Climatic signals in tree rings of Burkea africana and Pterocarpus angolensis from semiarid forests in Namibia

Esther Fichtler, Valerie Trouet, Hans Beeckman, Pol Coppin, Martin Worbes

Research output: Contribution to journalArticle

90 Scopus citations

Abstract

Tree-ring studies contribute worldwide to the understanding of climate and its relation to tree growth. Long tree-ring chronologies serve as climate proxies for the reconstruction of past, pre-instrument climate and its recent change. In tropical regions, the availability of exactly dated tree-ring chronologies is limited. The dendroclimatic potential of two dominant species from dry forests in northern Namibia was examined in the study presented in this paper. Both species (Burkea africana Hook and Pterocarpus angolensis DC) were sampled at two sites (ca. 900 km apart), and the response to several climatic variables, including ENSO indices, is studied. All specimens showed distinct growth rings and cross-dating between radii was successful for all trees. Species-specific mean curves were built for both sites. The mean curves of different species of the same site synchronised significantly, allowing the construction of a site-specific chronology. Synchronisation between sites was not possible, but spectral analysis of the chronologies implied that both show similar long-term (6.7 year) oscillation patterns. B. africana is more sensitive to rainfall variation than P. angolensis at both sites. Growth response to rainfall was positive, but a time-lag in the reaction occurred between the sites, corresponding to the time-lag of the beginning of the rainy season. Air temperature showed a negative correlation with stem increment at both sites. The response at the westernmost site to two ENSO indices indicates a tree growth decrease during El Niño years, which are generally dry in southern Africa.

Original languageEnglish (US)
Pages (from-to)442-451
Number of pages10
JournalTrees - Structure and Function
Volume18
Issue number4
DOIs
StatePublished - Jul 2004
Externally publishedYes

Keywords

  • Burkea africana
  • El Niño Southern Oscillation
  • Pterocarpus angolensis
  • Semiarid Africa
  • Tree rings

ASJC Scopus subject areas

  • Forestry
  • Physiology
  • Ecology
  • Plant Science

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