Dinámica de la vegetación en un enclave semiárido del río Chicamocha, Colombia.

We present an approach to the dynamics that determine current distribution of vegetation in the semiarid enclave Canyon Chicamocha River (Pescadero sector). The disturbance regime determine different successional patterns in a high spatial and temporal heterogeneity. The main types of dynamics and vegetation changes are related to disturbances such as landslides or soil removal in hillside areas, grazing goats estabulizado not, agroecosystems Quaternary terraces and fluctuations in river levels. In the case of landslides are different processes in succession high slopes areas and in areas of low slopes. We evaluated areas with primary successions submitted after landslides and river fluctuations, secondary successions agricultural product, and estate regeneration on slopes with grazing goats. The grazing of goats is a continuous disturbance and more decisive in the transformation of plant communities for loss of tree elements and increasing the abundance of unpalatable species. We found that on the slopes overlooking Lippia origanoides, forming extensive homogeneous matrix and mixed with patches of Prosopis juliflora and Stenocereus griseus slopes at the base of sloping floor or cones produced by landslides. The use of agricultural land on slopes low and terraced dynamics is related to the types short cycle crop. The dynamics associated with seasonal fluctuations in the water level of the river Chicamocha generates colonizing of short life cycle species and low requirements in structuring their micro-habitat. Finally, we present a conceptual model for the interpretation of the dry forest degradation and its relationship with the aridity phenomena. [ABSTRACT FROM AUTHOR]