Scientists & Staff

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Alejandro Royo

Research Ecologist
335 National Forge Road
Irvine, PA, 16329-0267
Phone: 814-563-1040

Contact Alejandro Royo

Current Research

My main research focus investigates the role of the factors that regulate the diversity and abundance of vascular plants in forest understories.  These drivers include natural and anthropogenic disturbances, herbivory, competing vegetation, pests and pathogens, and climate change.  I am involved in multiple projects throughout the United States and Canada asking questions on various subsets of these forces on plant diversity.  These projects range from invasive pests decimating Ash populations, to American chestnut reintroduction efforts, to ungulate impacts on plant communities, to the role climate-adaptive management strategies can play in mitigating climate change effects on forests.

Research Interests

I plan on continuing my research programs on the maintenance of tree and herbaceous species diversity in both temperate hardwood and mixed-wood systems in the tension zone between the temperate hardwoods and boreal systems.

Past Research

Past research had a focus on the maintenance of herbaceous species diversity in both temperate and tropical systems and the role of seed-banking as a mechanism to retain and promote diversity in forests.  A substantial part of my early work was on the role of recalcitrant understory layers inhibiting plant diversity, the impact of soil-borne pathogens on early tree establishment, and forest recovery following catastrophic wind disturbance and salvage logging.

Why This Research is Important

Among the many factors that determine forest understory diversity prior to any overstory disturbance, competition and herbivory are typically thought of as preeminent. Understanding how these two factors, alone and in concert, act to promote or reduce plant diversity is key to the sustainable management of forest resources.


  • University of Pittsburgh, Ph.D. Ecology and Evolutionary Biology, 2005
  • University of North Carolina, Greensboro, M.S. Department of Biological Sciences, 1998
  • University of North Carolina, Greensboro, B.A. Department of Biological Sciences, 1993
  • University of Pittsburgh, Graduate Certificate Latin American Studies, 2005

Professional Organizations

  • Ecological Society of America

Featured Publications & Products

Publications & Products

National Research Highlights

Researcher injecting an ash tree with insecticide.

Genetic Information on Ash Informs Treatments for Emerald Ash Borer 

Year: 2018

Forest managers can use insecticide treatments to protect ash trees from emerald ash borer to conserve the genetic diversity of ash. But which trees should be protected? Research at the Allegheny National Forest is underway to develop new strategies to conserve ash tree diversity.

Managing the foodscape to alleviate deer browsing

Year: 2017

Forest plant biodiversity is being degraded by browsing from overabundant deer herds, but forest management can alleviate impacts. Research by Forest Service scientists and their partners has expanded understanding of how forage availability throughout the landscape, or the “foodscape,” influences browsing to provide guidelines forest managers can use to reduce browse impacts.

Maple stump with browsed sprouts outside fence and unbrowsed, tall sprouts within fence. Alejandro A. Royo, U.S. Department of Agriculture Forest Service.

Sprouts as Rapid Bioassays of Browse Impact

Year: 2016

Effective browse pressure indicators are necessary to adaptively manage forest landscapes with resident deer. Hardwood tree stump sprouts are a reliable and easily measured phytoindicator in disturbed forests. Deer browsing reduced sprout height by 39 percent when averaged across tree species. Browse impacts on sprout height at local (2.5 acre) scales is a valuable indicator of estimated deer densities at larger (1 square mile) scale.

Salvage operation following windthrow in the Allegheny high plateau region. USDA Forest Service

International Symposium Improves Understanding of Disturbance and Salvage Logging and Forest Sustainability

Year: 2015

The Forest Service’s Northern Research Station along with the University of Pittsburgh and the Carnegie Museum of Natural History sponsored an international symposium in May 2015 where international research teams and forest managers addressed the ecological and economic costs and benefits of disturbance and salvage logging in diverse forest biomes and disturbances.

Greenhouse seed bank germination trials with closeup of one tray. Todd E. Ristau, Forest Service

Can We Bank on Forest Seed Banks

Year: 2012

Community composition of seeds stored in forest soils becomes increasingly divergent over time

Various fern species growing on the Bisley Experimental Watersheds are important to forest succession in the Luquillo Experimental Forest. Omar Perez Reyes, College of Natural Resouces, Utah State University

Hurricanes Disturb Non-tree Subtropical Wet Forest Species Composition

Year: 2011

Hurricane disturbance caused pronounced and persistent changes in the non-tree species composition of a subtropical wet forest. A unique long-term Forest Service dataset tracked the response and recovery of tropical forest herb, shrub, and vine communities to multiple hurricanes over 21 years on the 13-ha Bisley Experimental Watersheds in the Luquillo Experimental Forest, Puerto Rico.

Landscape-level Deer Herd Reductions Restore Forest Understory Plant Communities but Not Species Diversity

Year: 2010

Since 2001, NRS scientist Alejandro Royo has tracked the response of herbaceous plant communities to deer herd reductions throughout the 70,000-acre Kinzua Quality Deer Cooperative (KQDC) in northwestern Pennsylvania.

Last modified: Wednesday, September 30, 2020