Martha’s Vineyard is disappearing. The south shore retreats three to five feet a year, swallowed up by swelling seas, and questions of development on the island abound. In his new book “A Meeting of Land and Sea: Nature and the Future of Martha’s Vineyard’’ (Yale), Harvard biology faculty member David R. Foster offers a deeply researched, thorough, and hopeful examination of how the island has been shaped by man and nature over time — and how we might best think about preserving it. The handsome volume is full of useful maps and charts and has striking photographs of the island. “The land that this volume explores is that of Vineyarders who live and work to make the Island a thriving and solidly real place, day by day, summer after summer, and through . . . delightfully varying winters,” he writes.