Non-native tree plantations (NNTP) are an increasingly relevant global source of timber. Their expansion may lead to tradeoffs with important local ecosystem services (ES) that need to be evaluated for a sound and sustainable landscape planning. For a mountain area in southern Chile, we assessed the effects of NNTP expansion and potential NNTP timber-ES tradeoffs through a spatial tradeoff typology based on ES supply variations. We evaluated changes in prioritized ES (native timber supply, forage supply, water regulation, and recreation opportunities) and NNTP timber supply based on a probabilistic projection of NNTP expansion at two administrative levels (the municipality and small, medium and large farm properties). Results show that NNTP expansion triggered an increase of 361% in NNTP timber supply at the expense of decreases in provision of selected ES, such as forage supply (16.3%), native timber supply (9.4%), water regulation (0.4%) and recreation opportunities (66.8%). Tradeoffs were restricted to small geographic areas but were considerably high in terms of the magnitude of ES supply losses. Tradeoffs were highest in medium farms as compared to small and large properties. Results corroborate that tradeoffs arise from the interplay of several factors, such as ES type and ES productivity, and they are site-specific and scale dependent. If NNTP continue to expand at the current rate (yearly 9.6%) and under the current management (large scale monocultures), significant ES supply changes are inevitable. These results can inform landowners, landscape planners and governments to better anticipate and mitigate tradeoffs arising from afforestation.