There is limited understanding of the influence of fire and vegetation structure on bird communities in dry oak (Quercus spp.) savannas of the Upper Midwest and whether bird communities in restored savanna habitats are similar to those in remnant savannas. During the 2001 and 2002 breeding seasons, we examined the relationship between bird communities and environmental variables, including vegetation characteristics and site prescribed-burn frequencies, across a habitat gradient in dry oak savannas in central Minnesota. The habitat gradient we studied went from: (1) prairie to (2) remnant oak savanna to (3) oak woodland undergoing savanna restoration via fire or mechanical removal of woody vegetation to (4) oak woodland. We conducted fixed-radius point counts (n = 120) within habitats with either prairie groundcover or predominately oak canopy. We described canopy and groundcover characteristics at a sub-sample (n = 28) of non-prairie points, and collected canopy and woody species richness data and prescribed-burn frequencies over the past 20 years for all points. Observed bird communities were most strongly correlated with canopy cover and burn frequency and, to a lesser extent, attributes of the shrub component. Most savanna points had bird communities that were distinct from those found at oak woodland or oak woodland points undergoing restoration via burning. Savanna points similar to oak woodland points were in areas managed by periodic cutting rather than burning. Remnant savanna bird communities were more strongly associated with prescribed burning than those in other habitat types, but it appeared that most oak woodlands that had undergone ≥ 20 years of prescribed burning remained ecologically distinct from remnant savannas. This suggests that some savannas that have converted to oak woodlands may exist in an alternative, or stable, ecological state even following extended restoration efforts.

Spruce-fir forests in the southern Appalachian Mountains receive high atmospheric nitrogen inputs and have high nitrate levels in soil solution and streamwater. High levels of excess nitrogen have been associated with reduced tree vigor. Additionally, the balsam woolly adelgid (Adelges piceae Ratz.) has killed the majority of endemic Fraser fir [Abies fraseri (Pursh) Poir.] trees, resulting in large amounts of coarse woody debris. As part of a biogeochemical study in the Great Smoky Mountains National Park, coarse woody debris was sampled to determine volume, mass, change in density, and change in concentration and content of carbon and nitrogen over the decomposition process. Dead wood volume was highly variable across the watershed, ranging from 4.5 m³ ha⁻¹ to 306.8 m³ ha⁻¹ for standing boles and from 21.2 m³ ha⁻¹ to 402.7 m³ ha⁻¹ for down boles. Wood density decreased significantly for all three major overstory species [red spruce (Picea rubens Sarg.), yellow birch (Betula alleghaniensis Britt.), and Fraser fir] by approximately 60%, from slightly decayed boles to boles in advanced decay. Standing and down dead biomass averaged 39.4 Mg ha⁻¹ and 33.8 Mg ha⁻¹, respectively. Carbon concentrations remained relatively constant and were approximately 47% for all decay classes and all species. Nitrogen concentrations increased sharply between live wood and highly decayed wood. The nitrogen content in live wood, compared to wood in advanced decay, increased by 40% to 118% for the species tested. At the watershed level, live bole wood contained 108.4 kg ha⁻¹ of nitrogen, and dead bole wood contained 101.5 kg ha⁻¹. Total carbon in live and dead bole wood averaged 93.8 Mg ha⁻¹ and 34.9 Mg ha⁻¹, respectively. The magnitude of coarse woody debris in this system is among the highest reported in the literature for the eastern United States, emphasizing the high degree of disturbance that has taken place in this ecosystem.

Using a unique sterile design intended to eliminate outside seed contamination of horse feces, we investigated whether weed seeds germinate after digestion by horses. Feces were collected from selected National Parks and other locations in central and northern California. All potted fecal samples were irrigated and grown in an enclosed sterile nursery environment. Thirty-two plant species emerged from these fecal samples, 24 of which were not native to California. None of these were identified on the California Department of Agriculture's Noxious Weed List, which is used as a basis to certify equine feed as weed free. However, seven of the non-native species are identified as moderately invasive on the California Invasive Plant Council's (Cal-IPC) list. These species are: Hirschfeldia incana, Hordeum marinum, Lolium multiflorum, Mentha pulegium, Rumex acetosella, Trifolium hirtum, and Vulpia myuros. In addition, the following four non-native plants are listed at the limited invasiveness level on the Cal-IPC list: Hypochaeris glabra, Lythrum hyssopifolium, Medicago polymorpha, and Poa pratensis. Because we did not survey invasive plant cover in locations from which we sampled, we cannot guarantee that species identified in our samples would have also germinated in the field. Our results add to a growing body of literature documenting germination of seeds after passing through the digestive system of horses and suggest that conscientious horse owners should select feed sources that are free of weeds. We also find that the current list of noxious weeds used to certify weed-free feed for equines should be comprehensive.

Weevils (Coleoptera: Curculionidae) may play a role in the reduced regenerative ability of oak (Quercus L.) species in the hardwood forests of eastern North America. Presently, because of biome-wide regeneration failure, silvicultural treatments of prescribed fire and mechanical thinning are being implemented as a means to enhance natural oak regeneration. The effect that these treatments may have on the diversity and population structure of non-target organisms like weevils (oak seed predators) remains unclear. This study provides an evaluation of the weevil populations of two experimentally managed, mixed-oak forests in southeastern Ohio. Each of the two sites used in this study was divided into four 20 ha treatment plots consisting of: (1) untreated control, (2) thin only, (3) thinning followed by prescribed burning, and (4) prescribed burning only plots. Pyramid style traps (N = 48) were placed in each treatment unit to sample weevils. Overall, we identified 26 species of Curculionid weevils representing nine genera from five different tribes and two subfamilies. Weevil communities were generally dominated by a few highly abundant species and a moderate number of uncommon to rare species. Generally, treatments increased overall weevil diversity and influenced the abundance of certain rare species. However, there was no significant effect on number of weevils or on occurrence of the two major acorn infesting genera (Curculio L. and Conotrachelus Dejean). Based upon our findings, prescribed spring burning had little effect on overall weevil populations and is not likely to substantively aid in silvicultural endeavors to promote oak regeneration; however, effects on rare species need to be carefully considered.

Wilson's Creek National Battlefield in Republic, Missouri, protects a large concentration of the rare, glade-endemic, winter annual Lesquerella filiformis Rollins (Missouri bladderpod; scientific nomenclature follows USDA PLANTS Database). A sustained monitoring effort provided the opportunity to assess a grid-based survey approach featuring the use of visual density class estimates. Population size intervals, which include the uncertainty associated with the use of density classes, were compared to sample-based population size estimates from a computer simulation of the L. filiformis population. A 100% population size interval was similar to a sample-based 95% confidence interval and much narrower than a 99.9% confidence interval. If the distributions of observations within density classes are not symmetrical, however, a sample-based approach will yield more accurate point estimates. Observers frequently underestimated plant densities when using density classes, although counts of plants provided correction factors. Following recalibration of the density class scale, the grid-based survey approach supported the calculation of population metrics based on historical occupancy and abundance in individual grid cells. For some rare plant populations, conservation practitioners may determine that the advantages of such cell-based metrics outweigh the disadvantages of uncertainty and observer error stemming from the grid-based survey approach.

Maintaining native plant diversity through fire management is challenging in the wildland-urban interface. In subtropical South Florida, fragments of fire-dependent, globally imperiled pine rockland forest are scattered throughout urban areas. To determine the effects of recent fire frequency, major soil type, and fragment size on species composition, we measured understory vascular plant presence and cover in 162 plots distributed among 16 publicly-owned pine rockland preserves in 1995 and 2003. Fragments received either 0, 1, or > 1 burn(s) between sampling periods. Native plant richness was very high overall. Major soil type, which varies regionally and is associated with latitude and elevation, strongly influenced the assemblage of species present at a given site. Native species cover was significantly different across different burn categories. Fragment size was positively associated with plant species richness, but small fragments had high variance in the total number of native plant species they supported, with some having nearly as many plant species as the largest fragment. Examining trends over time for rare native and invasive non-native plant species revealed the spread of the invasive grass Rhynchelytrum repens (Willd.) C.E. Hubb. and showed no major decreases in rare plant species. In general, this study provided encouraging results for managers of small urban forest fragments, showing that they can maintain high levels of native plant diversity, even when fire occurs infrequently.

We compared avian communities and vegetation characteristics in invaded and uninvaded pine barren ecosystems to test whether invasive woody plants were altering native bird communities. We hypothesized that structural changes in vegetation caused by the invasion of fire-intolerant deciduous trees were altering bird communities in the Albany Pine Bush, east central New York State. We recorded bird calls at 55 stations during breeding season to estimate abundances of breeding birds in areas dominated by fire-dependent pine-shrub savanna and areas dominated by invasive hardwoods (black locust, Robinia pseudoacacia, and aspens, Populus tremuloides and P. grandidentata). Vegetation surveys were conducted surrounding each station to quantify woody plant composition and structure. Sites characterized as invaded had more vegetation layers, twice as much closed canopy, and higher tree stem densities in all but the largest (> 25 cm dia) size classes. Forty-seven bird species were recorded; thirty-three at both invaded and uninvaded sites. Grassland/shrubland birds, such as prairie warbler (Dendroica discolor), field sparrow (Spizella pusilla), red-breasted nuthatch (Sitta canadensis), and eastern towhee (Pipilo erythrophthalmus), were twice as frequent and three times as abundant at uninvaded sites. Native bird species characteristic of closed-canopy forest were more frequent and abundant at stations in invaded sites. Multivariate analyses indicate distinct associations of particular birds with unique combinations of vegetation characteristics that differed between invaded and uninvaded points. A campaign of adaptive fire management holds promise to restore critical avian habitat in protected areas of this threatened barrens ecosystem.

The role of ungulates as contributors to establishment and spread of non-native invasive plants in natural areas is not well known. The objectives of this study were to document whether or not sulfur cinquefoil (Potentilla recta L.) is grazed by ungulates and to quantify the effects of ungulate herbivory on the density and demography of sulfur cinquefoil. Despite reports suggesting sulfur cinquefoil is minimally grazed, our results indicate that substantial grazing of sulfur cinquefoil occurs in a northeastern Oregon natural area. The number of sulfur cinquefoil flowers and seed heads differed significantly (P < 0.0001) among all grazing treatments at all sampling periods. Cattle (Bos Taurus) grazed sulfur cinquefoil throughout early summer, resulting in smaller plants with few flowers and subsequent seed heads. Sulfur cinquefoil was grazed by deer (Odocoileus heminous and O. virginianus) and elk (Cervus elaphus) primarily in the fall and winter by specifically removing just the seed heads. As sulfur cinquefoil reproduces only by seed and seeds typically fall within 3 m of a parent plant, grazing by ungulates and subsequent deposition of the seeds by endozoochory may explain the establishment of satellite infestations across susceptible natural areas.

A tract of land owned by the Horry County South Carolina Solid Waste Authority is being developed as a landfill and as an environmental education and recreation facility. Parts of the tract are used as sorting facilities for storm debris and cap dirt excavation areas. The remainder of the 480-ha tract is planned for the development of an environmental education, nature-based tourism, and outdoor recreation center. It possesses the diversity and size to support multiple research projects and provide a destination for school and community groups to learn about the environment and history of the area. A geographic information system (GIS) was produced for the tract and used to assist in making decisions on the placement of interpretive trails and in developing education resources.

Grasslands around the world have experienced dramatic decline for more than a century. The spatial extent and condition of grasslands in many regions of the world are poorly understood because they lack conservation priority relative to other ecological systems. We developed a simple, yet broadly applicable rapid assessment expert system approach that can be used to assess these aspects of grassland status for improved conservation planning and management. Here we apply our approach to the semi-arid grasslands of the Arizona, New Mexico, and Mexico borderlands. We specifically used a combination of expert input and field verification. The accuracy of the expert input was 71%–77%. Native grasses dominate nearly 50% of identified grasslands. However, over two-thirds of these grasslands have experienced a moderate level of shrub encroachment. These areas may be restorable to open grassland with use of prescribed fire. Non-native perennial grasses are common to dominant on 12% of the study area. More than 67% of native grasslands occur on private and state land where there is little legal protection. In a region experiencing substantial development pressure, grasslands are at risk of becoming increasingly fragmented and vulnerable to non-native species invasion. Now, with our approach to assessing grassland status, conservation practitioners and partners are better positioned to protect and restore the remaining grasslands in the U.S.-Mexico borderlands and elsewhere.