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Scientists & Staff

Robert P. Long

Emeritus Research Plant Pathologist
Sustaining Forests in a Changing Environment
335 National Forge Road
Irvine, PA, 16329
Phone: 814-563-1040

Contact Robert P. Long


Featured Publications & Products

  • Long, Robert P.; Horsley, Stephen B.; Hall, Thomas J. 2011. Long-term impact of liming on growth and vigor of northern hardwoods. Canadian Journal of Forest Research. 41(6): 1295-1307.
  • Knight, Kathleen S.; Herms, Daniel A.; Cardina, John; Long, Robert; Gandhi, Kamal J.K.; Herms, Catharine P. 2011. Emerald ash borer aftermath forests: the future of ash ecosystems. In: McManus, Katherine A; Gottschalk, Kurt W., eds. 2010. Proceedings. 21st U.S. Department of Agriculture interagency research forum on invasive species 2010; 2010 January 12-15; Annapolis, MD. Gen. Tech. Rep. NRS-P-75. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 97.
  • Balci, Y.; Long, R.P.; Mansfield, M.; Balser, D.; MacDonald, W.L. 2010. Involvement of Phythophthora species in white oak (Quercus alba) decline in southern Ohio. Forest Pathology. 40: 430-442.
  • Knight, Kathleen S.; Herms, Daniel A.; Cardina, John; Long, Robert; Rebbeck, Joanne; Gandhi, Kamal J.K.; Smith, Annemarie; Klooster, Wendy S.; Herms, Catherine P.; Royo, Alejandro A. 2010. Emerald ash borer aftermath forests: The dynamics of ash mortality and the responses of other plant species. In: Michler, Charles H.; Ginzel, Matthew D., eds. 2010. Proceedings of symposium on ash in North America; 2010 March 9-11; West Lafayette, IN. Gen. Tech. Rep. NRS-P-72. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 11.
  • Knight, Kathleen S.; Long, Robert P.; Rebbeck, Joanne; Herms, Daniel A.; Cardina, John; Herms, Catherine P.; Gandhi, Kamal J.K.; Smith, Annemarie; Costilow, Kyle C.; Long, Lawrence C.; Cappaert, David L. 2010. Effects of emerald ash borer (Agrilus planipennis) on forest ecosystems. In: McManus, Katherine A; Gottschalk, Kurt W., eds. Proceedings. 20th U.S. Department of Agriculture interagency research forum on invasive species 2009; 2009 January 13-16; Annapolis, MD. Gen. Tech. Rep. NRS-P-51. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 82.

Publications & Products

National Research Highlights

Upper panel: Black cherry raceme with individual flowers. Robert Long, USDA Forest Service Lower panel: Mature black cherry seed at the base of a tree in fall 2010

Black cherry regeneration difficulties: Are They Related to Stand Age or Something Else?

Year: 2017

Forest managers report that black cherry regeneration is impeded by poor and erratic seed production. Tree stand age has been suggested as one of the causal factors affecting seed production. Forest Service scientists monitored black cherry seed production over seven years to see whether stand age affects seed production.

Photo 1: Reid Garrison in a regenerating stand where black cherry seedlings are thriving after a nitrogen fertilizer treatment. Photo 2: Figures show increased species diversity in fertilizer treated stands.

Using fertilizer to promote diverse seedling development in Allegheny hardwood forests

Year: 2017

Fertilizing the forest understory slows the development of dominance by sweet birch, favors development of black cherry following overstory removal, and favors red maple in partial cut shelterwood stands.

Variation in black cherry crown health: Left-- a healthy tree; Right--an unhealthy declining tree. Robert Long, U.S. Department of Agriculture Forest Service.

Black Cherry Crown Health and Mortality on the Allegheny National Forest

Year: 2016

Black cherry, an important timber and wildlife species in the Allegheny hardwood forest, is suffering from poor crown health and increased mortality across northern Pennsylvania. Research is in progress to determine the biotic and abiotic factors causing this change in black cherry health status and to provide guidance to managers for determining appropriate treatment options.

This black cherry seedling is infected with black cherry leaf spot. Managers and scientists have observed this infection more frequently in recent years. Robert Long, U.S. Department of Agriculture Forest Service.

Changes in Black Cherry on the Allegheny Plateau

Year: 2016

Increased tree mortality, decreased seed production, and seedling growth. Managers and scientists have been observing these changes in black cherry on the Allegheny Plateau and are working together to sharpen the research focus and utilize long-term research to improve forest management.

Lime application in 1985. USDA Forest Service

Long-Term Effects of Forest Liming on Soil, Soil Leachate, and Foliage Chemistry in Northern Pennsylvania

Year: 2015

In many areas of the northeastern United States and Canada, base cations have been depleted by long-term inputs of acidic deposition. Forest liming restores base cations, which improves the crown health, growth, and seed production of sugar maple. Forest Service scientists now know that forest liming changes soil chemistry and effects persist for 21 years.

Soil pit with golf tees marking horizons to be sampled. Robert Long, USDA Forest Service

Liming Effects Help Maintain Sugar Maple Growth and Health and Persist for More Than 20 years

Year: 2014

Long-term inputs of acidic deposition have depleted soils of calcium (Ca) and magnesium (Mg) on ridge-top, unglaciated sites in Pennsylvania. Sugar maple requires adequate supplies of these elements to maintain growth, crown health, and flower and seed production. Soils sampled as part of a long-term liming study in northern Pennsylvania show that Ca and Mg levels have remained elevated through the soil profile to a depth of 1.5 feet for 21 years after an initial treatment with 10 tons per acre of dolomitic limestone.

Last modified: Saturday, February 4, 2023