Exotic grass litter modulates seasonal pulse dynamics of CO2 and N2O, but not NO, in Mediterranean-type coastal sage scrub at the wildland-urban interface

摘要: Mediterranean shrublands adjacent to urbanization experience nitrogen deposition and exotic grass invasions which likely have downstream consequences for carbon emissions from soils. We tested a hypothesis that soil wetting produces trace gas pulses modified by seasonal history, litter availability, cover type in these systems. Over two seasons, we conducted 48-h experiments measured CO2, N2O, NO at an invaded, polluted California shrubland following addition sites dominated either invasive (Schismus barbatus) or native shrub (Erioginum fasciculatum). CO2 N2O consistently appeared 15 min post-wetting diminished within 12 h; peaked later remained elevated 24 h. All were stronger the dry season than wet season. Grass amendments increased dry-season without significantly modifying pulses. reduced compared cover. Our results support soils produce of during when is less frequent. show can provide labile C source stimulates but not NO,