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Roads are an increasingly important anthropogenic disturbance to tropical ecological systems. Although the ecological impacts of roads are now well recognised, there remains a lack of certainty regarding how roads in general and roads with different widths affect vital ecosystem services such as above-ground biomass (AGB) in tropics. Using a non-destructive sampling method, we investigated disturbance effects of roads on AGB and related attributes in Xishuangbanna, China. We surveyed woody plants in natural forests, rubber plantations, and tea plantations up to 100 m from the edge of three different road widths and estimated AGB using allometric equations at 10 m intervals. Two sample t-test results confirmed that natural forests stored more AGB than rubber and tea plantations, and less AGB at edges of wider road than at edges of narrower road. Linear mixed effects models revealed that land use, road width, and distance from edge significantly explained 68% (both fixed and random factors) variation in AGB. We observed two results that indicated wider roads altered more AGB than narrower road types in natural forests. First, AGB declined at road edges; second, the disturbance effects on AGB by wider road types went deeper than narrower roads did in natural forests. Our results suggest that both widening the existing roads and construction of new roads will degrade ecosystem productivity. We recommend that impacts assessments of roads on AGB should be considered and taken serious while planning and designing roads to avoid serious damages to many ecosystem services that AGB provides.