T. Bently Wigley

Monitoring herpetofauna in a managed forest landscape: effects of habitat types and census techniques

Abstract We surveyed the herpetofaunal (amphibian and reptile) communities inhabiting five types of habitat on a managed landscape. We conducted monthly surveys during 1997 in four replicate plots of each habitat type using several different methods of collection. Communities of the two wetland habitats (bottomland wetlands and isolated upland wetlands) were clearly dissimilar from the three terrestrial communities (recent clearcut, pine plantation, and mixed pine–hardwood forest). Among the three terrestrial habitats, the total herpetofaunal communities were dissimilar ( P

Priority research needs for the conservation of Neotropical migrant landbirds

Abstract Partners in Flight (PIF) is a consortium of professional and volunteer scientists and educators that promotes the conservation of landbird species. Central to the PIF conservation effort is the development of Bird Conservation Plans specific to each physiographic region of the United States. Without a coordinated prioritization of research needs, land managers, researchers, and funding agencies seeking to conserve landbirds lack direction. To address this issue, we (the Research Working Group of Partners in Flight) identified research priorities that have emerged recently as a result of Bird Conservation Plan development. Research priorities for the coming decade focus on habitat, specifically the identification of high-quality habitats and landscapes for breeding, migration, and wintering. Identification of the scale of breeding and natal dispersal and describing linkages between wintering and breeding populations are also research priorities for the coming decade. A summary of research priorities for each of the PIF regions (Northeast, Midwest, West, and South) is also provided. Specific research needs associated with priority species and habitats in each physiographic area can be accessed in a searchable database: http://www.partnersinflight.org/pifneeds/searchform.cfm.

Landscape-level effects of forest management on faunal diversity in bottomland hardwoods

Abstract Forest management activities potentially influence ecosystems at many spatial scales. For most forest systems, influences at the stand level have been most intensively studied and are best understood. Management impacts at the larger, landscape scale are poorly understood and many hypotheses regarding landscape-level effects remain untested. This lack of knowledge is particularly acute in bottomland hardwood forest (BLH) ecosystems. Most hypotheses regarding landscape-level impacts were derived from theories about island biogeography and metapopulations. Thus, species presence and productivity sometimes are viewed as functions of patch characteristics such as size, shape, amount of edge, degree of isolation from larger, similar habitats, time since isolation, and dispersal, immigration, and extinction rates. Recommendations for mitigating fragmentation effects often include maintenance of reserves, increasing patch size, reducing edges, and enhancing connectivity through the use of corridors. While many of these theories are intuitively sound, there are few data to demonstrate their effectiveness in landscapes dominated by managed forests, including BLH forests. We suggest that high priority be given to using adaptive management to simultaneously test hypotheses about how biotic communities function in managed, BLH landscapes. Such information would help managers understand the consequences of their activities, provide them with more flexibility, and improve their ability to protect biological diversity while also meeting societys needs for forest resources.

Herbicides and forest biodiversity—what do we know and where do we go from here?

Abstract Use of herbicides to control competing vegetation in young forests can increase wood volume yields by 50–150%. However, increasing use of herbicides in forest management has caused widespread concerns among the public and biologists about direct toxicity to wildlife and indirect effects through habitat alteration. Abundant research has indicated that forest herbicide treatments target biochemical pathways unique to plants, do not persist in the environment, and have few toxic effects when operationally applied. Herbicides affect forest biodiversity by creating short-term declines in plant species diversity, altering vegetative structure, and potentially changing plant successional trajectories. For wildlife species, effects vary but generally are short-term. Despite these findings, public opinion against forest herbicides often has limited or restricted their use, likely due to peoples values associated with forests and a lack of technical knowledge. Future research efforts on relationships between forest herbicides and biodiversity should address landscape and site-specific issues, be based on rigorous experimental design, be relevant to public concerns, include comparisons of herbicide treatments with alternative treatments excluding herbicides, examine use of chemical mixtures, and determine the social, economic, and possible long-term ecological consequences of treatments.

Responses of Isolated Wetland Herpetofauna to Upland Forest Management

Measurement of responses of herpetofauna at isolated wetlands in the Coastal Plain of South Carolina to disturbance of adjacent loblolly pine forest. Many species of isolated wetland herpetofauna in the Southeastern Coastal Plain may tolerate some disturbance in adjacent upland stands. Responses of isolated wetland herpetofauna to upland silviculture and the need for adjacent forested buffers likely depend on the specific landscape context in which the wetlands occur and composition of the resident herpetofaunal community.

A review of wildlife changes in southern bottomland hardwoods due to forest management practices

One function of bottomland hardwood forests is provision of wildlife diversity and abundance. In this paper, we discuss the temporal and spatial changes in wildlife diversity and abundance often associated with forest management practices in bottomland hardwoods. Forest management activities after forest composition, structure, and spatial hetereogeneity, thereby changing the composition, abundance, and diversity of wildlife communities. Special habitat features such as snags, den trees, and dead and down woody material also may be impacted by forestry practices. More research is needed to fully understand landscape-level impacts of forest management.

A meta-analysis of bird and mammal response to short-rotation woody crops

Short‐rotation woody cropping (SRWC) refers to silvicultural systems designed to produce woody biomass using short harvest cycles (1–15 years), intensive silvicultural techniques, high‐yielding varieties, and often coppice regeneration. Recent emphasis on alternatives to fossil fuels has spurred interest in producing SRWC on privately owned and intensively managed forests of North America. We examined potential bird and small mammal response at the stand level to conversion of existing, intensively managed forests to SRWCs using meta‐analysis of existing studies. We found 257 effect sizes for birds (243 effect sizes) and mammals (14 effect sizes) from 8 studies involving Populus spp. plantations. Diversity and abundance of bird guilds were lower on short‐rotation plantations compared with reference woodlands, while abundance of individual bird species was more variable and not consistently higher or lower on SRWC plantations. Shrub‐associated birds were more abundant on SRWC plantations, but forest‐associated and cavity‐nesting birds were less abundant. Effects on birds appeared to decrease with age of the SRWC plantation, but plantation age was also confounded with variation in the type of reference forest used for comparison. Both guilds and species of mammals were less abundant on SRWC plantations. These conclusions are tentative because none of these studies directly compared SRWC plantations to intensively managed forests. Plantations of SRWCs could contribute to overall landscape diversity in forest‐dominated landscapes by providing shrubby habitat structure for nonforest species. However, extensive conversion of mature or intensively managed forests to SRWC would likely decrease overall diversity, especially if they replace habitat types of high conservation value.

Emulating Natural Disturbances for Declining Late-Successional Species: A Case Study of the Consequences for Cerulean Warblers (Setophaga cerulea)

Forest cover in the eastern United States has increased over the past century and while some late-successional species have benefited from this process as expected, others have experienced population declines. These declines may be in part related to contemporary reductions in small-scale forest interior disturbances such as fire, windthrow, and treefalls. To mitigate the negative impacts of disturbance alteration and suppression on some late-successional species, strategies that emulate natural disturbance regimes are often advocated, but large-scale evaluations of these practices are rare. Here, we assessed the consequences of experimental disturbance (using partial timber harvest) on a severely declining late-successional species, the cerulean warbler (Setophaga cerulea), across the core of its breeding range in the Appalachian Mountains. We measured numerical (density), physiological (body condition), and demographic (age structure and reproduction) responses to three levels of disturbance and explored the potential impacts of disturbance on source-sink dynamics. Breeding densities of warblers increased one to four years after all canopy disturbances (vs. controls) and males occupying territories on treatment plots were in better condition than those on control plots. However, these beneficial effects of disturbance did not correspond to improvements in reproduction; nest success was lower on all treatment plots than on control plots in the southern region and marginally lower on light disturbance plots in the northern region. Our data suggest that only habitats in the southern region acted as sources, and interior disturbances in this region have the potential to create ecological traps at a local scale, but sources when viewed at broader scales. Thus, cerulean warblers would likely benefit from management that strikes a landscape-level balance between emulating natural disturbances in order to attract individuals into areas where current structure is inappropriate, and limiting anthropogenic disturbance in forests that already possess appropriate structural attributes in order to maintain maximum productivity.

Toward an Experimental Basis for Protecting Forest Wildlife.

Social and economic debates over allocation of old-growth forests have spawned conservation strategies that are aimed at protecting sensitive wildlife species while allowing limited timber harvesting. We are interested in improving the scientific underpinnings for such conservation strategies, because doing so might both minimize costs of resource development and provide more reliable protection. Here, we discuss potential consequences from inductive inferencing systems used to develop technical support for protecting wildlife in temperate forests. For examples, we refer to recent conservation strategies for Northern Spotted Owls (Strix occidentalis caurina) and Red-cockaded Woodpeckers (Picoides borealis). Soft inferencing systems could result in conservation strategies that fail to meet intended goals, thereby exacerbating forestry-wildlife debates. Greater emphasis should be placed on hypothetico-deductive inferencing processes that vigorously employ adaptive management principles. Such processes simultaneously test alternative landscape patterns and forestry options as rigorous management experiments, and thus could incrementally predicate forest policy upon an experimental basis.

Achieving conservation goals in managed forests of the Southeastern Coastal Plain.

Managed forests are a primary land use within the Coastal Plain of the southern United States. These forests are generally managed under standards, guidelines, or regulations to conserve ecosystem functions and services. Economic value of commercial forests provides incentives for landowners to maintain forests rather than convert them to other uses that have substantially reduced environmental benefits. In this review, we describe the historical context of commercial forest management in the southern United States Coastal Plain, describe how working forests are managed today, and examine relationships between commercial forest management and maintenance of functional aquatic and wetland systems and conservation of biological diversity. Significant challenges for the region include increasing human population and urbanization and concomitant changes in forest area and structure, invasive species, and increased interest in forest biomass as an energy feedstock. Research needs include better information about management of rare species and communities and quantification of relationships between ecosystem attributes and forest management, including biomass production and harvest. Incentives and better information may help commercial forest managers in the Coastal Plain more efficiently contribute to landscape-scale conservation goals.