Conversion of tropical forests to agriculture contributes significantly to global warming, causing an estimated 12–18% of global greenhouse gas (GHG) emissions. However, estimates of ecosystem carbon fluxes are not accurate mainly because of the limited understanding of their belowground components. Root dynamics, i.e. root production, mortality and decomposition, are crucial elements of ecosystem functioning; an understanding of root dynamics is required to estimate the carbon cycle accurately.
This systematic review will assess the current evidence for how tropical and subtropical forest degradation and landuse changes to agriculture affects fine root dynamics. Several stages of forest degradation will be examined during the review process, including current agricultural conversion systems, such as oil palm plantations in Southeast Asia and soybean plantations and pastures in Latin America. The search strategy will follow a specific a priori review protocol. Searches will be conducted in English across six different scientific databases and Google Scholar will be used to ensure comprehensiveness of the evidence base. The retrieved articles will undergo a three-stage screening by title, abstract and full text using predefined inclusion/exclusion criteria. Screening consistency will be evaluated using kappa tests. From the final list of included studies, relevant information on fine root dynamics (i.e. rates and methods used), summary statistics (i.e. mean and variance), ecosystem (i.e. forest type or agricultural system), geographical location and climate and soil variables will be extracted and entered into a database. A meta-analysis will be conducted on subgroups such as root production, root mortality and root decomposition, to show how land-use change affects different components of fine root dynamics. The review will also synthesize the current methods used to assess fine root dynamics and discuss their methodological limitations and variances.