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Northern Research Station
One Gifford Pinchot Drive
Madison, WI 53726
(608) 231-9318
(608) 231-9544 TTY/TDD

You are here: NRS Home / Research Programs /Sustaining Forests / Methods to conserve and enhance forest resources / Biodiversity and structural and functional complexity of forests / Long-term Change at Hearts Content and Tionesta Scenic and Research Natural Area
Sustaining Forests

Long-term Change at Hearts Content and Tionesta Scenic and Research Natural Area

Research Issue

Our ability to understand how unmanaged forests develop over time through various climatic and environmental changes depends on long-term data from unmanaged forests, especially remnants of the forest that predated European settlement of our region. Impacts of acid deposition, deer overabundance, beech bark disease, recovery of vegetation after windthrow, climate change, invasive plants – all are better understood by examining their effects in forests that have not been directly manipulated by humans, as well as those that have been managed. Data from unmanaged forests provides a baseline for understanding the impacts of these factors and natural forest development trends.

 Our Research

  • Study implemented at Hearts Content in 1928 by Harold Lutz to study the old growth remnant before all representatives were gone. Overstory was re-measured by Gordon Whitney in 1978, and the study was re-opened and established as a long-term monitoring study in 2000 to describe changes in overstory and understory species composition. Results show a loss of the understory shrub layer and increased frequency of hayscented fern. These results are consistent with the hypothesis that deer browsing has been a principal driver of change in this forest. Number of species on sample plots also has declined over time.
  • Study implemented by Ashbel Hough in 1942 at Tionesta Scenic and Research Natural Area to describe changes in tree reproduction, shrubs, and herbs in the Tionesta Area caused by changes in overstory density, deer browsing, and other factors.
  • It is evident from this photo series and associated data that loss of the shrub layer has allowed for a persistent herbaceous understory dominated by hay scented fern and when gaps appear this fern expands its coverage.
1942 Hobblebush and browsed hemlock
1942 Hobblebush and browsed hemlock
1952 Hobblebush  and hemlock gone
1952 Hobblebush and hemlock gone
1962 Ferns  and herbaceous cover
1962 Ferns and herbaceous cover
1972 Dense hayscented fern
1972 Dense hayscented fern
1982 Hayscented fern and herbs
1982 Hayscented fern and herbs
1992 Hayscented fern and herbs
1992 Hayscented fern and herbs
2002 Hayscented fern and herbs
2002 Hayscented fern and herbs

Expected Outcomes

We expect to continue to develop our understanding of how the old-growth forest responds to changes in the environment. These data allow for more informed management decisions to be made in second growth stands because they are an unmanaged reference and allow for a separation of management impacts and “natural” change.

Research Results

Hough, A.F.  1965. A twenty-year record of understory vegetational change in a virgin Pennsylvania forest. Ecology 46:370-373.

Lutz, H.J. 1928. The Vegetation of Heart's content, A Virgin Forest in Northwestern Pennsylvania. Ecology, Vol. 11(1): 1-29.

Whitney, G. G. 1984. Fifty Years of Change in the Arboreal Vegetation of Heart's Content, An Old-Growth Hemlock-White Pine-Northern Hardwood Stand. Ecology, 65(2) 403-408 .

Bjorkbom, John C.; Larson, Rodney G.  1977.  The Tionesta Scenic and Research Natural Areas. Gen. Tech. Rep. NE-31. Upper Darby, PA: U. S. Department of Agriculture, Forest Service, Northeastern Forest Experimental Station. 24 p.

Research Participants

Principal Investigator

  • Todd E. Ristau, US Forest Service - Northern Reseach Station Research Ecologist

Research Partners

  • Alejandro A. Royo, US Forest Service - Northern Reseach Station Research Ecologist
  • Susan L. Stout, US Forest Service - Northern Reseach Station Research Silviculturist and Project Leader
  • Gordon Whitney, Allegheny College, Meadville, PA

Last Modified: 01/27/2010