25,725 research outputs found

    Changes in the carbon balance of tropical forest: evidence from long-term plots

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    The role of the world’s forests as a “sink” for atmospheric carbon dioxide is the subject of active debate. Long-term monitoring of plots in mature humid tropical forests concentrated in South America revealed that biomass gain by tree growth exceeded losses from tree death in 38 out of 50 neotropical sites. These forest plots have accumulated 0.71 + 0.34 tons of carbon per hectare per year in recent decades. The data suggest that neotropical forests may be a significant carbon sink, reducing the rate of increase in atmospheric CO2

    Hepaticae of Cerro Venamo, Venezuela, collected by J. Steyermark

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    A revision of herbarium material (NY) from Cerro Venamo, Venezuela (5°59’ N, 61°23’ W, 1890 m) yielded 77 hepatic species in 44 genera and 13 families. Most species have a neotropical distribution (75,32%), 6,49%, are pantropical and 9,09% are reported only from the tepuis

    The origin and distribution of neotropical species of Campylopus

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    Of the 65 species of Campylopus known from tropical America, 33 are andine in distribution, 16 are found only in SE Brazil, 8 have wide ranges through Central and South America, 3 species are disjunct in SE-North America and Brazil, 3 are confined to the Caribbean and one species belongs to the circum-pacific and one to the tethyan element. For different parts of the Neotropics, the composition of phytogeographical elements is calculated. For the first time, bryophyte distributions are compared to the Pleistocene forest refuges proposed by zoologist and phanerogamists. The distribution of several rainforest species of Campylopus coincides with the major part of the montane refugia. Using an interpretation of the present-day ranges, a hypothetical survey is given of the origin and evolution of this genus in tropical South and Central America. The ranges of part of the species can be explained only by long distance dispersal, while the ranges of other species seem to be relictual

    Bibliography and checklist of foliicolous lichenized fungi up to 1992

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    Bibliographic records are presented of 324 scientific papers on foliicolous lichenized fungi published subsequent to Santesson’s survey of 1952. The 482 species presently known are listed in an alphabetical checklist, with references to important descriptions, keys and illustrations published by or after Santesson (1952), and an indication of the distribution. Also added are all synonyms used after 1952. Introductory chapters deal with the present state of research on foliicolous lichens and its history. The following new combination is proposed: Strigula smaragdula Fr. var. stellata (Nyl. & Cromb.) Farkas

    Further distribution of Gertrudielle validinervis (Herz.) Broth. in the Neotropics

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    Gertrudiella validinervis (Herz.) Broth. is additionally recorded for the dry forests in northwestern Argentina. Complete distribution in the Neotropics, including northwestern Argentina, are shown on the maps

    New bryophyte taxon records for tropical countries 1

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    This is the first in a series of papers listing new records, which will be published whenever sufficient new records have been found. The taxa are arranged by countries for an easier evaluation, e.g. updates of checklists. The initials of the contributor for each record is shown in square brackets after the record, and these initials are interpreted at the end of the paper

    Threatened bryophytes of the neotropical rain forest : a status report

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    Tropical deforestation, inevitably, leads to the local loss of bryophyte species. Recent studies show that the degree of species loss may vary considerably and depends on the scale or amount of habitat change that has occurred. Predictably, the shade epiphytes are most seriously affected by disturbance. An estimated 10% of the bryophyte species of neotropical rain forests are under threat. Based on data from recent monographs, a first list of 19 endangered and 27 rare species of these forests is presented. Critical areas for threatened species include Costa Rica and Panama, the Greater Antilles, the Chocó, southeastern Brazil, and parts of Amazonia. Protection of as much as possible of the remaining natural rain forest area seems the best approach to the conservation of the tropical bryophyte flora

    A new Megatheriinae skull (Xenarthra, Tardigrada) from the pliocene of northern venezuela – Implications for a giant sloth dispersal to central and North America

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    A skull of a ground sloth from the Pliocene San Gregorio Formation documents a northern neotropical occurrence of a megatheriine that addresses issues on intraspecific variation and biogeography. The new specimen is broadly similar in size and morphology to that of Proeremotherium eljebe from the underlying Codore Formation in the Urumaco Sequence, differing in several features such as a longer basicranial area and a more posteriorly projected basioccipital between the condyles. The living sloths species of Bradypus and Choloepus do not have unequivocal anatomical features that indicate sexual dimorphism. Nevertheless, fossil sloths may have shown such dimorphism, and speculations on this subject are part of the considerations that can be made when allocating fragmentary fossils (e.g., in the new skull the presence of a long sagittal crest could indicate a male individual and the absence of an extended crest in Proeremotherium eljebe a female one). We speculate that as early as the late middle Miocene, two main lines of Megatheriinae had clearly separated in two geographic areas, one in the rising Andean area and one at low latitudes on the lowlands of central and northern South America.Fil: Carlini, Alfredo Armando. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico de Paleontología de Vertebrados; ArgentinaFil: Brandoni, Diego. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Sánchez, Rodolfo. Museo Paleontológico de la Alcaldia de Urumaco; VenezuelaFil: Sánchez Villagra, Marcelo R.. Universitat Zurich; Suiz

    The mosses of sub-Saharan Africa : 2., endemism and biodiversity

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    Based on a recent moss checklist of sub-Saharan Africa, an analysis is made of moss diversity and endemism in the area. There are over 3000 taxa, 77% of which are endemic. Figures for diversity and endemism for each country are listed, mapped and graphed, and endemism is also considered at the genus level. As the bryophyte flora of Africa is comparatively poorly known, it is important to be prudent when drawing conclusions about biodiversity and endemism

    Manual of tropical bryology

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    Bryophytes belong to the oldest land plants. They existed already in the Palaeozoic 300 mio years ago in forms which were hardly different from the extant species. They remained relatively unchanged with relatively low evolution rates (and are thus often called a „conservative“ plant group), but could successfully establish themselves in an always varying environment from Devonian swamps to Permian forests, Mesozoic deserts and as epiphytes in Tertiary rainforests. They are not eaten by snails or insects, and are resistant against fungi and bacteria
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