3.1 Soil microclimate and soil N availability
Averaged across the three consecutive years, experimental warming by OTCs significantly increased upper (0-10 cm) soil temperature by 1.1 oC, increased soil inorganic N by 10.% (Fig. 1), and significantly decreased soil volumetric moisture by 2.8% unit. The interactive effects of warming and year on soil temperature and soil inorganic N were not statistically significant (Table S2). However, the warming effects on soil volumetric moisture differed significantly among years, with warming-induced decreases in soil volumetric moisture of 4.8, 2.6, and 1.2% unit in 2011, 2012, and 2013, respectively (Table S2).