Brian C. McCarthy

Microsite availability is crucial for recruitment success in natural populations as well as populations being established for restoration projects. Understanding the specific microsite requirements of a particular species targeted for restoration will increase the probability of success of any restoration project. Surface mining for coal represents one of the largest anthropogenic disturbances to the forests of the eastern United States. The original natural range of the American chestnut (Castanea dentata (Marsh.) Borkh.) overlaps the extent of the Appalachian Coal Basin. With American chestnut being readied for reintroduction trials, we sought here to determine some of the effects of microsite conditions on the establishment success of American chestnut on mine sites reclaimed using new, compaction-reducing techniques (i.e., “end-dump” reclamation) that create a series of loosely dumped mounds roughly 8-m diameter and 3-m tall to serve as a planting substrate. Specifically, we examined the effects of distance from existing forest edge, amount of existing cover of vegetation, small-scale topographic position, and a small set of soil variables on the growth and survival over three seasons of American chestnut seedlings planted on a reclaimed mine site in east-central Ohio. We found decreased tree survival adjacent to existing forest edges and greater annual growth rates at distances of 20 and 50 m from the existing forest edge. Microtopographic position had a significant effect on seedling growth and survival—seedlings planted higher on mounds had increased mortality and lower growth than those on the side slopes of those mounds. The amount of existing vegetative cover also affected survival and growth; trees growing in plots with higher vegetative cover values showed increased growth and survival. The compaction-reducing reclamation approach used here is relatively new and novel. Promising results that have been observed to date using American chestnut and this method seem to indicate that the combination may be very effective at restoring functional forests on lands degraded by surface mining.

Prescribed fire and thinning are commonly employed management practices in mixed-oak forests of the central Appalachians. The effects of these practices on the soil seed bank are important to consider in order to evaluate the full impact of these treatments on plant community dynamics in the understory. Species composition of the soil seed bank was examined under three treatments: thin, burn, and thin followed by burning, and an untreated control. Thinning was conducted in Fall 2000, and burns were conducted in Spring 2001. Soil samples were collected in March 2004, three years following treatment. Species composition was assessed by seedling emergence. Seventy total species were found in the seed bank. Ruderal species such as Erechtites hieraciifolia, Carex spp., and Rubus spp. were the most commonly occurring species across all treatments. No significant difference in species composition or proportion of functional groups was found between any of the treatment groups. However, as found in previ...

Silvicultural treatments alter fuel dynamics in forested systems, which may alter fire regime. Effects of thinning and prescribed fire on forest-floor fuels were studied in mixed-oak forests of south-eastern Ohio to examine fuel dynamics over time. Fuel characteristics were measured before, immediately after, and 3 years following fire and thinning treatments along 20-m transects (n = 432) following Brown’s planar intersect method. Measurements were taken to determine litter, duff, 1-h, 10-h, 100-h, and 1000-h sound (1000S) or rotten (1000R) fuel mass. Coarse woody debris (CWD) was sampled on 432 additional 80-m2 belt-transects. Repeated-measures analysis of variance with post-hoc Bonferonni comparisons was used to analyse the change in the fuels over time. The specific effects of silvicultural treatments varied over time with changes in larger, sound fuels (1000S and CWD) persisting longer than changes to finer (litter, duff, 1-h, 10-h, and 100-h) or less-sound (1000R) fuels, which appear to be more transient. Unlike in western North America where fuels accumulate over time, decomposition and productivity appear comparable in eastern mixed-oak forests. Aside from their impact on decomposition or productivity rates, silvicultural treatments appear to have little impact on fine-fuel loading in these systems.

The recruitment of native seedlings is often reduced in areas where the invasive Amur honeysuckle (Lonicera maackii) is abundant. To address this recruitment problem, we evaluated the effectiveness of L. maackii eradication methods and restoration efforts using seedlings of six native tree species planted within eradication and unmanipulated (control) plots. Two eradication methods using glyphosate herbicide were evaluated: cut and paint and stem injection with an EZ‐Ject lance. Lonicera maackii density and biomass as well as microenvironmental characteristics were measured to study their effects on seedling growth and survivorship. Mean biomass of Amur honeysuckle was 361 ± 69 kg/ha, and density was 21,380 ± 3,171 plants/ha. Both eradication treatments were effective in killing L. maackii (≥ 94%). The injection treatment was most effective on large L. maackii individuals (>1.5 cm diameter), was 43% faster to apply than cutting and painting and less fatiguing for the operator, decreased operator exposure to herbicide, and minimized impact to nontarget vegetation. Deer browse tree protectors were used on half of the seedlings, but did not affect survivorship or growth. After 3 years, survival of native seedlings was significantly less where L. maackii was left intact (32 ± 3%) compared with the eradication plots (p < 0.002). Seedling survival was significantly different between cut (51 ± 3%) and injected (45 ± 3%) plots. Species had different final percent survival and rates of mortality. Species survival differed greatly by species (in descending order): Fraxinus pennsylvanica > Quercus muehlenbergii ≥ Prunus serotina≥ Juglans nigra > Cercis canadensis > Cornus florida. Survivorship and growth of native seedlings was affected by a severe first‐year drought and by site location. One site exhibited greater spring soil moisture, pH, percent open canopy, and had greater survivorship relative to the other site (55 ± 2 vs. 30 ± 2%). Overall, both L. maackii eradication methods were successful, but restorationists should be aware of the potential for differential survivorship of native seedlings depending on species identity and microenvironmental conditions.

To better understand the response of eastern deciduous forest herbs to microenvironmental changes associated with logging, the effects of experimental light and soil compaction treatments were examined in six herbaceous plant species characteristic of varying successional stages. We found severe growth reductions and increased mortality of Osmorhiza claytonii (Michx.) C.B. Clarke, a shade-tolerant forest perennial, when grown in full sun and greater soil compaction. Deeply shaded conditions, similar to those beneath regenerating forests, resulted in reduced growth of early successional species such as Galium aparine L., and Eupatorium rugosum Houtt. Growth of other species such as Geum canadense Jacq., and Elymus hystrix L. appeared to increase in the patchy, intermediate light treatment mimicking mature eastern deciduous forests. Soil compaction caused severe reductions in height and biomass of Eupatorium rugosum and O. claytonii, early- and late-successional species, respectively. While harvested stands experience relatively uniform light environments, canopy gaps and sunflecks in mature eastern deciduous forests create heterogeneous light environments often correlated with recruitment, growth, and diversity of understory herbs. Therefore, management approaches that minimize alteration of forest environments and mimic natural disturbance patterns may be important to the maintenance and regeneration of forest herbs.

As interest in invasive species management increases, new information with respect to invasive species abundance and distribution in invaded habitats is imperative. One essential type of information is demographic data. When invasive plants colonize a new habitat, their numbers may be low at first, but the population may undergo rapid expansion. We were interested in the effect of intraspecific density on the population dynamics and life history attributes of Alliaria petiolata a Eurasian biennial herb that has become an invasive pest in portions of North America. Thirty plots were established in a mesic second-growth deciduous forest in high, medium and low density patches of A. petiolata rosettes. Demographic data were collected for all A. petiolata cohorts present in the plots from 1996–1998. In June 1998 all first year rosette and second year mature individuals were harvested, dried and weighed. Stage-based population projection matrices were constructed in order to compare demography among p...

Summary: 1 Alliaria petiolata, a European biennial herb, is an important pest in temperate North American deciduous forests. Habitat resource structure has probably been important for invasion and proliferation of this species. 2 Alliaria was grown in an experimental garden at two densities (equivalent to 17 and 170 plants m⁻²), three nutrient levels (no, low, or high nutrient addition) and three light levels (ambient sunlight and two shading treatments) to determine the effects of environmental heterogeneity on growth, reproduction and resource allocation in both mature and rosette plants. 3 Overall, rosette growth and allocation patterns were significantly affected by all three variables tested. Low plant density, nutrient addition and high light availability resulted in plants with more leaves and greater dry weight biomass. Biomass allocation to shoots was greatest for plants in high‐density and low‐light treatments. Leaf chlorophyll content was significantly greater for plants in the two shaded treatments. 4 Mature plants also responded to environmental manipulation with significantly greater total dry weight biomass at low plant density, high light availability and with nutrient addition. Low density and high light availability resulted in significantly higher seed production. Plants in the lowest light treatment allocated significantly more biomass to shoot production and less to root production. Leaf chlorophyll content was lowest for plants in the highest light treatment and increased with nutrient addition at the two highest light treatments. 5 Plants growing at high density responded to nutrient addition and light attenuation in the same direction but with greatly reduced magnitude compared with plants growing at low density. The effect of irradiance was the most important determinant of all facets of growth and allocation patterns in both rosettes and mature plants. 6 Our results indicate that although density and site fertility may play important roles in Alliaria invasion and establishment, light availability may be the most important factor affecting subsequent growth and proliferation.