Human impact on tropical-alpine plant diversity in the northern Andes

Abstract

Conserving paramo diversity and ecosystem services in the northern Andes is urgent, and understanding factors that control vegetation changes is therefore crucial. Although anthropogenic activities have been common in the Andean highlands for cen- turies, the role of human influence in shaping paramo vegetation remains unclear. To assess the relative importance of human disturbance associated with cattle farming and cultivation for plant species diversity and composition, we analyzed variables driven by both natural and human impact in the Santurbanp aramo, Colombia. Canonical corre- spondence analysis (CCA) showed that the main gradient in plant species composition is related to the gradient of human impact. Partial CCA showed that the pure effect of the variables driven by human impact on floristic composition is twice the size of the pure effect of the variables driven by natural impact. Forward selection procedure indicated that the impact of human disturbance on floristic composition is determined by the level of accessibility. Vegetation patterns are driven by a complex set of elevation-related envi- ronmental factors, and human disturbance plays a primary role. Strict protection should be granted to remote and upper sites of the paramo. Restriction of fire and agriculture along steep slopes may counteract negative effects of human disturbance on plant species diversity.