Ecoregion Classification Research Articles

Ecological scaling of aerobiological dispersal processes

A variety of organisms change their geographic locations during their life history, and many use the atmosphere to accomplish this shift. Biota that flow in the atmosphere range from very small (viruses, bacteria, pollen, and spores) to quite large (weed seeds, aphids, butterflies and moths, songbirds, and waterfowl). As these organisms move, they experience meteorological and ecological conditions that occur at a wide range of spatial and temporal scales. We present an ecological scaling approach that integrates concepts and elements of spatial and temporal scaling to understanding aerobiology and provide examples of the ecological scales important to the long-distance aerial movement of organisms and associated biological events and processes. An operational framework for ecological scaling of long distance biota movement is achieved by linking spatially-static ecoregion classification systems with temporally-dynamic measures of vegetation phenology. The ecoregions provide ecological boundaries for the phenological dynamics of plants. Operationally, this approach integrates the bi-weekly vegetation greening indices (NDVI) derived from AVHRR or TM satellite data (representing temporal scaling) with the less dynamic land cover–land use classification (IGBP) and the relatively static ecoregion boundaries (representing the spatial scaling). We argue that the correlation of the life histories of species, especially the timing of take-off, to ecosystem phenology through meteorological-based variables and indices (e.g., degree days and moisture indices), allows for dynamic characterization of source ecosystems and can be used to parameterize atmospheric models to forecast the flow of biota in the air. The scale of these processes, the diversity of the types of biota involved in long-distance movement, and the complexity of the processes require systems thinking. We anticipate that this paper will stimulate studies to enhance our understanding of the flow of organisms in the biosphere.

Locations and environments of U.S. army training and testing lands: An ecoregional framework for assessment

AbstractThe U.S. Army manages over 12 million acres of federal training and testing lands contained within military installations throughout the 50 United States. These lands are a critical national asset for defense readiness, dedicated to providing realistic training and testing environments for army units and equipment. The locations and physiographic diversity of the Army's current land inventory is a function of historical precedent, modern‐day land expansions, and requirements for strategic projection of forces. Many Army lands are relatively undeveloped, providing important ecological settings for a variety of flora and fauna, including many threatened and endangered species. As a responsible land steward, the Army is committed to protection and sustainable use of these natural resources, with concurrent benefit to both the army and the public. Army training and testing activities can cause environmental impacts that may be detrimental to the long‐term sustainment of ecological functions. These realities pose significant land management challenges to the Army. The application of established ecologicalframeworks for strategically assessing land‐use impacts and land management approaches is demonstrated for 31 major Army installations, using Bailey's “ecoregion classification system,” developed by the U.S. Forest Service. The Ecoregions framework is used to (1) classify and catalog the ecological diversity of Army lands, (2) provide a comparative framework for assessing land resiliencyfrom Army impacts, and (3) extrapolate knowledge of perturbed ecosystem behavior and response from one army installation to others in similar ecoregions.

SPATIAL PATTERNS AND ECOLOGICAL DETERMINANTS OF BENTHIC ALGAL ASSEMBLAGES IN MID‐ATLANTIC STREAMS, USA

We attempted to identify spatial patterns and determinants for benthic algal assemblages in Mid‐Atlantic streams. Periphyton, water chemistry, stream physical habitat, riparian conditions, and land cover/use in watersheds were characterized at 89 randomly selected stream sites in the Mid‐Atlantic region. Cluster analysis (TWINSPAN) partitioned all sites into six groups on the basis of diatom species composition. Stepwise discriminant function analysis indicated that these diatom groups can be best separated by watershed land cover/use (percentage forest cover), water temperature, and riparian conditions (riparian agricultural activities). However, the diatom‐based stream classification did not correspond to Omernik’s ecoregional classification. Algal biomass measured as chl a can be related to nutrients in habitats where other factors do not constrain accumulation. A regression tree model indicated that chl a concentrations in the Mid‐Atlantic streams can be best predicted by conductivity, stream slope, total phosphorus, total nitrogen, and riparian canopy coverage. Our data suggest that broad spatial patterns of benthic diatom assemblages can be predicted both by coarse‐scale factors, such as land cover/use in watersheds, and by site‐specific factors, such as riparian conditions. However, algal biomass measured as chl a was less predictable using a simple regression approach. The regression tree model was effective for showing that ecological determinants of chl a were hierarchical in the Mid‐Atlantic streams.

Ecoregions as a level of ecological analysis

There have been many attempts to classify geographic areas into zones of similar characteristics. Recent focus has been on ecoregions. We examined how well the boundaries of the most commonly used ecoregion classifications for the US matched the boundaries of existing vegetation cover mapped at three levels of classification, fine, mid- and coarse scale. We analyzed ecoregions in Idaho, Oregon and Washington. The results were similar among the two ecoregion classifications. For both ecoregion delineations and all three vegetation classifications, the patterns of existing vegetation did not correspond well with the patterns of ecoregions. Most vegetation types had a small proportion of their total area in a given ecoregion. There was also no dominance by one or more vegetation types in any ecoregion and contrary to our hypothesis, the level of congruence of vegetation patterns with ecoregion boundaries decreased as the level of classification became more general. The implications of these findings on the use of ecoregions as a planning tool and in the development of land conservation efforts are discussed.

An Ecoregion Classification of the South Island, New Zealand

Ecoregion classifications have been widely used, particularly in North America by freshwater biologists, as a tool for assessing environmental management techniques and conservation measures. We propose an ecoregion classification for the South Island of New Zealand and Stewart Island based on six macro-environmental variables: vegetative cover, bedrock geology, soils, relief, rainfall normals, and Meteorological Service Climatic Regions. South Island maps (1:1 000 000 and 1:2 000 000 scale) of these variables were digitized into a geographic information system (GIS), linework was merged, and composite ecoregion maps generated. Twelve ecoregions are proposed. Each ecoregion is distinguished by a suite of “typical” macro-environmental characteristics. Some ecoregions can be divided into subregions on the basis of variations from these typical characteristics, primarily vegetative cover, and climatic conditions if this is desired for management purposes.

Ecoregional classification of malaria vectors in the neotropics.

An ecoregional approach to the classification of malaria in the neotropics region can give health personnel a new prespective on how to manage malaria control programs. We propose an ecoregional classification based on vector distribution and important environmental determinants, including vegetation type, rainfall patterns, mean temperatures, elevation, and geomorphology. The following 5 ecoregions are described: (1) coastal, (2) piedmont, (3) savanna, (4) interior lowland forest, and (5) high valley. Subregional differences are classified when appropriate. Because human activities and extensive changes in land use usually leads to increased human-vector contact and alter local vector distribution and abundance, it is important that these changes be considered in the classification of vector ecoregions. Using this approach, risk areas can be classified as to the presence and potential abundance of particular vectors. Then, in combination with other components of malaria transmission (e.g., migration, cultural practices, living conditions), areas for surveillance and intervention can be prioritized. It is hoped that this forum will be a catalyst for discussion, future research, and the development of ecologically orientated malaria control programs.

Transboundary Conservation: An Ecoregional Approach to Protect Neotropical Migratory Birds in South America

/ Future conservation efforts will need to transcend geopolitical boundaries in efforts to protect entire landscapes and ecosystems. Neotropical migratory birds are as a group a useful conservation tool for linking diverse landscapes and people due to their dependence on multiple habitats, sensitivity to habitat changes, and universal public appeal. The conservation of neotropical migrants can therefore function as a powerful hemispheric umbrella for ecosystem protection. Efforts to protect neotropical migratory birds on their nonbreeding grounds have traditionally been focused on Mexico, Central America, and the Caribbean. To assess the importance of South America to neotropical migrants, an ecoregional classification system was used to determine species distributions in the Andean/Southern Cone Region (Bolivia, Colombia, Ecuador, Paraguay, Peru, and Venezuela). The occurrence of migrants in protected areas that are part of The Nature Conservancy's Parks in Peril program was also assessed. Of the 406 neotropical migrant species, nearly one third (132) occur as regular nonbreeding residents in the region and for almost half of these species (53), South America is their main nonbreeding ground. All Parks in Peril sites were found to harbor neotropical migrants. Forty-eight species (36%) have declining long-term North American Breeding Bird Survey population trends and/or high Partners in Flight concern scores and thus are of significant conservation concern. Most importantly, 29 species (22%) of conservation concern use South America as their primary nonbreeding ground, indicating a need for focused conservation action. The nature of the ecoregional approach used in this endeavor makes future prioritization of ecoregions and conservation strategies for neotropical migrants across national boundaries possible. The ability to link diverse landscapes using a common element such as migratory birds allows for unique transboundary partnerships and opportunities for habitat conservation, which support the goal of the Conservancy's new Migratory Bird Initiative.KEY WORDS: Neotropical migratory birds; Transboundary conservation; Ecoregions; Protected areas; South America

Landscape-Level Ecological Regions: Linking State-Level Ecoregion Frameworks with Stream Habitat Classifications

Regionalization is a form of spatial classification, where boundaries are drawn around areas that are relatively homogeneous in landscape characteristics. The process of delineating ecological regions, or ecoregions, includes the analysis of ecosystem structure. To date, ecoregions have been developed at national and state scales for research and resource management. Stream classification is another method to order the variability of aquatic habitats that spans spatial scales from microhabitat to valley segment. In this study, landscape-level ecoregions are developed for the upper Grande Ronde River basin in northeastern Oregon, 3000 sq km in area. The ecoregion framework presented here is proposed to bridge the gap between stream habitat and state-level ecoregion classifications. Classification at this scale is meant to address issues of management at local scales: to aid in sampling design, in extrapolation of the results of site-specific studies, and in the development of best management practices that are more predictive of ecosystem response than current methods.

A Quantitative Approach to Developing Regional Ecosystem Classifications

Ecological land classification systems have recently been developed at continental, regional, state, and landscape scales. In most cases, the map units of these systems result from subjectively drawn boundaries, often derived by consensus and with unclear choice and weighting of input data. Such classifications are of variable accuracy and are not reliably repeatable. We combined geographic information systems (GIS) with multivariate statistical analyses to integrate climatic, physiographic, and edaphic databases and produce a classification of regional landscape ecosystems on a 29 340‐km2 quadrangle of northwestern Wisconsin. Climatic regions were identified from a high‐resolution climatic database consisting of 30‐yr mean monthly temperature and precipitation values interpolated over a 1‐km2 grid across the study area. Principal component analysis (PCA) coupled with an isodata clustering algorithm was used to identify regions of similar seasonal climatic trends. Maps of Pleistocene geology and major soil morphosequences were sued to identify the major physiographic and soil regions within the landscape. Climatic and physiographic coverages were integrated to identify regional landscape ecosystems, which potentially differ in characteristic forest composition, successional dynamics, potential productivity, and other ecosystem‐level processes. Validation analysis indicated strong correspondence between forest cover classes from an independently derived Landsat Thematic Mapper classification and ecological region. The development of more standardized data sets and analytical methods for ecoregional classification provides a basis for sound interpretations of forest management at multiple spatial scales.

Ecosystem mapping methods for British Columbia

Most resource professionals in British Columbia recognize the value of ecosystem classification in providing a conceptual framework and common language for organizing ecological information and management experience about ecosystems.Ecosystem mapping utilizes principles of ecosystem classification in order to provide a permanent record of the location and distribution of ecosystems. This spatial framework is often required for developing, applying, and monitoring landscape level and site-specific management prescriptions for many potential resource values.Over the past 20 years, several approaches to ecosystem mapping have been applied throughout the province. Standard procedures for provincial resource inventories and standards for medium and large scale ecosystem mapping (1:10 000 to 1:100 000 scales) have recently been proposed for the province. The proposed mapping approach combines elements of two classification systems currently in use in the province: ecoregion classification and biogeoclimatic ecosystem classification (BEC). Ecoregion and biogeoclimatic units stratify the landscape into broad physiographically and climatically uniform units. Within this broad framework, permanent landscape units are then delineated based on terrain features. Ecosystem units represent the lowest-level mapping individuals and are derived from the site series classification within BEC. Ecosystem units thus reflect moisture and nutrient regime and the climax vegetation potential of the site. Additional site modifiers are included to recognize variation in topography and soils within the site series. Structural stage and seral association modifiers are included to describe existing vegetation characteristics.The mapping methods present a core list of attributes required for basic resource interpretations, as well as additional attributes required for more specific interpretations.

An ecological framework for resource management in British Columbia

British Columbia's landmass encompasses a complex diversity of ecosystems as a result of its diverse physiography, geology and climate. Resource planners and managers, depending upon their management objectives, use ecological information at different scales, from the very broad regional level to the local or site-specific level. The Ecoregion Classification and the Biogeoclimatic Ecosystem Classification systems provide the means for resource managers and others in British Columbia concerned with the environment to understand, manage, and communicate about the diverse ecosystems of the province.This paper outlines this multi-level regional ecological classification and describes how it is being applied by resource managers from various resource agencies and organizations responsible for forest, wildlife and habitat management in British Columbia.

Correspondence Between the Distribution of Fish Assemblages in Wisconsin Streams and Omernik's Ecoregions

-Recently, Omernik divided the conterminous United States into ecoregions, areas with similar land-surface form, soils, potential natural vegetation and land use, for management of aquatic resources. Most of Wisconsin is in four of these ecoregions. I used multivariate analyses of fish and habitat data from three size-classes of streams in western and southern Wisconsin to evaluate the correspondence between ecoregions and geographic patterns in the distribution of fish assemblages. Overall, correspondence was better than expected by chance, and improved with increasing stream size. For all three size-classes of streams, agreement between the ecoregion classification of sampling stations and a classification based on a nonhierarchical cluster analysis of fish species abundance data was statistically significant. Detrended correspondence analysis ordinations of fish data showed differences among sampling stations that were associated with ecoregion membership. Catches of several fish species differed significantly among ecoregions, even with conservative significance levels. However, the ecoregion classification was fairly imprecise, and some sampling stations were more similar to stations in other ecoregions than they were to stations in their own ecoregion. Thus, in Wisconsin, ecoregions will be most useful in setting management policies for broad geographic areas containing many streams, and less useful in dealing with limited geographic areas and individual streams. Several analyses suggested that data on four general habitat characteristics, water temperature, stream gradient, substrate composition and shoreline vegetation characteristics, could be used to develop a more precise classification of Wisconsin streams. However, unlike the ecoregion classification, this classification would probably be applicable only to Wisconsin and only to fish assemblages.

Correspondence Between Ecoregions and Spatial Patterns in Stream Ecosystems in Oregon

Multivariate analyses of biotic assemblages and physicochemical measures, species richness, diversity, and composition were used to evaluate the robustness of Omernik's ecoregion classification for small streams in the eight ecoregions of Oregon. Clearest differences were between the montane and nonmontane regions. For the three nonmontane regions, ordinations of fishes, macroinvertebrates, water quality, and physical habitat measures show the clearest differences, with the Willamette Valley ecoregion being consistently most unlike all other regions. Differences between the Columbia Basin and High Desert regions were clearest for water quality and physical habitat measures and fish assemblages. Differences among the montane regions were subtle. Of these regions, the East Cascade Slopes showed the greatest variability, as shown by the ranges of ordination scores for fishes, water quality, and physical habitat. Regional patterns in periphyton assemblages were markedly different from the patterns in the other groups of variables. Ecoregions can be used as a broad-scale geographic framework for classifying streams. This framework provides managers of lotic resources a useful alternative to river basins.

Evaluation of an Aquatic Ecoregion Classification of Streams in Arkansas

ABSTRACT The efficacy of a regional stream classification system, based on the principle that streams reflect the character of the lands they drain, was evaluated in Arkansas. The classification consisted of six aquatic ecoregions defined by relatively homogeneous types of land-surface form, soil, potential natural vegetation and land use. Fish, physical habitat and water quality were sampled in 22 streams throughout the state. Data subjected to ordination analysis generally showed greater similarity in streams within the same ecoregion than in streams in different ecoregions. The patterns developed separately from fish, physical habitat and water quality data sets were relatively concordant. The null hypothesis that the classification did not reflect fundamental differences among the streams was rejected. We concluded that a regional stream classification is potentially useful for evaluating and managing streams. The identification of regions containing streams with similar character can aid in selecting...