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Montane Areas (montane + area)
Selected AbstractsCounting elephants in Montane forests: some sources of errorAFRICAN JOURNAL OF ECOLOGY, Issue 2 2009Hilde Vanleeuwe Abstract The dung count method is widely used to estimate elephant numbers in forests. It was developed in the lowland forests of Central Africa but it is also used in Montane forests in eastern Africa. Using data collected on Mount Kenya and computer simulations, this paper explores the following issues associated with dung surveys in Montane forests: ,,High rainfall at 3000 m altitude on Mount Kenya was expected to accelerate dung pile decay but no significant difference was found between 3000 and 2500 m where less rain falls, possibly because high rainfall at 3000 m is counteracted by lower temperatures; ,,Physical obstacles make it difficult to walk long, straight transects in Montane forests. Deviating from a straight line pushes the distribution of distance measurements from dung piles to the transect centre line (pdist) towards a negative exponential (NE), which complicates data analysis and may give inaccurate estimates. Using short transects largely alleviate this problem; ,,Analysis of dung count simulations shows that the expected sightability curve of pdist pushes towards a NE with increasing numbers of obstacles blocking the view, even along perfectly straight transects; ,,Extrapolating measured dung density to map area on Mount Kenya resulted in an underestimate of c. 13%. An unstratified correction of map area to ground area for Montane areas would be biased because of the strong tendency for elephants to avoid steeply sloping areas. Résumé La méthode par comptage des crottes est largement utilisée pour estimer le nombre des éléphants en forêt. Elle a été mise au point dans les forêts de basse altitude d'Afrique centrale, mais elle est aussi employée dans les forêts de montagne d'Afrique de l'Est. Utilisant les données collectées sur le Mont Kenya et des simulations informatiques, cet article explore les questions suivantes liées au comptage des crottes dans les forêts de montagne: ,,Les fortes chutes de pluies à 3 000 mètres d'altitude sur le Mont Kenya étaient censées accélérer la décomposition des tas de crottes, mais on n'a pas trouvé de différence significative entre 3 000 et 2 500 mètres où il tombe moins de pluie, peut-être parce que les fortes pluies à 3 000 mètres sont compensées par de plus basses températures; ,,Les obstacles physiques rendent plus difficiles de marcher le long de transects rectilignes dans les forêts de montagne. Le fait de dévier de la ligne droite pousse la distribution des mesures des distances entre les tas de crottes et la ligne droite du transect (pdist) vers un modèle exponentiel négatif (EN) qui complique l'analyse des données et peut donner des estimations inexactes. Le fait de recourir à des transects courts réduit considérablement ce problème; ,,L'analyse des simulations de comptages de crottes montre que la courbe de visibilité attendue de pdist pousse vers un EN lorsque le nombre d'obstacles bloquant la vue augmente, même le long de transects parfaitement rectilignes; ,,L'extrapolation de la densité mesurée des crottes sur une carte du Mont Kenya a abouti à une sous-estimation d'environ 13%. Une correction non stratifiée de la surface cartographiée des zones montagneuses vers une surface plane serait biaisée étant donné que les éléphants ont fortement tendance àéviter les zones escarpées et glissantes. [source] Phytogeography of the bryophyte floras of oak forests and páramo of the Cordillera de Talamanca, Costa RicaJOURNAL OF BIOGEOGRAPHY, Issue 9 2005Ingo Holz Abstract Aim, Central America is a biogeographically interesting area because of its location between the rich and very different biota of North and South America. We aim to assess phytogeographical patterns in the bryophyte floras of oak forests and páramo of the Cordillera de Talamanca, Costa Rica. Location, Tropical America, in particular the montane area of Cordillera de Talamanca, Costa Rica. Methods, The analysis is based on a new critical inventory of the montane bryophyte flora of Cordillera de Talamanca. All species were assigned to phytogeographical elements on the basis of their currently known distribution. Absolute and percentage similarities were employed to evaluate floristic affinities. Results, A total of 401 species [191 hepatics (liverworts), one hornwort, 209 mosses] are recorded; of these, 251 species (128 hepatics, one hornwort, 122 mosses) occur in oak forests. Ninety-three per cent of all oak forest species are tropical in distribution, the remaining 7% are temperate (4%) and cosmopolitan (3%) species. The neotropical element includes almost 74% of the species, the wide tropical element (pantropical, amphi-atlantic, amphi-pacific) only 19%. A significant part of the neotropical species from oak forests are species with tropical Andean-centred ranges (27%). As compared with bryophyte species, vascular plant genera in the study region are represented by fewer neotropical, more temperate and more amphi-pacific taxa. Bryophyte floras of different microhabitats within the oak forest and epiphytic bryophyte floras on Quercus copeyensis in primary, early secondary and late secondary oak forest show a similar phytogeographical make-up to the total oak forest bryophyte flora. Comparison of oak forest and páramo reveals a greater affinity of the páramo bryophyte flora to temperate regions and the great importance of the páramo element in páramo. Surprisingly, oak forests have more Central American endemics than páramo. Main conclusions, (1) Providing first insights into the phytogeographical patterns of the bryophyte flora of oak forests and páramo, we are able to confirm general phytogeographical trends recorded from vascular plant genera of the study area although the latter were more rich in temperate taxa. (2) Andean-centred species are a conspicuous element in the bryophyte flora of Cordillera de Talamanca, reflecting the close historical connection between the montane bryophyte floras of Costa Rica and South America. (3) High percentages of Central American endemics in the bryophyte flora of the oak forests suggest the importance of climatic changes associated with Pleistocene glaciations for allopatric speciation. [source] Morphology and environment: geographic distribution, ecological disjunction, and morphological variation in Actinocephalus polyanthus (Bong.) Sano (Eriocaulaceae)FEDDES REPERTORIUM, Issue 7-8 2008M. Trovó Most Brazilian Eriocaulaceae have highly restricted geographic distributions. Actinocephalus polyanthus (Bong.) Sano is one of the few widely distributed species; furthermore this distribution includes an interesting ecological disjunction. Actinocephalus polyanthus occurs in montane areas from northern Minas Gerais to Paraná, as well as coastal sand dune habitats in Santa Catarina and Rio Grande do Sul. In attempt to investigate whether there is any correlation between the ecological disjunction and the patterns of morphology exhibited by this species, eight populations were sampled covering the geographic distribution and the ecological disjunction. We used multivariate statistical methods (UPGMA, PCA and DF) to describe the morphology, and to verify its correlation with its distribution and habitat. We conclude that sand dune populations are morphologically different from the montane populations. The main difference in these plants is the robustness. The sand dune plants are significantly smaller than the plants from montane areas. We also verified that these populations have a morphological identity. The occurrence of this species in such diverse environments may reflect the morphological diversity of the various populations of the species, and may be the primary cause of the difference in these populations. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Morphologie und Umgebung: geographische Verbreitung, ökologische Disjunktion und morphologische Variabilität bei Actinocephalus polyanthus (Bong.) Sano (Eriocaulaceae) Die meisten brasilianischen Eriocaulaceae haben nur eine eng begrenzte geographische Verbreitung. Actinocephalus polyanthus (Bong.) Sano ist eine der wenigen weit verbreiteten Arten. Diese Verbreitung zeigt eine interessante ökologische Disjunktion: Actinocephalus polyanthus tritt auf in den Gebirgsregionen vom nördlichen Minas Gerais bis Paraná und in den Küsten-Sanddünen in Santa Catarina und Rio Grande do Sul. Im Versuch, ob sich irgendeine Korrelation zwischen der ökologischen Disjunktion und der morphologischen Ausprägung bei dieser Art finden lässt, sammelten wir acht Populationen aus dem geographischen Verbreitungsgebiet und der ökologischen Disjunktion. Es wurden multivariate statistische Methoden (UPGMA, PCA und DF) eingesetzt um die Morphologie zu beschreiben und diese Korrelation zwischen Verbreitung und Habitat zu vergleichen. Wir konnten daraus schließen, dass die Populationen der Sanddünen sich von den montanen Populationen unterscheiden. Der Hauptunterschied liegt in der Robustheit der Pflanzen: die der Sanddünen sind deutlich kleiner als die aus den Bergregionen. Wir beobachteten auch, dass diese Populationen morphologisch identisch sind. Das Vorkommen dieser Art in so unterschiedlicher Umgebung widerspiegelt die morphologischen Unterschiede der verschiedenen Populationen der Art, und stellt vermutlich die Hauptursache für die Unterschiede zwischen den Populationen dar. [source] Effects of drought on avian community structureGLOBAL CHANGE BIOLOGY, Issue 8 2010THOMAS P. ALBRIGHT Abstract Droughts are expected to become more frequent under global climate change. Avifauna depend on precipitation for hydration, cover, and food. While there are indications that avian communities respond negatively to drought, little is known about the response of birds with differing functional and behavioural traits, what time periods and indicators of drought are most relevant, or how response varies geographically at broad spatial scales. Our goals were thus to determine (1) how avian abundance and species richness are related to drought, (2) whether community variations are more related to vegetation vigour or precipitation deviations and at what time periods relationships were strongest, (3) how response varies among avian guilds, and (4) how response varies among ecoregions with different precipitation regimes. Using mixed effect models and 1989,2005 North American Breeding Bird Survey data over the central United States, we examined the response to 10 precipitation- and greenness-based metrics by abundance and species richness of the avian community overall, and of four behavioural guilds. Drought was associated with the most negative impacts on avifauna in the semiarid Great Plains, while positive responses were observed in montane areas. Our models predict that in the plains, Neotropical migrants respond the most negatively to extreme drought, decreasing by 13.2% and 6.0% in abundance and richness, while permanent resident abundance and richness increase by 11.5% and 3.6%, respectively in montane areas. In most cases, response of abundance was greater than richness and models based on precipitation metrics spanning 32-week time periods were more supported than those covering shorter time periods and those based on greenness. While drought is but one of myriad environmental variations birds encounter, our results indicate that drought is capable of imposing sizable shifts in abundance, richness, and composition on avian communities, an important implication of a more climatically variable future. [source] Pliocene forest dynamics as a primary driver of African bird speciationGLOBAL ECOLOGY, Issue 1 2010Gary Voelker ABSTRACT Aim, Montane tropics are areas of high endemism, and mechanisms driving this endemism have been receiving increasing attention at a global scale. A general trend is that climatic factors do not explain the species richness of species with small to medium-sized geographic ranges, suggesting that geological and evolutionary processes must be considered. On the African continent, several hypotheses including both refugial and geographic uplift models have been advanced to explain avian speciation and diversity in the lowland forest and montane regions of central and eastern Africa; montane regions in particular are recognized as hotspots of vertebrate endemism. Here, we examine the possible role of these models in driving speciation in a clade of African forest robins. Location, Africa. Methods, We constructed the first robustly supported molecular phylogenetic hypothesis of forest robins. On this phylogeny, we reconstructed habitat-based distributions and geographic distributions relative to the Albertine Rift. We also estimated the timing of lineage divergences via a molecular clock. Results, Robust estimates of phylogenetic relationships and clock-based divergences reject Miocene tectonic uplift and Pleistocene forest refugia as primary drivers of speciation in forest robins. Instead, our data suggest that most forest robin speciation took place in the Late Pliocene, from 3.2 to 2.2 Ma. Distributional patterns are complex, with the Albertine Rift region serving as a general east,west break across the group. Montane distributions are inferred to have evolved four times. Main conclusions, Phylogenetic divergence dates coincide with a single period of lowland forest retraction in the late Pliocene, suggesting that most montane speciation resulted from the rapid isolation of populations in montane areas, rather than montane areas themselves being drivers of speciation. This conclusion provides additional evidence that Pliocene climate change was a major driver of speciation in broadly distributed African animal lineages. We further show that lowland forest robins are no older than their montane relatives, suggesting that lowland areas are not museums which house ,ancient' taxa; rather, for forest robins, montane areas should be viewed as living museums of a late Pliocene diversification event. A forest refugial pattern is operating in Africa, but it is not constrained to the Pleistocene. [source] Fallback foods of temperate-living primates: A case study on snub-nosed monkeysAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Cyril C. Grueter Abstract Only a few primate species thrive in temperate regions characterized by relatively low temperature, low rainfall, low species diversity, high elevation, and especially an extended season of food scarcity during which they suffer from dietary stress. We present data of a case study of dietary strategies and fallback foods in snub-nosed monkeys (Rhinopithecus bieti) in the Samage Forest, Northwest Yunnan, PRC. The snub-nosed monkeys adjusted intake of plant food items corresponding with changes in the phenology of deciduous trees in the forest and specifically showed a strong preference for young leaves in spring. A non-plant food, lichens (Parmeliaceae), featured prominently in the diet throughout the year (annual representation in the diet was about 67%) and became the dominant food item in winter when palatable plant resources were scarce. Additional highly sought winter foods were frost-resistant fruits and winter buds of deciduous hardwoods. The snub-nosed monkeys' choice of lichens as a staple fallback food is likely because of their spatiotemporal consistency in occurrence, nutritional and energetic properties, and the ease with which they can be harvested. Using lichens is a way to mediate effects of seasonal dearth in palatable plant foods and ultimately a key survival strategy. The snub-nosed monkeys' fallback strategy affects various aspects of their biology, e.g., two- and three-dimensional range use and social organization. The higher abundance of lichens at higher altitudes explains the monkeys' tendency to occupy relatively high altitudes in winter despite the prevailing cold. As to social organization, the wide temporal and spatial availability of lichens strongly reduces the ecological costs of grouping, thus allowing for the formation of "super-groups." Usnea lichens, the snub-nosed monkeys' primary dietary component, are known to be highly susceptible to human-induced environmental changes such as air pollution, and a decline of this critical resource base could have devastating effects on the last remaining populations. Within the order Primates, lichenivory is a rare strategy and only found in a few species or populations inhabiting montane areas, i.e., Macaca sylvanus, Colobus angolensis, and Rhinopithecus roxellana. Other temperate-dwelling primates rely mainly on buds and bark as winter fallback foods. Am J Phys Anthropol 140:700,715, 2009. © 2009 Wiley-Liss, Inc. [source] Isolation and high genetic diversity in dwarf mountain toads (Capensibufo) from South AfricaBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2010KRYSTAL A. TOLLEY Traditional models of amphibian dispersal and gene flow point to low dispersal and high philopatry. In recent years, this traditional view has been challenged and it appears that no general model holds across taxa. Conservation of amphibians cannot be addressed on an over-arching scale, but must come on a case-by-case basis, especially for range-restricted species where information on gene flow and migration must be incorporated into conservation efforts. The only two members of the genus Capensibufo Grandison, 1980 (Anura: Bufonidae) are range restricted small bufonids, with distributions limited to montane areas in South Africa. Using a Bayesian analysis of two mitochondrial markers (16S and ND2), we examined the genetic patterns in Capensibufo rosei and Capensibufo tradouwi in order to understand both taxonomic and geographic boundaries. These species were not monophyletic, and demonstrate no clear taxonomic boundaries. Instead, the genus is extremely diverse genetically, with distinct lineages confined to isolated mountains that represent geographic boundaries. In addition, bioclimatic modelling using MAXENT and scenarios of climatic conditions at both the present and last glacial maximum suggest multiple bioclimatic and physical barriers to gene flow at present and in the past. We conclude that members of the genus have very low vagility, that current taxonomic boundaries are inadequate, and that strong geographic structuring has undoubtedly contributed to genetic diversity at the species level, rather than the population level. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 822,834. [source] | ||||||||||