Use este identificador para citar ou linkar para este item:
Título: A comparison of delta13C ratios of surface soils in savannas and forests in Amazonia
Autor(es): William E. Magnusson
Albertina Pimentel Lima
L. A. Martinelli
Reinaldo L. Victoria
Ana Luisa Kerti Mangabeira Albernaz
Ana Luisa Kerti Mangabeira Albernaz
Tânia Margarete Sanaiotti
ISSN: 0305-0270
Revista: Journal of Biogeography
Volume: 29
Resumo: Aim To determine the relationship between stable carbon isotope ratios in surface soils and the present vegetation in Amazonian savannas.Location Areas in and around savannas in the Brazilian Amazonian States of Amazonas, Para, Amapa, Roraima, Mato Grosso and Maranhao.Methods delta(13)C ratios were measured from surface (0-5 cm depth) soils in fifty-two plots in savanna plots with different covers of trees, shrubs, and grasses, and in ten adjacent areas covered by forest.Results Soil delta(13)C ratios varied widely (-24.9 to -15.2parts per thousand) among and within savannas, but were distinguishable from delta(13)C ratios under forest (-30.3 to -27.3parts per thousand). One site close to forest with 38% tree cover, 44% shrub cover and 45% grass cover was distinguishable from both forest and savanna on Landsat TM5 images, and had a delta(13)C ratio of -26.7parts per thousand. Tree density (TD), basal area (BA) and cover differed strongly between savanna and forest areas. However, most savanna areas had soil organic matter with delta(13)C ratios closer to those of forest trees than C-4 grasses.Main conclusions In Amazonia, soil delta(13)C values >-25parts per thousand can be unequivocally attributed to savannas irrespective of depth. However, there is no precise relationship between tree or grass cover in savannas and surface-soil delta(13) C values. This is partly because shrubs, as well as trees and grasses, contribute significantly to soil organic matter delta(13)C ratios, and partly because there is a stronger negative relationship between area of bare ground and cover of C-4 grasses than between area of bare ground and cover of trees or shrubs. This means that the ratio of C-3 to C-4 plants tends to increase with a decrease in total cover. Areas with large amounts of open ground, may have a small proportion of grass cover relative to tree and shrub cover. Although we did not encounter any such places in this study, very harsh conditions could lead to desert-like formations with little grass cover and soil organic-matter delta(13)C ratios similar to forest areas.
ISSN: 0305-0270
Aparece nas coleções:Coordenação de Biodiversidade (CBIO)

Arquivos associados a este item:
Não existem arquivos associados a este item.

Este item está licenciada sob uma Licença Creative Commons Creative Commons