Soil conditions in treatments representing native, naturalized, or invasive annuals, and controls. Given is mean (+ SE) a available ammonium (NH4+) content b available nitrate (NO3−) content, and c soil moisture (volumetric water content); as measured in 2018. For each variable, means that do not share letters are significantly different, as evaluated with post-hoc comparisons when the treatment effect was significant (P < 0.05).