Original article Different spatial organisation strategies of woody plant species in a montane cloud forest Alicia Ledo a, * , Fernando Montes b , Sonia Condés a a Universidad Politécnica de Madrid, ETSI de Montes, Ciudad Universitaria s/n, 28040 Madrid, Spain b CIFOR-INIA, Ctra. de La Coruña km 7.5, 28040 Madrid, Spain article info Article history: Received 12 January 2011 Accepted 10 September 2011 Available online xxx Keywords: Spatial pattern Tree distribution Tropical forest Peru Ripley’s K function Community structure Biodiversity abstract The coexistence of a high number of species in the forest is a central issue in tropical ecology. In this paper, we aim to characterise the spatial pattern of woody species in an Andean montane cloud forest to determine whether differences exist among the species in terms of spatial organization and if so, whether these differences are related to the life-form, primary dispersal mode, shade tolerance or the diameter distribution of the species. For this purpose, we analysed the spatial pattern of each species as well as the spatial relationships between young and adult individuals. Almost all the analysed species showed a cluster pattern, followed by a random pattern at larger distances. The cluster size is more evident for the young trees whereas adult trees tended to be more randomly distributed. The shade- tolerant species showed greater distances of aggregation than gap or medium-shade-tolerant species. Species primarily dispersed by wind and small birds showed larger distances of aggregation than species dispersed by mammals or big birds. All the under-story woody plants showed a notable cluster pattern, whereas canopy trees showed a variety of spatial patterns, with clustering at small scales being the most frequent. In the case of emergent trees, association was found between young and adult individuals on a large scale. Positive associations between young and adult individuals predominate at small scales for medium and shade tolerant species and at larger scales for bird-dispersed species whereas negative spatial associations at smaller scales were found for shade tolerant species and wind dispersed species. Our study confirms that conspecific organization varies among the woody plants in the analysed forest, and that the spatial pattern of woody plants is partially linked to shade tolerance, primary dispersal mode and life form of the species. Ó 2011 Elsevier Masson SAS. All rights reserved. 1. Introduction The spatial pattern and arrangement of individuals of any species is fundamental in ecological theory (Dale, 1999; Condit et al., 2000) and provides us with an understanding of the inter- actions among the elements of the ecosystem and dynamics that take place (Legendre, 1993; Picard et al., 2009). Therefore, the study of ecosystems should include an analysis of plant distribution (Law et al., 2001) to provide an insight into the ecological processes underlying population dynamics (He et al., 1996). Data regarding the distribution of trees are essential when analysing the way in which trees use the resources available to them (Condit et al., 2000), and resource usage patterns are thought to differ from one species to another (Picard et al., 2009). Furthermore, by analysing the spatial distribution of individuals of each species in a forest, their different niches can be characterised (Kneitel and Chase, 2004) and the contribution of different factors to the formation of this pattern can be identified. These factors include dispersal strategies, establishment requirements, development, competition and mortality processes as well as physical processes such as soil formation or rock scouring. Hence, by analysing the distribution patterns of the different species, it is possible to shed light on the role of each species and the interactions which exist among them (Saldaña-Acosta et al., 2008). Spatial analysis methods based on the second-order characteris- tics of the distribution of individuals have recently been developed in a wide range of fields. Point pattern techniques, for example, have been widely used in ecology to analyse the spatial structure of ecosystems. The K(d) function (Ripley, 1977) and related functions have been employed to describe the second-order properties of the spatial pattern as a function of the inter-point distance in a wide range of ecological applications (Dixon, 2002; Wiegand et al., 2007; Picard et al., 2009). In addition, several functions have been devel- oped to analyse bivariate spatial point processes (Lotwich and * Corresponding author. E-mail address: a.ledo@upm.es (A. Ledo). Contents lists available at SciVerse ScienceDirect Acta Oecologica journal homepage: www.elsevier.com/locate/actoec 1146-609X/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.actao.2011.09.003 Acta Oecologica xxx (2011) 1e9 Please cite this article in press as: Ledo, A., et al., Different spatial organisation strategies of woody plant species in a montane cloud forest, Acta Oecologica (2011), doi:10.1016/j.actao.2011.09.003