CPV code 77211500 designates Tree-maintenance services in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
77211500 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 77211000 (Services incidental to logging).