Effects of topographic factors on distribution of cacti along an elevation gradient in Brazilian Caatinga

Abstract The Cactacea family comprises 128 genera and 1450 species with predominantly neotropical distribution. Cacti are commonly found in arid semi-arid regions have great ecological relevance due to their interactions animals other groups of plants. Abiotic interactions, such as topography, altitude, rainfall, temperature soils, also influence the composition distribution cacti. objective present study was assess patterns for cacti along an elevation gradient Brazilian Caatinga vegetation. Four transects (composed by 25 plots 100 m² each) were established at each two mountain sites. topographic variables elevation, slope, rockiness soil depth evaluated determine if they affect richness abundance using Spearman's (rs) correlation coefficient. A total 554 individuals five (Pilosocereus gounellei, Pilosocereus pachycladus, Tacinga palmadora, inamoena Melocactus zehntneri) sampled. be negatively correlated slope rockiness, positively (p<0.05). All exhibited aggregate spatial patterns, which may related different environmental conditions produced among (slopes, depth), that synergistically gradient.