bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elephants versus butterflies: the ecological role of large herbivores in the evolutionary history of two tropical worlds
Authors: Cristoffer Cris , Peres Carlos A. 
Published: August 2003

AbstractAimLarge herbivores have important effects upon Paleotropical ecosystems, but attain much lower biomass densities in the Neotropics. We assess how this difference in herbivore activity has generated different ecological and evolutionary trajectories in the New and Old World tropics. We also propose an explanation for how the greater biomass density in the Old World came about.LocationData were compiled primarily from moist tropical forests, although more of the relevant information to address most of our hypotheses was available from the mainland areas of Africa, Asia, and South America than elsewhere.MethodsWe gleaned data from published information and personal communication. We compared body masses and a variety of other types of information for the New‐ and Old‐World tropics. We proposed that interhemispheric differences exist in a variety of processes, including herbivory, frugivory, and flower visitation. We erected hypotheses and evaluated them qualitatively, and, when information was available, tested them using simple ratios of species in various taxonomic and trophic categories. To make the comparisons more meaningful, we specified appropriate data selection criteria.ResultsA general pattern of differences emerges from this review. Compared with Neotropical forests, the much greater biomass densities of large herbivores in Paleotropical forests are associated with a lesser diversity of small herbivores, different hunting methods used by indigenous humans, larger arboreal vertebrates, larger fruits, different patterns of fruit and flower dispersion in space and time, a lesser abundance of most types of reproductive plant parts, and other features. The existence of a species‐rich fauna of large herbivores in the pre‐Holocene Neotropical rain forest was not supported.Main conclusionsThe potential for large herbivores to cause functional differences between the New and Old World tropical forests has been virtually unexplored, despite the well‐known importance of large herbivores in the Old World tropics. The evaluations of our hypotheses suggest that the abundance of large herbivores in the Old World tropics has launched it onto a different evolutionary trajectory than that of the NewWorld tropics. The relevant evidence, although scanty, suggests that the interhemispheric ecological differences are not an artefact of recent megafaunal extinctions in the New World. Recent human activities have, however, reduced population sizes of large wild herbivores in the Old World, and increased population sizes of livestock. This has likely created a rather homogeneous, anthropogenic selection pressure that tends to erase the evolutionary differences between the two tropical worlds.
Explaining bird species composition and richness in eucalypt‐dominated remnants in subhumid Tasmania
Authors: MacDonald Michael A. , Kirkpatrick J. B. 
Published: August 2003

AbstractAim To determine the factors influencing the distribution of birds in remnants in a fragmented agricultural landscape.Location Forty‐seven eucalypt remnants and six sites in continuous forest in the subhumid Midlands region of Tasmania, Australia.Methods Sites were censused over a two‐year period, and environmental data were collected for remnants. The avifauna of the sites was classified and ordinated. The abundances of bird species, and bird species composition, richness, abundance and diversity were related to environmental variables, using simple correlation and modelling.Results There were two distinct groups of sample sites, which sharply differed in species composition, richness, diversity and bird abundance, separated on the presence/absence of noisy miner (Manorina melanocephala Latham) colonies, remnant size, vegetation structural attributes and variables that reflected disturbance history. The approximate remnant size threshold for the change from one group to another was 20–30 ha. Remnant species richness and diversity were most strongly explained by remnant area and noisy miner abundance, with contributions from structural and isolation attributes in the second case. Segment richness was explained by precipitation, logging history and noisy miner abundance. Bird abundance was positively related to precipitation and negatively related to tree dieback. The 28 individual bird species models were highly individualistic, with vegetation structural variables, noisy miner abundance, climatic variables, variables related to isolation, area, variables related to floristics, disturbance variables, the nature of the matrix and remnant shape all being components in declining order of incidence. Age of the remnant did not relate to any of the dependent variables.Main conclusions Degraded and small remnants may have become more distinct in their avifaunal characteristics than might otherwise be the case, as a result of the establishment of colonies of an aggressive native bird, the noisy miner. The area, isolation and shape of remnants directly relate to the abundance of relatively few species, compared to vegetation attributes, climate and the abundance of the noisy miner. The nature of the matrix is important in the response of some species to fragmentation.
Area, shape and isolation of tropical forest fragments: effects on tree species diversity and implications for conservation
Authors: Hill Jennifer L. , Curran Paul J. 
Published: August 2003

AbstractAim To quantify the influences of forest area, shape and isolation on tree species diversity in Ghana and to compare their significance with the influences of climate (average annual rainfall) and disturbance (fire burn, logging, agriculture).Location The forest zone of southern Ghana, West Africa (between 5 and 8° N).Methods For twenty‐two forest fragments (1) bivariate regression analyses of tree species diversity (number and composition) were employed with forest spatial geometry, climate and disturbance variables. (2) Multivariate regression analyses of tree species number and all seven environmental variables were used to determine the variability in tree species number that could be accounted for by these environmental variables.Results Forest area, shape and isolation accounted for sharply decreasing proportions of variability in tree species diversity. Large forest fragments contained the greatest numbers of tree species and the highest proportions of rare tree species; irregular fragments had high proportions of regenerating, light‐demanding pioneers and mature, animal‐dispersed species and isolated fragments were floristically similar to less isolated fragments. Fire burn and average annual rainfall accounted for small, but nevertheless significant, proportions of variability in tree species diversity. Logging and agriculture were non‐significant variables.Main conclusions (1) Forest area is the most important consideration when planning tropical forest reserves. (2) Management of disturbance should take priority over management of forest shape if higher levels of tree diversity and species quality are to be maintained. (3) If new reserves are to be designated, they should be located within different climatic zones in order to capture a large fraction of the regional biota. (4) Biogeographers have an important role to play in formulating and testing hypotheses at a broad spatial scale and ultimately, informing conservation management within the tropical biome.
Phytogeography of upwelling areas in the Arabian Sea
Authors: Schils Tom , Coppejans Eric 
Published: August 2003

AbstractAim The identification of the marine plant communities of two islands from different upwelling areas of the Arabian Sea, with a similar diversity in biotopes. A comparison of the species composition of these macroalgal communities and their biogeographical affinities within the Indian Ocean should give insight into the biogeographical position of the Arabian Sea within the larger Indian Ocean. The incorporation of environmental parameters in the analysis is instructive in understanding their importance in shaping the diverse marine assemblages of the Arabian Sea.Location Arabian Sea: (1) the Socotra Archipelago (Yemen; 12.47° N, 53.87° E) in the Somali upwelling area, (2) Masirah Island (Oman; 20.42° N, 58.79° E) in the upwelling area of the southern Arabian Peninsula.Methods The marine flora of different biotopes around both islands were examined by means of qualitative assessments. Ordination analysis [detrended correspondence analysis (DCA)] was used to identify the different plant communities and to correlate these with environmental parameters. The species composition of the identified communities were compared (tripartite similarity index) and their biogeographical affinity with nations bordering the Indian Ocean was determined. Indicator species analyses were performed to identify the characteristic species of the different plant communities and their biotopes.Results The DCA analysis shows a clustering of sites (plant communities) corresponding with their geographical position, linked in turn to the prevailing environmental conditions of the different coastal areas. The combined interpretation of the ordination, similarity and biogeographical analyses results in the aggregation of similar plant communities of both upwelling areas into four biotopes.Main conclusions The north coast communities of Socotra and the west coast communities of Masirah can be grouped into three biotopes related to the degree of exposure (to upwelling) and sedimentation. These biotopes are typified by indicator species, characteristic for specific substrata, and have a high biogeographical affinity with the East African coast. The plant communities of Socotra's south coast and Masirah's east coast constitute a fourth biotope, being diverse and species rich, typified by a large proportion of red macroalgae including the characteristic species of the unique Arabian Sea flora. This biotope has a pronounced biogeographical affinity with distant regions (disjunctly distributed taxa) as South Africa's East Coast and Western Australia. Within the different biotopes, the communities of Masirah are more divergent from an East African flora in comparison to Socotra, the latter being a stepping stone between the East African and Arabian Sea flora.
Effects of fire and drought in a tropical eucalypt savanna colonized by rain forest
Authors: Fensham R. J. , Fairfax R. J. , Butler D. W. , Bowman D. M. J. S. 
Published: August 2003

AbstractAimThis study documents the effects of multiple fires and drought on the woody structure of a north Australian savanna never grazed by domestic stock.LocationThe study was conducted in a 500 ha pocket ofEucalyptus‐dominated savanna surrounded by a late Quaternary lava flow. The flow is known as the Great Basalt Wall, locatedc.50 km northeast of Charters Towers in semi‐arid north‐eastern Australia. This region was exposed to the largest 5‐year rainfall deficit on record between 1992 and 1996.MethodsAll individual woody plants were tagged within a 1.56 ha plot. Species were segregated into their habitat affinities (rain forest, ecotone, savanna) and regeneration strategy (resprouter, seeder). The survivorship of plants within these categories was analysed in relation to fire intensity from the first fire, and to each of four fires lit between 1996 and 2001.ResultsBefore the first fire, the plot contained thirty‐one tree species including twenty‐one typical of the surrounding dry rain forest. These rain forest species were represented by small individuals and constituted <1% of the total basal area of woody plants. The basal area of savanna trees was 7.5 m2 ha−1at the commencement of monitoring, although 31% had recently died and others had major crown damage. Further death of the drought debilitated savanna trees was substantial during the first year of monitoring and the basal area of live savanna trees declined to 1.1 m2 ha−1after 5 years. Most species from both rain forest and savanna were classified as resprouters and are capable of regenerating from underground organs after fire. Species without this ability (rain forest seeders and ecotone seeders) were mostly eliminated after the first two consecutive fires. Among resprouters, survivorship declined as fire intensity increased and this was more pronounced for rain forest than for savanna species. Repeated burning produced a cumulative effect of decreasing survivorship for rain forest resprouters relative to savanna resprouters.Main conclusionsThe study provides evidence that savanna and rain forest trees differ in fire susceptibility and that recurrent fire can explain the restricted distribution of rain forest in the seasonally arid Australian tropics. The time of death of the savanna trees is consistent with the regional pattern after severe drought, and highlights the importance of medium term climate cycles for the population dynamics of savanna tree species and structure of Australian savannas.
The pristine rain forest? Remnants of historical human impacts on current tree species composition and diversity
Authors: van Gemerden Barend S. , Olff Han , Parren Marc P.E. , Bongers Frans 
Published: August 2003

Abstract Aim Tropical rain forests are often regarded as pristine and undisturbed by humans. In Central Africa, community‐wide disturbances by natural causes are rare and therefore current theory predicts that natural gap phase dynamics structure tree species composition and diversity. However, the dominant tree species in many African forests recruit poorly, despite the presence of gaps. To explain this, we studied the disturbance history of a species‐rich and structurally complex rain forest.Location Lowland rain forest in Southern Cameroon.Methods We identified the recruitment conditions of trees in different diameter classes in 16 ha of species‐rich and structurally complex ‘old growth’ rain forest. For the identification of recruitment preference we used independent data on the species composition along a disturbance gradient, ranging from shifting cultivation fields (representing large‐scale disturbance), to canopy gaps and old growth forest.Results In nine of sixteen 1‐ha forest plots the older trees preferred shifting cultivation fields for recruitment while younger trees preferred gaps and closed forest conditions. This indicates that these nine sites once experienced large‐scale disturbances. Three lines of evidence suggest that historical agricultural use is the most likely disturbance factor: (1) size of disturbed and undisturbed patches, (2) distribution of charcoal and (3) historical accounts of human population densities.Main conclusions Present‐day tree species composition of a structurally complex and species‐rich Central African rain forest still echoes historical disturbances, most probably caused by human land use between three to four centuries ago. Human impact on African rain forest is therefore, contrary to common belief, an issue not of the last decades only. Insights in historical use will help to get a more balanced view of the ‘pristine rain forest’, acknowledging that the dualism between ‘old growth’ and ‘secondary’ forest may be less clear than previously thought.
Phytogeography of Hong Kong bryophytes
Authors: Zhang Li , Corlett Richard T. 
Published: August 2003

AbstractAimHong Kong is in a biogeographically interesting location on the northern margins of the Asian tropics. This paper analyzes the phytogeography of Hong Kong's bryophyte flora for the first time.LocationHong Kong lies on the South China coast, 22°9′–22°37′ N, 113°52′–114°30′ E. It is one of the most densely populated places in the world, but because of the rugged topography only 20% of the total land area of 1100 km2is urbanized. Although 130 km south of the Tropic of Cancer, it has a subtropical climate with distinct hot, humid and cool, dry seasons.MethodsThe analysis is based on a new and relatively complete inventory of Hong Kong's bryoflora. Each taxon was assigned to a phytogeographical pattern on the basis of its present worldwide distribution. Krober's percentage similarity was employed to evaluate the floristic affinities between different regions.ResultsThe bryophyte flora consists of at least 360 species and twelve infraspecific taxa in 159 genera and seventy families, of which four taxa are locally endemic. The largest families are Lejeuneaceae (fifty‐one taxa), Fissidentaceae (28), Hypnaceae (21), Dicranaceae (20), Calymperaceae (18), and Sematophyllaceae (15). The largest genera areFissidens(28),Cololejeunea(17),Lejeunea(10),Syrrhopodon(9),Frullania(8), andMacromitrium(8). Fourteen phytogeographical patterns are recognized. The East Asian pattern is the commonest (seventy‐three taxa, 19.6%), followed by Asian–Australian–Oceanian (45, 12.1%) and Temperate (44, 11.8%). Overall, a third of taxa have tropical distributions. The bryofloras of eleven regions were compared with that of Hong Kong. The most similar regions are Hainan Province, Taiwan Province, and Japan. Mosses and liverworts show very similar phytogeographical distributions.Main conclusions(1) The Hong Kong bryoflora is best described as northern marginal tropical, with a strong Eastern Asian and Temperate influence; (2) the region of closest phytogeographical affinity for which information is available is Hainan; (3) in comparison with vascular plants, vertebrates and those invertebrate groups for which there is information, the bryoflora has a relatively low proportion of tropical taxa; (4) the bryoflora of Hong Kong appears to be exceptionally rich for its small area.
Biodiversity and biogeography of the islands of the Kuril Archipelago
Authors: Pietsch Theodore W. , Bogatov Victor V. , Amaoka Kunio , Zhuravlev Yuri N. , Barkalov Vyacheslav Y. , Gage Sarah , Takahashi Hideki , Lelej Arkady S. , Storozhenko Sergey Y. , Minakawa Norobu , Bennett Daniel J. , Anderson Trevor R. , Ôhara Masahiro , Prozorova Larisa A. , Kuwahara Yasuhiro , Kholin Sergey K. , Yabe Mamoru , Stevenson Duane E. , MacDonald Erin L. 
Published: August 2003

Abstract Aim Based on seven consecutive seasons of biotic survey and inventory of the terrestrial and freshwater plants and animals of the 30 major islands of the Kuril Archipelago, a description of the biodiversity and an analysis of the biogeography of this previously little known part of the world are provided.Location The Kuril Archipelago, a natural laboratory for investigations into the origin, subsequent evolution, and long‐term maintenance of insular populations, forms the eastern boundary of the Okhotsk Sea, extending 1200 km between Hokkaido, Japan, and the Kamchatka Peninsula of Russia. A chain of more than 56 islands, the system is only slightly smaller than the Hawaiian Islands, covering an area of 15,600 km2 and providing 2409 km of coastline.Methods Collections of whole specimens of plants and animals, as well as tissue samples for future molecular studies, were made by teams of scientists from Russia, Japan, and the USA, averaging 34 people for each of the seven annual summer expeditions (1994–2000). Floral and faunal similarities between islands were evaluated by using Sorensen's coefficient of similarity. The similarity matrix resulting from pair‐wise calculations was then subjected to UPGMA cluster analysis.Results Despite the relatively small geographical area of all islands combined, the Kuril Island biota is characterized by unusually high taxonomic diversity, yet endemism is very low. An example of a non‐relict biota, it originated from two primary sources: a southern source, the Asian mainland by way of Sakhalin and Hokkaido, and a northern source by way of Kamchatka. The contribution of the southern source biota to the species diversity of the Kurils was considerably greater than the northern one.Main conclusion The Bussol Strait, lying between Urup and Simushir in the central Kurils, is the most significant biogeographical boundary within the Archipelago. Of lesser importance are two transitional zones, the De Vries Strait or ‘Miyabe Line’, which passes between Iturup and Urup in the southern Kurils, and the fourth Kuril Strait, between Onekotan and Paramushir in the northern Kurils.
The phytogeographical affinities of the Pitcairn Islands – a model for south‐eastern Polynesia?
Authors: Kingston Naomi , Waldren Steve , Bradley Una 
Published: August 2003

AbstractAim To identify how the Pitcairn group relates biogeographically to the south‐eastern Polynesian region and if, as a subset of the regions flora, it can then be used as a model for biogeographical analyses.Location The Pitcairn group (25°4′ S, 130°06′ W) comprises four islands: Pitcairn, a relatively young, high volcanic Island; Henderson, an uplifted atoll, the uplift caused by the eruption of Pitcairn; and two atolls, Ducie and Oeno. The remote location, young age and range of island types found in the Pitcairn Island group makes the group ideal for the study of island biogeography and evolution.Methods A detailed literature survey was carried out and several data sets were compiled. Dispersal method, propagule number and range data were collected for each of the 114 species that occurs in the Pitcairn group, and environmental data was also gathered for islands in Polynesia. Analyses were carried out using non‐metric multidimensional scaling and clustering techniques.Results The flora of the Pitcairn Islands is derived from the flora of other island groups in the south‐eastern Polynesian region, notably those of the Austral, Society and Cook Islands. Species with a Pacific‐wide distribution dominate the overall Pitcairn group flora. However, each of the islands show different patterns; Pitcairn is dominated by species with Pacific, Polynesian and endemic distributions, with anemochory as the dominant dispersal method (39.5%); Henderson is also dominated by species with Pacific, Polynesian and endemic distributions, but zoochory is the dominant dispersal method (59.4); Oeno and Ducie are dominated by Pantropic species with hydrochory as the most common dispersal method (52.9% and 100%, respectively).Main conclusions • Habitat availability is the most significant factor determining the composition and size of the flora.• South‐east Polynesia is a valid biogeographical unit, and should include the Cook, Austral, Society, Marquesas, Gambier, Tuamotu and Pitcairn Islands with Rapa, but should exclude Easter Island, Tonga and Samoa.• Regionalization schemes should take island type into consideration.• The Pitcairn Island group can serve as a useful model for Pacific biogeographical analyses.