bluuebunny/crossref_metadata_2025_split huggingface dataset:
The distance decay of similarity in biogeography and ecology
Authors: Nekola Jeffrey C. , White Peter S. 
Published: March 2003

SummaryAimOur aim was to understand how similarity changes with distance in biological communities, to use the distance decay perspective as quantitative technique to describe biogeographic pattern, and to explore whether growth form, dispersal type, rarity, or support affected the rate of distance decay in similarity.LocationNorth American spruce‐fir forests, Appalachian montane spruce‐fir forests.MethodsWe estimated rates of distance decay through regression of log‐transformed compositional similarity against distance for pairwise comparisons of thirty‐four white spruce plots and twenty‐six black spruce plots distributed from eastern Canada to Alaska, six regional floras along the crest of the Appalachians, and six regional floras along the east–west extent of the boreal forest.ResultsSimilarity decreased significantly with distance, with the most linear models relating the log of similarity to untransformed distance. The rate of similarity decay was 1.5–1.9 times higher for vascular plants than for bryophytes. The rate of distance decay was highest for berry‐fruited and nut‐bearing species (1.7 times higher than plumose‐seeded species and 1.9 times higher than microseeded/spore species) and 2.1 times higher for herbs than woody plants. There was no distance decay for rare species, while species of intermediate frequency had 2.0 times higher distance decay rates than common species. The rate of distance decay was 2.7 times higher for floras from the fragmented Appalachians than for floras from the contiguous boreal forest.Main conclusionsThe distance decay of similarity can be caused by either a decrease in environmental similarity with distance (e.g. climatic gradients) or by limits to dispersal and niche width differences among taxa. Regardless of cause, the distance decay of similarity provides a simple descriptor of how biological diversity is distributed and therefore has consequences for conservation strategy.
The land use history (1278–1990) of a mixed hardwood forest in western Belgium and its relationship with chemical soil characteristics
Authors: Verheyen K. , Bossuyt B. , Hermy M. , Tack G. 
Published: March 2003

Summary Aim During the last decades, an increasing number of studies have stressed the importance of historical human influence on the ecology of forests and on the characteristics of forest soils. Therefore, the objectives of this study are (1) the quantification of the land use history of Ename Wood from 1278 to 1990 and (2) to find out whether the former land use of the forest has long‐lasting effects on present‐day chemical soil properties. Location The 62‐ha present‐day Ename Wood is situated in western Belgium and is the remainder of the 145‐ha historical Ename Wood. Methods We disposed of eighteen land‐use maps for the period between 1278 and 1990 which were digitized using a geographic information system (GIS). Transition between the different land uses and Shannon–Wiener diversity indices were calculated to quantify the history of changing land use. Mixed soil samples were taken in lots delimited on the basis of the historical data. Next, the soil properties were combined with the land‐use variables using redundancy analysis and
ANOVA. Results The quantification of the land use changes showed that the present Ename Wood is the result of several forest regression and progression phases, with a complete clearance in the nineteenth century. Diversity in land use was maximal between the fourteenth and the sixteenth century due a variety of transitional forms between forest and pasture. A positive correlation between the duration of arable land use since the 19th century clearance and soil pH, calcium and phosphate content was observed and a negative correlation was found with the carbon content, the total nitrogen content and the C:N ratio. These correlations are probably caused by a combination of acidification processes and the accumulation of organic matter under forest in combination with manuring practices in the twentieth century. Present‐day forest lots which have been pastured for some time between 1278 and nineteenth‐century clearance still had a significantly lower pH and degree of base saturation, which is probably caused by the export of nutrient rich plant material at that time. Discussion and conclusions The results demonstrate that the developed methodology is successful and confirm that historical land use, even in the distant past, can still influence present‐day soil characteristics. For this reason, long‐term historical land use should always be considered in forest ecological research.
Biogeography and ecology of freshwater diatoms in Subantarctica: a review
Authors: Van de Vijver Bart , Beyens Louis 
Published: March 2003

SummarySubantarctica is situated between the Antarctic and the Subtropical Convergence and consists of the islands in the southern Atlantic, Indian and Pacific Oceans. Diatoms are an important component of all Subantarctic aquatic, moss and soil habitats. Taxonomic studies reveal a high diversity and species richness in both the present‐day and the fossil diatom flora. Planktonic diatoms are almost completely absent. A similarity analysis of the diatom composition from different localities in the southern zone (below 40°S) resulted in a biogeographical zonation. Three regions could be formed, based on their diatom composition: Subantarctica, Maritime Antarctica and the Antarctic Continent. The diatom communities in the different regions are all characterized by a high proportion of cosmopolitan species. A second feature of the southern diatom floras is the decreasing diversity when moving southwards.
Floristic analysis of vascular plant genera of North America north of Mexico: characteristics of phytogeography
Authors: Qian Hong 
Published: March 2003

SummaryThe phytogeographical characteristics of North America north of Mexico (NANM) were examined based on an analysis of the 1904 indigenous genera of the vascular plants known to the area. According to the worldwide distribution patterns of the genera, the 1904 genera were grouped into ten phytogeographical elements (categories). About 67.3% of the genera found in the native flora of NANM also occur in other areas of the world; of these, 71.4% occur in the Old World. About 32.7% of the 1904 genera are endemic to North America. The origins of the floristic relationships between North America and the rest of the world and the origin of the present‐day flora of North America are discussed. The current floristic patterns of the NANM vascular plant genera resulted in part from palaeogeological events such as the unification of tectonic plates into a single supercontinent, Pangaea, and then the breakup of the united supercontinent into Laurasia and Gondwana followed by the fragmentation of Laurasia and Gondwana into individual continents as they are today due to the movement of plate tectonics. Many of the endemic genera of North America likely originated in the North American continent during the Tertiary, particularly during the uplifting of Rocky Mountains.
Fire regimes and forest changes in mid and upper montane forests of the southern Cascades, Lassen Volcanic National Park, California, U.S.A.
Authors: Taylor A. H. 
Published: March 2003

Abstract Aim Spatial and temporal variation in fire regime parameters and forest structure were assessed. Location A 2630‐ha area of mid‐ and upper montane forest in Lassen Volcanic National Park (LVNP). Methods Two hypotheses were tested concerned with fire‐vegetation relationships in southern Cascades forests: (1) fire regime parameters (return interval, season of burn, fire size, rotation period) vary by forest dominant, elevation and slope aspect; and (2) fire exclusion since 1905 has caused forest structural and compositional changes in both mid‐ and upper montane forests. The implications of the study for national park management are also discussed. Results Fire regime parameters varied by forest compositional group and elevation in LVNP. Median composite and point fire return intervals were shorter in low elevation Jeffrey pine (Pinus jeffreyi) (JP) (4–6 years, 16 years) and Jeffrey pine–white fir (Abies concolor) (JP‐WF) (5–10 years, 22 years) and longer in high elevation red fir (Abies magnifica)— western white pine (Pinus monticola) (RF‐WWP) forests (9–27 years, 70 years). Median fire return intervals were also shorter on east‐facing (6–9 years, 16.3 years) and longer on south‐ (11 years, 32.5 years) and west‐facing slopes (22–28 years, 54‐years) in all forests and in each forest composition group. Spatial patterns in fire rotation length were the same as those for fire return intervals. More growing season fires also occurred in JP (33.1%) and JP‐WF (17.5%) than in RF‐WWP (1.1%) forests. A dramatic decline in fire frequency occurred in all forests after 1905. Conclusions Changes in forest structure and composition occurred in both mid‐ and upper montane forests due to twentieth‐century fire exclusion. Forest density increased in JP and JP‐WF forests and white fir increased in JP‐WF forests and is now replacing Jeffrey pine. Forest density only increased in some RF‐WWP stands, but not others. Resource managers restoring fire to these now denser forests need to burn larger areas if fire is going to play its pre‐settlement role in montane forest dynamics.
Altitudinal zonation of Andean cryptogam communities
Authors: Kessler Michael 
Published: March 2003

AbstractTo test whether cryptogamic plant communities in tropical Andean rain forests are distributed in floristically discrete communities corresponding to altitudinal belts, I subjected the elevational distribution of pteridophytes along two elevational gradients in Bolivia, and of bryophytes and lichens along two transects in Peru and Colombia (data from Gradstein & Frahm, 1987;
Wolf, 1993) to an analysis of deviance. All well‐defined elevational boundaries in floristic composition were related to marked ecological changes: the transition from the steep mountains to the hilly lowland zone coupled with a change in geological substrate at 400 m along the Bolivian Carrasco transect, a strong humidity gradient at 1000 m at the Bolivian Masicurí transect and at 1250–1980 m along the Colombian transect, and the transition from mixed cloud forests to forests dominated by Polylepis or Podocarpus at 3400–3600 m in Carrasco, at 1650–1800 m in Masicurí, and at 3670 m in Colombia. Consequently, floristic elevational belts appear to be well‐defined at strong environmental boundaries and in fairly species‐poor forest communities where the presence or absence of one or a few tree species influences the whole ecosystem while they are ill‐defined in species‐rich communities such as tropical forests at low to mid‐elevations.
The relationship between cave biodiversity and available habitat
Authors: Christman Mary C. , Culver David C. 
Published: March 2003

AimThe goal of this study was to determine the role habitat availability plays in the distribution of obligate subterranean cave fauna in eastern North America.LocationThe numbers of stygobites, troglobites and caves in the counties of the south‐eastern USA were analysed.MethodsThe data were characterized by large numbers of zeroes and by spatial clustering of non‐zeroes in five regions. Regression and conditional autoregressive (CAR) models were used to elucidate the patterns and relationships between numbers of species and numbers of caves both locally and regionally.ResultsLocal effects (regions and numbers of caves in counties) accounted for 45% of the variation in troglobite counts (P=< 0.001) and 24% of the variation in stygobite counts (P=< 0.001). Significant spatial autocorrelation among both stygobites and troglobites (P=< 0.0001) was found as well.ConclusionOverall, habitat availability as measured by cave numbers influenced species richness. Spatial and regional effects also played an important role in determining the observed distributions of the subterranean fauna. Terrestrial and aquatic communities showed very different patterns in their relationship to habitat and within the different regions.
Comparison of methods to estimate historic species richness of mammals for tests of faunal relaxation in Canadian parks
Authors: Wiersma Yolanda F. , Nudds Thomas D. 
Published: March 2003

AimSome recent tests of faunal change in reserves have relied on, but been limited to, estimates of species richness from random samples of historic range maps. We evaluated a different, Geographic Information Systems (GIS)‐based, approach to count species directly, as the latter method might facilitate rapid estimation of historic species richness as well as composition for samples of the same size, shape and exact location as present‐day reserves.LocationNational parks throughout Canada.MethodsGeographic Information System.ResultsThe GIS‐based method tended to count, in exact locations of modern parks, fewer species (on average, seven disturbance intolerant and five disturbance tolerant) present historically than extrapolated from randomly sampled sites, but the differences were not greater than expected by chance. However, correlations between number of species lost and park size were weaker than reported previously, suggesting a greater potential for other factors to influence a change in species richness (and composition) than inferred earlier.Main conclusionsDirect counts of historic range maps using GIS tools provided a quick means to estimate site‐specific historic species richness not statistically different from estimates produced by random sampling. As well, the GIS‐based method could yield data about historic species composition for the specific location and size of modern reserves, which may be more ecologically meaningful in terms of assessing what factors may have contributed to the observed species losses.
Halffter’s Mexican Transition Zone, beetle generalized tracks, and geographical homology
Authors: Morrone Juan J. , Márquez Juan 
Published: March 2003

AimHalffter’s Mexican Transition Zone is a complex area in which the Neotropical and Nearctic regions overlap. We test its existence and extension through a track analysis of beetle taxa, and discuss the implications of geographical homology.LocationThe area analysed corresponds to the Caribbean subregion, which occupies Mexico, Central America, north‐western South America, and the Western Indies.MethodsThe panbiogeographic or track analysis was based in the comparison of 134 individual tracks belonging to different beetle taxa (species and supraspecific groups). A Parsimony Analysis of Endemicity (PAE) was applied in order to classify the areas by their shared taxa according to the most parsimonious cladogram, and the nested sets of areas were represented as generalized tracks.ResultsTwo generalized tracks resulted: (1) northern generalized track: comprising the Sierra Madre Occidental, Sierra Madre Oriental, Transmexican Volcanic Belt, Balsas Basin and Sierra Madre del Sur biogeographic provinces; and (2) southern generalized track: comprising the Chiapas, Mexican Gulf, Mexican Pacific Coast and western Panamanian Isthmus biogeographic provinces.Main conclusionsThe generalized tracks obtained correspond broadly to Halffter’s Nearctic and Mesoamerican patterns, respectively; however, in contrast to Halffter’s Mesoamerican pattern, the southern generalized track extends further north through the lowlands of the Pacific and Mexican Gulf coasts.
Biogeography of the Antilles based on a parsimony analysis of orchid distributions
Authors: Trejo‐Torres J. Carlos , Ackerman James D. 
Published: March 2003

AimWe obtain biogeographical patterns based on the distributions of shared orchid species of the Caribbean. These patterns are used to define biogeographical zones. We then analyse the concordance between the distributional patterns with ecological and physical features of the islands.LocationWe use orchid species recorded on 49 islands of the Greater, Lesser, and southern Antilles, and the Bahamas. Three continental areas are included: Florida (North America), the Yucatan (Central America), and the Guianas (South America).MethodsWe use a parsimonious analysis of species distributions that produces the best arrangements of shared taxa among areas. The analysis uses 356 shared orchid species of the 863 species recorded for studied areas. The methodology has been used to infer historical relationships among areas but we interpret the results as static or ecological patterns of biogeographical affinities.ResultsTwo kinds of island groupings are revealed. (1) Groups with common geology and geomorphology: the Bahama Archipelago, the Virgin Islands, the Cayman Islands and the southern Dutch Antilles. (2) An aggregation of distant islands with a heterogeneous geology but a common physiography: the Greater Antilles/Trinidad/Lesser Antilles/Margarita‐Tobago. The Guianas are linked with the Greater Antilles, while the Yucatan and Florida are linked to the Bahamas.Main conclusionsGroupings of islands are congruent with their gross ecological features either from similar geomorphology or common physiography. The strong affinity among islands considerably distant among each other is explained by the high vagility of dust‐seeded orchids. Then, floristic affinities seem determined by ecological characteristics of islands rather than by dispersal barriers. We predict that other plant groups with dust‐like diaspores and animals with good vagility should show comparable biogeographic patterns. Parsimony analysis of distributions (PAD) is an alternative methodology to multivariate analysis to compare biotas, and a graphic complement to quantitative methods producing numerical values.
Biogeography of Australian freshwater fishes
Authors: Unmack Peter J. 
Published: March 2003

AimTo investigate biogeographic patterns of obligate freshwater fishes.LocationAustralia.MethodsSimilarity indices, parsimony analysis, and drainage‐based plots of species’ ranges were used to identify patterns.ResultsRelationships among regions were deduced largely by concordance between methodologies, then summarized into a proposed series of faunal provinces.Main conclusionsThe most striking pattern was in the incidence of endemism across the continent. Provinces in southern, central, and western Australia have high numbers of endemic fishes, presumably resulting from isolation by aridity and drainage divides. With exception of one region, northern and eastern Australia provinces have few endemics, probably explained in the north by high drainage connectivity during times of lowered sea levels. This does not account for low endemism in the east because drainages appear to have remained isolated during lowered sea levels and patterns suggest an absence of distinct barriers of other kinds. By default, climate again seems the most probable cause of species’ distributional limits. Whatever the case, most patterns were almost certainly established in the distant past, perhaps as early as Miocene. Influences of Plio–Pleistocene events on broad patterns of freshwater fish distributions seem minimal.
Rarity, specialization and extinction in primates
Authors: Harcourt A. H. , Coppeto S. A. , Parks S. A. 
Published: March 2003

AimTo determine and explain biological traits that distinguish rare from common primate taxa.LocationAfrica, Americas, Asia, Madagascar.MethodsWe compare the biology of rare primate taxa with the biology of common taxa. Rarity is defined by (1) small size of geographic range; (2) small geographic range plus low local population density; and (3) small geographic range plus low local density plus narrow habitat specificity. After a linear comparison of size of geographic range with various biological traits, globally and by realm, extremes of rarity and commonness per realm are identified, and then combined for a global analysis. Tests are done both with genera treated as independent data points (n=62), and also with phylogenetic control by use of an independent contrasts test. Extinction risk in vertebrates, including primates, often correlates with high resource requirements, slow population recovery rate, and specialization. The three indices of rarity are therefore compared with these three general traits. Measures of resource use are body mass, local density, annual range size, and group size; of recovery rate, interbirth interval, and maximum intrinsic rate of natural population increase; and of degree of specialization, variety of diet, of habitats, maximum latitude, and morphological variety. All data come from the literature. Because several measures are compared, probabilities are Bonferroni corrected.ResultsIf rarity in primates correlates with any biological attribute, it consistently correlates with only measures of specialization, and not with measures of high resource use, or slow population recovery rate. Without phylogenetic correction, the first two indices of rarity associate significantly with all four measures of specialization, and the third with maximum latitude. With phylogenetic correction, the first index still associates with all four, the second with two (maximum latitude, number of species per genus), and the third shows no significant associations. While the four measures of specialization are strongly interrelated, stepwise regressions on geographic range indicate that maximum latitude has the strongest effect, followed by dietary variety and number of species per genus and, finally, habitat variety.Main conclusionsThe most commonly demonstrated traits of susceptibility to extinction are those of high resource use, slow recovery rate, and specialization. Yet, while rarity (almost however, it is defined) is an inevitable precursor to extinction, specialization is the only trait found to correlate with rarity in this study. We cannot explain this apparent contradiction.