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Historical accounts describe savanna-like conditions over portions of the Piedmont of the southeastern United States dating at least as far back as the 1500s. These open habitats are thought to have declined because of human development, fire suppression, and loss of native grazing animals. Unfortunately, conservation efforts to restore and sustain Piedmont savanna are hampered by our current rudimentary understanding of community assembly and maintenance dynamics. Such understanding would be facilitated by a robust classification of species into specialist and generalist guilds related to canopy openness, a classification that is currently unavailable on a broad scale. Consequently, our objective was to develop a shade-tolerance classification for the upland Piedmont herbaceous flora of the Carolinas and Virginia, based on quantitative plot data from the region. To achieve this objective, we utilized a dataset of plot records (representing natural and semi-natural vegetation) from the Carolina Vegetation Survey. These are permanent plots on public and private land that were surveyed between 1977 and 2015. Following quality control, the dataset contained 1300 plots and 1550 species (including 835 native herbaceous species after single occurrences were removed), with species abundances in plots reported in cover classes. We estimated the canopy cover of each plot from the cover codes of its tree species and assigned each plot to habitat shade classes: open (<25% canopy cover; n = 63), semi-open (25–75% canopy cover; n=140), or closed (>75% canopy cover; n=1097). We calculated point biserial correlation coefficients (rpb), which provided a positive or negative value for each species, dependent on its abundance and habitat association. We considered single (open, semi-open, or closed) and combined (open+semi-open, closed+semi-open, or open+closed) habitat classes during our analysis. Of the 835 native herbaceous species in the dataset, we found 141 (17%) to be heliophytes (specialists of open habitats with canopy cover <25%), and only 81 (10%) to be sciophytes (specialists of closed habitats with canopy cover >75%), despite 84% of plots in the dataset being classified as closed habitats. Our work suggests that open and semi-open habitats may contain a disproportionate diversity of regional herbaceous flora and provides the first quantitative shade-tolerance classification for over 800 herbaceous species. This work provides a resource that can be used by field biologists and land managers to identify heliophyte communities, and to assess the success of habitat restoration and creation efforts.
Nonnative, invasive plant species have been notoriously problematic for many ecosystems by outcompeting native plant species and disrupting habitat for insects and other animal life. Within the last decade, a nonnative orchid, Epipactis helleborine L. Crantz (Orchidaceae), has become increasingly present in Minnesota and is considered invasive in some eastern states, including Wisconsin. This study provides insights into the presence and habitat preferences of E. helleborine in Winona County, in southeastern Minnesota. A large portion of Winona County lies within the Driftless region, which is characterized by bluff land and unique plant communities that have been greatly impacted by invasive species. This study used MaxEnt software to create a habitat suitability model for E. helleborine using six environmental predictors: elevation, slope, aspect, soil type, land cover, and distance to roads. The results were a model with high habitat suitability predictability with elevation and slope being the most important predictors, whereas other variables contributed little to the final model. The final model showed relatively small areas with high suitability, where management efforts should be concentrated. Based on the model, this species does not seem to be a substantial threat to areas of great conservation concern, such as southwestern facing bluff prairies.
Baird's pocket gopher (Geomys breviceps) is the only species of pocket gopher in Louisiana. Interest in this species' natural history has increased due to its close association with the Louisiana pine snake (Pituophis ruthveni), which recently was listed as threatened under the Endangered Species Act. Approximately 75% of P. ruthveni's estimated prey biomass consists of G. breviceps, whose burrow systems also provide shelter and hibernacula. Therefore, increasing densities of G. breviceps may assist in the recovery and management of P. ruthveni. Previous studies have identified specific habitat characteristics that are preferred by G. breviceps, but none have assessed how different habitats affect pocket gopher density. Live trapping was conducted at sixteen sites throughout Louisiana to determine relative density of G. breviceps. Vegetation and soil data were collected, and a multi-model selection approach was used to determine which variable(s) best explained variation in relative density. Relative densities of G. breviceps ranged from 0 to 12.5 gophers/ha with an average of 3.44 gophers/ha. Canopy cover best predicted numbers of G. breviceps across the study area. Soil data was not a good predictor; however, all sampling plots possessed sandy loam or loamy sand soils, which is preferred by Geomys spp. Management strategies aimed at increasing density of G. breviceps should focus on continued restoration of longleaf pine forest and supplemented by opening patches of forest, especially in areas with preferred soil textures.
Past and current anthropogenic practices have resulted in dramatic alterations to ungulate population densities worldwide. When ungulate populations are overabundant, they can alter the dynamics, structure, and function of ecosystems. White-tailed deer (Odocoileus virginianus), specifically, can occur at densities far greater than their historical records in parts of their native range, which includes forests in the northeastern U.S. They have been shown to alter community structure of native plants, indirectly impact animal communities, and promote the success of invasive species. Despite much research into the effects of overabundant ungulates and deer in particular, less is known about the effects of deer on soil microbial communities. Here, we utilized soil samples from inside and outside of six deer exclosures located in a regional second growth mixed hardwood forest on the Binghamton University campus in Vestal NY, U.S.A. A metagenomic analysis was conducted on DNA extracted from the soil to identify the microbes present. Soil characteristics, including soil organic matter, soil moisture, pH, and electrical conductivity were also measured. Soil samples from inside exclosures had on average lower pH, higher soil moisture and organic matter, and higher electrical conductivity. The microbial communities across all samples were dominated by Proteobacteria, Acidobacteria, and Actinobacteria. However, the structure of the microbial soil community appeared to differ between samples taken inside and outside the exclosures, with those taken outside more closely resembling other outside samples and those sampled inside soils showing more variability in community structure. Overall, our results suggest that overabundant deer may have a homogenization effect on the soil abiotic environment and the soil microbial community.
Patterns of species' occurrences across space and time are fundamental components to understanding their ecology, as this variation often reflects responses to local environmental gradients. We built species-specific models to understand the spatial and temporal factors predicting captures and activity of five snake species in upland pine forests: copperhead (Agkistrodon contortrix), racer (Coluber constrictor), coachwhip (Masticophis flagellum), western ratsnake (Pantherophis obsoletus), and western ribbonsnake (Thamnophis proximus). From mid-May to mid-July across 3 y (2018, 2019, 2020), we monitored boxtraps in two upland pine forests experiencing different management regimes: (1) subjected to frequent thinning and prescribed burning, and (2) subjected to infrequent thinning and prescribed burning. Significantly more copperheads and western ribbonsnakes were captured at the infrequently thinned and burned forest, whereas significantly more racers were captured at forest subjected to frequent thinning and burning. As the summer progressed, captures decreased each subsequent month for both racers and western ratsnakes, with the fewest captures in July. Western ratsnakes were the only species to exhibit a response to the weather in that activity decreased with increasing rainfall. No variables were significant predictors of coachwhip captures. The variation in captures across space may be attributed to the physiological tolerances of each species based on their habitat preferences or differences in prey availability at each forest. Interactions between the physiological tolerances, foraging behaviors, or their reproductive phenology may be underlying the temporal variation in activity patterns.
Insectivorous lizards can alter arthropod community structure and composition. Collared lizards (Crotaphytus collaris) are believed to be keystone predators for Ozark glade grasshopper (Orthoptera) communities by increasing species richness on smaller glades. However, the interaction between collared lizard presence and glade area on orthopteran species richness has been inconsistent between studies on glades in southeastern Missouri. In this study, we explored the effects of collared lizard presence on orthopteran abundance, diversity, and assemblage composition in Ozark glades located in northern Arkansas. We found the presence of predatory collared lizard populations significantly affected orthopteran assemblage composition. However, the presence of collared lizards did not affect orthopteran abundance or diversity. Additionally, there were no interaction effects between collared lizard presence and glade area on orthopteran assemblages. We did find that month had the most consistent effect on orthopteran abundance, diversity, and assemblage composition. These results contrast with other studies that indicate collared lizards influence orthopteran species richness on other glade communities within the region. In this study, seasonal effects, glade area, and unmeasured bottom-up effects appear more important for determining orthopteran diversity than predation. Our results provide further evidence that the strength of top-down effects can vary across a predator's range and could have implications for glade restoration plans in the region.
Species richness and abundances of fluvial specialist fishes often decrease within waters impounded by dams, but mechanisms underlying these decreases are poorly understood. Purpose of this study was to assess the effects of impounded water on fluvial specialist Greenthroat Darter Etheostoma lepidum by quantifying differences in life history (i.e., age structure, life span), reproduction (i.e., gonadosomatic index [GSI], stages of ovarian development), and stomach contents (i.e., diet items and parasites) between a population taken from a lentic environment (Lake Site) and a lotic environment (River Site). Among fishes taken from both sites, Greenthroat Darters lived up to 1.5 y, spawned for 11 mo, and consumed primarily aquatic insects and crustaceans. Differences in reproduction were not detected between populations at the Lake Site and at the River Site. Greenthroat Darters taken from Lake Site consumed fewer diet items, fewer aquatic insects, and greater number of crustaceans than those taken from River Site; however, diet weight, percent stomach fullness, and percent empty stomachs were similar between sites. Greenthroat Darters taken from Lake Site exhibited lower condition factors than those taken from River Site, which corresponded with a greater number of parasites (i.e., Acanthocephala and Nematoda) in individuals taken from Lake Site. Differences quantified herein were not sufficient to cause extirpation of Greenthroat Darters in the impounded waters, given the species has persisted in the impounded water at least since the late 1800s; however, differences in diets and parasites might explain the lower abundance of Greenthroat Darters in Lake Site compared to River Site.
Utility rights-of-way (ROW) serve as nesting areas and maintain a high diversity of early successional birds. ROW incorporating wire zone–border zone and integrated vegetation management can be used as examples of early successional habitat management for bird conservation more generally in the Northeastern United States, given artificial disturbances not created solely for natural resource conservation comprise approximately 80% of early successional habitats. The objective of our study was to determine the effect of herbicide and mechanical vegetation management approaches on the abundance, species richness, and reproductive success of breeding bird species occupying an electric transmission line ROW in central Pennsylvania. The overall abundance of birds was significantly lower within the wire and border management zones, following initiation of a new vegetation management cycle at State Game Lands (SGL 33) than in the years prior to management. Sections of ROW with no border zones contained the lowest abundance and species richness of breeding birds compared to sections with borders prior to the initiation of a new management cycle. Sections of ROW with no border zones and mowing sections had the lowest bird abundance and species richness of all ROW sections at the onset of a new management cycle, and contained the lowest number of bird species displaying evidence of breeding, both prior to and at the beginning of management cycles. Sections of ROW managed using herbicides were comparable or more beneficial to bird communities in terms of abundance, species richness, indices of productivity, and nesting success than sections maintained via mechanical treatments (mowing and hand cutting), both at the end and beginning of management cycles within a forested landscape in the central Appalachian Mountains and surrounding forested regions in the northeastern United States.
The Mexican Woodnymph (Eupherusa ridgwayi) is endemic to west-central Mexico with a narrow distribution range and relatively small population size. The species nest, nesting activities and nestling's characteristics were unknown until now. We generated a map of this species using data from BirdLife International, the Global Biodiversity Information Fund database, e-Bird, and the Naturalista. We used the Mexican Woodnymph records in Jalisco and projected them on a vegetation map. We documented a female constructing a nest, later nesting, until the nestlings flew out of the nest in the cloud forest in central-western Mexico: Jalisco state. The nest site was characterized and the materials used for the nest construction were determined. In addition, we documented several observations made on territorial and foraging behavior.
Grassland insect pollinators have undergone population declines due to habitat loss and degradation. Patch-burning is a management method used to reduce woody plant encroachment and maintain grassland habitats. However, the impacts of fire on the quality and quantity of floral resources (nectar volume, total sugar, and sucrose concentration) available to insect pollinators are understudied. Evaluating how time since last fire and season of fire impact nectar quality and quantity is vital to understanding the overall impact of fire on insect pollinator communities. For this study, 10 flowering forb species (Asclepias viridis, Baptisia alba, Cirsium undulatum, Desmodium canadense, Monarda citriodora, Monarda fistulosa, Oenothera speciosa, Penstemon tubaeflorus, Ruellia humilis, Spiranthes cernua) were selected in The Nature Conservancy's Joseph H. William's Tallgrass Prairie Preserve in an area managed with patch-burning and cattle grazing. Study sites were burned in spring 2018, summer 2018, summer 2019, and spring 2020, with three replicates of each treatment (for 12 total burn units). In each unit, we collected nectar from flowering individuals of each plant species with microcapillary tubes to measure standing crop or the nectar in flowers at any given time that is available to insect pollinators. Total volume of nectar and sucrose concentration were recorded, and total mg of sugar was calculated. Desmodium canadense flowering individuals were only located in units burned the previous spring, whereas P. tubaeflorus flowering individuals were only located in units burned the previous summer. For the eight remaining species, total volume of nectar, total mg of sugar, and sucrose concentration varied with different burn regimens for different species. Cirsium undulatum inflorescences with crab spiders (Thomisidae) had higher volumes of nectar and higher amounts of sugar available. This study highlights how a patch-burn approach with different fire return intervals may benefit insect pollinators at the community level by providing a wide range of nectar qualities and quantities to support insect pollinators with different nutritional needs.
The ability of an animal to acquire enough food to meet its caloric needs is key to its survival and fitness. Understanding the composition of that animal's diet is a crucial element to consider when assessing the species' health and overall role in its ecosystem. We conducted a dietary study of Northern River Otter (Lontra canadensis) at 18 sites across 12 different watersheds in Wisconsin, U.S.A., from summer 2017 through winter 2018. We report the frequency of prey remains found in river otter scats (n = 190) collected at these sites. Fish of any kind appeared in 86% (n = 163) of all scat samples, while crayfish (Cambaridae) were the most commonly occurring individual prey item, appearing in 62% (n = 117) of all scat samples. The second most common prey groups were the bottom feeder fish (Catostomidae and Cyprinidae) group and the panfish (Centrarchidae) group, which both occurred in 45% of all scats. While identifying prey species, we found small, spherical objects that did not appear to be of biological origin in 48% (n = 92) of all scats. After testing the objects using multiple approaches, we confirmed the objects as microbeads, defined as small beads of plastic composition no larger than 5mm in size. This is the first recorded observation of plastic microbeads associated with river otters in North America, and may indicate bioaccumulation of these objects in inland waterways.
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