California’s rangelands encompass 40 million grazed acres, which support a 3 billion dollar cattle industry critical to the state’s economy. Nearly half of grazed lands are privately owned and there is growing recognition that this acreage contributes critical ecosystem services, including carbon storage, water cycling, and habitat to support biodiversity. Given rangelands’ critical economic and ecological contributions, there is a need to increase use of conservation practices designed to sustain and enhance ecosystem services on rangelands, such as prescribed grazing and other practices promoted by the Environmental Quality Incentives Program (EQIP). Yet to date, few studies have investigated patterns of availability of ecosystem services in rangelands. This study aims to bridge this critical knowledge gap by evaluating indicators of soil carbon at 0-10cm and 10-40cm, water infiltration, vegetation communities, and bird diversity on 70 ranch sites across California.
The study sites comprised a range of soil types, textures and habitat types. Soil texture determines soils’ potential to store carbon, but is not a strong predictor of variation of percent soil carbon. Baseline measures of soil carbon revealed that percent soil carbon in surface soils (0-10cm) and 10-40 cm depth were positively correlated. Plant community composition is significantly correlated with variation in soil carbon. Additionally, soils under vegetation communities with higher functional diversity, and especially more perennial grasses, have higher soil carbon across the network of study sites. Plant community composition is reliably correlated with variations in soil organic carbon in California rangelands. Plants associated with low levels of soil carbon included Erodium spp., Plagiobothrys, (popcorn flower) and Silene gallica. Plants associated with medium levels of soil carbon included Briza maxima (rattlesnake grass), Agrostis capillaris (colonial bentgrass) and Rytidosperma steud (wallaby grass). Plants associated with higher levels of soil carbon included Carduus pycnocephalus (Italian plumeless thistle), Anchusa arvensis (small bugloss), Vicia spp. (vetch), Juncus spp. and Bromus carinatus (California brome). Bird focal species associated with different habitat types can provide strong indicators of management influence on soils, vegetation communities in working rangelands.