Four teams of staff from UPM Tilhill will carry out the work in the first contract the firm has undertaken in Network Rail's London North Eastern north-east area.
The work, which includes felling dead, dying and diseased trees, extends along 32km of the York Malton Scarborough line and 19km of the line south of York to Fairburn.
Following the award of the contract to UPM Tilhill's Yorkshire District, the firm has promoted Guy Strickett to rail contracts manager from his role as rail supervisor in the Wessex district office. Strickett is joined by David Garstang as rail supervisor to oversee the work and manage the four contract teams.
District manager Simon Rochester said the team was determined to maintain high standards: "Our priority will be first-class maintenance of the lineside environment."
The contract also includes vegetation clearance and maintenance of the flail strip each side of the track, as well as keeping signals and level crossings clear. The rail team consulted with Natural England and Defra on sections passing through conservation areas.