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Geophysical Monograph Series

 

Keywords

  • Rain forest ecology—Amazon River Region
  • Biosphere—Research—Amazon River Region
  • Climatic changes—Amazon River Region
  • Amazon River Region—Climate

Article

GEOPHYSICAL MONOGRAPH SERIES, VOL. 186, PP. 463-484, 2009

Ecophysiology of forest and savanna vegetation

J. Lloyd

School of Geography, University of Leeds, Leeds, UK


M. L. Goulden

Earth System Science, University of California, Irvine, California, USA


J. P. Ometto

Centro de Ciências do Sistema Terrestre, Instituto Nacional de Pesquisas Espaciais, São José dos Campos, Brazil


S. Patiño

Grupo de Ecología de Ecosistemas Terrestres Tropicales, Universidad Nacional de Colombia, Sede Amazonia, Instituto Amazónico de Investigaciones-Imani, Leticia, Colombia


N. M. Fyllas

School of Geography, University of Leeds, Leeds, UK


C. A. Quesada

Institito Nacional de Pesquisas da Amazônia, Manaus, Brazil


Ecophysiological characteristics of forest and savanna vegetation are compared in an attempt to understand how physiological differences within and between these vegetation types relate to their geographical distributions. A simple ordination first shows that although precipitation exerts a key effect on Amazonian vegetation distributions, soil characteristics are also important. In particular, it is found that under similar precipitation regimes, deciduous forests tend to occur on more fertile soils than do cerrado vegetation types. A high subsoil clay content is also important in allowing the existence of semievergreen forests at only moderate rainfall. Such observations are consistent with biome specific physiological characteristics. For example, deciduous trees have higher nutrient requirements than do evergreen ones which also tend to have characteristics associated with severe water deficits such as a low specific leaf area. Nutrient contents and photosynthetic rates are lower than for savanna than for forest species with several ecosystem characteristics suggesting a primary limitation of nitrogen on savanna productivity. By contrast, phosphorus seems to constrain the productivity of most Amazonian forest types. Differentiation is made between the fast-growing, high-nutrient-requiring forest types of western Amazonia and their counterparts in eastern Amazonia, which tend to occupy infertile but deeper soils of high water-holding ability. On the basis of observed physiological characteristics of the various vegetation forms, it is argued that, should Amazonian precipitation decline sharply in the future, the slower growing forests of eastern Amazonia will transform directly into an evergreen cerrado type vegetation but with the more fertile western Amazonian forests being replaced by some form of drought-deciduous vegetation.

Citation: Lloyd, J., M. L. Goulden, J. P. Ometto, S. Patiño, N. M. Fyllas, and C. A. Quesada (2009), Ecophysiology of forest and savanna vegetation, in Amazonia and Global Change, Geophys. Monogr. Ser., vol. 186, edited by M. Keller et al., pp. 463–484, AGU, Washington, D. C., doi:10.1029/2008GM000740.

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