What’s a tree like you doing in a place like this? Or West meets East

By Dr. Dario Martin-Benito

In the northeastern part of Turkey, the highest Pontic Mountains meet the Black Sea. Here altitude drops from more than 3900m to sea level in a less than 30 miles. Both the orographic effect of mountains and the lake effect (well, better sea effect) cause very high precipitation, allowing for rich and productive temperate forest to grow. Snow accumulations of several meters are not rare even at mid elevations as we could observe in a trip a couple of weeks ago. Despite the warm weather we experienced, some roads were still blocked from last winter’s snow, so access to many places was still not possible.

This temperate rainforest is very rich in tree species, including mainly broadleaved species (oaks, beech, maples), but also many conifers such as fir, spruce and pines. Coming from Western Europe, where forests have been logged, managed or mismanaged for hundreds of years, a forest with more than six or seven dominant tree species is a biodiversity hotspot to me. For those used to the forests in the American east or the tropics these forests might seem species-depauperate. But they shouldn’t.

Turkey lies at the crossroads between Asia and Europe. The enchanting city of Istanbul, with its amazing culture and long history as a bridge uniting the East and the West, symbolizes this better than any other place. Actually, Istanbul is the only big city in the world that lies on the border of two different continents. The diversity of the Turkish forests also reflects many species migrations over hundreds of thousands of years and might have served as a glacial refuge for many plant species during the last glacial maximum around 16,000 to 60,000 years ago. This way Turkish flora has evolved to be one of the richest floras in Europe or Asia by having components from both continents.

The wet northeastern Turkey also offers some very interesting flora surprises, like the unique umbrella pine (Pinus pinea) growing on a steep slope near the city of Artvin. Umbrella pine receives its common name because, well, it looks a bit like an umbrella: Its crown grows round when the tree matures and it is almost completely free of lower branches. The fact that it is also called Italian Stone pine (it was a main character in Vittorio de Sica’s film “Villa Borghese,” known in English as “It happened in the Park”) gives an idea of its distribution range. We can find it all along the Mediterranean and the Iberian Peninsula on the western side comprises more than 75% of its distribution area. But the Artvin forest is very far from the Mediterranean coast and more than 1000 km away from the closest umbrella pine forest.

The same processes that create high precipitation near the Black Sea coast are responsible for a rain shadow effect further south, as high mountains block precipitation, creating much drier conditions in some valley bottoms. In a matter of less than 32 kilometers precipitation drops from more than 2000mm per year to less than 700mm. That’s like going from Scotland to Rome in less than half an hour’s drive.

Along its broad distribution range, umbrella pine grows together with many different species of the Mediterranean flora, like evergreen oaks, colorful rockroses, or scented herbs like rosemary or oregano. But in this relict forest at 600m of elevation, on the banks of the Çoruh River near the Kaçkas Mountains, umbrella pine has some non-habitual neighbors like Scots pine, hornbeams or hazel, more common in the wetter and colder climates that abound in the surrounding forest as we climbed in great elevation not far from here. The view of these forests reminded me of some deep valleys in Northern Spain, where a similar combination of lake effect and rain shadow creates Mediterranean vegetation dominated by the evergreen holm and cork oaks on southeast facing slopes, while north-facing slopes are covered by beech and deciduous oaks.

Humans have favored umbrella pine for thousands of years for its delicious seeds, which are eaten in many different forms but mainly used for some of the best pastries. Still today, pine nuts are the most valuable product of these pine forests in countries like Spain and Portugal, where they are commercially harvested. So these trees were extensively planted within and outside their natural distribution range probably as early as Roman times. In general, people have been great natural vectors of many tree species, mainly agricultural crops or related trees. Take for example the English Elm, which turned out to be, again, a very Roman clone. The history of the Old World complicates the attribution of whether some of its forests are natural or not. Northeastern Turkey has a centuries-long history as a frontier land, first between the Byzantines and the Turks and later between the Ottoman and the Russian empires. The Artvin Province changed hands several time as late as the early 20^th century. Long before that, the southern Black Sea coast was explored by Greek and Phoenician sailors, and Arrian wrote his Periplus Ponti Euxini, a sort of maritime guide describing these coasts. Even in Greek mythology, Jason is thought to have visited the area with the Argonauts in his quest for Colchis (present day Georgia).

Despite the long history of human settlement and land use in these regions, probably some of the few old growth temperate forests left are found here, like the Camili Biosphere reserve. But still, little is known about the ecology and dynamics of these forests. We hope that our research in this area will allow us to add some very interesting new perspectives on the ecology and history of both the broadleaved temperate rain forest and this relict pine stand.

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Note: The origin of this stand is unknown. Some say it is a natural stand while others think it was planted by Russians in the late-1800s. Our coring of these trees might or might not solve this question.