Pine Nut Tree

Stone pine (Pinus pinea L.) is a coniferous tree species belonging to the Pinaceae family, distributed across the Mediterranean climatic zone and valued for its high economic and ecological importance. Its Latin species name, pinea, means “female,” referring to its large and conspicuous female cones.

Stone pine naturally occurs across the Mediterranean basin, ranging from Portugal to Anatolia. In Türkiye, it is found locally or widely in the provinces of Artvin, Trabzon, Bartın, Bursa, İzmir, Aydın, Muğla, Antalya, and Kahramanmaraş. It grows naturally in areas under the influence of the Mediterranean climate, up to 600 meters above sea level. The species can extend up to 70 kilometers inland from the coast and has been recorded at elevations up to 860 meters.

Stone pine is a long-lived tree reaching heights of 25–30 meters and diameters of up to 1.5 meters. Its crown has a parasol-like, broad, and dome-shaped structure. The trunk is straight and covered with thick, reddish-gray bark. Shoots vary from yellowish-brown to grayish-brown and are glabrous. Its resin-free buds measure 6–12 mm in length. Needles are arranged in pairs, each 8–16 cm long, thick, slightly curved, and toothed along the margins. Leaves remain alive for 2–4 years and bear numerous stomata on both surfaces. Cones are 8–15 cm long, spherical in shape, and short-stalked. Each cone contains 50–100 large seeds. Cones mature over 2–3 years and open upon maturity to release their seeds. Seeds are typically 1.5–2 cm long and possess a small wing remnant. The seed surface is covered with a dark purplish powder. Locally, these seeds are known as “pine nut.”

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The stone pine is primarily cultivated for its edible oily seeds, with timber being a secondary product. Pine nuts are used in a variety of food products such as stuffed dishes, pilaf, desserts, and halva. They are also utilized in various industrial sectors due to their medicinal and nutritional value. Although more than twenty species of pine produce edible nuts, Pinus pinea is the principal commercial species in this regard.

The stone pine is notable for its resilience to dry conditions and poor soils. Thanks to its deep root system, it is highly drought-tolerant and thus plays a significant role in erosion control, desertification mitigation, and reforestation efforts. In southeastern regions of Türkiye, successful stone pine plantations have been established in areas prone to desertification.

A low correlation has been observed between annual diameter growth and nut yield. However, a high correlation has been identified between nut yield and precipitation and humidity levels during the vegetation periods of one and two years prior (R² ≈ 0.79–0.81). This indicates that environmental factors indirectly influence the species’ productivity. Both the quantity and timing of rainfall are decisive for yield.

Stone pine production is a labor-intensive and multi-stage process. Cones, which reach several meters in height, are collected using traditional methods or specialized harvesting machinery. The nuts are then extracted from the cones, their shells are cracked, and the product is marketed. Harvesting methods include traditional poles (keye), platform plus pole systems, and mechanical branch shakers. In Türkiye, pine nut production is concentrated primarily in forested areas of İzmir, Balıkesir, Bursa, Adana, and Muğla. According to the General Directorate of Forestry’s inventory, a usable nut stock of 27,880 tons exists across 84,809 hectares. Production in 2022 reached 1,141 tons, of which 85 percent was exported. Based on the average of the last three years, annual nut exports of 565 tons generate approximately 33 million US dollars in foreign exchange revenue.

Stone pine harvesting is carried out using traditional methods, and those who perform this work are known as “pine nut harvesters.” This profession relies on local knowledge and practices passed down through generations; however, the number of practitioners has been declining over time. Due to the limited use of personal protective equipment, the risk of occupational accidents is high. The species is now included under forestry standards for “non-timber product collection.” It has been emphasized that, within a lifelong learning framework, the preservation of the traditional harvesting profession and support for its professional development are essential.