Spatial distribution and environmental preferences of the piassaba palm Aphandra natalia (Arecaceae) along the Pastaza and Urituyacu rivers in Peru Thomas Boll a , Jens-Christian Svenning a , Jaana Vormisto a , Signe Normand a , Ce ´sar Gra ´ndez b , Henrik Balslev a, * a Institute of Biological Sciences, University of Aarhus, Building 540, Ny Munkegade, 8000 Aarhus C., Denmark b Universidad Nacional de la Amazonı ´a Peruana, Facultad de Ciencias Biolo ´gicas, Apdo. 326, Iquitos, Peru Received 22 April 2004; received in revised form 17 February 2005; accepted 30 March 2005 Abstract Aphandra natalia (Balslev and Henderson) Barfod, an economically important fibre producing palm, is common in rainforest on low terraces along the Pastaza and Urituyacu rivers in Amazonian Peru. The aim of this study was to investigate the spatial distribution and environmental preferences of Aphandra in old-growth terrace forest to which it is limited in this region. Densities of immature and mature individuals were 507  212 (S.D.) ha 1 and 19  8 ha 1 , respectively, in 11 (5  500 m) transects placed in old growth terrace forest near four villages and 739  188 ha 1 and 96  49 ha 1 , respectively, in six irregular transects placed in what the local villagers considered dense Aphandra stands. We examined environmental and spatial correlates of Aphandra occurrences using stepwise multiple autologistic regressions. Site, soil moisture, slope inclination, and topographic position influenced the spatial distribution of Aphandra. Furthermore, the distribution was strongly clumped, independently of environmental factors, with particularly the concentration of immature individuals around adults pointing to dispersal limitation as the likely causal mechanism. # 2005 Elsevier B.V. All rights reserved. Keywords: Dispersal limitation; Ecological sustainability; Fibre plants; Non-timber forest products; Palms; Recruitment; Resource availability; Tropical rainforest; Extractivism 1. Introduction For economically important species subject to extraction from natural stands it is of obvious importance to understand their occurrence, spatial variation and environmental preferences because these features are intrinsically related to their sustainable management. Tropical rainforest species have con- spicuous spatial variation in occurrence at all scales including very large ones over thousands of kilometres (Pitman et al., 2001), over intermediate ones of tens of kilometres (Tuomisto et al., 2003) to the very small www.elsevier.com/locate/foreco Forest Ecology and Management 213 (2005) 175–183 * Corresponding author. Tel.: +45 8942 4707/8942 2743; fax: +45 8942 4747/8613 9326. E-mail address: henrik.balslev@biology.au.dk (H. Balslev). 0378-1127/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.foreco.2005.03.020