Measure the diameter of the tree at 4 1/2 feet from the ground. Valuable black walnut trees have a diameter of at least 19 inches and a 60-inch circumference. Call the local county extension office to get names of certified arborists and foresters who give on-site appraisals and removal estimates.
Ask a certified arborist or forester for his assessment of the walnut tree's value and recommendations of potential clients. Balance the cost to remove the tree with the value of the wood it contains. A black walnut tree needs nine feet of clear straight trunk with no defects to qualify as veneer grade.
Create a listing that includes a photograph and information from the arborist's estimate. Advertise and promote the listing to local wood workers, craftsmen, artisans and furniture makers using on-line resources.