William Sharpe, Ph.D.

Academic Interests

Affiliated Programs

Intercollege Graduate Degree Program in Ecology .

Professional Affiliation

American Geophysical Union

American Fisheries Society

American Waterworks Association

Pennsylvania Forestry Association

Recent Research/Educational Projects

The relationship of soil acid-base status and plant available aluminum to sugar maple decline Although gross growth data may indicate that sugar maple throughout the Northeast appears to be healthy and growing; well, regional and local declines are problematic. More than 100,000 acres of the Allegheny National Forest are reported to be suffering from some degree of sugar maple decline. Symptoms begin with discoloration of foliage (chlorosis) and gradual crown deterioration which worsens gradually until the affected tree dies. No specific cause or causes of this decline have been determined. We are evaluating soil acidification as a predisposing stress for the decline, with emphasis on calcium, magnesium, and potassium nutrition and aluminum toxicity.

The role of soil acidification in northern red oak decline in southwestern Pennsylvani Southwestern Pennsylvania has historically perceived large amounts of acidic deposition. The region suffers from acidic runoff episodes that have resulted in the extirpation of all fish from many headwater streams. In recent years, mortality of northern red oak and northern red oak regeneration problems have become evident. Preliminary work indicates that soil acidity is a major factor in both the tree decline and the regeneration problem. This research program will hopefully lead to appropriate silvicultural and management schemes to alleviate these problems.

Acid runoff episodes Current work is directed to the effects of acid runoff episodes in Stone Run on brook trout and slimy sculpin. The importance of chemical refugia in sustaining brook trout in Stone Run has recently been investigated. In addition, study of the spawning behavior of slimy sculpin in the presence of acid runoff episodes is under investigation. Although gross growth data may indicate that sugar maple throughout the Northeast appears to be healthy and growing; well, regional and local declines are problematic. More than 100,000 acres of the Allegheny National Forest are reported to be suffering from some degree of sugar maple decline. Symptoms begin with discoloration of foliage (chlorosis) and gradual crown deterioration which worsens gradually until the affected tree dies. No specific cause or causes of this decline have been determined. We are evaluating soil acidification as a predisposing stress for the decline, with emphasis on calcium, magnesium, and potassium nutrition and aluminum toxicity.

Selected Publications

Heard, R.M., W.E. Sharpe, R.F. Carline, W.G. Kimmel.  1997. Episodic acidification and changes in fish diversity in Pennsylvania headwater streams. Transactions of the American Fisheries Society. 126:977-984.

Hart, D.H. and W.E. Sharpe.  1997. Response of potted northern red oak and hay-scented fern to additions of calcium, magnesium, potassium, and phosphorus. Proceedings 11th Central hardwood Forest Conference, USFS North Central Forest Experiment Station, Gen. Tech. Rpt. NC-188:304-312.

Drohan, J.R. and W.E. Sharpe. 1997. Long-term changes in forest soil acidity in Pennsylvania, USA. Water, Air, Soil Pollution 95:299-311.

Van Sickle, J., J.P. Baker, H.A. Simonin, B.P. Baldigo, W.A. Kretser, and W.E. Sharpe. 1996. Eipsodic acidification of small stream in the Northeast United States. III: Effects on fish mortality during field bioassay. Ecological Applications 6(2):408-421. Sharpe, W.E. and B.R. Swistock.  1996. Soil acidification and sugar maple decline in northern Pennsylvania. Maple Syrup digest 8A(1):32-35.

Pickens, C.J. and W.E. Sharpe. 1996. Comparative resiliency of red oak and red  maple seedlings to simulated deer browsing and acid precipitation stress.  IUFRO Air Pollution and Multiple Stresses, Proceedings of the 16th International Meeting for Specialists in Air Pollution Effects on Forest Ecosystems, Sept. 7-9, 1994, Fredericton, new Brunswick.

Lyon, J. and W.E. Sharpe.  1996. Hay-scented fern (Dennstaedtiapunctilobula [Michx.] Moore) interference with the growth of northern red oak (Quercusrubra L.) seedlings. Tree Physiol. 16:923-932.

Baker, J.P., J. Van Sickle, C.J. Gagen, D.R. DeWalle, W.E. Sharpe, R.F. Carline, B.P. Baldigo, P.S. Murdoch, D.W. Bath, W.A. Kretzer, H.A. Simonin, and P.J. Wigington, Jr. 1996. Episodic acidification of small streams in the Northeast United States. IV: Effects on fish populations. Ecological Applications 6(2):422-437.

Carline, R.F., C.J. Gagen, and W.E. Sharpe. 1994. Brook trout (Salvelinus fontinalis) population dynamics and mottled sculpin (Cottus bairdi) occurrence in relation to acidic episodes in streams. Ecology of Freshwater Fish 3:107-115.

Dow, C.L., D.R. DeWalle, J.A. Lynch, and W.E. Sharpe. 1994. Blizzard's effects on stream chemistry assessed. EOS, Trans. Amer. Geophy. Union 75:389-390.

Gagen, C.J., W.E. Sharpe, and R.F. Carline. 1994. Downstream movement and mortality of brook trout (Salvelinusfontinalis) exposed to acidic episodes in streams. Can J. Fish. Aquatic Sci. 51:1620-1628.