“…Analyses of δ 13 C have greatly increased our understanding of the relationships between water and carbon use by desert plants (Ehleringer, 1993). Nitrogen isotope ratio (δ 15 N) provides information on ecosystem nitrogen cycling (Högberg et al, 1995;Roggy et al, 1999;Ometto et al, 2006;Bai et al, 2009) and plant nitrogen isotope discrimination is related to the availability of nutrients and water (Högberg, 1997;Swap et al, 2004;Aranibar et al, 2008;Wang et al, 2010b). Previous studies showed that succession affected N cycling and it was reflected in foliar δ 15 N (Davidson et al, 2007;Wang et al, 2007), and foliar δ 15 N signatures decreased as successional age increased at both the plant community and species levels (Wang et al, 2007).…”