As with buying or selling a house, you’ll need to know the value of your land to determine the value of your easement and any potential charitable deductions.
Not all appraisers are versed in open land or easements. This database from the American Society of Farm Managers and Rural Appraisers (ASFMRA) lets you search by state to find appraisers with experience appraising rural properties.
This article is general to property appraisal, but its recommendations are good advice for what to look for and what to ask potential appraisers before hiring them.