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Changes in climate, grazing pressure and nutrient inputs affect the structural integrity and functioning of Andean shrublands

Abstract:

Background: Changes in climate and the intensity of agriculture expansion can alter plant population dynamics and community composition and structure of dry shrublands. Aims: We tested how temperature and moisture along an elevation gradient, grazing, and nutrient addition in soil affected demographic attributes of Croton shrubs and the composition and structure of plant species in an inter-Andean dry shrubland. Methods: At three elevations, we installed grazing and exclusion plots, combined with four nutrient treatments: control, and addition of nitrogen (N), phosphorous (P) alone and in combination. We measured recruitment and survival of Croton seedlings, as well as survival, growth, fruiting of adult Croton and the composition and structure of neighbouring plants. Results: Grazing exclusion improved adult survival of Croton at all three elevations. Grazing exclusion and addition of N and P increased adult growth of Croton at low and medium elevations. Croton seedling recruitment and survival decreased with distance to adult plants. The cover of Croton had a positive relationship with plant abundance and diversity. Conclusions: Temperature, moisture, grazing and nutrient addition can alter the demography and cover of Croton, as well as the composition and structure of its neighbouring plants threatening the functioning of the inter-Andean dry shrubland.