Alan S. Weakley

A community-derived classification for extant lycophytes and ferns

Phylogeny has long informed pteridophyte classification. As our ability to infer evolutionary trees has improved, classifications aimed at recognizing natural groups have become increasingly predictive and stable. Here, we provide a modern, comprehensive classification for lycophytes and ferns, down to the genus level, utilizing a community‐based approach. We use monophyly as the primary criterion for the recognition of taxa, but also aim to preserve existing taxa and circumscriptions that are both widely accepted and consistent with our understanding of pteridophyte phylogeny. In total, this classification treats an estimated 11 916 species in 337 genera, 51 families, 14 orders, and two classes. This classification is not intended as the final word on lycophyte and fern taxonomy, but rather a summary statement of current hypotheses, derived from the best available data and shaped by those most familiar with the plants in question. We hope that it will serve as a resource for those wanting references to the recent literature on pteridophyte phylogeny and classification, a framework for guiding future investigations, and a stimulus to further discourse.

On The Use Of Taxonomic Concepts In Support Of Biodiversity Research And Taxonomy

Future biodiversity research will make increased use of distributed data networks, scientific workflows, and powerful mechanisms for resolving a broad spectrum of primary data. This paper outlines the anatomy of an ecological niche modeling workflow and concomitant needs for taxonomic resolution. Contemporary Linnaean names and synonymy relationships are shown to be too imprecise too support these needs. Taxonomic concepts (i.e., the meanings of names as specified in a particular source) and a new vocabulary for expressing their semantic interrelationships are introduced as a more reliable long-term solution. The concept approach has so far been implemented with success in select taxonomic databases and regional floristic treatments. Quantitative analyses have added further weight to the claim that taxonomic concepts are suitable to overcome the problem of name/meaning disjunction inherent in conventional nomenclature. Therefore, full documentation of the taxonomic process will depend on a wider adoption of concept taxonomy. The concept approach will improve communication about nature without compromising any of the useful properties of the Linnaean system.

Non-alluvial wetlands of the Southern Blue Ridge : diversity in a threatened ecosystem

The generally steep landscape of the Southern Blue Ridge is not conducive to the formation of extensive wetlands, but wetlands do occur. Wetlands in this region are mostly small in size (< 10 ha), and are found in locations where topography is unusually gentle or where seepage is unusually strong or constant. Despite their rarity and small size, such wetlands show great species and community diversity, and are one of the most important habitats for rare (endemic and disjunct) plants and animals in the region. Community species composition seems to vary primarily in relation to elevation, topographic position, hydrology, underlying bedrock composition, recent land use, and biogeographic history. Based on differences hi vegetation structure and composition, landscape position, and hydrology, we recognize nine groups of non-alluvial wetlands in the Southern Blue Ridge. An inventory of non-alluvial wetlands in the mountains of North Carolina revealed that the majority of these naturally rare communities are now destroyed or severely altered. Bogs and fens of the North Carolina mountains have been reduced nearly six-fold from an original extent of about 2000 ha, so that only about 300 ha remain in reasonably intact condition, and most of the remnants are compromised by hydrologic alteration and nutrient inputs. Because wetlands tend to be concentrated in valley bottoms and at low elevations where most land is privately owned, efforts to assure their long-term viability will require innovative protection and restoration tools.

Conservation of the endangered Pinus palustris ecosystem based on Coastal Plain centres of plant endemism

Abstract Question: Can the geographic patterning of endemic plant species inform reserve selection in a region of high endemism? Location: The southeastern Coastal Plain of North America, focusing primarily on the imperiled Pinus palustris (longleaf pine) ecosystem. Methods: We documented the high level of plant endemism in the region, and characterized the endemic taxa into distributional subregions. Results: A total of 1630 plant taxa are endemic to the Coastal Plain, a large proportion of which are endemic to phytogeographical subregions within the Coastal Plain, with particularly large numbers of narrow endemics occurring in the East Gulf Coastal Plain and Florida Peninsula. Conclusions: This pattern of local endemism presents challenges in conserving the full biota of the region: a reserve system focusing on few and large conservation areas has theoretical benefits for long-term management and viability, but will fail to capture many local endemics. We propose that the dispersed distribution of endemic species will require a mixture of large core reserves and smaller satellite reserves. Nomenclature: Kartesz (1999) with minor exceptions and modifications and updates from the taxonomic literature.

EcoVeg: a new approach to vegetation description and classification

A vegetation classification approach is needed that can describe the diversity of terrestrial ecosystems and their transformations over large time frames, span the full range of spatial and geographic scales across the globe, and provide knowledge of reference conditions and current states of ecosystems required to make decisions about conservation and resource management. We summarize the scientific basis for EcoVeg, a physiognomic-floristic-ecological classification approach that applies to existing vegetation, both cultural (planted and dominated by human processes) and natural (spontaneously formed and dominated by nonhuman ecological processes). The classification is based on a set of vegetation criteria, including physiognomy (growth forms, structure) and floristics (compositional similarity and characteristic species combinations), in conjunction with ecological characteristics, including site factors, disturbance, bioclimate, and biogeography. For natural vegetation, the rationale for the upper le...

Classification of Pocosins of the Carolina Coastal Plain

Pocosins are nonalluvial Coastal Plain wetlands with strongly acidic and nutrient-poor soils, and a generally dense shrub layer composed of a characteristic suite of species. A diversity of pocosin vegetation occurs in the Carolinas, occupying a range of topographic, hydrologic, geographic, and pedologic situations. To help clarify this diversity, a classification was developed, integrating vegetation, site factors, and ecological dynamics. Eight community types are recognized — Low Pocosin, High Pocosin, Pond Pine Woodland, Peatland Atlantic White Cedar Fores, Bay Forest, Streamhead Pocosin, Streamhead Atlantic White Cedar Forest, and Small Depression Pocosin. White cedar forests, while they have not usually been considered pocosins, occupy the same sites as pocosins in temporally shifting mosaic determined by catastrophic fire events and share many species. The eight pocosin types can be distinguished by vegetation, peat depth, topographic setting, fire regime, water source, size, and shape. Pocosins occur in five main topographic and physiographic situations: peat domes of the outer Coastal Plain, Carolina bays primarily of the outer and middle Coastal Plain, headwaters of Coastal Plain blackwater streams (especially in the Sandhills), broad poorly-drained swales in the outer and middle Coastal Plain, and various isolated small depressions throughout the Coastal Plain.

RELATIONSHIPS OF THE NEW ENGLAND BONESET, EUPATORIUM NOVAE-ANGLIAE (ASTERACEAE)

Abstract Resolution of the systematic relationships of the New England Boneset, Eupatorium novae-angliae, has been elusive. This rare species, known from only 15 sites in Massachusetts and Rhode Island, has been demonstrated to be male-sterile and agamospermous, and thus inferred to be polyploid, but its progenitor diploids have not been identified clearly. In a study that hinged on a combination of fieldwork and morphological study together with molecular analysis, we have demonstrated that E. novae-angliae contains ITS repeats characteristic of two sexual diploid species of the genus. One is the widespread E. perfoliatum, the second is a previously unrecognized endemic to clay-based Carolina bay and depression meadow habitats in the Carolinas, that had been included in E. leucolepis and is now recognized as a separate species, E. paludicola. The molecular data highlight the distinctiveness of E. novae-angliae and underscore the need for efforts to continue to protect it in its native habitat.

How a national vegetation classification can help ecological research and management

The elegance of classification lies in its ability to compile and systematize various terminological conventions and masses of information that are unattainable during typical research projects. Imagine a discipline without standards for collection, analysis, and interpretation; unfortunately, that describes much of 20th-century vegetation ecology.

EUPATORIUM PALUDICOLA (ASTERACEAE): A NEW SPECIES FROM THE COASTAL PLAIN OF NORTH AND SOUTH CAROLINA

Abstract Eupatorium paludicola (Asteraceae) is a new species from the Atlantic Coastal Plain of North and South Carolina. It resembles E. leucolepis (DC.) Torr. & A. Gray, from which it is most readily distinguished by very narrow (2–4.5 mm wide) ascending-recurved to erect-incurved leaves, and by shorter involucres, pappi, and cypselae. It inhabits isolated, herb-dominated wet depressions with variable hydrology such as clay-based Carolina bays.

Wetlands of the Interior Southeastern United States: Conference summary statement

The wetland resources in the southern United States are diverse, being characterized by bottomland hardwoods, forested riparian zones, swamps, marshes, bogs, and fens. Recognizing the importance of the wetland resource, the need to develop information on the diversity of wetland types, and the evolving public debate regarding the protection and management of wetlands, this conference was organized to (1) provide a forum for the presentation and discussion of current research and information on wetland ecosystems, (2) to develop a basis on which to improve wetland conservation and management, (3) to provide a forum to encourage collaboration in the study and management of wetland resources, and (4) to suggest actions that would benefit wetland conservation and management. Twenty-three invited technical papers and three working group sessions addressed topics encompassing the full spectrum of wetland issues, including resource status, ecological and hydrological processes, management and conservation, and restoration and creation. Major findings discussed at the conference included the need to distinguish between functions and values, the development of a hydrogeomorphic classification system for assessing wetland functions, and assessment methodologies for planning and implementing effective wetland restoration projects. Papers summarizing the current understanding of wetland soil and vegetation processes in the region highlighted the important role wetlands play in landscape function, yet the understanding of those processes is incomplete. Insights developed from the study of wetlands in the interior southeastern United States have widespread applicability to other regions because of similarities in hydrogeomorphic setting and vegetation communities, and the management and conservation issues.