Bird communities associated with differing cliff variables in Jefferson County, Colorado, were sampled using point counts. Species-specific density estimates and community diversity values were compared among four cliff types: small cliffs, medium cliffs, large cliffs, and non-cliff sites. A model selection was run to determine if cliff variables were associated with changes in species richness. Cliff variables included cliff height, cliff length, cliff verticality, cliff surface roughness, and distance to the nearest cliff. None of the cliff variables were good predictors of variability in species richness. Although no differences existed for bird community diversity estimates, there were significant differences in densities among cliff types for particular bird species. The rock wren (Salpinctes obsoletus Say), canyon wren (Catherpes mexicanus Swainson), violet-green swallow (Tachycineta thalassina Swainson), and white-throated swift (Aeronautes saxatalis Woodhouse) were detected more frequently at the large cliffs than the other cliff types (the differences for the canyon wren were not statistically significant). Larger cliffs appear to be necessary for these cliff-obligate species.

Exotic species research has generated several paradigms about the effects of invasion on native ecosystems and the site characteristics that promote invasibility. We are interested in translating these theoretical paradigms into management recommendations. Using vegetation surveys of urban riparian forests in central North Carolina, we tested the competition and resource availability paradigms. We assessed the association between exotic and native species and identified potential resources that promote invasion. Exotic and native species richness was negatively correlated (r = −0.66, p = 0.0009), conforming to the predictions of the competition paradigm. In particular, native woody species were negatively associated with several exotic growth forms. Two of the most common exotic species, Hedera helix (English ivy) and Microstegium vimineum (Japanese stilt grass), did not co-occur with several native woody plants, suggesting that they may preclude the establishment and regeneration of native woody plant communities. Our results have less direct implications for the resource availability paradigm. There were no correlations between light availability (indexed by canopy cover) and either cover or richness of exotic species. However, exotic species richness was generally positively correlated to soil fertility. These results suggest that the competition and resource availability paradigms are useful for understanding the dynamics of urban riparian forests that are invaded by a suite of exotic species. Removal efforts should focus on two of the most common invasive plants, H. helix and M. vimineum, and native woody plants should be re-established. While soil fertility is difficult to manage at a site level, we urge managers to lobby for strict regulations on nutrient inputs from upstream and adjacent development.

Deciduous forests in the eastern United States have been dynamic over both geological and historical time scales, particularly since humans have modified the landscape. Historically, the central hardwood forest has been subject to considerable human disturbance, especially fire, and these anthropogenic disturbances have contributed to the dominance of shade-intolerant oak (Quercus) and hickory (Carya) species within the central hardwood region. Current research indicates that many of these forests are changing to dominance by shade-tolerant species, mainly sugar maple (Acer saccharum Marsh.). This change has been attributed to a lack of disturbance. The objective of this study was to document long-term changes in structure and composition of a mature oak-hickory stand at the Ross Biological Reserve in Indiana. There has been little disturbance at the Ross Biological Reserve in the past 55 years, and a similar trend of increased shade-tolerant species was expected. Results of decadal tree censuses suggest that a successional change toward the dominance of sugar maple has been occurring during the 40-year study period, and an abundance of sugar maple saplings suggests that the increasing importance of sugar maple will continue with a lack of disturbance. The increased abundance of sugar maple may be having a negative effect on regeneration of oak-hickory species as well as on understory species such as flowering dogwood (Cornus florida L.). Such changes in the plant community also suggest changes in resources for animals. Management of the Ross Biological Reserve, and similar areas, requires an appreciation of forest dynamics on a variety of time scales.

Given the continuing degradation of freshwater wetland ecosystems throughout the Southeast, there has been significant interest in developing methods and indices to evaluate and monitor wetland biological integrity. The purpose of this study was to adapt and test the ability of a vegetation-based assessment technique known as Floristic Quality Assessment to detect the level of human impact in hardwood flat wetlands of Southeastern Virginia. We measured plant species diversity and composition within each vertical stratum [herbaceous, woody understory (shrub and sapling), and canopy] of 11 wetlands. We calculated a Floristic Quality Index (FQI) for each layer, and tested for relationship to land use disturbance patterns within defined site buffer and watershed areas. We found floristic quality of the herbaceous layer and the sapling portion of the woody understory layer to be negatively correlated with level of land use disturbance at both buffer and watershed scales, suggesting that FQI scores within these strata reflect current anthropogenic stress. While FQI of the canopy layer and the shrub portion of the woody understory layer were not reliable indicators of current land use disturbance, we found that a comparison of sapling and canopy layer FQIs gave insights into historic vs. recent floristic integrity of sites. Overall, our findings support the use of floristic quality assessments in evaluating wetland biological integrity when sampling and index calculation methodology are carefully adapted to local flora and community types.

Increasing numbers of cougars (Puma concolor) have been documented in Great Plains and Midwestern states in recent years. This includes numerous reports of cougars in Michigan; however, evidence of a natural population has not been obtained. We conducted track surveys and operated camera stations from November 2004 through April 2005 in Sleeping Bear Dunes National Lakeshore (SBDNL), Michigan. We obtained no images of cougars during 863 camera nights and did not observe cougar tracks or associated sign (e.g., scats, hair, kill sites) during 493 km of track surveys. Presence of 10 carnivore species, including bobcat (Lynx rufus), coyote (Canis latrans), and domestic dog (Canis familiaris) was documented. We also investigated four cougar sightings and one report of cougar tracks within and adjacent to SBDNL. We were unable to locate any cougar sign at the sighting locations but did observe sign of coyote and bobcat. A domestic dog made the reported cougar tracks. We found no evidence supporting the presence of cougars at SBDNL.

Recognizing the importance of invasive plant species is necessary to preserve, protect, and manage for biodiversity in riparian habitats. Non-metric multidimensional ordination of 28 study sites along a successional gradient on the Willamette River indicated that abundance of reed canarygrass (Phalaris arundinacea L). was strongly correlated with stand plant composition and abundance. High abundance of reed canarygrass was also correlated with lower values of understory species diversity and total species richness. Considering older stands only (n = 19), reed canarygrass presence and abundance was the most highly correlated plant species with overall stand plant species presence and abundance. This was probably due to this invasive species inhibiting establishment of understory tree, shrub, herbaceous species, and late-successional tree species during understory reinitiation. Without intervention to control the establishment and survival of reed canarygrass, and perhaps some other invasive species, such as Himalayan blackberry (Rubus armeniacus L.) and English ivy (Hedera helix L.), it is conceivable that these species will become more influential through time with adverse effects ensuing for overall biodiversity at the riverscape level.

We examined the role of suburban white-tailed deer (Odocoileus virginianus Zimmerman) in dispersal of exotic plants in forests bordered by medium-density housing in southern Connecticut. Estimated deer density on the research site was 23 deer/km² with higher local densities along the suburban/woodland interface. In 2002, 90 pellet groups were gathered periodically from September through December. In 2003, eight pellet groups were collected weekly from early June through late December for a total of 236. All pellet groups were vernalized at 5°C for 60 days. Pellet groups were placed in a growing medium in trays in a temperature controlled greenhouse for six months. Seeds germinated from 47% of pellet groups, which included 656 seedlings of 57 species. Seeds (n = 326) of 32 species not native to Connecticut germinated in 23% of pellet groups. We estimated that the deer herd on site had the potential to disperse 586-1046 viable exotic seeds/day/km² during the 2002 sampling period and 390-696 viable exotic seeds/day/km² during the 2003 sampling period. Birds, small mammals, and abiotic factors are known dispersal agents for exotic plants, some of which are invasive. Our results indicate that white-tailed deer are another important dispersal agent of exotic species. Thus, white-tailed deer may not only alter vegetation structure through direct browse damage of established plants, but also indirectly by lowering reproductive output of native plants and simultaneously distributing seeds of exotic species.

The widely invasive grass Rhynchelytrum repens (Willd.) C.E. Hubb. invades globally-imperiled pine rockland forests of South Florida. To examine whether its spread into and persistence in undisturbed areas pose a threat to native species, we investigated whether the presence of R. repens was associated with a decline in the diversity and abundance of native pine rockland understory plants. We showed R. repens density class was strongly associated with a reduction in native species diversity, with high density (20% cover) plots having five fewer species than low density (0.2%) ones. When we separated species by functional groups, we found that graminoids were affected much more than other native species, with R. repens cover explaining 23% of the variation in graminoid diversity. Rhynchelytrum repens is indeed causing harm to pine rockland diversity, and we recommend that land managers take action to: (1) treat infestations before they reach 30% cover, and (2) remove infestations of any density adjacent to natural areas.

The endangered Carson wandering skipper (Pseudocopaeodes eunus obscurus [Austin and Emmel]) survives as a relict species in four major pluvial basins in the western Great Basin of Nevada and California. This Hesperiinae is distinct from other subspecies in the genus, likely resulting from a vicariance event during the Holocene. Surviving in disjunct refugia, this butterfly has highly specialized habitat requirements and feeds only on saltgrass (Distichlis spicata var. stricta [Greene] Thorne) as larvae. Conservation of habitat patches has been highly successful. However, land development and groundwater withdrawal are in high demand surrounding the species' habitat and pose significant impacts on its survival. The species survival or extinction will be dictated by these land uses. Land development may decrease dispersal capabilities, and groundwater withdrawal may cause a vegetation shift resulting in the loss of skipper populations. Recovery will depend on the adaptive management of land uses that conserves current populations and on permits dispersal among the network of habitat patches.

The network of protected areas and the magnitude of forestry in Canada result in a mosaic of working and conservation forests in the landscape. Forestry activities immediately adjacent to protected areas can affect ecological processes and organisms within the protected area. Effects include physical and biological changes to streams that flow into or out of protected areas. Harvesting trees adjacent to protected areas creates edge effects. These effects include changes to physical characteristics of a site, old growth, and interior species of the adjacent protected forest, and can increase invasion of alien species. Road construction for forest access can increase isolation of protected areas and affect hydrological processes. Some general guidelines for forest managers to consider when operating near protected areas are: (1) retain or restore natural climax forest species composition; (2) reduce edge contrast between working forest and protected areas; (3) maximize protection of watercourses draining into protected areas; and (4) plan road network to minimize undesirable effects on nearby protected areas.