Application of the seed tree regeneration method in Anatolian black pine (Pinus nigra subsp. pallasiana) in Tandir-Eskisehir

The Anatolian Black Pine (Pinus nigra Arnold ssp. pallasiana), one of the main tree species in Turkey, covers about 4.2 ha national forest areas. The mature trees of the species with long height and large diameter have very valuable wood characteristics and have been used for many purposes for centuries in Anatolia. Shelterwood method has generally been preferred in natural regeneration of P. nigra forests. On the other hand, the seed tree regeneration method has been applied for many forest tree species especially in Northern America. The seed tree method is generally suitable light demanding trees with light seed weight. In the current study, the research field of P. nigra is located in Eskisehir-Tandır. The altitude of the study site is 1200-1300 m and the slope is about 5-30%. The total area of the site is 27,9 ha. 14 ha and 13,9 ha of the site have been taken to the natural regeneration operation in 2015 and 2016, respectively. About 17 seed trees/ha are left on the site. Deep soil tillage and site preparation have been applied before the seed dispersal. Additionally, one-year-old P. nigra seedlings were also planted in the site in the spring of 2016 and 2017. Adjacent to study site, stand without silvicultural treatment were also selected to compare with study stands. The seedling survival rate, the direction, distance and number of seedlings originated from the scattered seed; diameter, height, age, increment, volume, bark and crown diameter of remaining trees were measured in the autumn of 2017. The obtained data were evaluated in terms of seed tree natural regeneration method for Anatolian black pine. The applicability of seed tree method for P. nigra was discussed in the scope of literature and the results. The method was compared to classical shelterwood natural regeneration system used in P. nigra forests. The results indicated that the planted seedling survival rate is 80.5%. It was determined that seedlings originated from the scattered seeds were mostly scattered in north direction and between 4th, 5th and 6th meters according to the seed tree. The total number of seedlings originated from the scattered seeds was calculated as 91.540 in 27.9 ha total study area. The seed tree method was partially successful in Anatolian black pine stand at the low-yield capacity Eskisehir-Tandır. The success rate of the seed tree method can be increased by seed supplement. The potential use of the method for the native tree species in Turkey should also be investigated.