“…Nitrogen addition can increase (Brenner et al, 2005;Lu et al, 2011;Corre et al, 2014), decrease (Lovett et al, 2013;Cai et al, 2014), or have no effect (Brenner et al, 2005;Wang et al, 2014) on net nitrification. Similarly, denitrification was found to increase (Perez et al, 2010), decrease (Bengtsson and Bergwall, 2000;Berntson and Aber, 2000), or remain unchanged (Wallenstein et al, 2006) under N addition. A meta-analysis indicated that N addition significantly increased net N mineralization, nitrification, and denitrification by 25, 154, and 84%, respectively, but did not change N immobilization (Lu et al, 2011).…”