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Wildlife habitat condition in open pine woodlands: Field data to refine management targets
Abstract
Open pine ecosystems of the southern United States are a conservation priority for many agencies, organizations, and private landowners. These woodlands, characterized by moderately-stocked overstories, low cover of midstory, and grass-dominated herbaceous groundcover, provide important habitat for a suite of rare and declining wildlife species. To provide guidance for land managers engaged in habitat restoration in open pine ecosystems, ranges of desired conditions for elements of vegetation structure have been developed using literature survey and expert opinion. We compared empirical data on habitat occupancy for 17 wildlife species from second-growth longleaf pine woodlands in southwestern Georgia with recommended ranges for basal area (BA) of all pine, BA of pine ≥ 35.5 cm dbh, percent canopy cover, percent herbaceous cover, and percent shrub cover. Vegetation data were taken from 864 monitoring plots and Mahalanobis distance models were used to develop habitat suitability indices from the wildlife data. Recommendations for shrub cover and BA of pines ≥ 35.5 cm fit well with model predictions for all wildlife species. However, mean BA of all pines at sites used by wildlife were at the low end of the recommended range. Herbaceous cover at sites used by wildlife was well below the recommended range, whereas canopy cover was well above recommendations, suggesting these ranges should be expanded. These modifications could provide managers of open pine ecosystems greater flexibility, allowing them to incorporate a broader suite of objectives in their management while still providing habitat for wildlife species of concern. Moreover, our models suggest that monitoring presence of open pine indicator bird species may be an efficient method to assess restoration or management progress of open canopy pine systems.
... In the southeastern United States, longleaf pine once existed in vast savannas. Today, remaining longleaf pineforests are well-recognized, fire-maintained, disclimax communities that have garnered considerable conservation interest (McIntyre et al., 2019). ...
... Decline of this forest type occurred because of European settlement and associated timber harvest coupled with reduced frequency or elimination of fire from the system (Ware et al., 1993, Landers et al., 1995, Van Lear et al., 2005. To halt further decline of the longleaf pine ecosystem, its conservation and restoration are receiving much interest throughout its geographical range (Van Lear et al., 2005, Outcalt and Brockway, 2010, McIntyre et al., 2019. Because longleaf pine is fire-dependent, prescribed fire is a critical component of both restoring and managing this system (Frost, 2006, Mitchell et al., 2006. ...
... This resulted in each burn unit being burned on an approximate twoyear rotation and a landscape that consisted of both burned and unburned forested patches. The regular application of fire reduced hardwood encroachment, promoted a dense herbaceous understory, provided germination sites for longleaf seeds, and maintained habitat for a variety of endemic wildlife species (Smith et al., 2006, McIntyre et al., 2019. In some burn units, deviations from this burn regime occurred in association with research projects or to meet specific management objectives. ...
Longleaf pine (Pinus palustris) forests are among the most fire-dependent forest types in the world and once dominated much of the southeastern United States. Loss and fragmentation of longleaf pine shrank its distribution to approximately 4% of its historic range; as a result, longleaf pine forests currently receive much conservation and restoration emphasis. In all cases, this emphasis includes prescribed fire. Prescribed fires promote herbaceous understories which maintains habitat for some small mammals, but fires can also result in temporary declines of small mammal populations. Therefore, short return intervals may not allow small mammal populations to recover between fires, and long return intervals may result in declining habitat quality and reduced small mammal abundance. During the first phase of our research, we studied the long-term influence of prescribed fire on small mammals. We annually estimated small mammal abundance and species richness during 2001 – 2014 in eight longleaf pine-dominated plots in southwestern Georgia, USA. Plots were either biennially burned (reference) or had fire excluded during the study. Small mammal species richness was similar in fire-excluded and reference sites. Overall small mammal abundance was greatest in reference plots. Five species were captured with sufficient frequency to justify species-specific analyses. Of these, three (hispid cotton rats, Sigmodon hispidus; oldfield mice, Peromyscus polionotis; and house mice, Mus musculus) were more abundant in reference plots. For the second phase of our research, we reintroduced fire in half of the fire excluded plots (burned during 2015, 2016, and 2017) and began sampling small mammals in three additional plots that were burned annually since 2003. We collected data during 2017 and 2018 for this phase of the research to evaluate small mammal response to four prescribed-fire return intervals (annual growing season burns since 2003, biennial burns since 2001 (reference), fire excluded since 2001, and fire excluded since 2001 and then burned during 2015, 2016, and 2017). Small mammal species richness was not affected by burn interval. Cotton rat abundance was greater in reference plots than in other treatments, whereas cotton mice (Peromyscus gossypinus) and oldfield mice were most abundant in the annually burned treatment. Three prescribed fires occurred in fire reintroduced plots prior to sampling, but these fires were insufficient to restore small mammal abundance to that of annually or biennially burned plots. Our work provides further evidence that fire is important for maintaining habitat for some small mammals and that time between fires has a species-specific effect on small mammal abundances. Thus, manipulating fire return interval is a promising tool for managing relative abundance of small mammals and likely other wildlife.
... Northern bobwhite abundance was strongly influenced by canopy cover (< 60%), midstory shrub cover (10-40%), vertical stratification of groundcover, and bare ground cover (~10%; McIntyre et al., 2019, Cram et al., 2002, Taylor and Burger, 2000. In the Southeastern Coastal Plains, occupancy and foraging success were associated with low midstory shrub cover (10-25%; McIntyre et al., 2019, Burke et al., 2008, Taylor and Burger, 2000. ...
... Northern bobwhite abundance was strongly influenced by canopy cover (< 60%), midstory shrub cover (10-40%), vertical stratification of groundcover, and bare ground cover (~10%; McIntyre et al., 2019, Cram et al., 2002, Taylor and Burger, 2000. In the Southeastern Coastal Plains, occupancy and foraging success were associated with low midstory shrub cover (10-25%; McIntyre et al., 2019, Burke et al., 2008, Taylor and Burger, 2000. In the Great Plains and Rio Grande Plains ecoregions, sites become more suitable for bobwhite nesting as shrub cover increases (e.g., in excess of 25%; DeMaso et al., 2014, Lusk et al., 2006, and may reflect the importance of shrub cover to daytime loafing, escape cover, and winter cover. ...
... Waldron et al. (2008) found that the probability of use by eastern diamondback rattlesnake increased 1.5 times for every 25% decrease in canopy cover at a pine savanna preservation site maintained with prescribed fire. Habitat suitability modeling using long-term vegetation and faunal data in southwestern Georgia suggested that eastern diamondback rattlesnake occupy stands with lower basal area, canopy closure, and shrub and herbaceous understory coverages than observed for our other focal species (McIntyre et al., 2019). Radio telemetry data and occupancy modelling have demonstrated that while eastern diamondback rattlesnakes are primarily associated with pine-grassland communities, they can use other land cover types (e.g., mixed pine hardwood, mesic and xeric hammock; Steen et al., 2012, Lee, 2009, Timmerman, 1995 and seem to respond positively to a limited hardwood component (Steen et al., 2012, Waldron et al., 2008. ...
The decline of early successional and open forests and their wildlife inhabitants has resulted in increased efforts to understand and conserve these communities. Natural and anthropogenic disturbances that historically created and maintained open forest conditions have been disrupted, necessitating wildlife use of alternative habitat sources (e.g., pine plantations, utility rights-of way, abandoned agricultural fields) to carry out their life history. We reviewed available literature to estimate the range of structural conditions suitable for four open forest species in regional decline and compared these ranges to available structure in loblolly pine (Pinus taeda) forests managed for economic return. Species included Bachman’s sparrow (Aimophila aestivalis), northern bobwhite (Colinus virginianus), prairie warbler (Dendroica discolor), and eastern diamondback rattlesnake (Crotalus adamanteus). We estimated habitat availability and connectivity for each of these four species during a 60-year simulation on an economically- and operationally-feasible pine landscape (>22,000 ha) managed for sawtimber production in the West Gulf Coastal Plain. Habitat requirements, including minimum patch size and dispersal constraints, of Bachman’s sparrow, northern bobwhite, prairie warbler, and eastern diamondback rattlesnake are generally met by pine stands in stand establishment and thinned, mid-rotation stages. However, habitat availability in pine plantations may be highly ephemeral, tends to occupy the upper end of basal area and canopy closure tolerance, and may be more suitable for open woodland species (e.g., Bachman’s sparrow) than grassland species (e.g., northern bobwhite). The range of habitat associations in this literature review highlights the need to refine targets of structural metrics identified by open pine restoration initiatives to encompass the full range of conditions occupied by open forest species. Current literature is strongly biased to avian habitat associations. Few papers explore habitat associations of herpetofauna of conservation concern in the southeastern U.S., and these species tend to be less mobile and therefore, more vulnerable to landscape changes and the ephemeral nature of open vegetative structure in pine plantations.
... The Southern United States (US) supplies 55 percent of all roundwood products, despite only having 32 percent of the forestlands nationwide (Oswalt et al. 2019). These forestlands offer a wide variety of economic, social, and ecological benefits, including income opportunities such as logging, selling hunting licenses, recreation, clean water and air, erosion prevention, absorption of greenhouse gasses, and habitat and food for wildlife (Bailey et al. 2021;Dudley and Stolton 2003;Gunnoe, Bailey, and Ameyaw 2018;McIntyre et al. 2019;van Deusen 2010). Currently, about 92 percent of forestlands in the region are owned by private landowners, out of which almost two-thirds are families (Butler and Wear 2013). ...
... Of the 24 million acres of forestland in Georgia, 55 percent is privately owned by individuals, 29 percent is owned by corporations, 6 percent is owned by the forest industry, and 9 percent is in public hands (Georgia Forestry Association 2021). Considering the high amount of privately owned forestland in Georgia, understanding what drives conservation intent, including potential gender differences, is important as forests offer many environmental benefits such as maintaining clean water (Dudley and Stolton 2003), carbon sequestration (van Deusen 2010), and habitat for wildlife (McIntyre et al. 2019). ...
Forests offer critical social, economic, and ecological benefits. As fifty-five percent of Georgia's forests are family-owned, management decisions of these forest landowners have a considerable impact on the state's environment and beyond. So far, little is known about what drives the conservation intentions of forest landowners and how these drivers vary by gender. However, several studies outside the field of forestry have theorized that place attachment predicts pro-environmental views and behaviors. To test this theory , we surveyed 1,143 family forest landowners in Georgia. Our results show that male landowners report stronger attachments to their forest, except for continuing family legacies which is of greater importance for female landowners. Regression models show that all dimensions of place attachments (dependence, identity, satisfaction, and family legacy) are strong predictors for conservation intentions in males. In contrast, the level of education and only a few dimensions (satisfaction and, to a lesser extent, dependence) of place attachment predict conservation intentions in females. As gender demographics in forest landowners are shifting and environmental degradation is an increasingly pressing concern, this study provides important insights and offers directions for further research for policymakers, researchers, and extension agents.
... At the local or stand scale, open condition within a pine patch (or stand as synonym) is one of key factors affecting plants and animals, especially birds of conservation concern, e.g., red-cockaded woodpecker (Leuconotopicus borealis), Bachman's sparrow (Peucaea aestivalis), and northern bobwhite (Colinus virginianus) (Greene et al. 2019;McIntyre et al. 2019). Closed canopy and hardwood encroachment result in dense vegetation but very low herbaceous vegetation cover on the ground, simplifying vegetation structure within a patch and reducing diversity and abundance of birds (Allen et al. 1996;Melchiors 1991). ...
... I calculated hardwood basal area and softwood basal area separately within a plot using the DBH data and for each basal area, averaged the value across all four plots. Most of these vegetation features are often considered important to wildlife in pine forests (Dickson et al. 1993;Lee andCarroll 2014, 2018;McIntyre et al. 2019;Melchiors 1991). ...
Increasing land conversion of agriculture and forest by urban growth in the southern United States has altered the landscape matrix surrounding pine forests, creating varying mixtures of urban and agricultural cover types. I investigated the avian diversity-environment relationship in the southern pine forests along an urban-agriculture-wildland gradient by quantifying multiple dimensions of biodiversity: taxonomic (Shannon-Wiener index), functional (RaoQ and its standardized effect size), and phylogenetic (mean pairwise distance, mean nearest taxon distance, and their standardized effect size) diversity. I also considered habitat guilds and single traits correlated with RaoQ. I used breeding bird data collected at 162 pine stands in Georgia. Taxonomic and functional diversity increased with agricultural cover within the landscape (1 km-radius area). In particular, shrub habitat guild and shrub nesters showed a strong positive response to the variable. Insectivores and tree nesters (two predominant traits in pine forests) responded negatively to urban and agricultural covers. Both taxonomic and functional diversity decreased and increased with increasing hardwood vegetation cover and herbaceous vegetation cover within a stand, respectively. Pine-grassland and shrub habitat guilds, omnivores, and shrub nesters also showed the similar responses to these variables. Phylogenetic diversity metrics were not associated with environmental variables. The findings of this study suggest that open habitat features within a stand are important to promote functional diversity as well as taxonomic diversity in pine forests. They also indicate that agricultural matrix does not act as an environmental filter and low to moderate levels of less intensive agricultural (hay/pasture) matrix may improve avian diversity.
... The primary species of interest was Bachman's Sparrow (Peucaea aestivalis), a ground-nesting species dependent on herbaceous understories characteristic of frequently burned longleaf pine stands (Tucker et al., 2004(Tucker et al., , 2006, including young stands . Bachman's Sparrow is of high conservation concern throughout its range (Rosenberg et al., 2016), is an indicator of suitable structure for open-canopy pine wildlife species (Hannah et al., 2017;McIntyre et al., 2019), and, as described above, also indicates whether the stands are within desired ecological conditions. Therefore, we considered occurrence of Bachman's Sparrows in PFW stands as the most important measure of restoration success. ...
... We detected few Bachman's Sparrows or other grassland species during our study, indicating that PFW longleaf pine forests may not have been restored to the primary desired ecological conditions. Mean herbaceous cover across stands was 39% (SD = 23%), which is close to the minimum of 40% preferred by Bachman's Sparrows, but mean woody cover was 38% (20%), which is much greater than the preferred value of <20% (Greene et al., 2019, McIntyre et al., 2019. A potential caveat of our study is that Bachman's Sparrows typically occupy mature pine stands. ...
Longleaf pine (Pinus palustris) forests have become a major focus of large-scale restoration efforts across the southeastern United States over the past two decades, but the success of these efforts are not often measured. One example is Partners for Fish and Wildlife (PFW), which is administered by the U.S. Fish and Wildlife Service (USFWS) and designed to assist private landowners with longleaf pine (Pinus palustris) planting. An objective of this program is to provide habitat for species like the Bachman’s Sparrow (Peucaea aestivalis), which is reliant on fire-maintained longleaf pine savannas. To assess this program’s success, we conducted avian point counts and vegetation surveys in longleaf pine stands enrolled in the Mississippi PFW program during 2018–2019. We surveyed 51 stands (≥16 ha; ≤16 years old) and conducted 194 point count surveys. Across all stands, coverage of woody vegetation averaged 38% (SD = 20%), herbaceous cover 39% (23%), and canopy closure 68% (25%). We detected 6 Bachman’s Sparrows in 3 stands at 4 points (5.8% of stands, 2.1% of points), indicating the stands are providing inappropriate conditions for this species due to inadequate prescribed burning. We detected Prairie Warblers (Setophaga discolor) in 37 stands (72%) and at 94 points (48%), and Northern Bobwhites (Colinus virginianus) in 43 stands (83%) and at 101 points (52%), indicating PFW stands are providing habitat for declining shrubland species. If providing habitat for grassland birds like Bachman’s Sparrow continues to be an objective for PFW stands in the Southeast, we recommend stricter requirements for landowner enrollment in the program (e.g., agreements to maintain a burn interval of ∼2 years), and more assistance in meeting those requirements. More broadly, maintenance of appropriate disturbance regimes will be critical to restoration of disturbance-dependent forests and may require longer-term investment than is customary.
... Some mesophytic hardwood species also create less pyric conditions in the understory (Kane et al. 2008). Management strategies aimed at reducing mature mesophytic hardwoods in previously fire-suppressed pine savanna may help to restore understory habitat for native fauna (Cram et al. 2002, Askins et al. 2007, Hiers et al. 2014, McIntyre et al. 2019. Avian and herpetological communities respond positively to restoring southeastern pine savanna by reintroducing fire and reducing hardwood canopy (Provencher et al. 2002, Steen et al. 2013a. ...
... Bachman's Sparrow is an effective indicator species for management efforts aimed at restoring pine savanna vegetation structure to benefit a wide range of native species (McIntyre et al. 2019). This study suggests that mechanical hardwood reduction on sites with old-field ground cover that are managed intensively for bobwhite will not dramatically influence Bachman's Sparrow populations via changes in vital rates. ...
Where historical fire regimes have been disrupted, reduction in woody vegetation is often used to maintain or restore habitat for grassland and early successional birds. In pine savanna ecosystems of the southeastern USA, mechanical hardwood canopy reduction can restore pine savanna communities and is often employed on privately owned lands to improve habitat for the Northern Bobwhite (Colinus virginianus), although scant empirical evidence exists of its effects on target or non‐target species. We measured the response of a pine savanna specialist, the Bachman's Sparrow (Peucaea aestivalis), to large‐scale hardwood reduction in a before–after–control–impact design on two properties where two‐year fire‐return intervals were established and the Bachman's Sparrow population was stable. We investigated the effects of mechanical hardwood reduction on Bachman's Sparrow daily nest survival, cause‐specific nest mortality and adult male annual survival. During the four‐year study, we monitored 107 Bachman's Sparrow nests, recorded 49 nest predation events, and banded 113 adult male Bachman's Sparrows. We found Bachman's Sparrow nest and adult survival were resilient to changes in the hardwood canopy and did not differ significantly between treatment and control sites. Average annual adult male survival was 0.41 (0.32–0.52) and daily survival rate of nests with surveillance declined annually from 0.94 (0.92–0.96) to 0.88 (0.83–0.92). The identity of predators at nests was dominated by two snake species, black racer (Coluber constrictor) and corn snake (Pantherophis guttata). We found evidence for opposing treatment effects on the frequency of nest depredations by the dominant species; racers responded positively and corn snakes responded negatively. Our results suggest a moderate midstory canopy does not limit Bachman's Sparrow vital rates when management includes frequent prescribed fire. Our results also suggest hardwood reduction to mitigate nest predation may be complicated with a diverse predator suite.
... Along with many other species characteristic of the fire-dependent longleaf pine (Pinus palustris) ecosystem, the southeastern pocket gopher is of conservation concern due to large scale conversion, fragmentation, and degradation of open-pine communities (Jordan, 2004;Parsons, 2019;Duncan et al., 2020). As studies more precisely define vegetative conditions suitable for southeastern pocket gophers (Warren et al., 2017a), land managers can use prescribed fire, herbicide treatments, and mechanical tree removal to provide these conditions (Brockway et al., 1998;Miller and Miller 2004;Varner et al., 2005;McIntyre et al., 2019). Little can be done about the distribution of appropriate soil types, but managers need the ability to identify suitable soils when planning conservation efforts such habitat restoration and population reintroductions. ...
... In a previous systematic study of habitat selection, southeastern pocket gopher occupancy in southwest Georgia was tied more strongly to soil characteristics than vegetation structure (Warren et al., 2017a). However, upland portions of their study area were dominated by open-canopy pine forests with a long history of regular prescribed fires (McIntyre et al., 2019). In contrast, we expected to find strong differences in vegetation structure between occupied and unoccupied sites due to the heterogeneous mix of forest structural states and management histories in our study area. ...
... Along with many other species characteristic of the fire-dependent longleaf pine (Pinus palustris) ecosystem, the southeastern pocket gopher is of conservation concern due to large scale conversion, fragmentation, and degradation of open-pine communities (Jordan, 2004;Parsons, 2019;Duncan et al., 2020). As studies more precisely define vegetative conditions suitable for southeastern pocket gophers (Warren et al., 2017a), land managers can use prescribed fire, herbicide treatments, and mechanical tree removal to provide these conditions (Brockway et al., 1998;Miller and Miller 2004;Varner et al., 2005;McIntyre et al., 2019). Little can be done about the distribution of appropriate soil types, but managers need the ability to identify suitable soils when planning conservation efforts such habitat restoration and population reintroductions. ...
... In a previous systematic study of habitat selection, southeastern pocket gopher occupancy in southwest Georgia was tied more strongly to soil characteristics than vegetation structure (Warren et al., 2017a). However, upland portions of their study area were dominated by open-canopy pine forests with a long history of regular prescribed fires (McIntyre et al., 2019). In contrast, we expected to find strong differences in vegetation structure between occupied and unoccupied sites due to the heterogeneous mix of forest structural states and management histories in our study area. ...
Pocket gophers (Geomyidae) require soils amenable to burrowing and vegetation communities that provide adequate foods. We examined the interplay of soil texture and vegetation structure in determining site occupancy of the southeastern pocket gopher (Geomys pinetis), a species of conservation concern throughout its range. Using a case-control sampling design, we compared vegetation structure and soil texture between occupied and unoccupied sites in southeastern Alabama. All occupied sites had soil clay content �8.05% at 0–20 cm depth. In logistic regression modeling, clay content had
overwhelming support as the most important single habitat variable distinguishing occupied from unoccupied sites. Based on soil results, we focused our examination of vegetation structure on the subset of our sites with <10% clay at 0–20 cm depth. Relative odds of occupancy were highest at intermediate levels of canopy cover; however, canopy cover at occupied sites ranged widely. Compared to unoccupied sites, occupied sites contained less midstory cover and greater ground cover of graminoids and shrubs. Our results demonstrate that although vegetation structure is important in determining site suitability, soil texture may be an overriding constraint limiting potential habitat for this species. Conservation actions for southeastern pocket gophers such as habitat restoration and population translocations should ensure that target sites have suitable low-clay soils.
... To identify unprotected areas of high-quality pine habitat for protection and lower-quality areas for restoration, The Nature Conservancy (TNC) of North Carolina created a remotely sensed metric that incorporated measures of habitat structure, composition, and landscape context to describe pine forest quality across over 45,000 km 2 of southeastern North Carolina. The habitat quality index (HQI) measures open canopy forest structure, which corresponds to the presence of many species of conservation concern such as northern pine snake (Pituophis melanoleucus) and Bachman's sparrow (Peucaea aestivalis) (McIntyre, et al. 2019). The HQI heavily weights forests with an open canopy dominated by pines, containing larger pines and minimal midstory vegetation, habitat in which RCWs preferentially forage within our study area (Zwicker & Walters 1999;Walters et al. 2002). ...
Remote sensing data can be a powerful and cost-effective method for determining the extent, composition, and structure of ecosystems across large areas. To use this tool for effective conservation of individual species, we need to test the assumption that remotely sensed habitat indices correspond to both patch suitability (i.e., presence) and value (i.e., demographic rates) for the species reliant on those habitats. We built an open pine habitat quality index (HQI) from remotely sensed spectral data to identify the condition of pine stands. We correlated the HQI with presence, group size, and fledgling production of an avian species (red-cockaded woodpecker, Dryobates (=Picoides) borealis, RCW) associated with longleaf pine (Pinus palustris) using Bayesian logistic regressions and structural equation models. The HQI was correlated with RCW cavity tree and foraging area presence, with 10.8 and 16.0 increased odds of RCW presence with each unit increase in the HQI, respectively. However, the HQI was not correlated with RCW demographic performance. Given that RCWs are an umbrella species and are currently limited by habitat, that the HQI successfully identifies areas of higher quality habitat for RCW is useful for conservation planning. Improving the specificity of the remotely sensed index could improve the link between the HQI and RCW demographic performance, but might limit its application to RCW, instead of the entire open pine endemic community. Our study suggests that linking generalized habitat indices to species habitat suitability is possible and strengthens the justification for their use in cost-effective, large-scale conservation of imperiled ecosystems.
... However, forest management interests vary by gender and age (Butler et al. 2017. Keeping privately owned forests productive and healthy is important because working forests make contributions to the local economy, offer recreational opportunities, and are vital for clean water and air, erosion prevention, absorption of greenhouse gasses, and habitat for wildlife (e.g., Gunnoe et al., 2018;McIntyre et al., 2019;Bailey et al., 2021). Thus, research on the interests of specific forest landowner demographics is needed to satisfy forestry education needs, environmental programs, and forestry-related regulations and policies. ...
This qualitative study uses open-ended responses from ninety-four female forest landowners in Georgia, United States, to analyze their unique experiences with forest landownership. By focusing on the most frequently mentioned themes-forest management and income, family legacy, and conservation-we expose a broad range of female forest landowners' experiences. Acknowledging that these three themes might be relevant to any forest landowner and age group, we draw a typology based on life-course junctures to show that the focus on specific aspects of their forest landownership shifts with age. We conceptualized three age-based typologies of female forest landowners: (1) pre-retirement (<65) female forest landowners who mainly focused on forest management and generating additional forest-based income; (2) post-retirement (65-74) female forest landowners who shift their attention to family connections and legacy planning; and (3) elderly (>75) female forest landowners who focus more on forest conservation. We also show that the interests of male forest landowners differ substantially from female forest landowners, whose interests consistently centered around forest management topics such as maintenance, timber harvest, and taxation throughout their life-course. Our findings offer important insights into female forest landowners in the southern United States.
... Naturally regenerated longleaf stands managed with frequent prescribed fire typically have low basal areas, sparse midstories, and diverse herbaceous ground cover [3]. These stand conditions also support many species of conservation concern, such as the gopher tortoise (Gopherus polyphemus) and red-cockaded woodpecker (Leuconotopicus borealis) [4], in addition to a highly diverse pyrogenic ground flora [5]. For wet-mesic longleaf pine sites maintained with prescribed fire, the mean species richness at the scale of 3 m 2 quadrats was 36 plant species, which was more than double that of xeric sites [6]. ...
Longleaf pine (Pinus palustris Mill.) savannas and woodlands are known for providing numerous ecosystem services such as promoting biodiversity, reducing risk of wildfire and insect outbreaks, and increasing water yields. In these open pine systems, there is also interest in managing carbon (C) in ways that do not diminish other ecosystem services. Additionally, there may be management strategies for accomplishing these same objectives in plantations and degraded stands that developed from natural regeneration. For example, C accumulation in live trees and C storage in harvested wood products could be increased by extending rotations and converting plantations to multi-aged stands. Belowground C storage could be enhanced by incorporating pyrogenic C into the mineral soil before planting longleaf pines in clearcut areas, but this may be contrary to findings that indicate that minimizing soil disturbance is important for long-term soil C storage. We suggest examining approaches to reduce total ecosystem C emissions that include using targeted browsing or grazing with domesticated livestock to supplement prescribed burning, thereby reducing C emissions from burning. The mastication of woody vegetation followed by a program of frequent prescribed burning could be used to reduce the risk of substantial C emissions from wildfires and to restore function to savannas and woodlands with hardwood encroachment and altered fire regimes. Many of these approaches need to be validated with field studies or model simulations. There is also a need to improve the estimates of dead wood C stocks and C storage in harvested wood products. Finally, eddy covariance techniques have improved our understanding of how disturbances influence longleaf pine C dynamics over multiple time scales. However, there is a need to determine the degree to which different silvicultural approaches, especially those for adapting ecosystems to climate change, influence C accumulation. Overall, our review suggests that there are numerous opportunities for research on C dynamics in longleaf pine ecosystems, and these systems are likely well-positioned to accomplish C objectives while offering other ecosystem services.
... We selected the Jones Center at Ichauway, an 11,700 ha managed longleaf pine-dominated forest in Baker County, Georgia, U.S.A. (hereafter, Ichauway), as our source of pocket gophers for translocation (hereafter, donor area) due to access and presence of an established pocket gopher population (Smith et al. 2006;Warren et al. 2017aWarren et al. , 2017bMcIntyre et al. 2019) (Fig. 1). Areas that received pocket gophers (hereafter, translocation areas) included Ichauway (in areas with no evidence of pocket gopher presence), Silver Lake Wildlife Management Area in Decatur County, Georgia (Silver Lake) and a private property in Baker County, Georgia. ...
The longleaf pine (Pinus palustris Mill.) savanna ecosystem in North America has declined by 97% from its historic range and its restoration is a conservation priority. The southeastern pocket gopher (Geomys pinetis), an ecosystem engineer in longleaf pine savannas, is absent from most of its historic range. Translocation of pocket gophers may be needed to reestablish ecosystem services of restored longleaf savannas. To determine translocation feasibility, we quantified survival, site fidelity, and homing of pocket gophers translocated using soft releases (with a starter burrow system; n = 13), hard releases (without a starter burrow system; n = 17), or released into their own burrows (control, n = 10). Naïve survival was 46% and 35% for soft‐ and hard‐released individuals, respectively, and 80% for controls. Most mortalities of translocated individuals (75.0%) occurred within 12 days. Including all radiotagged pocket gophers, daily survival of soft‐released animals (Ŝ = 0.990) was intermediate between hard‐released (Ŝ = 0.986) and controls (Ŝ = 0.993), and only hard‐released was lower than controls. Using only individuals that survived >14 days, we found no difference in daily survival. Site fidelity was low, with 70% of translocated pocket gophers making aboveground movements away from release point. However, soft‐released individuals stayed at the release point 3 times longer than hard‐released animals. No pocket gopher exhibited homing. Our results suggest translocation has potential for establishing pocket gopher populations into restored longleaf pine savannas and that mitigating mortality during establishment will increase the likelihood of success. This article is protected by copyright. All rights reserved.
... Because burrow width and vegetation obstruction both influence detection probability of burrows, the identification of missed burrows in the set of n A augmented burrows required us to model the underlying distribution of both variables for all observed and unobserved burrows (Royle and Dorazio 2008). We assumed that the distribution of amount of vegetation obstruction was independent of burrow locations, as previous studies suggest gopher tortoises will place burrows in a wide range of shrub densities (McIntyre et al. 2019). Accordingly, for each missed burrow in the population i = 1, …, (N-n ) ind , we assigned a vegetation measurement (v i ) drawn from a beta distribution informed by all raw vegetation measurements (v r ) taken at the site: ...
Line‐transect distance sampling (LTDS) surveys are commonly used to estimate abundance of animals or objects. In terrestrial LTDS surveys of gopher tortoise ( Gopherus polyphemus ) burrows, the presence of ground‐level vegetation substantially decreases detection of burrows of all sizes, but no field or analytical methods exist to control for spatially heterogeneous vegetation obstruction as a source of variation in detection. We propose the addition of a simple measurement of ground‐level vegetation that serves as a covariate for the detection function. We present a Bayesian hierarchical model in which covariates burrow width and nearby vegetation height help to account for detection bias and improve precision of estimated density. We investigate the performance of this covariate by simulation and by using real LTDS data collected before and after application of prescribed fire. We collected data in 2018 at the Jones Center at Ichauway in Newton, Georgia, USA. Across all simulations, our model including both covariates produced the most accurate density point estimates of any of the models tested. For our case study, our Bayesian model with vegetation covariates tended to produce similar estimates of density before and after burns. Our study indicates that any level of spatial variation in vegetation obstruction decreases detection of burrows and may lead to underestimation in population size (≤68%) and proportion of individuals with small burrow sizes (≤32%) when not considered during analysis. Our work is extensible to other terrestrial sampling efforts where systematic measurement of a spatially distributed obstructing feature is feasible during the LTDS survey.
... Many wildlife species of conservation concern are associated with fire-maintained longleaf pine forests including the gopher tortoise (Gopherus polyphemus) and redcockaded woodpecker (Leuconotopicus borealis). McIntyre et al. (2019) used empirical data on habitat occupancy to predict that gopher tortoises preferred habitat with canopy cover of 61.47 ± 14.25% (mean ± SD) and herbaceous cover of 49.27 ± 20.55. The red-cockaded woodpecker requires open stand conditions for foraging and trees ≥ 60 years old for nesting (Engstrom and Sanders, 1997;Mitchell et al., 2009). ...
Naturally-regenerated, second-growth longleaf pine woodlands of the southern USA are often composed of stands with low canopy cover (25–60%) and diverse herbaceous ground cover. These conditions are maintained using prescribed fire and multi-aged management approaches to achieve multiple landowner objectives such as reducing the risk of wildfire and enhancing plant and animal diversity. However, managing longleaf pine to meet these objectives conflicts with C market protocols that require landowners to retain live tree C stocks above a “common practice” baseline. The common practice baseline is an estimate of the average live tree C stock of forests with species composition and site quality similar to the forest being considered for a C project. Maintaining live tree C stocks above current baselines might reduce habitat for plant and animal species of conservation concern and decrease streamflow and ground water recharge. While some level of insect- and drought-related tree mortality is inherent in longleaf pine woodlands, trees may also be more vulnerable to drought and insect outbreaks in stands with live tree C stocks that are above current baselines. Lastly, longleaf pine stands managed at low densities are a source of high-quality wood products (e.g., flooring, ceilings, beams, trim, and paneling) that store C over long periods of time (sometimes > 100 years), and inclusion of wood products and better accounting for storage in these products could make longleaf a viable candidate for C offset projects. Funds generated from C offsets could enable landowners who are considering other forms of forest management or land use to continue managing longleaf pine to meet multiple ecosystem objectives.
... The broad-scale loss of grassland and early successional plant communities throughout the southeastern United States has been detrimental to birds and other native fauna that rely on these plant communities (Askins et al., 2007;Brennan & Kuvlesky, 2005). Management strategies aimed at reducing mesophytic oaks in pine savanna that was previously fire suppressed may help restore understory vegetation (Hiers et al., 2014), with potential positive impacts on wildlife (Cram et al., 2002;McIntyre et al., 2019), including some species of birds (Askins et al., 2007). ...
Disruption of historic fire regimes has led to the expansion of hardwoods into pine savanna ecosystems in the southeastern United States. Management strategies that reduce mature mesophytic oaks in pine savanna that was previously fire suppressed may help restore understory vegetation and positively affect understory birds. Many private lands in the Southeast are managed intentionally for the Northern Bobwhite (Colinus virginianus; hereafter bobwhite), a species with high cultural and economic importance to the region. Mechanical hardwood reduction is used to restore southeastern pine savanna and as a pre-dation management tool to enhance populations of bobwhite although its utility has not been empirically tested. We measured the demographic response of bobwhite to a large-scale hardwood reduction using a before-after-control-impact (BACI) study replicated at two properties in the Red Hills region of northern Florida, United States, that had a relatively low density of mature, mesophytic hardwoods and were already managed for bobwhite with 2-year fire return intervals, supplemental feeding, and meso-mammal control. We monitored reproduction at 561 nests and survival of 1529 adults tracked with radiotelemetry. In treated sites, mean daily nest survival was 0.98 and did not change following hardwood reduction. Reproductive effort declined each year (pre-and post-treatment; 2015-2018) in one treated site and varied relatively little in the other. At both treated sites, weekly adult survival decreased to 0.93-0.94 immediately following the treatment, then increased gradually but did not exceed pretreatment weekly survival (0.98) within 2-3 years following the treatment. Our results suggest hardwood reduction may not benefit bob-white adult survival or productivity within 2-3 years of application on sites that are already managed intensively with prescribed fire, predator control, and supplemental feeding and that hardwoods in this system may not have direct negative impacts on understory birds. Further study is necessary to determine under what conditions hardwood reduction may be beneficial and whether other metrics such as chick survival or immigration are affected. Our study sites represent typical land management in the Red Hills region, and we
... creating candidate models, we evaluated correlation among predictor variables using the car package in program R (Fox and Weisberg 2011;R Core Team 2018) and considered variables with a correlation coefficient |r| ≥ 0.70 to be strongly correlated (Fox and Weisberg 2011). Canopy closure and total basal area were correlated (r = 0.79), we therefore omitted total basal area from subsequent modeling, because we believed that canopy closure potentially was more biologically important in that it directly influences growth of herbaceous groundcover (McGuire et al. 2001;McIntyre et al. 2019). ...
Pocket gophers provide vital ecosystem services; however, species like the southeastern pocket gopher (Geomys pinetis), endemic to the southeastern United States, are declining. Long-term conservation of this species requires greater understanding of its habitat characteristics. Our objective here was to determine habitat features associated with southeastern pocket gopher occurrence at the local (100 ha) and home-range (0.09 ha) scales. We assessed occurrence and carried out vegetation surveys at 177 sites across the species’ range during the growing season (March–September) 2016–2017. At the local scale, we found a negative relationship between occurrence and groundcover height and a quadratic relationship with canopy closure. At the home-range scale, occurrence was positively related to grass groundcover and had a quadratic relationship with canopy closure. Restoration of southeastern pocket gopher habitat should focus on creating or maintaining areas with intermediate canopy (~45–55%) and an understory dominated by grasses and forbs.
... Because of their ecological services, pocket gophers are considered ecosystem engineers and indicators of ecosystem health (Reichman and Seabloom, 2002). Geomys pinetis Rafinesque (southeastern pocket gopher; henceforth pocket gopher) is commonly associated with Pinus palustris Mill (longleaf pine) and other open pine forests in the southeastern U.S., and considered an indicator of the quality of the system (McIntyre et al., 2019). Longleaf pine forests require frequent fires, and prescribed fire is commonly used to manage longleaf pine and other open pine forests. ...
Animals living underground deal with multiple physiological challenges, such as hypoxia and hypercarbia, but may have reduced thermoregulation demands because of the more stable underground microclimate. Southeastern pocket gophers (Geomys pinetis Rafinesque) occur in the fire-adapted, open-pine forests of the southeastern Atlantic Coastal Plain where prescribed fire is commonly used to manage understory vegetation. They are almost exclusively fossorial, and their tunnels provide ecological services, including shelter, for a suite of commensal vertebrates and invertebrates. To quantify potential thermoregulation benefits of southeastern pocket gopher tunnels, we compared temperatures in active tunnels (n ¼ 31) to aboveground temperatures during winter (December 2018-February 2019), and to aboveground temperatures during prescribed fire events (n ¼ 16) occurring in spring (March-May 2019). During winter, tunnels provided a more stable thermal environment (average range ¼ 6.5 6 0.8 C; mean 6 SE) relative to aboveground (average range ¼ 24.8 6 1.8 C) temperatures. Similarly, mean tunnel temperature range (2.05 6 0.5 C) was significantly narrower than aboveground temperature range associated with fire events (497.0 6 101.4 C). Clearly, tunnels provide a stable thermal environment for pocket gophers and commensals that use their tunnel systems.
... The Integrated Science Agenda (ISA) developed by the Gulf Coastal Plain and Ozarks Landscape Conservation Cooperative (GCPO LCC) proposed a pine basal area of 9.2-16.1 m 2 /ha to support indicator species in mature open pine systems [35]. However, [36] surveyed conditions associated with open pine indicator species in southwest Georgia and found that species presence was robust to minor deviation from basal area recommendations proposed in the ISA. Further, [37] found that mid-rotation thinning can provide ephemeral conditions appropriate for open canopy species, even in stands managed for economic return (i.e., thinned less intensively). ...
Tree stocking and the associated canopy closure in production forests is often greater than optimal for wildlife that require an open canopy and the associated understory plant community. Although mid-rotation treatments such as thinning can reduce canopy closure and return sunlight to the forest floor, stimulating understory vegetation, wildlife-focused thinning prescriptions often involve thinning stands to lower tree densities than are typically prescribed for commercial logging operations. Therefore, we quantified the accuracy and precision with which commercial logging crews thinned pre-marked and unmarked mid-rotation loblolly pine (Pinus taeda) stands to residual basal areas of 9 (low), 14 (medium), and 18 (high) m2/ha. Following harvest, observed basal areas were 3.36, 1.58, and 0.6 m2/ha below target basal areas for the high, medium, and low basal area treatments, respectively. Pre-marking stands increased precision, but not accuracy, of thinning operations. We believe the thinning outcomes we observed are sufficient to achieve wildlife objectives in production forests, and that the added expense associated with pre-marking stands to achieve wildlife objectives in production forests depends on focal wildlife species and management objectives.
... If we took the forest landscape as source patches, the area of habitat was 8143km 2 (accounting for 66.1% of the total area of the study area); however, the areas of suitable habitat (HSI > 6) based on the HSI ranged from 5983.6 (SL) to 10,245.1 km 2 (SH) (48.6-82.8% of the total study area; Table 2). The difference between the area of suitable habitats caused by two different methods indicated that habitat suitability is often much more complex than can be simply described by land use or vegetation cover (McIntyre et al., 2019), and not all forest patches detected with land cover maps may be suitable for a particular animal species that prefers forest habitation. ...
The decline and fragmentation of habitats areas are two main factors that lead to the reduction of biodiversity in landscape ecosystems. As a kind of large carnivores, South China tiger (Panthera tigris amoyensis) is one of the most endangered tiger subspecies and considered to be extinct wildly. The Chinese government has intended to release a certain number of tigers into two of their historically habitats areas, Hupingshan–Houhe national nature reserves (NNR) in central–south China that provides suitable habitats for P. tigris. Because wild boar (Sus scrofa) is a prey of P. tigris, spatially characterizing the populations of the prey and its habitats is critical for the success of habituating the tigers to the areas. Although there has been effort made to protect the habitats of wild boar, there have been no report that deal with investigation and analysis of the habitat suitability and potential for wild boar, especially in terms of landscape connectivity. Here we present the novel integration of the habitat suitability index (HSI) and graph–based network to identify the priority areas for wild boar dispersal in and around the NNR. In addition, a novel method to identify the proper connectivity distance to avoid excessive connectivity when the field data are essentially non-existent. Results showed that in summer and winter, the potential habitat areas were 6,848–10,245 and 5,984–10,152 km², respectively. The total area of the priority patches was 1,590 km², approximately occupying 16% of the suitable habitat area. Our study indicated that the novel integration of the HSI and network analysis led to an effective approach to spatially characterize priority patches to support decision-making for landscape planning. The results shown here also have implications for future efforts for habituating large carnivores into their historical habitat regions.
... Additionally, they provide critical habitat for many sensitive (i.e., redcockaded woodpecker, Leuconotopicus borealis; Sherman's fox squirrel, Sciurus niger Shermani) and common (i.e., eastern rat snake, Pantherophis alleghaniensis) wildlife species (Conner et al., 1991;Engstrom and Sanders, 1997;Howze et al., 2019;Jackson and Jackson, 1986;Landers and Boyer, 1999;Perkins and Conner, 2004;Walters et al., 2002;Zwicker and Walters, 1999). McIntyre et al. (2019) reported that basal area of pine trees > 35.5 cm DBH was an important predictor of quality habitat for multiple wildlife species associated with open pine woodlands. In particular, larger longleaf pine trees are an important source of natural regeneration and fuels needed to maintain frequent prescribed fire (Croker and Boyer, 1976;Jack and McIntyre, 2017;Mitchell et al., 2009). ...
Hurricanes occur regularly along the Atlantic and Gulf Coasts of the southern United States and can have intense ecological and economic impacts on forests. Frequent low-intensity fire plays a well-known role in many coastal plain upland forests, including longleaf pine (Pinus palustris). Hurricanes may also play a critical role in shaping these communities. Field studies investigating wind susceptibility of coastal tree species often rank longleaf pine among the most wind-resistant species. This assertion is usually based on analyses that evaluate whether the fraction of downed trees is greater than expected by chance. However, tree species' associations with different soil types and landforms, and differences in tree size and spatial distribution can confound inferences. Accounting for tree, stand, and landscape factors can improve estimates of species differences in probability of wind damage. Following Hurricane Michael in 2018, we used observations from more than 3000 trees and generalized linear mixed models to investigate how tree-level factors (species and DBH), stand-level factors (stand density and soil type), and landscape-level factors (wind exposure and landscape configuration) affect tree vulnerability to hurricane winds in a longleaf pine-dominated landscape. Probability of damage varied between species, was dependent on soil type, and increased with increasing diameter for all species. Longleaf pine was in the lower range of treefall probability for all soil types and showed the lowest variability in wind susceptibility, confirming findings from other studies. However, we observed important interactions between species and soil types. Oak (Quercus spp.) species were more susceptible to treefall on drier soils, while pine (Pinus spp.) species were more resistant, suggesting that hurricanes, along with frequent fire, may play a role in shaping the landscape-scale structure of southeastern pine systems. Understanding the role of hurricanes in disturbance-prone forests can provide insight on the ecological processes structuring diverse coastal forest systems while informing activities critical for their management and conservation. Additionally, multi-aged silvicultural approaches may serve to increase the hurricane resilience of forests.
... Areas with high levels of pine canopy cover or basal area are less likely to have the dense understory strata required for northern bobwhite to remain present (Cram et al., 2002;Rosche et al., 2019), especially on lower site index soils (Landers and Mueller, 1986). Similarly, high pine basal area likely has negative effects on the foraging strategy of red-headed woodpecker (Vierling et al., 2009), and the grass component required for Bachman's sparrow (McIntyre et al., 2019). Our results indicate that forest thinning is needed to maintain appropriate conditions for these bird species. ...
Prescribed fire and other forest management practices aimed at restoring longleaf pine (Pinus palustris) communities often focus on the reduction, or removal, of upland hardwoods with the goal of providing habitat for threatened and endangered plant and animal species, including the federally endangered red-cockaded woodpecker (Leuconotopicus borealis), and restoring forests to pre-settlement conditions. Although contemporary restoration and management practices benefit species dependent on the resulting conditions, recent research has called attention to the ecological value of retaining upland hardwoods, especially for mast-dependent wildlife (e.g., fox squirrels [Sciurus niger]). Moreover, retention of indigenous hardwoods in upland longleaf pine communities may benefit a variety of birds. We used fixed-radius, breeding season point counts to sample the presence-absence of 15 avian species and assessed forest composition and structure around each point. We developed single-season single-species occupancy models with an emphasis on the influence of overstory hardwood cover on occupancy. Due to issues with model fit, we were unable to model occupancy for 3 of the 15 focal species. Occupancy probabilities for 6 out of the 12 focal species were positively influenced by overstory hardwood cover or stem density, whereas occupancy probabilities of 4 out of 12 of the focal species was negatively influenced by hardwood cover or stem density. Overstory hardwood cover between 5 and 15% resulted in high occupancy probabilities for the species that were positively influenced but did not result in substantially low occupancy probabilities for the species that were negatively influenced. Longleaf pine uplands with lower and upper bounds of 5% to 15% hardwood overstory cover with hardwood stem densities of ≤250 stems/ha could be targeted to provide habitat for the greatest diversity of birds while avoiding negative impact to species associated with upland longleaf pine communities.
... Response to canopy cover and ultimately the understory vegetation is a conservation concern for the species. Many open pine canopy forests in the southeastern United States have transitioned into hardwoodencroached, closed canopy forests due to a history of fire suppression, some forest management practices (Frost, 1993;Jose et al., 2007;McIntyre et al., 2019), and increased atmospheric CO 2 that favors C 3 Table 4 Model selection results for integrated models that explain Geomys pinetis distribution at the 10-km scale. (Bond and Midgley, 2000). ...
Longleaf pine (Pinus palustris) savanna characterized by open‐canopy, diverse herbaceous vegetation, and high amounts of bare soil once covered much of the southeastern United States Coastal Plain. The unique structural and vegetative conditions of this ecosystem support endemic reptiles and amphibians that have declined as longleaf pine forests have been lost or degraded. Private working pine (Pinus spp.) forests managed for timber production now occur throughout the southeastern United States and have replaced much of the historical longleaf pine savanna. The examination of herpetofaunal (reptile, amphibian) communities in private working loblolly pine (P. taeda) landscapes, particularly in the western Gulf Coastal Plain is lacking. Using repeated field surveys and hierarchical community occupancy models, we examined occupancy and species richness of herpetofauna across 81 sites spanning gradients of management practices, vegetative conditions, and soil composition in northwestern Louisiana, USA, 2017–2019. Young pine stands (<6 yr) exhibited structural characteristics most similar to mature longleaf pine reference sites (>30 yr), while mid‐aged stands (13–26 yr) often featured closed canopy and dense midstory. Vegetation conditions varied widely depending on landscape characteristics and site‐specific disturbance regimes. We documented 43 species of herpetofauna, including 9 open‐pine‐associated species. Occupancy of open‐pine‐associated herpetofauna was positively associated with open‐canopy and understory conditions, and sandy soil area. Sites providing open‐canopy conditions were often occupied by open‐pine‐associated species regardless of overstory type and disturbance method. Overall richness of herpetofauna was greatest at sites with moderate canopy cover outside of sandy soil regions. Working pine landscapes in the western Gulf Coastal Plain can support diverse herpetofaunal assemblages, including open‐pine‐associated species, when management practices maintain open‐canopy conditions on sandy, upland soils. More broadly, our results provide insight into how forest management practices affect herpetofauna and may guide practices that can contribute to conservation value of working pine forests. This study highlights the potential and limitations of pine forests under varying management regimes and featuring different landscape characteristics to support a range of herpetofaunal species. This research will guide management decisions targeting herpetofaunal conservation on a regional and site‐specific basis by illustrating the influence of site‐specific structural conditions and larger‐scale landscape characteristics on an area's ability to support a variety of species.
Population viability analyses are useful tools to predict abundance and extinction risk for imperiled species. In southeastern North America, the federally threatened gopher tortoise (Gopherus polyphemus) is a keystone species in the diverse and imperiled longleaf pine (Pinus palustris) ecosystem, and researchers have suggested that tortoise populations are declining and characterized by high extinction risk. We report results from a 30‐year demographic study of gopher tortoises in southern Alabama (1991–2020), where 3 populations have been stable and 3 others have declined. To better understand the demographic vital rates associated with stable and declining tortoise populations, we used a multi‐state hierarchical mark‐recapture model to estimate sex‐ and stage‐specific patterns of demographic vital rates at each population. We then built a predictive population model to project population dynamics and evaluate extinction risk in a population viability context. Population structure did not change significantly in stable populations, but juveniles became less abundant in declining populations over 30 years. Apparent survival varied by age, sex, and site; adults had higher survival than juveniles, but female survival was substantially lower in declining populations than in stable ones. Using simulations, we predicted that stable populations with high female survival would persist over the next 100 years but sites with lower female survival would decline, become male‐biased, and be at high risk of extirpation. Stable populations were most sensitive to changes in apparent survival of adult females. Because local populations varied greatly in vital rates, our analysis improves upon previous demographic models for northern populations of gopher tortoises by accounting for population‐level variation in demographic patterns and, counter to previous model predictions, suggests that small tortoise populations can persist when habitat is managed effectively. © 2021 The Wildlife Society. Small gopher tortoise populations (10–50 individuals) may be stable and persist with low extinction risk if adult female survival is sufficiently high (≥0.95).
Natural resource professionals must have current, reliable information to make informed and competent decisions regarding the management of forests. Many decisions regarding the tending and management of forests require quantitative assessments of forests and natural resources. Foresters and natural resource managers must make daily, weekly, and monthly decisions regarding land management and the allocation of personnel, budgets, technology, and equipment. Along these lines, foresters and natural resource managers make decisions regarding when and where to implement silvicultural activities, which may have long-term implications for a stand, forest, or landscape. As a result, each decision should be made in pursuit of the objectives of the landowner or the land management organization in which an individual is employed. Economic, ecological, and social assessments of forest value are a component of each decision and can be made qualitatively and subjectively; however, these assessments typically require quantitative measures of a forest's condition. Measures can include characteristics of trees, soils, water, air, and other resources necessary to satisfactorily analyze a situation, any of which may be influential in the development of a plan.
The U.S. Fish and Wildlife Service is responsible for reviewing the biological status of hundreds of species to determine federal status designations under the Endangered Species Act. The longleaf pine Pinus palustris ecological system supports many priority at-risk species designated for review, including five species of herpetofauna: gopher tortoise Gopherus polyphemus, southern hognose snake Heterodon simus, Florida pine snake Pituophis melanoleucus mugitus, gopher frog Lithobates [Rana] capito, and striped newt Notophthalmus perstriatus. To inform status decisions and conservation planning, we developed habitat suitability models to 1) identify habitat features that best predict species presence and 2) estimate the amount and distribution of suitable habitat across each species' range under current conditions. We incorporated expert judgment from Federal, State, and other partners to capture variation in ecological settings across species' ranges, prioritize predictor variables to test in models, mitigate data limitations by informing the selection of pseudo-absence points, qualitatively evaluate model estimates, and improve the likelihood that experts will trust and use model predictions for conservation. Habitat suitability for all species was strongly influenced by soil characteristics, land cover, and fire interval. Suitable habitat was distributed on known species strongholds, as well as private lands without known species records. Between 4.7% (gopher frog) and 14.6% (gopher tortoise) of the area in a species' range was classified as suitable habitat, and between 28.1% (southern hognose snake) and 47.5% (gopher frog) of suitable habitat was located in patches larger than 1 km2 (100 ha) on publicly-owned lands. By overlaying predictions for each species, we identified areas of suitable habitat for multiple species on protected and unprotected lands. These results have direct applications to management and conservation planning: partners can tailor site-level management based on attributes associated with high habitat suitability for species of concern; allocate survey effort in areas with suitable habitat but no known species records; and identify priority areas for management, land acquisitions, or other strategies based on the distribution of species records, suitable habitat, and land protection status. These results can aid regional partners in implementing effective conservation strategies and inform listing decisions of the U.S. Fish and Wildlife Service.
Habitat management for an endangered species may affect nontarget communities. We examined avian community response to pine‐grassland restoration for red‐cockaded woodpeckers (Picoides borealis) and traditional United States Forest Service pine saw‐timber management at Homochitto National Forest, Mississippi from 1994–1996. Thirteen species were more abundant in pine‐grassland restoration stands, whereas 5 species were more abundant in traditionally managed pine sawtimber stands. Mature restored pine‐grassland stands had greater avian species richness, total bird abundance, and avian conservation value than traditionally managed pine sawtimber stands. We used logistic regression models in an exploratory analysis to predict occurrence of selected species using stand‐ and landscape‐scale habitat characteristics. Probability of red‐eyed vireo (Vireo olivaceus) occurrence increased with increasing hardwood canopy cover, and probability of yellow‐breasted chat (Icteria virens) occurrence increased with increasing grass ground cover. Species richness, total avian abundance, and occurrence of red‐eyed vireos and Bachman's sparrows (Aimophila aestivalis) increased with increasing values of Shannon's Habitat Diversity Index. Pine‐grassland restoration for red‐cockaded woodpeckers created vegetation composition and structure at the stand and landscape scales that may benefit numerous avian species of regional conservation concern.
The southeastern pocket gopher Geomys pinetis is absent from a large portion of its historical range. Translocation may represent a viable management technique to reestablish populations into suitable habitat. However, several aspects of the species’ ecology are poorly understood, making development of an effective translocation approach challenging. Therefore, we used radiotelemetry to examine home range, survival, dispersal, and daily activity patterns of the southeastern pocket gopher in southwestern Georgia. We measured soil and vegetation characteristics within individual home ranges and examined relationships between home range size, habitat variables, and body mass. Mean home range size of 17 radio-tagged pocket gophers was 921.9 m² (range = 43.4-2246.8 m²). Home range size was positively related to body mass, percent silt at a depth of 25 cm, and soil carbon content at 75 cm and was negatively related to percent sand at 25 cm, percent clay at 50 cm, and ground cover of grasses other than wiregrass Aristida beyrichiana. Survival rate was 0.78 (range = 0.50-1.00) over the 51-wk study, and we documented predation, likely by avian predators, on two individuals. Three individuals dispersed, with a maximum dispersal distance of 319.1 m (range = 143.2-319.1 m), the farthest known southeastern pocket gopher dispersal. Pocket gophers exhibited greater activity from 0000 to 0400 hours and from 1600 to 2000 hours, contrasting previous research that southeastern pocket gophers were equally active throughout the diel period. Our home range size estimates for southeastern pocket gophers are the first determined using radiotelemetry and are considerably smaller than previous estimates. Although we documented dispersal distances more than 300 m, the fragmented nature of current and restored habitats likely will prevent large-scale natural colonization. Our results provide information important for maximizing success in future southeastern pocket gopher translocation efforts.
Ephemeral wetlands surrounded by Pinus palustris (Longleaf Pine) flatwoods support diverse herpetofaunal communities and provide important breeding habitat for many species. We sampled herpetofauna in 3 pine flatwoods wetlands on Eglin Air Force Base, Okaloosa County, FL, over 2 time periods (1 wetland [1] from 1993 to1995 and 2 wetlands [2 and 3] from 2010 to 2015) using drift fences that completely encircled each wetland. We documented 37, 46, and 43 species of amphibians and reptiles at wetlands 1, 2, and 3, respectively. Herpetofaunal communities were remarkably similar across all 3 wetlands (Sorenson Index values > 0.97) despite sampling that occurred 15-20 years apart on wetlands located approximately 10 km apart. Ambystoma bishopi (Reticulated Flatwoods Salamander), Pseudacris ornata (Ornate Chorus Frog), and Eurycea quadridigitata (Dwarf Salamander), all species of conservation concern, were captured at all 3 wetlands, indicating that these wetlands provide habitat for specialist species. Overall, habitat conservation and management has succeeded in maintaining suitable habitat for herpetofauna in recently surveyed wetlands, despite continued range-wide threats from changes to historic fire regimes and climate change.
Resumen
Los lineamientos para el uso de especies de mamíferos de vida silvestre en la investigación con base en Sikes et al. (2011) se actualizaron. Dichos lineamientos cubren técnicas y regulaciones profesionales actuales que involucran el uso de mamíferos en la investigación y enseñanza; también incorporan recursos nuevos, resúmenes de procedimientos y requisitos para reportes. Se incluyen detalles acerca de captura, marcaje, manutención en cautiverio y eutanasia de mamíferos de vida silvestre. Se recomienda que los comités institucionales de uso y cuidado animal (cifras en inglés: IACUCs), las agencias reguladoras y los investigadores se adhieran a dichos lineamientos como fuente base de protocolos que involucren mamíferos de vida silvestre, ya sea investigaciones de campo o en cautiverio. Dichos lineamientos fueron preparados y aprobados por la ASM, en consulta con profesionales veterinarios experimentados en investigaciones de vida silvestre y IACUCS, de quienes cuya experiencia colectiva provee un entendimiento amplio y exhaustivo de la biología de mamíferos no-domesticados. La presente versión de los lineamientos y modificaciones posteriores están disponibles en línea en la página web de la ASM, bajo Cuidado Animal y Comité de Uso: (http://mammalogy.org/uploads/committee_files/CurrentGuidelines.pdf). Recursos adicionales relacionados con el uso de animales de vida silvestre para la investigación se encuentran disponibles en (http://www.mammalsociety.org/committees/animal-care-and-use#tab3).
Bachman's Sparrow (Aimophila aestivalis) has declined over much of its range in the last fifty years. To understand the role of habitat loss in this decline, we examined patterns of habitat occupancy by this species in two areas of South Carolina. At both sites we recorded relatively high densities of breeding sparrows in mature (>80 yr old) pine stands, and relatively low densities in young pine stands. Habitat occupancy varied between sites in clearcuts and middle-aged pine stands. Sparrows used areas with open understories and dense ground covers of grasses and forbs. Habitat occupancy differed between the two main study areas because these preferred vegetation characteristics were found in different habitats in the two areas. Timber management practices (especially burning rotations, site-preparation techniques, and thinning) have a strong effect on understory vegetation and, therefore, habitat suitability for the sparrow. Management practices that produce suitable habitat for Red-cockaded Woodpeckers (Picoides borealis) also provide habitat for Bachman's Sparrow. We believe that, even though the sparrow may use open habitats that appear to be relatively common, its habitat requirements are relatively strict, and that habitat loss may be an important factor in this species' population decline.
The Brown-headed Nuthatch (Sitta pusilla) is listed as a species of conservation concern throughout most of its range. Forest conditions that support the imperiled Red-cockaded Woodpecker (Picoides borealis) are thought to provide excellent habitat for the nuthatch, but ambiguity exists because the nuthatch has disappeared from some areas where the woodpecker persists. We studied Brown-headed Nuthatches in two forest types that spanned an environmental gradient in central Florida and also differed in terms of forest structure and the presence of woodpeckers. Sandhill forests had mature timber that supported a large woodpecker population (similar to 70 territories); flatwood forests were dominated by younger pines and supported no Red-cockaded Woodpeckers. We used repeated surveys incorporating broadcast vocalizations and patch-occupancy analysis to assess variation in nuthatch occupancy and detection in relation to forest type, four structural covariates (snag density, basal area of pines and hardwoods, and pine diameter), and proximity to Red-cockaded Woodpecker territories. In our best model, occupancy and detection varied in relation to forest type and pine basal area. Occupancy and detection probabilities were higher in the younger flatwood forests and averaged 0.96 and 0.75 as compared to 0.56 and 0.37, respectively, in older sandhill forests. Occupancy and detection were not influenced by proximity to Red-cockaded Woodpecker territories. The higher encounter rates recorded in younger flatwood forests likely stemmed from differences in habitat quality, while variation attributable to forest structure and woodpecker distribution warrants further study.
Resource availability and planted longleaf pine (Pinus palustris Mill.) seedling and understory vegetation response within and among three sizes of experimentally created canopy gaps (0.11, 0.41, 1.63 ha) in a mature longleaf pine savanna were investigated for 2 years. Longleaf pine seedlings and understory vegetation showed increased growth in gaps created by tree removal. Longleaf pine seedling growth within gaps was maximized approximately 18 m from the uncut savanna. Increased longleaf pine seedling survival under the uncut savanna canopy observed after the first year suggests that the overstory may facilitate establishment of longleaf pine seedlings rather than reduce survival through competition. Despite the relative openness of the uncut longleaf pine forest, light quantity was increased by tree removal. Light was also the resource most strongly correlated with seedling and understory vegetation growth. Although net N mineralization was correlated to seedling response, the amount of variation explained was low relative to light. Belowground (root) gaps were not strong, in part because of non-pine understory roots increasing in biomass following tree removal. These results suggest that regeneration of longleaf pine may be maximized within gap sizes as small as approximately 0.10 ha, due largely to increases in light availability.Pendant 2 ans, les auteurs ont étudié la disponibilité des ressources et la réaction de la végétation de sous-étage et de semis transplantés de pin des marais (Pinus palustris Mill.) à l'intérieur et entre des trouées de trois dimensions (0,11, 0,41 et 1,63 ha) créées artificiellement dans une savane de pin des marais. Les semis de pin des marais et la végétation de sous-étage ont eu une croissance accrue dans les trouées créées par l'enlèvement des arbres. La croissance des semis de pin des marais dans les trouées était maximale à 18 m approximativement de la limite de la savane non coupée. L'augmentation de la survie des semis de pin des marais, qui a été observée après un an sous couvert dans la savane, laisse croire que l'étage dominant pourrait faciliter leur établissement plutôt que de réduire leur survie à cause de la compétition. Malgré que la forêt non coupée de pin des marais soit relativement ouverte, l'enlèvement des arbres augmente la quantité de lumière. La lumière est la ressource la plus étroitement corrélée avec la croissance des semis et de la végétation de sous-étage. Quoique la minéralisation nette de N soit corrélée avec la réaction des semis, la part de variation expliquée est faible comparativement à la lumière. Les trouées souterraines (racines) ne sont pas importantes, en partie à cause de l'augmentation de la biomasse racinaire des plantes de sous-étage autres que le pin des marais, suite à l'enlèvement des arbres. Ces résultats indiquent que la régénération de pin des marais pourrait être maximisée par des trouées aussi petites qu'environ 0,10 ha, surtout à cause de l'augmentation de la disponibilité de la lumière.[Traduit par la Rédaction]
Spatial aggregation of forest structure strongly regulates understory light and its spatial variation in longleaf pine (Pinus palustris Mill.) forest ecosystems. Previous studies have demonstrated that light availability strongly influ- ences longleaf pine seedling growth. In this study, the relationship between spatial structure of a longleaf pine forest and spatial pattern of understory light availability were investigated by comparing three retention harvest treatments: single-tree, small-group, large-group, and an uncut control. The harvests retained similar residual basal area but the spatial patterns of the residual trees differed. Hemispherical photographs were taken at 300 stations to calculate gap light index (GLI), an estimate of understory light availability. Stand-level mean, variation, and spatial distribution of GLI were determined for each treatment. By aggregating residual trees, stand mean GLI increased by 20%, as well as its spatial variation. Spatial autocorrelation of GLI increased as the size of the canopy gaps increased and the gaps were better defined; thus, the predictability of GLI was enhanced. The ranges of detrended semivariograms were in- creased from the control to the large-group harvest indicating the spatial patterns of understory GLI became coarser textured. Our results demonstrated that aggregated canopy structure of longleaf pine forest will facilitate longleaf pine seedling regeneration.
Less than 4% of the once extensive Pinus palustris (longleaf pine) ecosystem remains today. Although longleaf pine habitats are recognized for their high species diversity, few published accounts document the vertebrate faunas of remaining tracts. Here we report on the vertebrate species richness of Ichauway, an 11,300-ha property in Baker County, GA. The property includes ca. 7300 ha of longleaf pine with native ground cover, along with more than 30 seasonal wetlands and ca. 45 km of riparian habitat associated with Ichawaynochaway Creek, Big Cypress Creek, and the Flint River. The fauna includes 61 species of fish, 31 amphibians, 53 reptiles, 191 birds, and 41 mammals. Despite the relative isolation of the property from other natural ecosystems, the vertebrate fauna of Ichauway is remarkably diverse and may offer an example of reference conditions to guide restoration of longleaf pine forests, associated seasonal wetlands, and riparian areas elsewhere in the southeastern US.
Simple univariate statistical techniques may not adequately assess the multidimensional nature of habitats used by wildlife. Thus, we developed a multivariate method to model habitat-use potential using a set of female black bear (Ursus americanus) radio locations and habitat data consisting of forest cover type, elevation, slope, aspect, distance to roads, distance to streams, and forest cover type diversity score in the Ozark Mountains of Arkansas. The model is based on the Mahalanobis distance statistic coupled with Geographic Information System (GIS) technology. That statistic is a measure of dissimilarity and represents a standardized squared distance between a set of sample variates and an ideal based on the mean of variates associated with animal observations. Calculations were made with the GIS to produce a map containing Mahalanobis distance values within each cell on a 60- x 60-m grid. The model identified areas of high habitat use potential that could not otherwise be identified by independent perusal of any single map layer. This technique avoids many pitfalls that commonly affect typical multivariate analyses of habitat use and is a useful tool for habitat manipulation or mitigation to favor terrestrial vertebrates that use habitats on a landscape scale.
We use the term ‘‘optimal niche gestalt’’ to refer to the concept,that there are structural features of the environment,that allow,a species to thrive over,and,above those that allow it to persist. Analyses of the covariation between,demographic,and habitat features can reveal a trajectory toward,this optimal,state. To help identify new,criteria for foraging-habitat guidelines,for the Red-cockaded,Woodpecker,(Picoides borealis , n the Apalachicola National Forest, we examine seven years of demographic data for the wood- pecker population and habitat in core stands, the naturally regenerated prime habitat in the centers of their territories. For both districts of the forest, two compound habitat variables are highly related to the average number of adult birds per social group, the average number of young fledged per group, and the density of groups. These variables are, first, the difference between the density of trees .35 cm dbh and that of trees 15‐25 cm dbh and, second, the difference, in the ground cover, between the percentage of wiregrass and that of woody-plus-palmetto vegetation. Although,the birds require a few,old relict trees for their cavities, a regression analysis shows that including data for variation in the availability of relict trees in this forest does not improve,the power,of the above,habitat variables to account,for variation in the demography,of the birds. Because,covariation,between,demographic,variables and,the recommendations,in the current federal guidelines,for the management,of foraging,habitat of the Red-cockaded Woodpecker is low, we conclude that experimental tests of whether causal mechanisms underlie the much,higher correlative relationships we have,found are warranted. Such tests should use differing levels of prescribed fire, which has dramatic effects on the ground cover. Smaller size classes of trees in closed-canopy stands should be thinned, creating patchy,openings,in the forest that will promote,natural pine regeneration. Traditional uneven- aged,silvicultural management,could adopt a target tree distribution similar to that on the Apalachicola Ranger District, which supports a population of woodpeckers that is deemed to have,recovered. We think that in addition to being beneficial for the birds the proposed program,of habitat management,is more,likely to promote,the long-term restoration of the longleaf,pine/wiregrass ecosystem,within,Red-cockaded,Woodpecker,habitat than are al- ternative scenarios.
We compared the effectiveness of five amphibian sampling methods in nine isolated wetlands in Baker County, Georgia, USA. Overall, aquatic funnel traps yielded the most species, although the number detected using frogloggers (automated frog call recording devices), funnel traps, dipnetting, and PVC pipe refugia was not significantly different among sampling techniques. We detected the same median number of species with funnel traps and frogloggers as with all five methods combined. Methods varied widely in their detection probabilities for individual species and life stages. Species occupancy estimates were strongly affected by method choice. Our results suggest that a combination of methods and prolonged sampling periods are necessary to detect the large number of species present in southeastern isolated wetlands. We recommend that future amphibian surveys in these habitats use a combination of floating funnel traps, frogloggers, and crayfish traps as sampling methods when an assessment of species richness is the objective of a study.
Fox squirrel (Sciurus niger) populations are declining in the southeastern United States, presumably as a function of habitat loss. Because the ecology of southeastern subspecies of fox squirrels differs greatly from their well-studied midwestern relatives, habitat studies of midwestern fox squirrels are of limited use for managing southeastern subspecies. Therefore, we initiated a radiotelemetry study to evaluate habitat use of fox squirrels (n = 101) in southwestern Georgia, USA. Our results indicated that sex of fox squirrels and season did not affect habitat use and that fox squirrels did not display habitat selection within the home range. However, when selecting a home range, fox squirrels preferred mature pine (Pinus spp.) and mixed pine–hardwood forests and avoided hardwood forests. To provide fox squirrel habitat in southeastern pine landscapes, management strategies should maintain mixtures of mature longleaf pine (P. palustris) and mature mixed pine–hardwood forests.
Status and trends of gopher tortoise (Gopherus polyphemus) populations are a critical information need for natural resource managers, researchers, and policy makers. Many tortoise populations are small and isolated, which can present challenges for deriving population estimates. Our objective was to compare abundance and density estimates for a small tortoise population derived using a total burrow count versus estimates obtained with line transect distance sampling (LTDS) using repeated surveys. We also compared results of the 2 survey methods using standard burrow-to-tortoise correction factors versus assessing occupancy of all burrows with a camera scope. In addition, we compared LTDS data obtained using a compass and measuring tape to define transects to those obtained using a Global Positioning System (GPS) and Personal Data Assistant (PDA) field computer to navigate transects. Line transect distance sampling with repeated surveys (both with a measuring tape and compass and with a GPS—PDA) yielded sufficient observations of tortoises to calculate population estimates. From 18% to 31% of burrows were occupied by tortoises as determined with the burrow camera. We found 25 burrows during the LTDS survey that we did not find in the total count survey, which demonstrated that the assumption of 100% detection for the total count was not met; hence, density or abundance measurements derived with this method were underestimates. We recommend using GPS—PDA technology, scoping all burrows detected, and using LTDS with repeated surveys to estimate abundance and density for small gopher tortoise populations.
We developed a density management diagram (DMD) for longleaf pine (Pinus palustris P. Mill.) using data from Forest Inventory and Analysis plots. Selection criteria were for purity, defined as longleaf pine basal area (BA) that is 90% or more of plot BA, and even-agedness, as defined by a ratio between two calculations of stand density index. The diagram predicts stand top height (mean of tallest 40 trees/ac) and volume (ft 3/ac) as a function of quadratic mean diameter and stem density (trees/ac). In this DMD we introduce a "mature stand boundary" that, as a model of stand dynamics, restricts the size-density relationship in large-diameter stands more than the expected self-thinning trajectory. The DMD is unbiased by geographic area and therefore should be applicable throughout the range of longleaf pine. The DMD is intended for use in even-aged stands, but may be used for uneven-aged management where a large-group selection system is used. Use of the diagram is illustrated by development of density management regimes intended to create and maintain stand structure desirable for the endangered red-cockaded woodpecker (Picoides borealis).
Conversion of established forests of undesirable species composition or structure to a multi‐age, native forest community is a common restoration goal. However, for some ecosystems, the complexity of multiple disturbances and biotic factors requires unique approaches to advance community development. We use the longleaf pine ( Pinus palustris Miller) ecosystem as a model of such a restoration paradigm with an approach that utilizes the undesirable species as a functional or structural bridge to foster ecological processes.
In the conversion of adult slash pine ( Pinus elliottii Engelm.) plantations to the biologically diverse longleaf pine forests that once dominated the south‐eastern US Coastal Plain, we examine techniques for restoring and maintaining critical structural and functional components. Through partial and variable retention of the undesirable slash pine canopy, establishment of longleaf pine seedlings is facilitated, while maintaining fuels essential for prescribed fire, a necessary management practice for longleaf pine. Furthermore, we project that with subsequent fires, fine fuels and species richness will be encouraged in the ground cover, and with future slash canopy harvest, established longleaf pine seedlings will be released.
In this study, we present a statistical approach that examines the compositional movement of vegetation in restoration sites over time relative to the reference conditions that are also changing through time.
Synthesis and applications . Restoration efforts that remove undesirable species initially may actually hinder rather than facilitate restoration. Restoration of fire‐maintained ecosystems in which the production of adequate fuels is an important consideration may require the retention of a portion of the existing canopy to provide fuels during the restoration process, even if the canopy is comprised of less preferred species. Individual species often provide similar structural features and influences on function within an ecosystem; thus, systems other than longleaf pine may also benefit from retention of the undesirable species through the restoration process. We conclude that a gradual approach to restoration may be advantageous when legacies of past management have altered complex ecological dynamics and promoted development along a successional pathway strongly differing from that of the reference conditions.
Density management diagrams (DMDs) are used to quickly examine alternative density management regimes. DMDs are based upon several ecological concepts, and thus demonstrate links between quantitative silviculture and ecology. We group the important ecological concepts incorporated into DMDs into three broad categories: (1) the generality of allometric relationships; (2) the nature of size-density relationships; and (3) the ability of relative density indices to characterize stand development. We review the evidence for each of these categories as they are applied in DMDs. There is strong evidence for the application of allometric relationships to predict stand yield and for the ability of relative density indices to characterize elements of stand development. Some ambiguity exists concerning the application of size-density relationships. Specifically, there is some evidence indicating that maximum size-density relationships may vary with genetics, management practices, and environmental conditions. In general, we conclude that DMDs rest on a strong conceptual foundation.
The longleaf pine (Pinus palustris) forest, one of the most diverse yet endangered ecosystems in North America, has received considerable interest from conservation biologists. Longleaf pine ecosystem management focuses on maintaining open mature pine savanna with reduced hardwood levels. Sherman's fox squirrel (Sciurus niger shermani), a near obligate species of the open mature longleaf pine forest and a species of concern, relies on embedded hardwood trees for food and shelter but avoids closed-canopy hardwood forests. So where is the middle ground of hardwood importance to the squirrel? Ecosystem-scale conservation focusing on intensive removal of hardwoods from within the longleaf pine matrix, may negatively impact Sherman's fox squirrels. To understand the importance of hardwoods to Sherman's fox squirrels, we conducted a radio telemetry study focusing on habitat components within fox squirrel home ranges. Our results suggest a range of acceptance to the ratio of mature pine to hardwood within longleaf pine forests with an 80% estimated probability of home range use when canopy cover is comprised of 88.2% mature pine savanna to 11.8% hardwood cover. Conservation and restoration efforts should maintain individual mature hardwood trees and small patches within the longleaf pine forest ecosystem to benefit Sherman's fox squirrel.
Regional wildlife-habitat models are commonly developed but rarely tested with truly independent data. We tested a published habitat model for black bears (Ursus americanus) with new data collected in a different site in the same ecological region (i.e., Ouachita Mountains of Arkansas and Oklahoma, USA). We used a Mahalanobis distance model developed from relocations of black bears in Arkansas to produce a map layer of Mahalanobis distances on a study area in neighboring Oklahoma. We tested this modeled map layer with relocations of black bears on the Oklahoma area. The distributions of relocations of female black bears were consistent with model predictions. We conclude that this modeling approach can be used to predict regional suitability for a species of interest.
Conservation and restoration of biodiversity and ecosystems is increasingly important due to negative impacts caused by expanding human populations, changing land use, and climate change. Understanding drivers of system processes supports efficient restoration and successful conservation of biodiversity and ecosystems. We describe a long-term forest monitoring program established as a component of a long-term ecological monitoring approach and used in conjunction with adaptive management to actively restore a longleaf pine (Pinus palustris) system. Eight panels of 108 monitoring points were selected within our 11,740 ha study area near Newton, GA, USA using a Random Tessellation Stratified design with hierarchical randomization. Each year two panels were sampled, resulting in a complete survey of all points every four years. To date, data have been collected over four sampling intervals (2002–2017). Collected data included basic forestry measurements and quantification of understory conditions. For an initial analysis of the data, we calculated estimates and error of average volume, change in volume, mortality, diameter distribution, and ingrowth. Additionally, we compared effects of management practices, which varied between plots, on these estimates. The tree volume on the study area is comprised primarily of longleaf pine with ∼80% of this volume from trees ≥34 cm DBH. Pine tree volume increased by 13.29 (±2.03) m3/ha between Intervals 1 and 4. Pine mortality during each sample interval was relatively stable over the study period, 2.98 (±0.39) - 4.56% (±0.58), and primarily attributed to timber harvest. Management activities resulted in increased longleaf pine ingrowth and reduced hardwood volume. Our analyses indicate that through our management actions we have successfully made progress towards achieving our overall restoration goals for the site. Data collected from the long-term monitoring program were also used to provide information for scientific studies regarding water conservation in longleaf pine systems and wildlife-habitat relationships. As monitoring progresses, collected data will be used to assess progress and guide further restoration using adaptive management and dynamic reference models.
Because of the dramatic decline in longleaf pine (Pinus palustris Mill.) acreage, concern about restoration and management of these ecosystems has increased in recent years and created a need for effective silvicultural management tools. Stocking charts are useful quantitative tools to allocate tree area to meet specific silvicultural objectives including restoration; however, there has not been one created specifically for longleaf pine forests. Because successful management of longleaf pine is often associated with density management at or near the onset of full site occupancy, which is readily determined on a stocking chart, the development of the chart for the species was needed. We developed a Gingrich-style stocking chart for longleaf pine forests using published approaches and models from the literature. Average maximum density (A-line stocking) was determined using forest inventory data whereas onset of full site occupancy (B-line stocking) was derived from an existing open-growth crown width equation. Reduced major axis regression was used to determine size-density relationships because it gives less biased and more efficient estimates than ordinary least squares regression. Previous studies, physiological data, and longleaf pine silvical traits all support the size-density characteristics depicted on this stocking chart. We found that percent stocking was better than basal area as a predictor of tree growth, although the difference between the two measures was not significant in understocked stands. The difference between percent stocking and stand density index as a predictor of tree growth was not statistically significant. With the stocking chart presented in this article, tree area relationships can be effectively and easily used to achieve specific silvicultural objectives. © Oxford University Press on behalf of the Society of American Foresters 2018.
"Species-centered Environmental Analysis" (SCEA) is a procedure for diagnosing species-specific environmental factors that limit the size of a population. It attempts to identify presently recognized biotic and abiotic limiting factors. Then, through comparisons and applications of the principles of experimental design, it evaluates the relative importance of the factors and searches for new ones. The advantage of SCEA is that it frames ecological hypotheses in a context that spans population-, community-, and ecosystem-level processes while keeping the research focused on ecological factors that directly or indirectly affect the size of a focal population. In the case of the endangered Red-cockaded Woodpecker (Picoides borealis), which lives in a mature pine forests of the southeastern United States, four types of environmental factors have been shown to limit its numbers, even on public land: (1) insufficient habitat due to hardwood midstory encroachment, (2) a shortage of suitable cavity trees, (3) loss and fragmentation of habitat, and (4) demographic isolation. As part of the research to identify other potentially limiting environmental factors in the Apalachicola National Forest of northern Florida, we studied a sample of 87 social units (each unit usually a mated pair of birds with or without helpers, but sometimes a single bird). Each unit was defending a cluster of cavity trees and a foraging territory of open longleaf pine (Pinus palustris) forest. We then developed regression models for predicting within-population variation in the size, density, and productivity of social units from data on habitat variation. We found that variation in the bird variables was not significantly related to the sizes or densities of pine trees in these territories. It was, however, highly significantly related to the ground cover composition and the extent of natural pine regeneration, both of which are indirect indicators of local fire history. This suggests that, in addition to the four main causes, environmental processes driven by the history of fire are also limiting the Red-cockaded Woodpecker population. Additional support for this idea comes from the fact that female Red-cockaded Woodpeckers on the Apalachicola Ranger District tend to lay larger clutches of eggs in the first breeding season after their territories have been buried. Because fire history affects soil nutrient dynamics, which in turn affect ground cover composition, our present hypothesis is that nutrient dynamics are affecting the health of animal populations in the system, including that of the Red-cockaded Woodpecker. The path by which this process operates, the particular nutrients involved, and its importance relative to other factors that limit the populations need to be addressed experimentally. If nutrient dynamics are a previously unrecognized limiting factor for animal populations in this ecosystem, then the role of fire is not restricted to its ability to reduce vegetation in the midstory, and managers should acknowledge that different regimes of prescribed fire are likely to have different effects on animal, as well as plant, populations.
Within the varied contexts of environmental policy, conservation of imperilled species populations, and restoration of damaged habitats, an emphasis on idealized optimal conditions has led to increasingly specific targets for management. Overly-precise conservation targets can reduce habitat variability at multiple scales, with unintended consequences for future ecological resilience. We describe this dilemma in the context of endangered species management, stream restoration, and climate-change adaptation. Inappropriate application of conservation targets can be expensive, with marginal conservation benefit. Reduced habitat variability can limit options for managers trying to balance competing objectives with limited resources. Conservation policies should embrace habitat variability, expand decision-space appropriately, and support adaptation to local circumstances to increase ecological resilience in a rapidly changing world.
From tiny, burrowing lizards to rainforest canopy-dwellers and giant crocodiles, reptile populations everywhere are changing. Yet government and conservation groups are often forced to make important decisions about reptile conservation and management based on inadequate or incomplete data. With contributions from nearly seventy specialists, this volume offers a comprehensive guide to the best methods for carrying out standardized quantitative and qualitative surveys of reptiles, while maximizing comparability of data between sites, across habitats and taxa, and over time. The contributors discuss each method, provide detailed protocols for its implementation, and suggest ways to analyze the data, making this volume an essential resource for monitoring and inventorying reptile abundance, population status, and biodiversity.
We compared northern bobwhite (Colinus virginianus) abundance and habitat characteristics in unmanaged mixed shortleaf pine (Pinus echinata)-hardwood stands and restored pine-grassland stands managed for the red-cockaded woodpecker (Picoides borealis) on the Ouachita National Forest, Arkansas, USA. To determine northern bobwhite (hereafter, bobwhite) population response in untreated control, thinned, and thinned and burned stands either 1, 2, or 3 growing seasons (Mar to mid-Oct) post-burn, we used whistling-male counts and covey-call counts as indices of population abundance. We estimated woody stem density, understory and overstory canopy cover, conifer and hardwood basal area, and the disc of vulnerability to characterize habitat response. Relative abundance of whistling males in the spring was greatest in thinned stands 3 growing seasons post-burn and in thinned but unburned stands. These stands had the smallest disc of vulnerability and the greatest understory shrub cover <2 m in height compared with other treatments. A threshold-like increase in bobwhite abundance was observed as a function of woody structure <2 m. Pine-grassland restoration provided suitable structure for bobwhites in spring, summer, and fall, but may not be adequate in winter. Further, data suggested that bobwhite density within a stand also was related to the amount of suitable habitat surrounding the stand. Bobwhite management efforts in similar shortleaf pine forests should include thinning to reduce midstory and overstory cover and frequent fire to maintain open woodland conditions - i.e., low basal area stands with limited midstory.
Plans exist to restore the are-dependent pine (Pinus spp.)-grassland community in Ouachita National Forest and potentially throughout the southeastern United States to benefit the endangered red-cockaded woodpecker (Picoides borealis). Restoration and management techniques include wildlife stand improvement (WSI; thinning of midstory and codominant trees) and prescribed fire. We evaluated how habitat improvement for the red-cockaded woodpecker affected other breeding bird species. We compared avian species frequency of occurrence and abundance during 2 breeding seasons in untreated pine-hardwood stands with that in treated stands after WSI and in 3 growing seasons following WSI and prescribed fire. Total bird densities were highest (P = 0.037) in the second growing season following WSI and fire and lowest in the control, whereas species richness did not differ (P = 0.399) among treatments. Densities of ground/shrub-foraging and shrub-nesting species increased (P = 0.002 and 0.002, respectively) the most following WSI and fire. Only ground-nesting species were more abundant (P < 0.001) in untreated stands than in treated stands. Restoration efforts may be beneficial to neotropical migrant species such as eastern wood-pewee (Contopus virens) and prairie warbler (Dendroica discolor), in addition to declining species of regional interest such as red-cockaded woodpecker, Bachman's sparrow (Aimophila aestivalis), and northern bobwhite (Colinus virginianus) that depend upon pine-grassland habitats.
The mean cumulative size of home ranges of Sciurus niger shermani was 42.8 ha for males and 16.7 ha for females during a 1-year period. Home ranges shifted position during a food shortage. Males moved long distances before and during the breeding season. Seed production of the two tree species in sandhill habitat was greater on low slopes, significantly so in turkey oaks (Quercus laevis). Longleaf pines (Pinus palustris) produced seeds in each of 2 years, half as many in the second as in the first. The crop of turkey oak acorns failed entirely in the 2nd year. Because acorns of live oak (Quercus virginiana) appeared to be a major food resource, best habitat for Sherman's fox squirrel may be along the edge of longleaf pine savanna and live oak forest. Low diversity and abundance of food resources and their variability in time and space may explain the large home ranges of this animal. Squirrels used leaf nests much more often than tree cavities. Nest counts are recommended for documenting the status of populations of Sherman's fox squirrels. Preservation and proper management of natural, old-growth longleaf pine forests is paramount for survival of this subspecies.
(1) Cover is among the most widely used measures of abundance of plant species because it is not biased by the size or distribution of individuals. This study compared cover estimates obtained by line interception, point interception, and cover-class estimation from 136 sample lines located systematically in sagebrush steppe in western U.S.A. (2) Line interception estimates of shrub cover were significantly higher than those obtained by point interception; estimates of `bare ground and litter' by point interception were higher than those of line interception by the same amount. These offsetting differences resulted from the assumption, used in line interception sampling, that shrubs completely cover the areas within the outlines of their canopies. Otherwise, point interception and line interception estimates were very similar. (3) Cover-class estimation provided reliable estimates only for the dominant shrub species. Typically, estimates for grasses and other species with small or rare individuals were high in comparison with the other techniques. This is a consequence of the assumption that cover values are uniformly distributed about the mid-points of the cover classes. (4) Point interception achieved about the same degree of precision as line interception in one-third less sampling time. Point interception is the most efficient of the three methods where estimates for most of the species in a community are needed. (5) Optimal combinations of numbers of lines and numbers of sample units per line in relation to the time involved for a particular level of precision were investigated. In general, increased precision was achieved by sampling more lines rather than more sample units per line.
Maintaining native plant diversity, detecting exotic species, and monitoring rare species are becoming important objectives in rangeland conservation. Four rangeland vegetation sampling techniques were compared to see how well they captured local plant diversity. The methods tested included the commonly used Parker transects, Daubenmire transects as modified by the USDA Forest Service, a new transect and "large quadrat" design proposed by the USDA Agricultural Research Service, and the Modified-Whittaker multi-scale vegetation plot. The 4 methods were superimposed in shortgrass steppe, mixed grass prairie, northern mixed prairie, and tallgrass prairie in the Central Grasslands of the United States with 4 replicates in each prairie type. Analysis of variance tests showed significant method effects and prairie type effects, but no significant method × type interactions for total species richness, the number of native species, the number of species with less than 1% cover, and the time required for sampling. The methods behaved similarly in each prairie type under a wide variety of grazing regimes. The Parker, large quadrat, and Daubenmire transects significantly underestimated the total species richness and the number of native species in each prairie type, and the number of species with less than 1% cover in all but the tallgrass prairie type. The transect techniques also consistently missed half the exotic species, including noxious weeds, in each prairie type. The Modified-Whittaker method, which included an exhaustive search for plant species in a 20 × 50 m plot, served as the baseline for species richness comparisons. For all prairie types, the Modified-Whittaker plot captured an average of 42.9 (± 2.4; 1 S.E.) plant species per site compared to 15.9 (± 1.3), 18.9 (± 1.2), and 22.8 (± 1.6) plant species per site using the Parker, large quadrat, and Daubenmire transect methods, respectively. The 4 methods captured most of the dominant species at each site and thus produced similar results for total foliar cover and soil cover. The detection and measurement of exotic plant species were greatly enhanced by using ten 1 m2 subplots in a multi-scale sampling design and searching a larger area $(1,000\ {\rm m}^{2})$ at each site. Even with 4 replicate sites, the transect methods usually captured, and thus would monitor, 36 to 66% of the plant species at each site. To evaluate the status and trends of common, rare, and exotic plant species at local, regional, and national scales, innovative, multi-scale methods must replace the commonly used transect methods of the past.
The longleaf pine (Pinus palustris) ecosystem is one of the most endangered ecosystems in the United States. Recent incentives have led to increased interest in longleaf pine restoration. These restoration efforts often emphasize reestablishing native groundcovers, yet there have been no studies that address the role of native groundcover on breeding bird communities within longleaf pine forests. Therefore, we studied breeding bird communities in mature longleaf pine stands with either native or disturbed groundcovers to determine the likely effects of groundcover reestablishment associated with longleaf pine reforestation. Avian species richness and diversity did not differ (P=0.823, P=0.571, respectively), and avian community similarity was high (Morisita's index=0.98) between native and disturbed groundcover. However, pine warblers (Dendroica pinus), gray catbirds (Dumetella carolinensis), eastern wood-pewees (Contopus virens), brown-headed cowbirds (Molothrus ater), and Bachman's sparrows (Aimophila aestivalis) were more abundant (P≤0.10) in areas with native groundcover, whereas indigo buntings (Passerina cyanea) were more abundant (P=0.058) in areas with disturbed groundcover. Although groundcover restoration may benefit some avian populations, overall avian species richness, diversity, and community composition may be unaffected. Restoration of native groundcover may be best justified for aesthetic values and as a tool to facilitate long-term stand management using prescribed fire.
Understanding the habitat requirements of red-cockaded woodpeckers (Picoides borealis), an endangered species that continues to decline in the southeastern United States, is crucial to successfully reversing this trend. We developed a discriminant function using habitat characteristics within 0.25 mile (0.4 km) of the cluster center as independent variables and a demographic measure of fitness as the dependent variable to model habitat quality for 29 red-cockaded woodpecker groups in the North Carolina Sandhills. The best fit model, which included number of cavities, average diameter of overstory pines, and average understory height, correctly classified 23 of 29 sites. Mean values for good and poor sites were: number of cavities, 6.5 and 3.7; pine diameter at breast height (dbh), 35.0 cm (13.8 in) and 38.1 cm (15.0 in); and understory height, 1.89 m (6.2 ft) and 3.26 m (10.7 ft), respectively. Our management recommendations developed from this study include ≥7 cavities/group, average pine overstory >20 cm (8 in) dbh, and average understory height <1.8 m (6 ft) throughout nesting and foraging habitat.
Longleaf pine is the key tree species in a complex of fire-dependent ecosystems long native to the Southeastern United States. This report is an assessment of the amount, location, ownership, and condition of the remaining longleaf ecosystem. These inventories were conducted on permanent sample plots systematically distributed across timberland to obtain a proportionate sample of all major forest types, sites, and ownership classes in the region.
Globally, there is a growing awareness that geographically isolated wetlands contribute to important landscape functions and ecological services. One of their most important functions is providing habitat to a diverse fauna and flora adapted to variable wet and dry environments. We focus on analysis of similarities among three distinct taxa, vascular plants, aquatic beetles, and amphibians, in isolated wetlands in the southeastern coastal plain of Georgia. Although species richness for these three taxa is quite high in isolated wetlands at a regional scale, we found a low degree of congruence in species richness and species composition among taxa. This finding demonstrates that none of these groups could be used as a surrogate for the overall biodiversity of these wetlands represented by the three taxa. We identified environmental factors influencing the complex patterns of species richness and distribution for the three groups that indicate biotic and abiotic processes operate at different scales for each taxonomic group and for individual species. Our study illustrates the importance of considering structural diversity, hydrologic variation and landscape position as key elements to understanding overall diversity represented by the three taxa in isolated wetlands and in developing assessment tools of wetland condition.
This book is about ways of dealing with uncertainty in the management of renewable resources, such as fisheries and wildlife. The author's basic theme is that management should be viewed as an adaptive process: one learns about the potentials of natural populations to sustain harvesting mainly through experience with management itself, rather than through basic research or the development of general ecological theory. The need for an adaptive view of management has become increasingly obvious over the last two decades, as management has turned more often to quantitative model building as a tool for prediction of responses to alternative harvesting policies. The model building has not been particularly successful, and it keeps drawing attention to key uncertainties that are not being resolved through normal techniques of scientific investigation. The author's major conclusion is that actively adaptive, probing, deliberately experimental policies should indeed be a basic part of renewable resource management.
The U.S. Forest Service plans to restore >40,000 ha of the fire-dependent shortleaf pine (Pinus echinata)-grassland community on the Ouachita National Forest and potentially >780,000 ha of the pine-grassland community throughout the Southeast to benefit the endangered red-cockaded woodpecker (Picoides borealis). Concern has arisen ove the impacts of large-scale conversion of closed-canopy forests to open pine-grassland woodlands. We evaluated how an ecosysem approach to habitat improvement for the red-cockaded woodpecker affected small mammals. During 2 winters we compared small mammal occurrence and abundance in untreated pine-hardwood stands to stands following wildlife stand improvement (WSI; midstory removal), and with WSI-treated stands in the first, second, and third dormant seasons following prescribed fire. Total abundance of small mammals was highest in WSI stands and was a more direct response to WSI (change in stand structure) than to fire. Increased species richness and diversity in the second year of this study was strongly related to both WSI and fire. No species was adversely affected by WSI or by fire. Rather, WSI and fire-reduced midstory, increased dead debris in the understory, promoted herbaceous production, and increased woody sprouting. Total comunity abundance, richness, and diversity were lowest in untreated stands. White-footed mice (Peromyscus spp.; primarily white-footed mouse [P. leucopus]) were the dominant species, accounting for 68% of the 611 individuals collected. Restoration efforts may be particularly beneficial to generalist species such as P. leucopus as well as to more specialized species, such as golden mouse (Ochrotomys nuttali) and fulvous harvest mouse (Reithrodontomys fulvescens) that historically may have depended upon pine-grassland habitats. Restoration of pine-grassland communities may enhance small mammal communities by reestablishing a landscape element that was present during presettlement times.
Fire is a dominant disturbance within many forested ecosystems worldwide. Understanding the complex feedbacks among vegetation as a fuel for fire, the effects of fuels on fire behavior, and the impact of fire behavior on future vegetation are critical for sustaining biodiversity in fire-dependent forests. Nonetheless, understanding in fire ecology has been limited in part by the difficulties in establishing the connections between fire behavior and vegetation response. To address this issue, we present the concept of the ecology of fuels, which emphasizes the critical role that fuels play in conceptually linking feedbacks between fire and vegetation. This article explores the ecology of the fuels concept for longleaf pine woodlands and illustrates its utility by evaluating the principles of ecological forestry (incorporating legacies of disturbances, understanding intermediate stand development processes, and allowing for recovery periods) in this chronically disturbed ecosystem. We review the research behind our understanding of these feedbacks in longleaf pine ecosystems of the southeastern United States and review the applications of these principles through the Stoddard-Neel method of ecological forestry. Understanding these feedbacks is critical for integrating fire ecology and ecological forestry in the Southeast and in other fire-dependent forest types.
As remaining longleaf pine forests become increasingly fragmented, wildlife management becomes a daunting task, especially for rare and relatively unstudied taxa such as the Black Pine Snake (Pituophis melanoleucus lodingi). Appropriate management for P. m. lodingi depends on our understanding of the ecology of this subspecies; consequently, there were two main objectives of this study: to address questions of spatial ecology for P. m. lodingi on a rangewide scale; and to employ small mammal trapping within home ranges of telemetered snakes to investigate the relationship between prey density and spatial ecology. Pituophis melanoleucus lodingi exhibited large home ranges (MCP, Minimum Convex Polygon home ranges, were 92–396 ha), frequently crossed roads, and average (nonzero) movement distance for these snakes was 338 m per location event. Core home ranges of telemetered P. m. lodingi were characterized by significantly greater abundances of hispid cotton rats (Sigmodon hispidus) and significantly higher total small mammal biomass. By better defining the relationship between spatial ecology and prey dynamics for P. m. lodingi, land managers will be better equipped to manage and conserve remaining populations of this longleaf pine specialist.
The eastern diamondback rattlesnake (Crotalus adamanteus) and timber rattlesnake (Crotalus horridus) are sympatric throughout most of southern Georgia, USA. We used rattlesnake sightings to quantify and compare habitat use by these 2 species in the Gulf Coastal Plain. At the largest scale examined, univariate statistics and logistic regression models indicated that eastern diamondback rattlesnakes were associated with roads but not with any of the specific habitat types we examined. In contrast, timber rattlesnakes were closely associated with hardwood habitat and riverine systems but not with roads and edges. To effectively conserve and manage both species in the Southeast, a habitat matrix of large intact patches of both hardwood and pine (Pinus spp.) forest may be necessary.
We evaluated variability in cover estimation data obtained by (1) two sampling teams who double sampled plots and (2) one team that used two methods (line intercepts and visual estimation of cover classes) to characterize vegetation of herbaceous wetlands. Species richness and cover estimates were similar among teams and among methods, but one sampling team scored cover higher than the other. The line intercept technique yielded higher cover estimates but lower species richness estimates than the cover class method. Cluster analyses of plots revealed that 36% and 11% of plots sampled consecutively by two teams or using two methods, respectively, were similar enough in species composition and abundance to be paired together in the resulting clustering tree. Simplifying cover estimate data to presence/absence increased the similarity among both teams and methods at the plot scale. Teams were very similar in their overall characterization of sites when cover estimation data were used, as assessed by cluster analysis, but methods agreed best on their overall characterization of sites when only presence/absence data were considered. Differences in abundance estimates as well as pseudoturnover contribute to variability. For double sampled plots, pseudoturnover was 19.1%, but 57.7% of pseudo-turnover cases involved taxa with ≤ 0.5% cover while only 3.4% involved taxa with > 8% cover. We suggest that vegetation scientists incorporate quality control, calibrate observers and publish their results.
Terrestrial habitats surrounding wetlands are critical to the management of natural resources. Although the protection of water resources from human activities such as agriculture, silviculture, and urban development is obvious, it is also apparent that terrestrial areas surrounding wetlands are core habitats for many semiaquatic species that depend on mesic ecotones to complete their life cycle. For purposes of conservation and management, it is important to define core habitats used by local breeding populations surrounding wetlands. Our objective was to provide an estimate of the biologically relevant size of core habitats surrounding wetlands for amphibians and reptiles. We summarize data from the literature on the use of terrestrial habitats by amphibians and reptiles associated with wetlands ( 19 frog and 13 salamander species representing 1363 individuals; 5 snake and 28 turtle species representing more than 2245 individuals). Core terrestrial habitat ranged from 159 to 290 m for amphibians and from 127 to 289 m for reptiles from the edge of the aquatic site. Data from these studies also indicated the importance of terrestrial habitats for feeding, overwintering, and nesting, and, thus, the biological interdependence between aquatic and terrestrial habitats that is essential for the persistence of populations. The minimum and maximum values for core habitats, depending on the level of protection needed, can be used to set biologically meaningful buffers for wetland and riparian habitats. These results indicate that large areas of terrestrial habitat surrounding wetlands are critical for maintaining biodiversity.
Because it is so difficult to monitor and manage every aspect of biodiversity, several shortcuts have been proposed whereby we monitor and/or protect single species. The indicator species concept is problematic because there is no consensus on what the indicator is supposed to indicate and because it is difficult to know which is the best indicator species even when we agree on what it should indicate. The umbrella species (a species that needs such large tracts of habitat that saving it will automatically save many other species) seems like a better approach, although often whether many other species will really fall under the umbrella is a matter of faith rather than research. Intensive management of an indicator or an umbrella species (for example, by transplant or supplemental feeding) is a contradiction in terms because the rest of the community to be indicated or protected does not receive such treatment. A flagship species, normally a charismatic large vertebrate, is one that can be used to anchor a conservation campaign because it arouses public interest and sympathy, but a flagship need not be a good indicator or umbrella. And conservation of flagship species is often very expensive. Further, management regimes of two flagship species can conflict. Ecosystem management, often on a landscape scale, is a proposed solution to problems of single-species management. Keep the ecosystem healthy, according to this view, and component species will all thrive. However, conservationists have concerns about ecosystem management. First, it is variously defined, and many definitions emphasize the commodities ecosystems provide for humans rather than how humans can protect ecosystems. Second, the term ‘ecosystem health’ is ill-defined and associated with an outmoded, superorganismic view of the ecosystem. Third, ecosystem management seems focused on processes and so would appear to permit losses of species so long as they did not greatly affect processes like nutrient-cycling. Fourth, ecosystem management is often implemented by adaptive management. This may make it difficult to study the underlying mechanisms driving an ecosystem and to know when an entirely new management approach is needed. Thus, some conservationists see ecosystem management as a Trojan horse that would allow continued environmental destruction in the name of modern resource management.The recognition that some ecosystems have keystone species whose activities govern the well-being of many other species suggests an approach that may unite the best features of single-species and ecosystem management. If we can identify keystone species and the mechanisms that cause them to have such wide-ranging impacts, we would almost certainly derive information on the functioning of the entire ecosystem that would be useful in its management. Some keystone species themselves may be appropriate targets for management, but, even when they are not, our understanding of the ecosystem will be greatly increased. Keystone species may not be a panacea, however. We do not yet know how many ecosystems have keystone species, and the experiments that lead to their identification are often very difficult.
We compared two assessments of the status of gopher tortoise populations at 10 protected sites in Florida, taken about a decade apart. We assessed status indirectly, using surveys of burrows along belt transects. Transect placement and timing were identical between surveys. We compared numbers of burrows, relative numbers of burrows of different activity conditions, and size distributions of burrows between surveys. The comparisons indicated that populations had declined at as many as eight of the sites. We found no strong connection between population decline and decline in habitat quality, as reflected in decreased ground cover and/or increased canopy cover between surveys. The response of a population to decline in habitat quality may depend on initial habitat structure, the degree of change in habitat structure, the period of time over which change is measured, the amount of habitat involved, and the level of habitat management.
Although private properties are predicted to play an increasingly significant role in conservation, surveys of species of special concern are rare on these lands. We created a template for a multi-county survey of randomly selected sites and sampled for burrows of the gopher tortoise (Gopherus polyphemus) in south-central Georgia, USA. Current land use was strongly correlated with tortoise population condition. The highest densities of tortoise burrows were found on lands with open-canopied pine stands that were managed with prescribed fire, a practice associated with types of selection forestry and/or wildlife management. Agricultural sites and unburned areas provided poor habitat and pine plantations were only slightly better. Our estimates of tortoise population densities indicated that the current landscape supports less than 20% of the animals present before implementation of modern land use practices. In addition, our estimate for density of active burrows was approximately one third of that projected for the entire state range 20 years ago by Auffenberg and Franz [Auffenberg, W., Franz, R., 1982. The status and distribution of the gopher tortoise (Gopherus polyphemus). In: Bury, R.B. (Ed.), North American Tortoises: Conservation and Ecology (US Fish and Wildlife Service Wildlife Research Report 12). pp. 95–126]. However, some good sites for gopher tortoises remain in south Georgia and our data also suggested that extraordinary conservation actions may not be required if ways can be developed to retain traditional land management practices on private property.
Range-wide conservation plan for longleaf pine. Regional working group for America's Longleaf
- America
America's Longleaf Restoration Initiative, 2009. Range-wide conservation plan for longleaf pine. Regional working group for America's Longleaf. March 2009. Available
online at < http://www.americaslongleaf.org/media/86/conservation_plan.
pdf > [Verified 15 June 2018].