Approximately one third of California is grazed by livestock, with most forage produced on annual rangelands, the common term for rangelands with a significant annual herbaceous component. Given the state's interest in mitigating climate change and growing public attention on grazing systems that enhance carbon sequestration, we investigate the impact of grazing management on soil carbon cycling on California annual rangelands, drawing on soil science, rangeland management, and policy analysis literature. We conclude that using managed grazing for augmenting soil organic carbon on California annual rangelands presents significant challenges. Challenges include the heterogeneity, biogeochemical characteristics, and nonequilibrium nature of California's Mediterranean region, where ecological site conditions, soil type and texture, and climate moderate carbon sequestration. Enduring unknowns in the science underlying soil carbon and the dearth of relevant California-based studies further obscure the potential climate change mitigation effects of grazing systems. Given this, grazing management on California annual rangelands should not be prioritized as a climate change mitigation strategy, unless it is for the purposes of data collection and research. Alternative climate change mitigation opportunities on these landscapes include preventing rangeland conversion and enhancing soil carbon stocks through the suite of range management practices known to augment soil organic carbon or prevent erosion, including marginal cropland restoration, riparian restoration, organic amendments, and silvopasture. In this review, we argue that single-purpose management is generally not fitting for the diverse portfolio of social-ecological services produced on California's vast and varied rangelands. When assessing the value of grazing systems for augmenting soil organic carbon, policymakers, landowners, and other decision makers should consider the potential impacts on the numerous ecosystem services supported by the landscape. The multidisciplinary method presented in this review provides a critical framework for evaluating the appropriateness of working lands carbon policies as Natural Climate Solutions for climate change mitigation are developed in California and other geographies.

加利福尼亚大约有三分之一的牲畜被放牧，其中大部分草料是一年生牧场的，草地具有一年生草本成分的常用术语。考虑到该州对缓解气候变化的兴趣以及公众对提高碳固存的放牧系统的关注，我们利用土壤科学，牧场管理和政策分析文献，研究了放牧管理对加利福尼亚年度牧场土壤碳循环的影响。我们得出的结论是，在加利福尼亚州的一年一度的牧场上使用管理放牧来增加土壤有机碳面临着重大挑战。挑战包括加利福尼亚地中海地区的异质性，生物地球化学特征和非平衡性质，那里的生态地点条件，土壤类型和质地以及气候适度的碳固存。土壤碳的科学基础上持久的未知数以及基于加利福尼亚的相关研究的缺乏进一步模糊了放牧系统对缓解气候变化的潜在影响。因此，除非将其用于数据收集和研究，否则不应将加利福尼亚年度牧场的放牧管理作为缓解气候变化的策略。在这些景观上替代性的缓解气候变化的机会包括通过一系列范围管理实践来防止牧场转换和增加土壤碳储量，这些范围管理实践被称为增加土壤有机碳或防止侵蚀，包括边际农田恢复，河岸恢复，有机改良和森林植被。在这篇评论中 我们认为，单一目的管理通常不适合在加利福尼亚广阔而多变的牧场上生产的多样化社会生态服务。在评估放牧系统增加土壤有机碳的价值时，决策者，土地所有者和其他决策者应考虑对景观所支持的众多生态系统服务的潜在影响。由于加利福尼亚州和其他地区都在开发缓解气候变化的自然气候解决方案，因此本综述中介绍的多学科方法为评估工作用地碳政策的适当性提供了关键框架。其他决策者应考虑对景观所支持的众多生态系统服务的潜在影响。由于加利福尼亚州和其他地区都在开发缓解气候变化的自然气候解决方案，因此本综述中介绍的多学科方法为评估工作用地碳政策的适当性提供了关键框架。其他决策者应考虑对景观所支持的众多生态系统服务的潜在影响。由于加利福尼亚州和其他地区都在开发缓解气候变化的自然气候解决方案，因此本综述中介绍的多学科方法为评估工作用地碳政策的适当性提供了关键框架。