The aim of the present study was to estimate changes in plant species composition in several forest communities caused by changes in endangered Key deer (Odocoileus virginianus clavium) densities in the National Key Deer Refuge in the lower Florida Keys. Baseline vegetation quadrats from a 1990 study were resampled in 2002 (the present study) in buttonwood transition, hardwood hammock, and mangrove wetland communities (all deer habitat) on 12 islands with low, medium, and high Key deer densities. On islands with high Key deer densities (>17 deer km⁻²), the relative densities of preferred plant species <1.2 m tall significantly decreased over time in each deer habitat, and nonpreferred species <1.2 m tall significantly increased in hammock and mangrove habitats. No significant changes were observed in densities of plant species <1.2 m tall on islands with low and medium Key deer densities (<8 deer km⁻²). Relative densities of preferred plant species >1.2 m tall (midstory/canopy) also significantly decreased in hammock on islands with high deer density, suggesting that heavy browsing is deterring plant growth/recruitment, thus already affecting regeneration of certain plant species into the midstory/canopy tiers. Plant species richness did not vary significantly between 1990 and 2002 for islands with high deer densities, but tended to increase slightly on islands with low deer density in buttonwood and hammock communities. Evidence from this study suggests that high densities of Key deer influence plant species composition on certain islands. We suggest that management plans for Key deer should incorporate both species protection components and population control techniques dependent on deer density-island associations.

The introduced Sapium sebiferum (Chinese tallow tree) has spread across the southeastern United States and is rapidly replacing native prairies with monospecific Sapium forests. Most attempts to control Sapium are only temporarily effective because of its large seed bank and ability to resprout from cut stumps. We performed a two-year field experiment to evaluate the effectiveness of using large shredding mowers to mulch live Sapium trees and restore Sapium-invaded prairies. We predicted that Sapium mulch would damp diurnal soil temperature fluctuations and suppress Sapium seed germination because Sapium seed germination is highly dependent upon those fluctuations. We manipulated mulch depths and types (0, 10, and 15 cm deep Sapium mulch and hardwood and straw mulch) in the field and measured soil temperatures beneath them. Diurnal soil temperature fluctuations were damped at depths as little as 5 cm, and Sapium mulch significantly reduced Sapium seedling emergence. Deep layers of Sapium mulch (15 cm) reduced seedling survival and native vegetation cover as well. Comparisons among Sapium mulch and alternative mulch materials revealed no allelopathic effects of Sapium mulch on Sapium seedling emergence, survival, or growth. Vigorous regrowth of native vegetation through 5 cm of Sapium mulch was evident by the end of the first growing season. With no trees or stumps remaining on the site, a mowing regime can be implemented immediately regardless of the pre-mulching density of the trees. A heavy closed-canopy Sapium forest might result in mulch depths that slow the return of native vegetation and delay accumulation of adequate fuel loads to support prescribed burning.

Tree plantings are striking landscape features that symbolize settlement of the West. Although grassland birds require large tracts of treeless grasslands, planting trees in prairie landscapes is still regarded by many as a positive management practice. We compared bird use of tree plantings (n=182) and natural riparian woodlands (n=37) to evaluate whether ecological costs of tree plantings to grassland birds is compensated for by the benefit they provide to forest birds of management concern. Findings indicate that ecological costs of tree plantings outweigh their benefits because they fail to provide habitat for forest birds of management concern. Thus, loss of native grassland bird communities is the currency in which we pay the ecological costs of plantings trees in prairie landscapes. We recommend that managers refrain from planting trees in or adjacent to grassland habitats. We further recommend that managers refocus their tree plantings efforts to restoration of riparian woodlands that maximize avian diversity in prairie landscapes.

Siberian pea shrub, or caragana, (Caragana arborescens Lam.), was intentionally introduced on the northern Great Plains of North America for erosion control and ornamental hedgerows, but has invaded the understory of native deciduous forests. Although this species is widespread, there is little information on the ecology of naturalized populations or impacts of invasion. Our objectives were to describe the demographic structure of an invasive population and changes in shrub community diversity along a gradient of caragana density in an upland aspen (Populus tremuloides Michx.) forest at Elk Island National Park, Alberta, Canada. This caragana population spread through the understory and increased from 50 to approximately 60,000 individuals over 75 years. More than 85% of individuals were immature (<10 yrs, <1 m tall, non-flowering), and the size class-frequency distribution best fit a negative power function curve. Several native shrub species, including the dominant beaked hazel (Corylus cornuta Marsh.), were negatively associated with caragana, and the relationship between diversity and caragana density was quadratic. Control efforts will require perseverance since immature pea shrubs are difficult to locate beneath the dense growth of beaked hazel and the immature phase can last a decade.

Long-term studies of the responses of plant populations to fire can inform adaptive management of ecosystems. I present results of an analysis of responses of a fire-adapted plant, Pityopsis graminifolia (Michx.) Nutt. (silkgrass goldenaster), to season of fire from 2001 to 2005 in a longleaf pine (Pinus palustris P. Miller) sandhill community in north Florida. Replicated May-burned and January-burned plots had been burned biennially from 1986 to 2004. Previous work in the early 1990s showed that populations of this species benefited more from fires during the peak lightning fire season (i.e., May) than from January fires. In 2001, however, shoot densities in both treatments were substantially lower than in 1992 and remained relatively low through March 2005. Shoot densities were significantly higher in May-burned plots than in January-burned plots between 2001 and 2005. May fires significantly increased shoot densities in 2002 (relative to January fires), but did not in 2004. Shoot densities in January-burned plots remained remarkably stable between 2001 and 2005. As in the early 1990s, May fires were consistently more effective than January fires at stimulating flowering, which in turn produced higher seedling densities. Seedling survival was low, however, as in the early 1990s. Positive short-term effects of lightning-season fires on long-term population trends in this fire-adapted species appear to be substantially reduced by periodic population crashes, inconsistent short-term effects on clonal growth, and inherently low seedling establishment rates.

Juniperus virginiana-Quercus muehlenbergii woodlands form isolated, rare communities limited to calcium-rich cliffs and rock outcrops within the larger matrix of Quercus-Carya forests in the central and southern Appalachians. The objective of this paper was to identify compositional, environmental, and age changes across the ecotone between a woodlands community and an adjacent forest at Pedlar Hills Natural Area Preserve, Virginia. We established eight belt transects from the Juniperus virginiana-Quercus muehlenbergii woodlands into the surrounding Quercus-Carya forest. All trees within transects were identified and cored to determine age. We determined soil depth, percent rock cover, slope, and aspect and recorded the location and species of all cut stumps. The woodland-forest ecotones that appeared to be relatively static were all located along physical boundaries such as ridgelines or rivers. In areas lacking physical boundaries, the forest-woodlands ecotone has shifted in the past 50 years. The Quercus-Carya forest appears to have been more successful than the woodlands community in regeneration following logging in the mid-1900s; this shift in community may have been facilitated by fire suppression. These results imply that conservation managers need to be aware of the spatial differences in community stability and concentrate their conservation efforts on community boundaries that lack physical barriers to plant invasion.

Although the negative impacts of urbanization on ecological communities are usually emphasized in the literature, urban parks may make positive contributions to conservation. We hypothesized that riparian forest parks surrounded by urban development would support greater numbers and diversity of wintering birds than similar forests in more rural landscapes due to improved food resources and microclimate conditions in urban landscapes. During winters 2001–2002 and 2002–2003, we surveyed bird communities three times each year at 36 sites located in riparian forests along a rural-urban gradient in central Ohio. At each forest site, we measured forest width (m), landscape characteristics (percentages of urban and forest cover within 1 km), and local variables describing both habitat and microclimate conditions. Species richness, total abundance, and numbers of nine of 10 species were positively related to urban development within 1 km. These patterns may be partially explained by positive associations between urban development within 1 km and winter temperatures, numbers of birdfeeders near sites, and understory stem densities. Unlike most studies of breeding birds, our results suggest that an urbanizing landscape matrix surrounding riparian forests may benefit some native birds in winter.

Seed germination phenology studies are important tools for determining whether seeds exhibit dormancy and what environmental conditions trigger germination. Within longleaf pine (Pinus palustris Miller) ecosystems of the southeastern United States Coastal Plain, little is known about dormancy patterns and germination cues of the suite of native species composing the diverse fire-maintained ground cover vegetation. We used two methods to determine if several dominant or functionally important herbaceous species were capable of forming a persistent soil seed bank, including: (1) a germination phenology study and (2) a buried seed bag study. Results indicate that within species studied from three common families (Asteraceae, 2 species; Fabaceae, 8 species; and Poaceae, 3 species), species within the Fabaceae family seem most capable of forming long-term persistent seed banks. Although most of the Poaceae and Asteraceae species examined exhibited little dormancy in the germination phenology study, evidence from the buried seed bag study indicates that several species may form transient or even short-term persistent seed banks under favorable conditions. The absence of evidence of persistent seed banking potential for several dominant species examined in this study suggests that seed reintroduction will likely be a necessary component in restoration efforts in longleaf pine ecosystems.

The exotic, invasive shrub European buckthorn (Rhamnus cathartica) is a major threat to natural areas in North America. While many publications describe buckthorn eradication methods, few compare the efficacy of different methods, and none are comprehensive. In this study, we tested the efficacy of 15 combinations of five commonly used herbicides and two physical interventions (cutting and girdling) on the regrowth of 317 buckthorn shrubs in northeastern Illinois. Treatments were performed randomly on plants with primary stems ≥3 cm, and effects on treated stems, untreated stems of multistemmed shrubs, and all stems were evaluated six months later. We found neither physical nor chemical methods alone to be optimal, but rather a combination of cutting or girdling with certain herbicides was best. We found Roundup Pro (Roundup), Stalker, and Tordon RTU (Tordon) to be more effective than either Garlon 4 or Brushmaster. Importantly, our data suggests that girdling or cutting of a single stem of multiple-stemmed buckthorn before using Roundup, Stalker, or Tordon usually results in the death of the entire shrub, thereby potentially saving a great deal of time and money. All herbicides were rated equally safe for human applicators by manufacturers, and required approximately equal time and effort to apply. Though Roundup was the most expensive of the three most effective herbicides, manufacturers' labels indicated that it is potentially safest for use in dry natural areas. However, none of the herbicides evaluated are appropriate for use in water, wetland areas, or in areas below mean high water marks.

Millions of dollars are spent annually on biodiversity conservation projects at natural areas around the world. Managers of natural areas must achieve a balance between taking conservation action, evaluating the effectiveness of actions taken, and monitoring the general status of biodiversity conservation targets and the threats they face. Conservation practitioners often struggle with decisions regarding the allocation of limited resources among these competing needs. Many conservation projects have only a limited monitoring component while other projects have an inexplicably high investment in a single type of monitoring. We offer a conceptual framework to help guide conservation practitioners towards a logical allocation of resources between taking action and different types of monitoring depending on the situation that they are facing. The framework consists of a decision tree that includes an explicit evaluation of three questions: (1) Are there substantial threats facing the conservation entities?; (2) Are there clear and feasible actions known to be effective at abating identified threats?; and (3) Does the project team have high confidence in their understanding of the overall conservation situation? Based on this tree, we present five scenarios that illustrate a range of logical allocations of resources between taking action and different categories of monitoring.