John Witter is the George Willis Pack Professor of Forest Entomology. He focuses on the effects of invasive insects and diseases on individual trees, ecosystems, and landscapes in the Great Lakes Region. He examines interactions of various disturbances, such as insects, drought, frost, pollution, and human actions, and their impacts on health and changes in forests.

Awards and Grants:
Current major grants: Monitoring and Evaluating the Health of Ash Trees in Michigan's Rural Forests. Beech Bark Disease Monitoring and Impact Analysis System for Michigan. National Forest Health Monitoring Program: Michigan Detection. Atmospheric Dry Deposition Monitoring. Honors and awards: George Willis Pack Professor of Forest Entomology.

Research Interests:
My current research concentrates on invasive insects and diseases, with emphasis on the impact that these organisms have on the conditions of forests in the Great Lakes region. I focus on specific pests or declines and their impacts on individual trees, whole ecosystems, and landscapes. Current and recent projects include beech bark disease, emerald ash borer, basswood decline, and gypsy moth.

Current/Recent Research:
Specific examples of current/recent projects: Monitoring and Evaluating the Health of Ash Trees in Michigan's Rural Forests. USDA Forest Service, NE Area State and Private Forestry. Joint project with Michigan Technological University. Results/benefits and location: This study is gathering baseline data on health of the ash resource in rural forests throughout the state of Michigan and monitoring changes over time related both to emerald ash borer and to other disturbance factors in stands with ash. Monitoring American Beech Conditions in Northern Hardwood Forests of Michigan and Delineating Spread of Beech Bark Disease. Michigan DNR. Results/benefits and location: Monitoring current conditions of American beech in Michigan and mapping the location and spread of beech scale and the associated Nectria canker that causes beech bark disease. Effects of an Exotic Disturbance and Silvicultural Management on Northern Hardwood Ecosystems: Tree Growth, Tree Regeneration, and Invertebrate Biodiversity. Source: USDA McIntire-Stennis Program. Results/benefits and location. Development of long-term research studies in Michigan on tree growth, tree recruitment, and invertebrate biodiversity in forest stands with and without beech bark disease. Basswood Decline in the Great Lakes Region. Source: USDA Forest Service. Results/benefits and location: Development of baseline data and monitoring on 100 northern hardwood stands, with emphasis on introduced basswood thrips and other stressors as they impact tree health. Michigan Impact Monitoring System: Analysis of Temporal and Spatial Change. Source: Michigan DNR. Results/benefits and location: Development of baseline data and monitoring long-term impacts of multiple disturbances in Michigan forests, with emphasis on drought, frost, and defoliation. Forest Health Monitoring Program: Michigan Detection. Source: USDA Forest Service. Results/benefits and location: Monitoring long-term impacts in Michigan forests with emphasis on soils, vegetation, ozone, and downed woody debris. Atmospheric Dry Deposition Monitoring: Newcomb Tract Site. Source: MACTEC Engineering and Consulting. Results/benefits and location: On-going monitoring of dry pollutant deposition and climate variables for southeast Michigan monitoring site; provides climate data for agroforestry studies at Newcomb Tract.

Teaching Interests:
entomology, pest management, forestry, applied ecology

Current/Recent Teaching:
Recently taught courses: ENVIRON 160. Habitats and Organisms. NRE 418/ENVIRON 418. Biology and Management of Insects. NRE 419/ENVIRON 419. Agroforest Pest Management. NRE 521. Insect Ecology.

Selected Publications:
Witter, J. A., J. L. Stoyenoff, H. A. Petrillo, J. L. Yocum, and J. I. Cohen. 2005. Effects of beech bark disease on trees and ecosystems. Pgs. 28-35. In: Evans, C. A., J. A. Lucas, and M. J. Twery. Beech Bark Disease: Proceedings of the Beech Bark Disease Symposium. Gen. Tech. Rep. NE-331. Newtown Square, PA, USDA Forest Service, Northern Research Station. 149 pgs.

Petrillo, H. A., J. A. Witter, and E. M. Thompson. 2005. Michigan beech bark disease monitoring and impact analysis system. Pgs. 48-51. In: Evans, C. A., J. A. Lucas, and M. J. Twery. Beech Bark Disease: Proceedings of the Beech Bark Disease Symposium. Gen. Tech. Rep. NE-331. Newtown Square, PA, USDA Forest Service, Northern Research Station. 149 pgs.

Petrillo, H. A. and J. A. Witter. 2005.. Invertebrate biodiversity in northern hardwood ecosystems under varying disturbance regimes. Pgs. 88-91. In: Evans, C. A., J. A. Lucas, and M. J. Twery. Beech Bark Disease: Proceedings of the Beech Bark Disease Symposium. Gen. Tech. Rep. NE-331. Newtown Square, PA, USDA Forest Service, Northern Research Station. 149 pgs.

Thompson, E. M. and J. A. Witter. 2003. Michigan Beech Bark Disease Monitoring and Impact Analysis System: Field Methods Protocol Handbook. Mich. Coop. For. Pest Mgmt. Hndbk 02-1 (3rd edition). Thompson, E. M. and J. A. Witter. 2003 (3rd edition). Michigan Beech Bark Disease Monitoring and Impact Analysis System: Annual Report 2002-2003. Mich. Coop. For. Pest Mgmt. Tech. Rep. 03-1. Ann Arbor, MI.

Stoyenoff, J. L. and J. A. Witter. 2000. Distribution of first instar gypsy moths (Lepidoptera: Lymantriidae) among saplings of four tree species common in the Great Lakes region. Great Lakes Entomologist 33:209-221.

Stoyenoff, J. L., J. A. Witter, and B. A. Leutscher. 2000. Protocol handbook for the Michigan Impact Monitoring System. 3rd ed. Mich. Coop. Forest Pest Mgmt. Handbk. 95-1. 48 pp.

MacDonald, N.W., J.A. Witter, D.D. Reed, A.J. Burton K.S. Pregetzer, and H.O. Liechty. 1998. Environmental stress effects on tree vigor, mortality, and growth along a pollution-climate gradient. Mich. Acad. 30:27-41.

Witter, J.A. and J.L. Stoyenoff. 1996. Integrated pest management in urban and rural forests. pp. 151-168. In:Forests: A Global Perspective. Majumdar, S.K., E.W. Miller, and F.J. Brenner (eds.). Penn. Acad. Sci.

Stoyenoff, J.L., J.A. Witter, and M.E. Montgomery. 1994. Gypsy moth (Lepidoptera: Lymantriidae) performance in relation to egg hatch and feeding initiation times. Envir. Entomol. 23:1450-1458.

Stoyenoff, J.L., J.A. Witter, and M.E. Montgomery. 1994. Nutritional indices in the gypsy moth (Lymantria dispar (L.)) under field conditions and host switching situations. Oecologia. 97:158-170.

Stoyenoff, J.L., J.A. Witter, M.E. Montgomery, and C.A. Chilcote. 1994. Effects of host switching on gypsy moth (Lymantria dispar (L.)) under field conditions. Oecologia. 97:143-157.

MacDonald, N.W., J.A. Witter, A.J. Burton, K.S. Pregitzer, and D.D. Richter. 1993. Relationships among atmospheric deposition, throughfall, and soil properties in oak forest ecosystems. Can. J. For. Res. 23 :2348-2357.

Chilcote, C.A., J.A. Witter, M.E. Montgomery, and J.L. Stoyenoff. 1992. Intra- and interclonal variation in gypsy moth larval performance on bigtooth and trembling aspen. Can. J. For. Res. 22:1676-1683.

Witter, J. A., J.L. Stoyenoff, and F. Sapio. 1992. Impacts of the gypsy moth in Michigan. Mich. Acad. 25:67-90.

Archambault, L., B.V. Barnes, and J.A. Witter. 1990. Landscape ecosystems of disturbed oak forests of southeastern Michigan, USA. Can. J. For. Research 20:1570-1582.

Witter, J.A. and I.R. Ragenovich. 1986. Regeneration of Fraser fir at Mt. Mitchell, North Carolina, after depredations by the balsam woolly adelgid. Forest Sci.32:585-594.

Lynch, A.M. and J.A. Witter. 1985. Relationships between balsam fir mortality caused by the spruce budworm and stand, site, and soil variables in Michigan