1Laboratoire Evolution et Diversité Biologique, UMR 5174 CNRS/UPS, Toulouse, France
2Fundación Puerto Rastrojo, Bogotá, Colombia
3Grupo de Estudio de Ecosistemas Terrestres Tropicales, Universidad Nacional de Colombia, Leticia, Colombia
4Museu Paraense Emilio Goeldi, 66077-530 Belem, Brazil
5Environmental Change Institute, School of Geography and the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, UK
6INRA, UMR Ecologie des Forêts de Guyane, BP 709, 97387 Kourou Cedex, French Guiana
7CNRS-Guyane, Station d'Etude des Nouragues, UPS 2561, French Guiana
8Universidad San Antonio Abad, Cusco, Perú
9Earth and Biosphere Institute, School of Geography, University of Leeds, Leeds LS2 9JT, UK
10Universidad de los Andes, Bogotá, Colombia
Received: 16 Dec 2008 – Discussion started: 27 Jul 2009
Abstract. The production of aboveground soft tissue represents an important share of total net primary production in tropical rain forests. Here we draw from a large number of published and unpublished datasets (n=81 sites) to assess the determinants of litterfall variation across South American tropical forests. We show that across old-growth tropical rainforests, litterfall averages 8.61±1.91 Mg ha−1 yr−1 (mean ± standard deviation, in dry mass units). Secondary forests have a lower annual litterfall than old-growth tropical forests with a mean of 8.01±3.41 Mg ha−1 yr−1. Annual litterfall shows no significant variation with total annual rainfall, either globally or within forest types. It does not vary consistently with soil type, except in the poorest soils (white sand soils), where litterfall is significantly lower than in other soil types (5.42±1.91 Mg ha−1 yr−1). We also study the determinants of litterfall seasonality, and find that it does not depend on annual rainfall or on soil type. However, litterfall seasonality is significantly positively correlated with rainfall seasonality. Finally, we assess how much carbon is stored in reproductive organs relative to photosynthetic organs. Mean leaf fall is 5.74±1.83 Mg ha−1 yr−1 (71% of total litterfall). Mean allocation into reproductive organs is 0.69±0.40 Mg ha−1 yr−1 (9% of total litterfall). The investment into reproductive organs divided by leaf litterfall increases with soil fertility, suggesting that on poor soils, the allocation to photosynthetic organs is prioritized over that to reproduction. Finally, we discuss the ecological and biogeochemical implications of these results.
Published: 05 Jan 2010
Chave, J., Navarrete, D., Almeida, S., Álvarez, E., Aragão, L. E. O. C., Bonal, D., Châtelet, P., Silva-Espejo, J. E., Goret, J.-Y., von Hildebrand, P., Jiménez, E., Patiño, S., Peñuela, M. C., Phillips, O. L., Stevenson, P., and Malhi, Y.: Regional and seasonal patterns of litterfall in tropical South America, Biogeosciences, 7, 43-55, doi:10.5194/bg-7-43-2010, 2010.