Journal of Tropical Ecology



The mechanism of general flowering in Dipterocarpaceae in the Malay Peninsula


Masatoshi  Yasuda  a1 c1 , Jun  Matsumoto  a2 , Noriyuki  Osada  a3 , San'ei  Ichikawa  a4 , Naoki  Kachi  a5 , Makoto  Tani  a6 , Toshinori  Okuda  a7 , Akio  Furukawa  a8 , Abdul Rahim  Nik  a9 and N.  Manokaran  a9
a1 Wildlife Ecology Laboratory, Forestry and Forest Products Research Institute, PO Box 16, Tsukuba Norin, Ibaraki 305-8687 Japan (myasuda@ffpri.affrc.go.jp)
a2 Faculty of Science, University Tokyo, Japan
a3 Faculty of Agriculture, Kyoto University, Kyoto, Japan
a4 Japan Science and Technology Corporation, Tokyo, Japan
a5 Faculty of Science, Tokyo Metropolitan University, Tokyo, Japan
a6 Forestry and Forest Products Research Institute, Ibaraki, Japan
a7 National Institute for Environmental Studies, Ibaraki, Japan
a8 Faculty of Science, Nara Women University, Nara, Japan
a9 Forest Research Institute Malaysia, Kuala Lumpur, Malaysia

Abstract

The mechanism of general flowering in Dipterocarpaceae in the Malay Peninsula is revealed through field survey and meteorological data analyses. The regions of general flowering coincide with those which experienced a low night-time temperature (LNT) c. 2 mo before flowering. This supports the hypothesis that low air temperature induces the development of floral buds of dipterocarps. LNT was found to be caused by radiative cooling during dry spells in winter when the northern subtropical ridge (STR) occasionally migrates southwards with a dry air mass into the equatorial region. LNT events usually occur in La Niña episodes, not in El Niño episodes as believed previously. This is because the southward migration of the STR is associated with the intensification of local meridional Hadley Circulation in the western Pacific, which is strengthened in a La Niña episode. Results suggest that El Niño-like climate change in increased atmospheric carbon dioxide concentrations may be critical for the tropical rain forest biome in south-east Asia.

(Accepted February 7 1999)


Key Words: Dipterocarpaceae; El Niño Southern Oscillation; general flowering; La Niña-STR hypothesis; low night-time temperature; Malaysia; reproductive ecology.

Correspondence:
c1 Wildlife Ecology Laboratory, Forestry and Forest Products Research Institute, PO Box 16, Tsukuba Norin, Ibaraki 305-8687 Japan (myasuda@ffpri.affrc.go.jp)