What evidence exists relating the impact of different grassland management practices to soil carbon in livestock systems? A systematic map in progress

Grasslands play a crucial role in supplying essential resources for the livestock industry and in supporting other ecosystem services such as biodiversity preservation and soil carbon (C) storage. However, the ability of these ecosystems to maintain these services is increasingly at risk due to over-exploitation, environmental degradation, and climate change, particularly weakening their ability to effectively store C in soils. Restoring degraded grasslands is a practical and cost-effective approach to mitigating climate change by increasing soil C storage while enhancing productivity and improving ecosystem resilience. The potential for C sequestration in these ecosystems is highly variable, influenced by factors such as climate, biome type, soil depth, and management. Better management requires addressing the existing gaps in research and resources.

Using a systematic mapping approach, this project aims to build a comprehensive global inventory of studies examining the effects of different management practices on soil C. The outcomes of this approach will be used to identify well-researched areas suitable for systematic reviews, as well as knowledge gaps for further research, ultimately enhancing our understanding of the evidence in this field.

We formulated the research question to guide the systematic map protocol using the PICO framework, in line with established standards for systematic evidence synthesis. A preliminary search string was developed by integrating search terms corresponding to the Population (permanent grasslands), Intervention (varied management practices), and Outcome (soil C and related terms) categories, along with an additional category for study types (focused on farm and field experiments). A comprehensive search of both peer-reviewed and grey literature was performed across several databases, including Web of Science, Scopus, CABI, Google Scholar, and specialised platforms such as Agrotrop. Searches were conducted in English, Spanish, Portuguese, French, German, and Mongolian (the language skills of the team). Data extraction was structured into four key sections (article information, PICO categories, study characteristics, and measurable parameters), which will be used to generate tables, figures, and evidence maps to form the systematic map. The entire process of literature screening and data extraction was performed using the software Covidence.

The literature search resulted in the identification of over 30,000 references, of which approximately 3,000 were selected for further analysis following a thorough full-text eligibility criteria screening. In this presentation, we will walk through the flow diagram that captures each step of the literature search and screening process, share the data extraction table to provide insights into the outcomes, and offer a preliminary assessment at the global distribution map of studies involved. This includes an overview of the primary grassland management practices assessed. In addition, critical questions will be discussed: i) is there underrepresentation of developing countries in the literature, where vast grassland areas often suffer from intense degradation? ii) Is our knowledge influenced by a potential overrepresentation of specific forage species, management practices or climatic conditions? These findings will enhance our understanding of the existing evidence on the impact of grassland management on soil C, paving the way for a more effective allocation of future efforts and resources in this field.