Survival and Growth of Three Invasive Plant Species in Five Different Forest Management Regimes across a Moisture Gradient

Research Issue

Forest site conditions (natural and anthropogenic, including forest management regimes) that restore native species composition to more desirable and sustainable conditions as well as decrease the likelihood of invasion by exotic plants need to be better defined. 

Our Research

Use of fire and harvesting to manage Eastern oak forests may facilitate invasion of these ecosystems by nonnative invasive plant species (NNIS).  Like oaks, NNIS may respond positively to an increase in light caused by disturbance.  This is especially true for intensive harvesting. Plant response to such treatments and fire behavior are also likely to vary across large- and small-scale moisture gradients.  Our first objective is to evaluate NNIS response to diameter-limit cutting compared to fire and shelterwood harvesting at both landscape and micro-topographic scales. Our study area includes the Ridge and Valley and Allegheny Plateaus Provinces in West Virginia and Ohio and north and south-facing slopes as landscape and topographic blocking factors, respectively.  Five forest management types will be evaluated, including single burns, repeat burns, shelterwood harvests, diameter-limit harvests, and no management.  Growth of three regionally problematic NNIS (Ailanthus altissima, Microstegium vimineum, and Alliaria petiolata) and the native species Quercus rubra will be evaluated in uninvaded sites. Secondly, we will compare dispersal rates and seed dormancy patterns of sites that have already been invaded.  We will also evaluate light thresholds for the three NNIS compared to Quercus rubra.  Finally, we will incorporate the site vulnerability, propagule pressure, and critical light level information into forest growth and yield models for each management type. Our findings will enable land managers to prioritize areas to burn or harvest or delay management. 

Expected Outcomes

Our earlier research (cited below) reveals that exotic plants tend to prefer resource-rich sites (i.e., ample water, light, and nutrients) during the early-establishment stage.  We, thus, anticipate that the more mesic sites of this new study will show the greatest survival and growth of the three focus NNIS. Because many native species also are more likely to be found on resource-rich sites, we expect to see a correlation of survival and growth with native species richness.  We also anticipate that the disturbances resulting in the most canopy opening (shelterwood and diameter limit harvests) will result in the greatest invasions and greatest positive native species response.  We hope to define a fine enough gradient that shows a point where positive native species response is increasing but positive invasive species survival and/or growth is beginning to decline. This response is likely to vary among the three species.  

Actual Outcomes

There were 363 species in our study area. Composition differed by province and aspect. Composition also differed by disturbance but with a significant province interaction. Although physiography was more important, some species served as disturbance indicators that differed by disturbance type with two possible outcomes. First, expected successional trajectories (as defined by the regional and local environmental filters) may deviate toward recovery of native species (e.g., Epigaea repens) that benefit from low-level disturbance (as defined by fire as a filter). Second, successional trajectories after a relatively severe disturbance (as defined by shelterwood harvest as a filter) may deviate toward systems that are vulnerable to invasion by exotics or dominant native species. Ridge and Valley (RV) sites have more open canopies, lower soil fertility, and lower plant species richness than Allegheny Plateau (AP) sites; northeastern (NE) aspects have higher soil fertility and plant species richness than southwestern (SW) aspects. Shelterwood sites have the most open canopies. Germination rates of all three invasive plant species are below 25%, but lowest in the control sites and higher in the RV and on NE aspects for all three species. Survival is above 70% for A. altissima, M. vimineum, and Q. rubra but below 20% for A. petiolata, with little difference among province, aspect, or management regime for all three species. Survival decreases significantly between measurements. Microstegium vimineum has the highest growth rates of the three species. Microstegium vimineum and A. petiolata grow best in shelterwoods and better in the RV and on NE aspects. Ailanthus altissima has more root growth in the RV than the AP and the least root growth in the control sites. Quercus rubra survived better in the RV and best in the harvested sites, though growth does not differ among the management regimes. These invasive species are similar to many native species during the early stages of colonization; their germination, survival and growth are initially precarious and dependent on adequate resources (NE aspects) with minimal competition (RV province). Our results suggest that the likelihood of colonization by invasive plants could be reduced by keeping canopy openings below 15% and encouraging native understory competition with deer exclusion and artificial regeneration where native seed sources are depleted.

Research Results

Redwood, Mame E.; Matlack, Glenn R.; Huebner, Cynthia D. 2019. Seed longevity and dormancy state in an invasive tree species: Ailanthus altissima (Simaroubaceae). The Journal of the Torrey Botanical Society. 146(2): 79-86.

Huebner, Cynthia D.; McGill, David W. 2018. The importance of disturbance versus physiography in defining vegetation composition and predicting possible successional trajectories. Castanea. 83(1): 54-76.

Huebner, Cynthia D.; Regula, Adam E.; McGill, David W. 2018. Germination, survival, and early growth of three invasive plants in response to five forest management regimes common to US northeastern deciduous forests. Forest Ecology and Management. 425: 100-118.

Redwood, Mame E.; Matlack, Glenn R.; Huebner, Cynthia D. 2018. Seed Longevity and Dormancy State Suggest Management Strategies for Garlic Mustard (Alliaria petiolata) and Japanese Stiltgrass (Microstegium vimineum) in Deciduous Forest Sites. Weed Science. 66(02): 190-198.

Huebner, Cynthia D.; Morin, Randall S.; Zurbriggen, Ann; White, Robert L. 2009. Patterns of exotic plant invasions in Pennsylvania''s Allegheny National Forest using intensive Forest Inventory and Analysis plots. Forest Ecology and Management. 257: 258-270.

Huebner, Cynthia D.; Tobin, Patrick C. 2006. Invasibility of mature and 15-year-old deciduous forests by exotic plants. Plant Ecology 186:57-68

Huebner, Cynthia D. 2003. Vulnerability of oak-dominated forests in West Virginia to invasive exotic plants: temporal and spatial patterns of nine exotic species using herbarium records and land classification data. Castanea. 68(1): 1-14.

Research Participants

Principal Investigator

  • Cynthia D. Huebner, USDA Forest Service, Northern Research Station, Research Botanist / Ecologist

Research Partners

  • Last modified: January 6, 2020