|Azure-winged Magpie (John Hawkins)|
|Winter dehesa (Martin Kelsey)|
Looking at the distribution map of the dehesa landscape, it matches almost exactly the well defined limits of the Azure-winged Magpie too. This is a species closely associated with this evergreen oak habitat and highly sedentary, abundant within its range and wholly absent beyond. And remarkable too in its bizarre disjunct global distribution, with the dehesa-linked pocket in the Iberian peninsula and then reappearing only again in the Asian Far East. DNA evidence shows that prior to glaciation the two populations were linked and over that the subsequent millenia genetic drift has pushed them into what many authorities now consider are separate species - making the Iberian Magpie a dehesa endemic.
My thoughts moved to this landscape on hearing the news this month of the death of Oliver Rackham (see the Guardian oliver-rackham obituary). I remember as a student being spellbound at a lecture he gave on ancient woodlands, his elegant interpretation of the living history of a tree and the intimacy between woodland and people. I took a group of students a few years ago to see the magnificent sweet chestnut tree near the town of Castañar del Ibor, which is estimated to be over 700 years old. I asked each of the 20 students to collect 35 sweet chestnuts from the ground and we placed them in a long line, all 700 of them, making the lifetime of this tree. At points along the file we could make landmarks in human history, and took with us the thought that if that tree's ancestors were as long-lived, its grandparents could have been growing in Roman times. But as well as ancient woodlands, Oliver Rackham studied the ecological history of the Mediterranean and visited Extremadura for this work. His book (co-authored with A.T. Grove) The Nature of Mediterranean Europe (2001) remains a constant reference source for me, especially his chapter of the dehesas, where he concludes that the dehesas near Trujillo, in the heart of Extermadura, are probably the historic heartland of this landscape, based on writings stretching back to early medieval times.
|Summer dehesa (Martin Kelsey)|