Abstract Background Environmental impacts of farm land abandonment can be viewed as either an opportunity for ecological restoration to a state prior to agricultural establishment, or as the loss of an on-going process of land management and an associated threat to biodiversity. Whether land abandonment poses an ecological opportunity or threat depends upon the agricultural history and the presence of ecological systems that depend upon regular management for their existence. In Europe, many ecosystems have developed in the presence of agriculture and the loss of continued management resulting from land abandonment can have significant negative ecological impacts. Around 56 percent of the utilised agricultural area (UAA) of the EU is classified as ‘less-favourable areas’ and much of this is mountainous. The small-scale and extensively managed farmlands that are common in mountain areas are particularly vulnerable to marginalisation and abandonment. The work herein will form the first systematic synthesis of the evidence of impacts of farm land abandonment in mountain areas across the globe. Methods This review will take the form of two interrelated systematic maps, cataloguing the existing evidence across a wide range of variables such as setting, methodology, scale, measured outcomes etc. Mapping will be undertaken both at abstract-level at a coarse scale and at full text-level at a finer scale. Literature databases, organisational web sites, and search engines will be used to collate all of the available literature regarding the impacts of agricultural land abandonment. All studies investigating farmland abandonment in mountainous regions with an appropriate comparator and measuring an appropriate outcome will be included. Outcomes will be coded in a partly iterative process but will include; natural hazards (fire-/flood risk, land/mud slides), soil (fertility, erosion), water (chemistry, eutrophication, sediment load, hydrology), ecosystem functioning (biodiversity, abundance, invasive species presence), socio-economics (e.g. health, wellbeing, employment). The systematic map outputs will be in the form of searchable databases of relevant and obtainable (full text only) literature, coded by subject, methodology and study design, and internal validity.