Papers by Cynthia Huebner
Forests
The goal of this study was to discover the nature and intensity of the interaction between an exo... more The goal of this study was to discover the nature and intensity of the interaction between an exotic invader Ailanthus altissima (Mill.) Swingle and its coexisting native Robinia pseudoacacia L. and consider management implications. The study occurred in the Mid-Appalachian region of the eastern United States. Ailanthus altissima can have a strong negative influence on community diversity and succession due to its allelopathic nature while R. pseudoacacia can have a positive effect on community diversity and succession because of its ability to fix nitrogen. How these trees interact and the influence of the interaction on succession will have important implications for forests in many regions of the world. An additive-replacement series common garden experiment was established to identify the type and extent of interactions between these trees over a three-year period. Both A. altissima and R. pseudoacacia grown in monoculture were inhibited by intraspecific competition. In the first year, A. altissima grown with R. pseudoacacia tended to be larger than A. altissima in monoculture, suggesting that R. pseudoacacia may facilitate the growth of A. altissima at the seedling stage. After the second year, R. pseudoacacia growth decreased as the proportion of coexisting A. altissima increased, indicating inhibition of R. pseudoacacia by A. altissima even though the R. pseudoacacia plants were much larger aboveground than the A. altissima plants. In early successional sites A. altissima should be removed, particularly in the presence of R. pseudoacacia in order to promote long-term community succession.
Forest Ecology and Management
Weed Science
An effective management plan for invasive herb populations must consider the potential for regene... more An effective management plan for invasive herb populations must consider the potential for regeneration from the soil seedbank. To test this potential, we examined two species, Japanese stiltgrass and garlic mustard, at deciduous forest sites in southeastern Ohio. Seeds were buried in nylon mesh bags and recovered at regular intervals over 24 mo. Recovered seeds were tested for germination and viability. Burial was replicated on north- and south-facing slopes to test for environmental control of dormancy state. Stiltgrass seeds experienced severe mortality in the soil, rarely surviving the full 24 mo. Stiltgrass showed fractional germination in the lab ranging from 86% to 89% of viable seeds in late spring (the season of natural seedling emergence) to complete nongermination in winter. Most garlic mustard seeds survived through the experimental period (82% and 88% survival across 24 mo) with consistently low mortality (0% to 13%) unrelated to season. Slope aspect had no significant ...
Invasive Plant Science and Management
Nonnative M. vimineum has been expanding rapidly in the eastern United States, where it can negat... more Nonnative M. vimineum has been expanding rapidly in the eastern United States, where it can negatively affect plant communities. Locally, the species is assumed to spread from roadsides into nearby forests, where it can form dense populations after disturbances, especially in light gaps. Using microsatellite markers, we quantified patterns of genetic variation and structure among populations at nine sites in West Virginia. We then examined patterns of local dispersal within each population, focusing on subpopulations along the roadside, those coalescing nearby along the forest edge, and subpopulations in the interior forest. We found that levels of genetic variation of M. vimineum were relatively low overall across populations but with genetic structure present among populations (Fst = 0.60). Within populations, subpopulations along the roadside were genetically variable, containing 4 to 22 unique, multilocus genotypes. Many of these genotypes were also identified in the adjacent fo...
Seed Science Research
Does seed dormancy allow disturbance-oriented forest herbs such asAgeratina altissimato persist i... more Does seed dormancy allow disturbance-oriented forest herbs such asAgeratina altissimato persist in heterogeneous natural communities? To document seed longevity and dormancy state,Ageratinaseeds were buried in nylon mesh bags in second-growth forest stands in south-eastern Ohio, USA. Bags were recovered at 2-month intervals, and seeds were tested for viability and germinability in the lab. Live seed numbers declined rapidly, with seed banks exhausted in an estimated 33–37 months. Seeds showed a strong dormancy polymorphism, with 71–84% of live seeds germinable between March and July, the season of natural seedling emergence. At other dates, most seeds appeared to be in a state of induced dormancy, allowing little (0–21%) germination. The slope aspect of the burial site, an important factor controlling above-ground vegetation, had no effect on seed longevity or dormancy condition. Dormancy inAgeratinaappears to be adapted to allow opportunistic germination in late spring–early summer...
Scutellaria saxatilis Riddell (smooth rock skullcap or rock skullcap, hereafter abbreviated as SR... more Scutellaria saxatilis Riddell (smooth rock skullcap or rock skullcap, hereafter abbreviated as SRS), a herbaceous perennial in the mint family, is a globally rare (G3) plant. In West Virginia, SRS is categorized as an S2 species (imperiled and at high risk of extinction due to a very restricted range, very few [<20] documented occurrences, or steep declines). The purpose of this study was to determine the effects of fire on SRS in West Virginia. Two forested sites (70+ years of age) within the Monongahela National Forest with no evident disturbance and with SRS populations of >1,000 individuals were selected, one in a burn area and the other in a nonburn area. Sites were sampled in early September of 2008 and 2009 (pre-burn) and 2010 and 2011 (postburn). The prescribed burn occurred in April and early May of 2010. A generalized linear mixed model with repeated measures and a spatial covariance matrix was used to determine the effects of the burn on SRS cover and associated variables including total vegetation cover, species diversity, bare ground, and litter cover. Bare ground cover increased and litter cover decreased in 2010 in response to the fire. Control and pre-burn sites did not differ significantly in terms of SRS cover over the 4-year period. The cover of SRS increased significantly in 2010 (first year postburn) compared to both pre-burn years, but decreased to pre-burn levels by 2011. Total cover of other understory vegetation increased significantly in 2010 and continued at 2010 levels in 2011 at the burn site. Thus, SRS has a temporary positive response to prescribed fire, but an increase in other ground vegetation may prevent a sustained positive response.
While dominant throughout much of the eastern United States, a recent decline in oak regeneration... more While dominant throughout much of the eastern United States, a recent decline in oak regeneration has merited substantial research. Ultimately, successful regeneration entails the establishment of advance reproduction of sufficient size and density to provide a high probability of ascendancy to dominant or co-dominant status. Potential prescriptions for achieving this include manipulation of light infiltration and control of competing vegetation through shelterwood harvests and prescribed burning. Diameter-limit cutting is a method used on private forests which creates diverse post-harvest conditions which can favor fastgrowing, shade-intolerant competition or shade-tolerant species depending on initial stand structure and diameters harvested. This study examines the effect of five management regimes on northern red oak (Quercus rubra L.) underplantings through a 2-year assessment of 1+0 bareroot seedlings. Treatments consist of: (1) control sites with no disturbance for at least 40 years; (2) a single prescribed burn; (3) repeat prescribed burns; (4) shelterwood harvests (average 25 percent residual basal area); and (5) diameter limit cuts removing merchantable trees of a minimum diameter. Each treatment is replicated on two sites within the Ridge and Valley physiographic province of West Virginia and Virginia. Transects are established on the east-northeast and south-southwest aspect of each site. Deer fences were constructed on half of all plots to test for the effect of deer herbivory. Survival after the first and second growing seasons is presented. No statistically significant differences in survival were found among management regimes in either year. Both first-and second-year results showed fencing to significantly increase survival. The fence x management regime interaction was also significant in both years. Survival on south-southwest aspects was statistically greater than on east-northeast aspects after two growing seasons.
Description: Supplement 1 makes the following changes to the original guide, which was published ... more Description: Supplement 1 makes the following changes to the original guide, which was published in 2004.? Replaces the title page.? Corrects and clarifies information in the original guide for two species: Microstegium vimineum (Japanese stiltgrass) and Rosa ...
Hierarchical Partitioning Analysis measures how much variation is explained by each variable when... more Hierarchical Partitioning Analysis measures how much variation is explained by each variable when they are simultaneously included in the regression model. Best Subset Analysis counts how many models out of a set of 20 "better" models included each explanatory variable.
ABSTRACT Background/Question/Methods Soil fertility gradients have received less attention than s... more ABSTRACT Background/Question/Methods Soil fertility gradients have received less attention than soil moisture gradients, topography, and local disturbances as factors that define vegetation distribution patterns. A summary of Forest Inventory and Analysis data has confirmed vegetation gradients for Kalmia latifolia, an interfering native shrub, and Rosa multiflora, a nonnative invasive shrub, in West Virginia, Pennsylvania, and Ohio.The purpose of this research is to determine whether or not a soil fertility gradient may help explain these vegetation patterns.We evaluated the regional scale by sampling four 1-km transects in each of the three states. The local scale was evaluated by using K. latifolia and R. multiflora as focal species. Ten shrubs of each species in each state were randomly selected and plots were established using each shrub as the center point. The transect and shrub plots were randomly selected in forests that were at least 70 years of age. Soil samples were collected from the B horizon. Additional data collected included species richness and diversity, canopy and subcanopy tree basal area, aspect, slope, elevation, light, and canopy opening. Data were analyzed using a generalized linear model. Results/Conclusions Results of both the regional scale and shrub-specific local scale confirmed a soil pH and fertility gradient, revealing higher soil pH, Ca, K, and Mg values in Ohio followed by Pennsylvania then West Virginia. An inverse relationship was found for total N and C as well as Mn, Fe, and Zn. Rosa multiflora plots were significantly associated with higher levels of plant species diversity, soil pH, Ca, K, and Mg than found for K. latifolia. Rosa multiflora’s tissue was typically higher in total N, as well as Ca, P, K, Mg, and Fe. Kalmia latifolia was limited to relatively extreme acidic sites in Ohio, even more acidic than the K. latifolia plots in Pennsylvania and West Virginia. Kalmia latifolia may be limited by Mn and Zn. However, the extreme acidity on which K. latifolia was found in Ohio may also result in absorption of Mn at toxic levels. These results enable us to predict that invasion of R. multiflora is more likely in areas of high soil fertility. Invasion of K. latifolia is more limited and less likely in areas of high soil fertility or low acidity. While elevation, moisture gradients, and historic disturbances play an important role in the current distribution of both species, our data show that soil pH and nutrients are also significant factors.
J Torrey Bot Soc, 2007
Ailanthus altissima tree seedlings were excavated from each of two habitats: (1) a forest adjacen... more Ailanthus altissima tree seedlings were excavated from each of two habitats: (1) a forest adjacent to a trail and stream and (2) a non-forested steep, barren slope adjacent to a major highway. Each seedling root system was examined for colonization by mycorrhizal structures using light microscopy and transmission electron microscopy. The roots were colonized by one or more endomycorrhizal fungi with Arum-type colonization. Endomycorrhizal colonization of the seedlings from the non-forested site (65.2%) was significantly greater than that of the seedlings from the forested site (37.9%). Colonization by intercellular hyphae and vesicles was significantly greater in the non-forested habitat than the forested habitat. This exotic invasive species may benefit from the rapid colonization of endomycorrhizae in more extreme open environments.
Description: Supplement 1 makes the following changes to the original guide, which was published ... more Description: Supplement 1 makes the following changes to the original guide, which was published in 2004.? Replaces the title page.? Corrects and clarifies information in the original guide for two species: Microstegium vimineum (Japanese stiltgrass) and Rosa ...
In this chapter, we evaluate nonnative invasive plant species of the urban-rural-natural area gra... more In this chapter, we evaluate nonnative invasive plant species of the urban-rural-natural area gradient in order to reduce negative impacts of invasive plants on native species and ecosystems. This evaluation includes addressing (i) the concept of urban areas as the primary source of invasive plant species and characteristics of urban nonnative plants, including their documented impacts on associated native plants and biodiversity along the urban-rural-natural area gradient, (ii) the most vulnerable land uses and potential barriers to invasion along the urban-rural-natural area gradient, and (iii) possible mitigation of invasions and urbanization using restoration or rehabilitation. Finally, we introduce three possible solutions: (i) use of spatially explicit land use planning and management that places invasion barriers between the urban core and the rural-natural area interfaces, (ii) increasing native and exotic species interactions within the urban core and rural-natural area interface, thereby increasing the number of pathogen and enemy interactions or the loss of novel weapons, and (iii) changing the horticultural trade and people's behavior, such that propagule pressure is kept below threshold levels required by growing invasive plant populations. The rate of urbanization in the United States is increasing (Alig et al., 2004); more than 8% of U.S. land may be classified as urban by the year 2050 (Nowak and Walton, 2005). Urbanization rates are on the rise globally as well (United Nations Population Division, 2006; Grimm et al., 2008). Among other ecological impacts, the expansion of urban areas is potentially increasing the rate of plant invasions and the extent of their corresponding effects on native plant species (Kareiva et al., 2007; McDonald et al., 2008; Williams et al., 2009). The goal of this chapter is to evaluate the reduction and containment of nonnative invasive plant species along the urban-rural-natural area continuum to prevent or alleviate their negative impacts on native species. Such negative impacts include local and global homogenization of plant species (McKinney, 2006), native species and community compositional changes, the displacement of native plant populations (Moffatt et al., 2004), and cascading effects on associated fauna (Callaway and Maron, 2006; Kagata and Ohgushi, 2006). We have organized this chapter into three sections: (i) urban areas as biodiversity hot spots and the primary source of nonnative invasive plant species, (ii) the urban-rural-natural area gradient in which both sites vulnerable to invasion and potential barriers to invasion
altissima (Mill.) Swingle) and garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande) wer... more altissima (Mill.) Swingle) and garlic mustard (Alliaria petiolata (M. Bieb.) Cavara & Grande) were primarily restricted to areas where logging occurred (i.e. coves and lower slopes) and other disturbed areas such as firelines.
Scutellaria saxatilis Riddell (smooth rock skullcap or rock skullcap, hereafter abbreviated as SR... more Scutellaria saxatilis Riddell (smooth rock skullcap or rock skullcap, hereafter abbreviated as SRS), a herbaceous perennial in the mint family, is a globally rare (G3) plant. In West Virginia, SRS is categorized as an S2 species (imperiled and at high risk of extinction due to a very restricted range, very few [<20] documented occurrences, or steep declines). The purpose of this study was to determine the effects of fire on SRS in West Virginia. Two forested sites (70+ years of age) within the Monongahela National Forest with no evident disturbance and with SRS populations of >1,000 individuals were selected, one in a burn area and the other in a nonburn area. Sites were sampled in early September of 2008 and 2009 (pre-burn) and 2010 and 2011 (postburn). The prescribed burn occurred in April and early May of 2010. A generalized linear mixed model with repeated measures and a spatial covariance matrix was used to determine the effects of the burn on SRS cover and associated variables including total vegetation cover, species diversity, bare ground, and litter cover. Bare ground cover increased and litter cover decreased in 2010 in response to the fire. Control and pre-burn sites did not differ significantly in terms of SRS cover over the 4-year period. The cover of SRS increased significantly in 2010 (first year postburn) compared to both pre-burn years, but decreased to pre-burn levels by 2011. Total cover of other understory vegetation increased significantly in 2010 and continued at 2010 levels in 2011 at the burn site. Thus, SRS has a temporary positive response to prescribed fire, but an increase in other ground vegetation may prevent a sustained positive response.
This paper links key plant invasive traits with key landscape traits to defme strategic managemen... more This paper links key plant invasive traits with key landscape traits to defme strategic management for five common forest invaders, using empirical data of Microstegium vimineum dispersal into forests as a preliminary model. Microstegium vimineum exhibits an Allee effect that may allow management to focus on treating its source corridor populations at local scales. Forest interior populations without a constant seed source from the corridor populations could potentially go extinct on their own. In contrast, species with long-distance dispersal are likely best managed at a landscape scale, focusing on new establishment sites rather than on removal of source corridor populations.
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Papers by Cynthia Huebner