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Amazonian Trees (amazonian + tree)

Distribution by Scientific Domains

Earth and Environmental Science	50%

Selected Abstracts

Fire Scars on Amazonian Trees: Exploring the Cryptic Fire History of the Ilha de Maracá

BIOTROPICA, Issue 4 2010
Jos Barlow
ABSTRACT The presence of charcoal in the soils and fire scars on 8.2 percent of tree stems strongly suggest that one of the best studied Amazonian research localities (the Ilha de Maracá in Roraima, Brazil) has burned. The patterns and images of fire scars that we present here could help researchers explore the burn history of other tropical forests, which has important implications for interpreting their present-day ecology. [source]

Demographic and life-history correlates for Amazonian trees

JOURNAL OF VEGETATION SCIENCE, Issue 6 2005
Henrique E.M. Nascimento
Abstract Questions: Which demographic and life-history differences are found among 95 sympatric tree species? Are there correlations among demographic parameters within this assemblage? Location: Central Amazonian rain forest. Methods: Using long-term data from 24 1,ha permanent plots, eight characteristics were estimated for each species: wood density, annual mortality rate, annual recruitment rate, mean stem diameter, maximum stem diameter, mean stem-growth rate, maximum stem-growth rate, population density. Results: An ordination analysis revealed that tree characteristics varied along two major axes of variation, the major gradient expressing light requirements and successional status, and the second gradient related to tree size. Along these gradients, four relatively discrete tree guilds could be distinguished: fast-growing pioneer species, shade-tolerant sub-canopy species, canopy trees, and emergent species. Pioneers were uncommon and most trees were canopy or emergent species, which frequently had low mortality and recruitment. Wood density was negatively associated with tree mortality, recruitment, and growth rates when all species were considered. Growth rates varied markedly among and within species, with pioneers exhibiting far faster and less variable growth rates than did the other species. Slow growth in subcanopy species relative to canopy and emergent trees was not a simple consequence of mean tree size, but apparently resulted from physiological constraints imposed by low-light and other conditions in the forest understorey. Conclusions: Trees of Amazonian rain forests could be classified with some success into four relatively distinctive guilds. However, several demographic and life-history traits, such as those that distinguish early and late successional species, probably vary along a continuum, rather than being naturally grouped into relatively discrete categories. [source]

Taxonomic identification of Amazonian tree crowns from aerial photography

APPLIED VEGETATION SCIENCE, Issue 4 2010
Carlos E. González-Orozco
Abstract Question: To what extent can aerial photography be used for taxonomic identification of Amazonian tree crowns? Objective: To investigate whether a combination of dichotomous keys and a web-based interface is a suitable approach to identify tree crowns. Location: The fieldwork was conducted at Tiputini Biodiversity Station located in the Amazon, eastern Ecuador. Methods: High-resolution imagery was taken from an airplane flying at a low altitude (600 m) above the ground. Imagery of the observable upper layer of the tree crowns was used for the analysis. Dichotomous identification keys for different types of crowns were produced and tested. The identification keys were designed to be web-based interactive, using Google Earth as the main online platform. The taxa analysed were Iriartea, Astrocaryum, Inga, Parkia, Cecropia, Pourouma, Guarea, Otoba, Lauraceae and Pouteria. Results: This paper demonstrates that a combination of photo-imagery, dichotomous keys and a web-based interface can be useful for the taxonomic identification of Amazonian trees based on their crown characteristics. The keys tested with an overall identification accuracy of over 50% for five of the ten taxa with three of them showing accuracy greater than 70% (Iriartea, Astrocaryum and Cecropia). Conclusions: The application of dichotomous keys and a web-based interface provides a new methodological approach for taxonomic identification of various Amazonian tree crowns. Overall, the study showed that crowns with a medium-rough texture are less reliably identified than crowns with smoother or well-defined surfaces. [source]

Unanticipated Effects of Stand Dynamism on Amazonian Tree Diversity

BIOTROPICA, Issue 4 2010
Susan G. W. Laurance
ABSTRACT We assessed a general hypothesis of tropical tree diversity that predicts that species richness will be positively correlated with stand dynamism. Our analysis was based one of the largest and longest-running datasets on Amazonian trees (,10 cm diameter at breast height), with data collected over a 23-yr period within 66 1 ha plots spanning a large (1000 km2) landscape. Within these plots, maximum tree-species richness (329 species/ha) and Fisher's , values (227.5) were among the highest ever recorded. Contrary to the diversity-dynamism concept, tree species richness in our landscape was significantly and negatively associated with stand dynamism (measured as the mean rate of annual tree turnover). Because of this unexpected finding, we critically re-evaluated the relationship between stand dynamism and tree diversity across the Amazon basin and the tropics as a whole. With the inclusion of additional data we found that the relationship between stand dynamism and tree diversity becomes non-significant at larger spatial scales. Abstract in Portuguese is available at http://www.blackwell-synergy.com/loi/btp [source]