Lianas are key elements in tropical forest that influence forest structure and dynamics despite their ecological importance population studies on this life form are rare. We still know little about the influence of environmental factors on the spatial distribution of individuals and on the population dynamics of lianas. This knowledge can be used to understand the functioning of disturbed forests dominated by lianas and also for management of lianas and forests. My main goal in this thesis is to investigate whether the demography and spatial pattern of two abundant Neotropical liana species relate to abiotic and biotic environmental variations. We studied the species Mansoa difficilis in the Atlantic forest in southern Brazil and the species Machaerium cuspidatum in the Amazon forest in east Ecuador. We investigated (1) whether the vital rates of an abundant liana species in Seasonal Semideciduous forest relate to environmental factors in short-term; (2) whether the spatial distribution of the life stages of this same species relate to environmental factors; and (3) whether the relative growth rate (RGR) and mortality of an oligarchic species (i.e. widely distributed dominant species) in Amazon forest relate to environmental factors in long-term. We found out that (1) the population growth rate (?) of M. difficilis is decreasing in the studied area (? = 0.962 in 2012-2013 and ? = 0.941 in 2013-2014) and the vital rates are influenced by environmental factors differently throughout lifespan in short-term. Moreover there was spatial variation in ?. (2) All stages of life of M; difficilis were randomly distributed. The spatial distribution of each stage of life is related to a different environmental factor and/or a spatial component. (3) The RGR of climbing individuals of M. cuspidatum was weakly positively related to dense understory and the mortality of seedlings was higher in areas with intermediate slope. The dynamics and spatial distributions of the species studied in the Atlantic forest were influenced by different environmental variables throughout lifespan however the RGR and mortality of the oligarchic species studied in the Amazon forest had low sensitivity to environmental factor