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Evergreen, understory shrubs, often members of the Ericaceae, have been implicated in the suppression of tree recruitment in many ecosystems. One possible mechanism of this suppression could be an allelopathic interaction between shrubs and seedlings. We tested the allelopathic potential of Kalmia latifolia L., an important component of southern Appalachian forest understories. Aqueous extracts of soil, humus, K. latifolia litter, mixed forest floor litter, and green leaves from K. latifolia did not inhibit germination or initial root elongation of our test species Lactuca sativa L. (lettuce). Root, shoot, and total biomass were reduced in P. rigida seedlings grown in forest floor substrate collected beneath K. latifolia compared to those grown in forest substrate without K. latifolia. While these differences were not significant, they could be exacerbated in the field when seedlings are exposed to multiple stressors (reduced light, water, and nutrient availability). Our findings suggest that allelopathy is not a strong mechanism in the inhibition of canopy tree recruitment by K. latifolia.
Species composition, cover, diversity, and temporal dynamics of the three main plant communities in the channelized Kissimmee River floodplain were evaluated to provide a baseline for tracking the success of an ongoing restoration project. Much of the drained floodplain supports an upland herbaceous community with cover dominated by the planted pasture grasses Paspalum notatum and Axonopus fissifolius. Mesophytic woody communities are comprised primarily of Myrica cerifera, Baccharis halimifolia, Ludwigia peruviana, and understory ferns, while Sagittaria lancifolia, Pontederia cordata, and Panicum hemitomon are dominant species in remnant wetland communities. Community composition and the associated gradient of weighted averages of wetland indicator species reflect prevailing hydroperiods and land uses on the drained floodplain. Managed hydrologic regimes have promoted temporal stability, with seasonal variability of plant community characteristics limited to a decline in live plant cover and species richness during winter months. Lower live vegetation cover during winter resulted from senescence of dominant herbaceous species, while the winter decline in species richness was due primarily to sampling error resulting from seasonal phenology of taxonomic characteristics and obscured growth of rare or diminutive species. The limited variability of plant community characteristics in the channelized floodplain reduces the potential for confounding uncertainty in evaluating successful restoration. Results indicate that functional assessment of plant community characteristics in this subtropical floodplain is most accurately measured in spring and summer.
We present a checklist of the beetles known to occur in and on the oyster mushroom, Pleurotus ostreatus Fries. A total of 136 taxa from 30 families are presented in our checklist. Taxa included in the checklist are known throughout North America with emphasis on those occurring in the southeastern United States. Both adult and larval forms are presented in the checklist along with the type of fungal association, of which ≈ 60% are obligate mycetobionts. A total of 58 beetle taxa were summarized from existing published records, and 78 taxa are new additions from our studies. A discussion of fungi as microhabitats for beetles is given using P. ostreatus and polyporoid fungi as examples.
Many urban areas contain forest remnants and city parks that may be used by birds as stopover and wintering sites. We conducted a case study on how construction of a new apartment complex in Gainesville, FL, affected avian communities both in a forest site and in a portion of a marsh in an adjacent city park. In fall and winter, 1995–1999, we conducted point count surveys of migrant, resident, and wintering birds and compared 1 year of pre-construction survey data to 2 years of post-construction survey data. We conducted analyses to explore changes in: 1) abundance and richness by residency status (resident and migrant guilds), and 2) individual species abundance. Combining pre- and post-construction surveys, we sighted 71 bird species in the developed site and adjacent marsh during the fall and 46 species during the winter. Resident and migrant guild abundance and species richness were not different before versus after construction on the forest site or in the marsh for both seasons. Several individual species did decline in post-construction years, most notably the ovenbird (Seiurus aurocapillus) during the fall migration period that went from 32 to 3 sightings, pre- to post-construction. Results suggest that within the timeframe of this study, the remnant forest patch and adjacent marsh continued to attract migrating and resident species, even after development. On-site preservation of tree canopy and natural buffer areas, in combination with existing vegetative features in the surrounding landscape matrix, may explain why development had a minimal impact on avian richness and abundance.
We conducted aerial surveys during 1996–1998 to estimate abundance and species composition of waterbirds using the channelized Kissimmee River to help understand how river channelization has altered bird use. For waterfowl, mean monthly species richness was 1.5 ± 0.3 (mean ± SE, n = 11 surveys); mean monthly abundance was 86 ± 43, 191 ± 70, and 13 ± 16 birds in 1996–97, 1997–98, and 1998–99, respectively. Blue-winged Teal (Anas discors Linnaeus) were the most abundant duck (74%) followed by Mottled Ducks (Anas fulvigula Ridgway, 21%). Mean wading bird species richness was 8.48 ± 0.35 (n = 20 surveys). Cattle Egret (Bubulcus ibis Linnaeus) were the most abundant wading bird species during the wet season (64 ± 22% of individuals); White Ibis (Eudocimus albus Linnaeus) were most common during the dry season (39 ± 23%). Mean total wading bird abundance was greater during the wet than dry season (F1,15 = 6.29; P = 0.02), with the increase driven by increases in Cattle Egret (F1,15 = 5.46, P = 0.03) and large-prey visual foragers (F1,15 = 5.47, P = 0.03). Compared to the 1950s, waterfowl species richness has declined 70% and abundance has declined 95%. For wading birds, mixed species breeding colonies no longer occur in the floodplain, and the community composition is dominated by the largely terrestrial foraging Cattle Egret during the wet season.
Tree cavities are rarely incorporated into surveys of forest ecosystem biodiversity, due to difficultly in their systematic sampling. We examined the feasibility of using southern flying squirrel (Glaucomys volans Thomas) nest boxes for monitoring arboreal vertebrates at 11 sites within the Savannah River Site, SC. We recorded 3130 vertebrates of 11 species (3 mammals, 3 birds, 5 reptiles) using nest boxes for nesting, roosting, and foraging. G. volans represented the majority of these with 3019 individuals, but flying squirrel occupancy did not affect occupancy of boxes by other species. Upland hardwood forests had the most species that used boxes; however, due to uneven sampling, nest boxes placed in dense-canopy plantations detected the most species per box. We conclude that nest boxes are a useful means of surveying for cavity-dwelling species. We recommend a protocol that uses different size nest boxes at varying heights to accurately survey a traditionally under-sampled component of forest ecosystems, those species using tree cavities.
Parental behavior and prey deliveries at a Bald Eagle (Haliaeetus leucocephalus) nest were monitored (628 observation hours) during three breeding attempts from 1997–1999 at a nest in inland south-central South Carolina. Attendance patterns varied between adults and among breeding attempts, with reduced attendance and incubation observed during a failed attempt. During the three nesting attempts, the female was most often in attendance and incubated more than the male. The eagle pair averaged approximately 4 foraging trips per day during the successful 1997 season, but only 3 trips per day during the 1999 season. Fish and waterfowl comprised 56% and 34% of diet in 1997, respectively, with largemouth bass (Micropterus salmoides) the major fish prey and American Coots (Fulica americana) the major avian prey. Fish (primarily bass and sunfish) comprised 91% of the diet in 1999. Later nesting and reduced waterfowl populations may have contributed to increased fish prey in 1999.
Predation by raccoons, Procyon lotor marinus (L.), is the primary cause of sea turtle nest loss in the Ten Thousand Islands archipelago. Four islands within Ten Thousand Islands National Wildlife Refuge were surveyed for sea turtle nesting activity from 1991–95. Raccoons depredated 76–100% of nests on Panther Key from 1991–94, until 14 raccoons were removed in 1995 resulting in 0% depredation and 2 more were removed in 1996 resulting in 0% depredation. Raccoon removal may be an effective management option for increasing sea turtle nest survival on barrier islands.
The winter roost-site selection of most North American foliage-roosting bats is relatively unknown. We examined winter roost-site selection of Seminole bats (Lasiurus seminolus) in the Lower Coastal Plain of South Carolina during January 2004. Seminole bats used a variety of day-roost structures including the canopy of overstory hardwood trees, hanging vines, pine needle clusters suspended from understory vegetation, and leaf litter on the forest floor. Although reported for red bats (L. borealis), this is the first report of Seminole bats roosting in forest floor leaf litter. Winter roost selection differed from previous observations of summer roosts, which consisted almost exclusively of live overstory pine (Pinus spp.) trees. Roost-site selection in winter likely is related to ambient temperature and optimizing exposure to solar radiation during the day. Management decisions in southeastern forests should consider seasonal changes in roosting behavior to minimize adverse impacts on forest bats.
The distributions of woodland jumping mice (Napaeozapus insignis Miller) and white-footed mice (Peromyscus leucopus Rafinesque) and their associated microhabitats were examined in four habitat types in the Pisgah National Forest of western North Carolina. A total of 115 jumping mice and 192 white-footed mice were collected using arrays of drift fences with pitfalls in 3 north-facing and 3 south-facing upland plots, and in 3 north- and 3 south-facing streamside plots, during the autumn of 1996 and the spring and summer of 1997. Napaeozapus were strongly associated with cooler, moister habitats with high volume of heavily decomposed logs, but P. leucopus were ubiquitous. Results indicate that P. leucopus is a habitat generalist whereas N. insignis is a habitat specialist. Indirect effects such as the availability of subterranean fungi as food may explain the distribution of Napaeozapus at smaller scales.
Freshwater mussel beds of the lower 68 km of the Cache River, AR, were delineated and sampled using diving and stratified random sampling methodology to determine species richness, density, size structure, and population and community numerical standing crop (CNSC). A total of 38 mussel beds were delineated, including 14 major beds (Mbeds) and 24 minor beds (mbeds). Twenty six species were collected, four of which were previously unknown from the Cache River. Amblema plicata, Megalonaias nervosa, and Plectomerus dombeyanus were the most abundant. Estimates of CNSC ranged from 3705 ± 1908 to 122,115 ± 24,194 individuals in Mbeds with mean densities ranging from 6.2 to 44.1 mussels/m2. Nine of 16 species with > 10 individuals had a unimodal size frequency distribution and the other seven had multi-modal distributions. This study found impressive mussel assemblages in the lower Cache River, previously thought to contain only refugial pockets of mussel assemblages. Further monitoring of some species is recommended based on lack of recruitment.
We surveyed tributaries of the Cumberland and Tennessee Rivers for populations of the Eastern Hellbender during the early 1990s. We captured 42 Hellbenders at the Collins River (Warren County), 28 at the Buffalo River (Lawrence County), four at the Calfkiller River (White County), and three at the Duck River (Coffee County). All Hellbenders collected from the Collins, Calfkiller, and Duck Rivers were sexually mature; by contrast, 25% of the Hellbenders collected at the Buffalo River were juveniles. We found that 41% of all mature Hellbenders had gross abnormalities; whereas, no physical abnormalities were noted on any juvenile Hellbenders. The abnormalities noted were similar at each river and included the absence of one or more digits, supernumerary digits, bifurcate manus or pes, absence of one or more limbs, and truncated tails. Fresh wounds (abnormalities) were found only during August and September. We interpret these data as an indication that the injuries were caused by either 1) intraspecific aggression between adult Hellbenders for diurnal retreats or nesting sites, or 2) predatory attacks that resulted in injury to large Hellbenders and death by ingestion to smaller Hellbenders. Regardless of the cause, the large percentage of injured individuals inhabiting middle Tennessee streams merits further study.
We surveyed for the presence of the Northern Curlytail Lizard, Leiocephalus carinatus armouri, from Port Salerno, Martin County, FL, northward to the Indian River-Brevard county line to determine the extent to which this species occurs along the Florida East Coast. The geographic range of L. c. armouri appears to be uninterrupted along the coast from northern Broward County through Palm Beach County. The heavily modified coastal habitat provided this species with the open sunny conditions and cement analogues to the rocky substratum to which it is adapted. Its ubiquity, rate of geographic expansion, combined with its carnivorous habits and large body size, have long since set the stage for an extensive restructuring of the indigenous and exotic lizard fauna in a way that has not been seen since its initial establishment in Palm Beach County almost one-half century ago. Urban heat island effects notwithstanding, frost isotherms predict instability of populations north of Fort Pierce and just below Sarasota on the West Coast.
For nine weeks during the summer of 2002, a mark and recapture technique was used to study homing behavior of Musk Turtles (Sternotherus odoratus) living in Lake Matoaka, VA. During the first three weeks of the study, 119 turtles (83 male, 36 female) were captured using unbaited crabpots, then marked and displaced from the site of capture. Turtles were displaced 100 m across open water 4 m deep, 520 m along the same shore, or 550 m across open water. For the last six weeks of the study, 110 turtles (65 males, 45 females) were captured and released with no displacement. Overall, 39% (49/126) of males and 21% (15/71) of females in this study were captured more than once. Seventy-five of 118 recaptures (64%) were at the site of most recent release (sedentary behavior) and 11 recaptures (9%) were at neither the original nor most recent site of capture (non-homing behavior). Thirty-four of 118 recaptures of displaced turtles (29%) occurred at the site of original capture, and 31 (91%) of these movements were made by males, a significant difference in homing behavior between males and females during the time of the study. Neither distance nor open water significantly impeded turtle homing.
An American Alligator (Alligator mississippiensis Daudin) was observed and photographed in the Gulf of Mexico on 4 May 2004, some 56 km south of Marsh Island, LA (approximately 63 km from the nearest point on mainland Louisiana). Alligators generally avoid saltwater and we are unaware of prior documentation of an alligator occurring this distance offshore.
The Southeast is the stronghold of US herpetofaunal biodiversity and comprises approximately half of the nation's species of amphibians and reptiles, of which about 20% are endemic. However, few areas have been inventoried, thus hampering efforts to monitor and protect populations. We conducted 2-year herpeto-logical inventories of 16 parks within the National Park Service's Southeast Coast Network. We used a wide variety of standard field techniques to document species occurrences and augmented our collecting records with historical data from museums, published literature, and personal collections. We documented the presence of 123 native species of amphibians and reptiles at the 16 parks, with numbers of species ranging between 6 and 64 per park. Many southeastern parks support rich assemblages of herpetofauna.