Research Issue
![[image:] Primary, secondary, and tertiary impacts of deer on forest understory communities](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_tSYmv4wbRncKWOqzQsQkE8sURTuJY4FsL3y3nFAoSeiZgyUe8JAVSAgaKESEnYTQS06QxIUKKvdO58akhObq_8qwkNp9oycBrvgOthloE2hIy6PrjnXmzI8a45zZo5RsYBTGkL6GCvcaMDtz2hWE6yomH4BX6YDf0eqg=s0-d)
Overabundant white-tailed deer (Odocoileus virginianus) herds have been shown to be a key determinant of understory plant species composition in many parts of eastern North America over the last century. The primary, direct effect of chronic overbrowsing is the reduction in growth and survival of browse-intolerant plant species which ultimately shifts species composition towards a few highly browse-tolerant or unpalatable species. Such shifts in plant dominance patterns may secondarily result in altered plant-plant competitive dynamics in forests understories. Finally, through modification of plant composition and structure, deer overbrowsing may also exert indirect effects on the habitat and foraging patterns of other animal species.
http://www.nrs.fs.fed.us/sustaining_forests/conserve_enhance/timber/contrasting_silvicultural_systems/
Overabundant white-tailed deer (Odocoileus virginianus) herds have been shown to be a key determinant of understory plant species composition in many parts of eastern North America over the last century. The primary, direct effect of chronic overbrowsing is the reduction in growth and survival of browse-intolerant plant species which ultimately shifts species composition towards a few highly browse-tolerant or unpalatable species. Such shifts in plant dominance patterns may secondarily result in altered plant-plant competitive dynamics in forests understories. Finally, through modification of plant composition and structure, deer overbrowsing may also exert indirect effects on the habitat and foraging patterns of other animal species.Our Research
Over the past 50 years we have examined deer impacts on forest vegetation. Preliminary research showed the effects of deer overabundance on understory species composition. In the early 1970s, localized studies using exclosures clearly demonstrated that protection from browsing was necessary to regenerate forests in Pennsylvania’s Allegheny Plateau region. By the 1980’s we moved beyond exclosure approaches to complete a stand-level enclosure study where vegetation development was monitored at 4 different known deer densities in four separate 160 acre sites. Our current work builds upon these prior efforts by scaling up at to examine deer impacts at the landscape. Across nearly 74,000 acres in the Kinzua Quality Deer Cooperative, deer population monitoring and extensive vegetation surveys are providing information on how both woody and herbaceous species respond to a systematic drop in deer levels. Furthermore, we are extending our work to evaluate how deer browsing interacts with other factors (e.g., canopy gaps and fire) to influence vegetation structure.
Results from this research and other regeneration research conducted by our unit in northwestern PA led to a partnership between the PA DCNR Bureau of Forestry and the US Forest Service Forest Inventory and Analysis (FIA) unit to include more detailed regeneration data collection on a subset of plots in Pennsylvania. The results from these statewide studieshad a substantial influence on statewide forest and deer management policies.
Expected Outcomes
Results from our deer impact work continue to inform private, state, and federal forest resource management agencies, particularly in the specific management treatment sequence necessary to promote sustainable silviculture in the Allegheny region. Our current work will provide insight into overcoming legacy effects of nearly a century of overbrowsing in the Allegheny region in order to sustain and promote biodiversity. We will continue to improve our deer population/deer impact techniques including work on indicator plant species. Finally, we will elucidate how deer impacts interact with other disturbances.
Research Results
Krueger, Lisa M., Peterson, Chris J., Royo, Alejandro, and Carson, Walter P., 2009. Evaluating relationshiops among tree growth rate, shade tolerance, and browse tolerance following disturbance in an eastern deciduous forest. Canadian Journal of Forest Research. 39: 2460 - 2469.
Reitz, S., A. Hille, and S. Stout. 2004. Silviculture in cooperation with hunters: The Kinzua Quality Deer Cooperative. In: Shepperd, W.D. and L.G. Eskew, compilers. Silviculture in special places: Proceedings of the National Silviculture Workshop. September 8-11, 2003, Granby, Co. Proceedings RMRS-P-34. Ft. Collins, CO, USDA Forest Service, Rocky Mountain Station, pp. 110-126.
Horsley, S.B., S.L. Stout, and D.S. DeCalesta. 2003. White-tailed deer impact on the vegetation dynamics of a northern hardwood forest. Ecological Applications 13(1): 98-118.
Marquis, D.A. 1981. Effect of deer browsing on timber production in Allegheny hardwood forests of Northwestern Pennsylvania. Res. Pap. NE-475. Broomall, PA: USDA Forest Service, Northeastern Forest Experiment Station. 10pp.
Research Participants
Principal Investigators
- Alejandro A. Royo, USDA Forest Service- Northern Research Station Research Ecologist
- Susan Stout, USDA Forest Service- Northern Research Station Project Leader/Research Forester
Research Partners
- Todd Ristau, USDA Forest Service- Northern Research Station Research Ecologist
- Stephen B. Horsley, USDA Forest Service- Northern Research Station Scientist Emeritus
- David DeCalesta, USDA Forest Service, Retired.
- Kevin McAleese, Sand County Foundation.
- Chris Peterson, University of Georgia
- Lisa Krueger, University of Georgia
- Walter P. Carson, Univesity of Pittsburgh
http://www.nrs.fs.fed.us/sustaining_forests/conserve_enhance/timber/contrasting_silvicultural_systems/
![[image:] Participants in a SILVAH Training Session conduct a systematic inventory of forest overstory and understory as part of a field exercise in the course.](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_v-SZfAZc_hq6UYXS7UIdCsVXPx7qQslgd3HzBtKx8xsTE1pjYxXU4dAQOc78TJ2U483hhtdgjIp3ea-qmbv1j9PwUnSUL3Z_r2OW-Gc2gMZkoht6XlbgXb2F0L6JKzwh3_N_uBLc5C2pLipOO-vS1-v9XZOg=s0-d)
When research results point to needed changes in forest management practice, it is often challenging to communicate those changes in practice to decision-makers and practitioners in land management agencies. SILVAH, a systematic framework integrating forest stand inventory, assessment, and prescription development supported by ![[image:] Top map shows the Racoon Ecological Management Area (Thin and Burn treatment) in 2000, before thinning and two burns, for 'competitiveness' for oaks and hickories. Bottom map shows the same (plus percent open sky as size of circles) after treatments and sampled in 2006. Blue points show non-competitive oaks, while red points show reasonably competitive oaks are present. Background colors reflect the integrated moisture index. See the featured publication for more details.](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_uwhXPhFVvqbIrsc11YmZbHL7EJGx3RshMDBdukkpN1XLvuyqJ8Zh80vwvEbCcLT3xQyt0baCk7lvWJ1Rm5Es03kaAui6U3qKwgp63mT2CuLpVY5l4hYo7HhEcOFqzH9jHtongmIy-wBqQednb-aCCty5yHg5BDjQc=s0-d)
Oak regeneration continues to be a problem in the Central Hardwoods region of the US. In the absence of regular fire (as was common before European settlement and fire regulatory agencies in the ~1920’s), the canopy closes and oak regeneration is often preempted by more shade-tolerant species like maples. The ![[image:] Graph shows relation of basal area, umber of trees, and average tree diameter to stocking percentage for upland central hardwoods.](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_tcvUwk21bY0fcvUPA_kevVJn2bM4QQeu_AEKO2aAtOo-X01T13XIqDCixyc-TauSqiPUmOmMLPfCOgLuhDBp-22xRGjPbFEpJ_YBptdc8AEXHqJKEfusTB8gp9sfu2YHAxu0Ibgeg7Mc42F3D26FcxiQDIPJo=s0-d)
Research Issue![[image:] The Tionesta Research Natural Area as seen in 2004 with beech mortality over 40%. The mortality reached 52% in 2006 and shows no sign of diminishing (see figure below). The foreground is an old Tornado swath of a much younger age class.](https://lh3.googleusercontent.com/blogger_img_proxy/AEn0k_vsaq8ULiOdCNpWkMevqDVv5U55pzgSGKAyYQw1dm4XWgW_kCT4JqP8zXODVMFaj_2vXf757j-WRB-isSCA4EenHMJvPbFQZMB8vXndLSiE4j8Qvirsb-CwKrcCGHWKoL9cfS9qGVobNYhuCld82-J7iwHwmWCK-AlsKTjQgA=s0-d)
Aerial photos of the Tionesta Scenic and Research Natural area revealed large areas of discoloration of foliage and defoliation suspected to be beech bark disease (BBD). In 2000, very high populations of the beech scale (Cryptococcus fagisuga) were observed when ground-truthing these areas of discoloration on the Tionesta Scenic and Research Natural Area. In anticipation of mortality, a small number of American beech trees were selected for continued monitoring. These trees were selected to mirror existing long term BBD monitoring plots elsewhere in its range. With beech mortality reaching 52% in 5 years it became obvious that the impact of BBD on old growth American beech-eastern hemlock forest required a more in-depth evaluation. We turned to plots installed by George Zimmermann in 1980. He established a grid of 676 plots on this 855 hectare remnant of unmanaged old growth hemlock–beech forest. In 1998 and 1999 USDA personnel relocated 588 of these plots and documented their GPS location and differential correction. 
