Patterns of nitrogen and phosphorus conservation in dominant perennial grasses and shrubs across an aridity gradient in Patagonia, Argentina

Abstract

The aim of this study was to assess the patterns of N and P conservation in dominant perennial grasses and shrubs across an aridity gradient in Patagonia. We analysed leaf dry mass per area, and N and P concentrations in green leaves and N and P resorption from senescing leaves in dominant species of each life-form across the gradient. Leaf dry mass per area and concentration of N and P in green leaves did not differ between life-forms, whereas, increasing N concentration in green leaves of perennial grasses and decreasing P concentration in green leaves of shrubs were related to the severity of aridity. Perennial grasses showed lower N concentration in senesced leaves, and higher N- and P-resorption efficiency than shrubs. In shrubs, N-resorption efficiency decreased with aridity while N concentration in senesced leaves increased with aridity. On the contrary, traits in senesced leaves of perennial grasses did not vary across the aridity gradient. These differences in the patterns of N and P conservation between life-forms are of adaptive significance and relevant in relation to decomposition pathways and nutrient cycling in the studied arid ecosystems.