NRS-2014-081	Pennsylvania Regeneration Study Assesses Overstory and Understory Tree Species Communities In 2001, the Commonwealth of Pennsylvania and Forest Service's Forest Inventory & Analysis (FIA) program launched the "Pennsylvania Regeneration ...	2014
NRS-2013-064	Scientists Study Long-term Response of Ground Beetle Communities to an Operational Herbicide Application Ground beetles comprise a large and diverse group of mostly predatory beetles that have long been recognized as a useful barometer of ecosystem ...	2013
NRS-2017-83	Using fertilizer to promote diverse seedling development in Allegheny hardwood forests Fertilizing the forest understory slows the development of dominance by sweet birch, favors development of black cherry following overstory remo ...	2017