Vegetation recovery alters soil N status in subtropical karst plateau area: Evidence from natural abundance δ15N and δ18O

Purpose Forest recovery from disturbance can alter soil nitrogen (N) status as a result of complex interactions in plant-soil system. The δ 15 N and δ 18 O are indicators that integrate complex soil N processes and can help elucidate changes in soil N status. Our objectives were to evaluate differences in soil N status among different forest recovery stages in karst plateau in southwestern China. Methods We established a forest recovery gradient with sites in cropland, abandoned cropland, shrub land, and early- and late-successional forests. We measured concentrations and isotopic compositions of soil total N, ammonium (NH 4 + ), and nitrate (NO 3 − ), and δ 15 N of plant tissue. Results With increased levels of recovery, concentrations of soil total N increased, and δ 15 N of soil total N (δ 15 N STN ) decreased at 0 ~ 10 cm depth. A positive relationship between δ 15 N STN in surface soil and δ 15 N of plant (P