This book examines the micro-scale variability in tree species composition, diversity and tree structure through a combination of ground-based plot studies and computer based analyses of terrain characteristics in two contrasting tropical forest sites; a tropical montane cloud forest environment, and a lowland Amazonian forest environment. The aim is to measure the micro-scale spatial variability in tree species diversity, composition and structure in tropical forests, and to quantify the role of topography, through both direct and indirect resource partitioning (of essential resources such as energy and water), in controlling this variability. The book shows correlations between terrain characteristics and tree species composition and diversity, and provides novel methodologies for testing the processes behind the maintenance of species diversity in tropical forests. The results lead to the conclusion that a combination of equilibrium and non-equilibrium, abiotic- and biotic- based processes are maintaining diversity in tropical forests.