Maryland shale barren (savanna) communities support rare, threatened, and endangered species, but biodiversity conservation sites are transitioning to pignut hickory woodland and forest as a result of fire exclusion. In Green Ridge State Forest, an exemplary community was studied for vegetation change after pignut hickory management and a prescribed burn. Portions of contiguous chestnut oak (Quercus montana) and streamside hardwood communities were also included. Prerestoration herbaceous layer characteristics were quantified in 2010 using transect plots before hickories were killed by herbicide. A prescribed burn was conducted in November 2011 followed by resampling in 2013. In the barren community, Carex pensylvanica remained the dominant herbaceous layer species, but codominant species changed. Ground cover increased from 63% to 76%, species richness from 48 to 52, and the Shannon-Wiener diversity index (H′) from 3.138 to 3.373. In the chestnut oak forest, the dominant herbaceous layer species changed, ground cover increased from 15% to 65%, species richness from 22 to 29, and H′ from 2.578 to 2.686. In the streamside community, ground cover increased from 50% to 83%, species richness from 38 to 50, and H′ from 3.114 to 3.319. Results emphasize the biodiversity importance of woody plant management and periodic ground fires to shale barren restoration.

In the beech-maple forest at Warren Woods State Park, the importance values of Fagus grandifolia and Acer saccharum have increased compared with their values from the 1829 Government Land Office survey of the same area—a small increase for F. grandifolia and a large increase for A. saccharum. For F. grandifolia the greatest increase between 1829 and 2014 was in basal area per tree, suggesting that numbers had not increased as much as size; while for A. saccharum the greatest increase was in all relative metrics, but not in basal per tree, indicating that abundance only had increased. From 1933 to the present, all size classes of F. grandifolia, except for the juvenile size class, decreased in density, while only the juvenile size class of A. saccharum decreased. Seedling densities for both species are highly variable from year to year, the highest densities occurring in years with deepest snow cover. For A. saccharum, high densities were probably the result of optimal germination temperatures due to prolonged snow cover. For F. grandifolia, the high seedling density in 2014 may have been due to an abundant seed crop and low seed predation on snow-covered seeds. The relative increase in A. saccharum and the concomitant decrease in F. grandifolia may be due, in part, to higher mortality of larger F. grandifolia trees due to windthrow. This differential mortality may be exacerbated with the increased frequency and severity of storms predicted to occur with global climate change.

Length of time since agricultural abandonment, variations in topography and soil, and forest fragmentation associated with suburban development can influence dominant vegetation and foster exotic species invasion in a secondary successional forest. The Middle Patuxent Environmental Area (MPEA) in Maryland is a regrowth forest adjacent to suburban sprawl that was abandoned from agriculture at staggered rates. I surveyed vegetation throughout the MPEA to investigate how these interrelated factors have influenced species distribution and abundance. My predictions were that time since abandonment would explain the broader differences in forest succession, but that topography and an interface with suburbia would be the strongest determinants of smaller-scale species discrepancies within an area of similar abandonment history. I performed a hard noise clustering analysis using the R package vegclust to classify the MPEA into herbaceous, shrub, and tree communities each dominated by similar species. Tree communities differed distinctly in accordance with agricultural abandonment, proximity to suburban edges, and soil nutrients, with sun-tolerant Liriodendron tulipifera dominating in more recently reforested areas versus the shade-tolerant Fagus grandifolia and Carpinus caroliniana in longer-forested sites. Shrub and herbaceous communities also displayed some pattern reflecting length of reforestation, but there was a greater dominance of invasive species in these strata. A prevalence of disturbance, and a resulting encroachment into the mature forest understory of invasive species such as the grass Microstegium vimineum, underscores the need for invasive species management in a suburban forest fragment to span various stages of succession.

We studied the habitat characteristics of Spiraea virginiana Britton (Virginia spiraea), a federally threatened riparian shrub, along eight rivers in western North Carolina. Comparisons between plots with and without S. virginiana revealed that S. virginiana plots were on steep, south-facing slopes and had a higher percentage of large substrate, lower herbaceous and vine cover, higher non–S. virginiana shrub density, lower tree influence, and higher visible sky than control plots. When relating these habitat attributes to the presence/absence of S. virginiana using conditional logistic regression, only substrate size and non–S. virginiana shrub density had significant effects on S. virginiana presence. Principal components analysis (PCA) of all plots (S. virginiana and control) found S. virginiana plots separating from controls that had higher vine and herb cover and lower non–S. virginiana shrub density and slope. Spiraea virginiana plots at the Cheoah River separated from other sites by having greater substrate size and tree influence, and lower visible sky and herb cover. Regression analysis between S. virginiana volume and PCA axes (of plots with S. virginiana only) indicated that volume increased with increasing small substrate, visible sky and non–S. virginiana shrub density, but decreased with increasing tree influence, herb and vine cover, and decreasing slope. Spiraea virginiana restoration efforts should focus on habitats with the attributes described in this study to favor its presence. To ensure S. virginiana vigor, competition from trees, non–S. virginiana shrubs, vines and herbs, especially aggressive nonnative species, should be reduced.

Since the early 1980s, Beavers' Meadow in Barbour County, West Virginia, has been well known for large populations of the orchids Cleistes bifaria and Platanthera ciliaris. Seven taxa of special concern in West Virginia were present at that time: Andropogon glomeratus var. glomeratus, Athyrium filix-femina subsp. angustum, C. bifaria, Rhynchospora recognita, Sericocarpus linifolius, Scleria triglomerata, and Xyris torta. We present a description of the 7.4-ha meadow today, an inventory of its species, and some comparisons to the flora as it was reported 26 years ago. Collections were first made in June 2007; parallel transects approximately every 3–5 m were walked once each in May and June 2009, twice monthly in July through September 2009, and once each in May and June 2010. Additional specimens were collected in 2011, 2013, and 2014. We identified 320 vascular plant taxa in 192 genera and 67 families. The taxon list includes 31 county records and one state record, Scleria verticillata. All seven species of concern documented 26 years ago were observed between 2007 and 2014. Three additional state-rare species were found: Calopogon tuberosus var. tuberosus, Pycnanthemum torrei, and Spiranthes lucida. Exotic taxa numbered 65, making up 20.3% of the flora. Establishment and maintenance of the diverse flora has probably been promoted by hydrologic gradients, low nutrient levels, and various anthropogenic activities, including annual rotary mowing that took place from the 1950s through 2003 and resumed in 2009.