Elizabeth and I are in Montesinho, a small village in the mountains of northeastern Portugal. The village is surrounded by Montesinho Natural Park, a rural landscape of pastures, farms, oak forests, and heath-cloaked hills. The park lacks any untouched wilderness — its land has been used and manipulated by humans for centuries — but it still supports much of the biological diversity of wilderness, including several packs of wolves. How could this be? Doesn’t biodiversity always decrease when wilderness gets altered? I would find out on today’s hike.
To start our hike, we just followed a cobblestone street out of the village until it turned into a dirt track. It was 10:30 in the morning and cool with a bright sun and a strong breeze: perfect weather for hiking. The elevation of the village was 3,300 feet, and we would be hiking a loop to the barragem da Serra Serrada, a small reservoir at an elevation of 4,100 feet.
We walked through plantations of chestnut trees (Castanea sativa) near the village and then a natural forest of Pyrenean oaks (Quercus pyrenaica) farther out. The latter, with deeply-lobed deciduous leaves, reminded me of California’s valley oaks (Quercus lobata) in both habitat and form. It was spring in the mountains, and the tree leaves were still pale and young, and shook in the steady breeze.
We left the forested valley and entered a landscape of round, fuzzy hills covered in shoulder-high shrubs. The shrubs were all blooming, painting the hillsides with patches of yellow (probably Cytisus scoparius or C. striatus), white (Cytisus multiflorus), and violet (Erica sp.). The scene was as pretty as any display of spring wildflowers or autumn foliage I’d seen. The huge granite boulders piled on top of the ridges added a nice touch of contrast. This was a heath, an ecological community associated with the hills of the British Isles, but which also grows in the highlands near the Atlantic coasts of Spain, France, and Portugal.
The shrubs were occasionally broken by soft green meadows. Their borders were oddly rectangular and seemed to follow the contours of the terrain. They looked natural, but were they man-made? As I would later find out, they were.
The meadows were actually lameiros, an ancient method of terrace-building that creates pastures on otherwise inhospitable terrain. In the valleys, lameiros are irrigated year-round by weirs and an intricate system of channels, but here in the uplands, they are simply irrigated by rain and snow. Because they are colonized by native plants, they don’t need pesticides, and because they are fertilized by the manure of the animals that graze them, they don’t need fertilizer.
But as Portugal’s economy improves and its countryside is depopulated by emigration to cities, the lameiros are being abandoned. Their maintenance requires a substantial amount of work; without it, they are drying up and being invaded by generalist bird and plant species. The distinct plants and animals they once supported are disappearing: the landscape is becoming more uniform, and biodiversity is decreasing.
This should give us pause. It’s common knowledge that the conversion of wild land — into a city or farm, say — decreases biodiversity. But here in the heath, the creation of lameiros has done the opposite. The same phenomenon is occurring in the highlands of Mexico, where the return of forests to abandoned fields has decreased biodiversity. The idea that wilderness supports more biodiversity than human-modified landscapes is often used to argue for its creation and protection; but it should be used carefully, because it is not always true.
We reached the highpoint of the loop, the barragem da Serra Serrada, a small reservoir of clear, deep-blue water. We stopped for lunch, then hiked down.
Below us was the village of Montesinho, nestled in a valley surrounded by a patchwork of native heaths and forests, chestnut and pine plantations, and lameiros. The landscape wasn’t pristine and wild like those I usually write about, but the patchwork of small, lightly tended agricultural lands harbored a greater diversity of native plant and animal life than would an untouched wilderness.
Here’s a map of the Porto Furado hike.