Impacts of invasive annuals on soil carbon and nitrogen storage in southern California

Data was collected to better understand how type-conversion by common invasive annuals impacts carbon (C) and nitrogen (N) storage in surface soils across southern California. Specifically, we examined how the identity of the invader (non-native grasses, Bromus spp.; and non-native forbs, Brassica nigra), microbial concentrations, and soil properties interact to influence soil nutrient storage in adjacent native and invasive habitat types at nine sites along a coast to inland gradient. All sites contained an area of intact sage scrub and adjacent type-converted non-native annual grassland or non-native forbland. Adjacent habitat types were within ~ 300 m of each other to control for variation in soil properties or microclimate within sites. We collected soil samples from nine sites in fall 2016 (October 14 through November 4) and spring 2017 (April 10 through May 2) that span a gradient from coastal Los Angeles County to San Bernardino County to compare total C and total N, other soil properties, and microbial abundances.