Climate Science

Uniformly Productive

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Science  03 Dec 2004:
Vol. 306, Issue 5702, pp. 1651
DOI: 10.1126/science.306.5702.1651b

Moist tropical forests of the Amazon basin experience a seasonal variation of rain, in which the radiation available for photosynthesis is much more abundant during the dry season. In spite of this fluctuation, these forests maintain high rates of primary production throughout the 5-to-6 month dry season. Two non-exclusive explanations have been proposed: the first is that many plants in the tropical forest have deep roots, which would allow them access to water during the dry season; the second is that they have developed patterns of leaf phenology (the cycle of leaf fall and emergence) that facilitate an even growth rate.

Xiao et al. have combined analyses of satellite images and field data from a CO2 flux tower site in a Brazilian forest in order to develop and validate a new satellite-based vegetation photosynthesis model for estimating the dynamics of production in seasonally moist tropical evergreen forest. They find that this forest displays subtle changes in the seasonal dynamics of leaf phenology and that the forest experienced no water stress in the dry seasons of 1998–2002. They use these data as input to a model that successfully predicts high productivity in the late dry season, consistent with observation. — HJS

Remote Sensing Environ. 94, 105 (2005).

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