This research was performed at the International Ministry of Forestry (MOF) Tropenbos-Kalimantan research station, East Kalimantan. We are grateful for the support we received from the many staff members working there, especially M. de Kam and A. Susilo. K. Sidiyasa, Ambriansyah, Z. Arifin and Adriansyah from the Wanariset Herbarium were responsible for the tree identifications, and the staff from the Wanariset forest economy and monitoring unit established the plots in Sungai Wain. The fieldwork benefited greatly from the dedication of J. Helleman, N. Syah, F. Udin and S. Laysa Putra. J.W.F. Slik kindly provided data from the Wartonokadri plots. We are grateful to J.A. Sayer, M. van Noordwijk, D.W. Dijkman and G.M. Fredriksson for their support and fruitful discussions. M.J.A. Werger, F.J. Sterck, Lisa Curran, Ferry Slik, G.M. Fredriksson and Joe Wright made valuable comments on earlier versions of this manuscript. Sally Wellesley, Indah Susilanasari and the CIFOR library staff helped D.S. to finalize the text for submission. The research was supported by the Netherlands Foundation for the Advancement of Tropical Research (WOTRO) with grant 84–408 to MvN. DS's work was supported by a grant to CIFOR from the European Commission.