Increasing tree cover on agricultural land is recognised as a potential mechanism to enhance ecosystem services. In this case study, we assessed and mapped the impacts on ecosystem services and dis-services of different land-sparing and land-sharing strategies for tree cover expansion on grassland and arable land in the Welsh uplands. In addition, we modelled the impacts of widespread adoption of these strategies on grassland and arable land on the total basket of ecosystem services derived from the Welsh uplands. Our modelling over a 120-year period suggests land-sharing strategies (agroforestry options) could lead to the greatest potential increase in ecosystem service benefits (+£2.62 billion for the Agroforestry – in field trees option). Such land-sharing strategies deliver a basket of ecosystem services primarily focused on private provisioning benefits, with only modest increases in public regulation and maintenance benefits. In contrast, land-sparing strategies (full afforestation options) deliver the highest level of public regulation and maintenance benefits (£7.60 billion), but at the cost of provisioning benefits (−£17.13 billion). Land-sharing strategies (agroforestry options) provide the highest level of in-situ ecosystem service benefits. Land-sparing strategies (full afforestation options) primarily provide ex-situ ecosystem service benefits and are likely to require livelihood shifts for private landowners and occupants.