Public Release: 

Beauty Is The Beast: How Rhododendron Bests The Mighty Oak

Virginia Tech

Rhododendron are lovely ornamentals that enhance many landscapes -- but in the hardwood forests of southern Appalachia and England, the showy evergreen shrubs are pests that suppress new growth of hemlocks, oaks, and other valuable trees.

Now researchers have determined how Rhododendron maximum L. rob the competition of nutrients and water - and it's not merely by shading out seedlings and beating them to underground resources. Researchers from the U.S. Forest Service Coweeta Hydrologic Lab in North Carolina and from Virginia Tech will present findings at the Ecological Society of America (ESA) annual meeting (Aug. 10-14, Albuquerque, N.M.) that demonstrate that Rhododendron actually make it impossible for some hardwoods to absorb nutrients.

Many trees and shrubs have established a symbiotic relationship with mycorrhizal fungi, which enhances the plants' ability to absorb water and nutrients, explains Erik Nilsen, professor of ecology at Virginia Tech. "In fact, hemlocks and oaks are dependent on mycorrhyzae."

Rhododendron precludes the fungus from forming an association with the mycorrhizae for some tree species, particularly hemlocks, he explains. This affect, in combination with the limitation of resources results in a situation that the canopy tree seedlings can't lick.

B.D. Clinton of the U.S. Forest Service, Nilsen, and Orson K. Miller Jr., Virginia Tech biology professor, along with Tom Lei, post doctoral student, and Virginia Tech students Shawn Semones and John Walker, have been conducting the research for the last 18 months.

Semones will present the findings on Wednesday, Aug. 13, at 9:30 a.m. (#51,West Complex-lower level-rooms w66,w68,w70), Clinton will present during the Thursday morning session on Ecosystems of Southern Appalachians (#86, convention center room W52, 10:30 a.m.), and there will be a poster presentation by Lei (Poster session 12, Tuesday, Aug. 12, 3:15-5 p.m.).

This year's ESA annual meeting is being held in conjunction with The Nature Conservancy. The theme is "Changing Ecosystems: Nature and Human Influences." The ESA is a scientific, non-profit, 7,200-member organization founded in 1915. Through reports, journals, membership research, and expert testimony to Congress, ESA promotes the responsible application of ecological data and principles to the solution of environmental problems.

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For additional information, contact
Dr. Barry Clinton at or (704)524-2128 ext. 124
Dr. Erik Nilsen after August 19 at (703) 306-1421
or Dr. Orson Miller after classes resume on August 25, (540)231-6765 or 231-5165.
PR Contact: Susan Trulove, 540/231-5646 or

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