DISTRIBUTION, ECOLOGY AND VARIATION OF PINUS BRUTIA IN TURKEY ¹

by

M. Arbez
Station d'Amélioration des Arbres Forestiers
Nancy, France

¹ This condensed version is based on the Author's original mimeographed “Rapport de Mission FAO (29.8–9.10.1971)”. By 31 August 1973 10 Turkish provenances had been collected by the Institute of Forest Tree Seeds and Improvement and were kept in store at the Istituto Sperimentale per la Silvicultura in Florence, Italy. See Forest Genetic Resources Information No.2/1973, pp. 64 (FAO 1973).

1. GENERAL

On the recommendation of the FAO Committee on the Coordination of Mediterranean Forestry Research, a mission was carried out to Turkey in the autumn of 1971. The primary purpose was to visit seed stands of Pinus brutia identified by the Institute of Forest Tree Seeds and Improvement in Ankara. The terms of reference were as follows:

1. to explore both the geographic and the ecological distribution of P. brutia in Turkey;

2. to make observations on the phenotypic variation of the species (growth and form, morphological characteristics of needles and cones);

3. to make proposals for sampling of provenances representative of the natural variation of the species, in accordance with the scope of the anticipated, international provenance trials and practical considerations in seed collection.

During the one-month mission 23 stands of Pinus brutia were visited. Each stand was described (location, ecological conditions, phenotypic characteristics of stand and trees) and measured (height, diameter and mean annual increment of 5 dominant trees). In addition, 25 cone bearing dominants of average or better than average form, standing at least 50 m apart, were chosen and marked for future seed collection.

2. DISTRIBUTION

The natural distribution of P. brutia in Turkey has been described by Selik (1958), Alemdağ (1962), Sefik (1964) and others ².

Four main distribution areas can be recognized, further divided into maritime and continental sub-areas:

1. Black Sea Area: Some small, isolated populations along the coast;

2. Sea of Marmara Area: Small populations south of Bursa, relatively well isolated from the main range of the species. The sites north of Eskişehir are characterized by a pronounced continental climate;

3. Aegean Sea Area: P. brutia occurs almost continuously from Çanakkale to Milâs on the coast and inland as far east as Uşak. The mountain chains run mostly in the direction East/West, which is likely to have favoured the spread of the species into the interior of the country as far as the Anatolian High Plateau;

4. Mediterranean Area: The Taurus mountains (with up to 2500 m high peaks) run parallel to the coastline in its central parts and P. brutia is not found inland beyond the mountains. At the extreme eastern end of the coastal area (Antakya) the species is found on the Ammanos Hills. At the western end the rather high mountain chains meet the coastline at right angles and are separated by valleys. Thanks to this favourable orientation of the mountains P. brutia here extends relatively far inland, especially in the areas of Fethiye, Acipayam and Gölhisar.

2.1 Altitudinal Range

In the northern parts of the natural distribution area (Black Sea, Sea of Marmara) Pinus brutia is found at an altitude of up to 500 m. From 400 m upwards the species generally grows in mixed stands together with Pinus nigra, and above 500 m it is replaced completely by that species. In the Aegean Sea area it grows up to an altitude of 750 m. In the Mediterranean area it occurs commonly at 0 – 1100 m; on south-facing slopes it occurs up to 1200 m and in a few areas (Mersin, Karakoy - Serisi) up to 1400 m. Above 900 m it often grows mixed with Pinus nigra also in this area. In the higher mountainous regions it sometimes grows in mixture with Cedrus libani and Abies cilicica.

Although P. brutia is found on all slopes the best stands generally have a northern exposure.

2.2 Climate

Considerable climatic differences are found within the natural range of P. brutia. (See table 2).

2.3 Soils

P. brutia seems to be tolerant to a vast range of different geological formations.

It is found both on metamorphic rock (often serpentine, more rarely schists) and on sedimentary rock (sometimes on sandstone, but above all on limestone). The main part of the stands grow on limestone, both marl and chalk.

2.4 Vegetation

The vegetation and the number of different species present vary according to the ecological conditions (type and depth of soil, altitude, type of climate, exposure) and density of the stand.

The low coastal sites on siliceous soils or soils deficient in calcium in the top layers are often covered with dense“maquis” which hinders all natural regeneration of the stands. The “maquis” vegetation reaches its optimum on deep soils over serpentine (Antalya - Dürzlercami, Antalya - Kizilağ, Mersin - Findikpinari, notwithstanding the high altitude of this last-mentioned region). The most commonly occurring species are Arbutus andrachne (more rarely A. unedo), Smilax aspera, Styrax officinalis, Phillyrea media, Pistacia lentiscus, Myrtus communis, Cystus sp., Erika sp.

The calcareous sites are occupied by a lower, less dense type of vegetation, characterized by the presence of Quercus coccifera. The high-altitude sites (more than 500 m on southern and 300 m on northern slopes) and the sites with a continental climate are characterized by a scarce, patchy vegetation of a limited number of scattered, mostly woody species. The soil is predominantly covered by old needles, cones, twigs and branches. Grazing is probably partly a cause of this phenomenon. Styrax officinalis is by far the most common species. On calcareous soils Quercus coccifera and Juniperus oxycedrus are often found.

The wide distribution and the variety of ecological conditions in which P. brutia is found indicates the great plasticity and adaptability of the species.

² Selik, M. 1958. Botanical Investigations on Pinus brutia especially in Comparison with P. halepensis. Istanbul Üniv. Orm. Fak. Derg. 8A(2), pp. 161–198.
Alemdağ, S. 1962. Development, Yield and Management Rules of Red Pine (Pinus brutia) Forests in Turkey. Orm. Araşt. Enst. Tek. Bült. No. 11, pp. viii-160.
Sefik, Y. 1964. Studies on the Cone and Seed of Pinus brutia. Istanbul Üniv. Orm. Fak. Derg. 14A(2), pp. 35–70.

3. TYPES OF FOREST AND NATURAL VARIATION

3.1 Types of Forest

Pinus brutia occurs in Turkey mostly in rather even, pure stands which are often used for grazing. In the north and at higher altitudes the species sometimes forms mixed stands with Pinus nigra. The most continental stands (Cuşak, Suçati) are rather open and irregular.

The height of the trees seen varied between 13 m (Uşak - Hopus) and 29 m (Mersin - Findikpinar). The best stands are mostly found in the Mediterranean area at medium altitudes of 500 – 800 m, on slopes with a northern exposure. In the same area, especially at lower altitudes, natural regeneration on burnt-over areas is abundant. Otherwise natural regeneration is generally scarce (except on alluvial terraces) because of dense “maquis”, grazing or lack of appropriate silvicultural measures (the mature stands are often too dense). This situation may be disconcerting from the point of view of conservation of genetic resources.

3.2 Natural Variation

Most of the stands visited were stands selected for seed collection, thus they were phenotypically superior to the average of local stands. They were growing in varying site conditions throughout the natural distribution. They thus provide a good sample for preliminary investigations on the variation of the species.

3.2.1 Stem Form and Branch Characteristics

The stands on the Aegean Sea are generally of poor form, with sinuous stems and coarse branches. This can be seen particularly clearly at Ayvacik - Beskidağ on the mountain ridges west of Kaz dagi (Mount Ida) and in the stands between Izmir and Kuşadasi.

Not until Mîlas at the extreme south of the Aegean coast, is there a marked improvement in stem form, but the characteristic of coarse branches still prevails. At lower altitudes in the Mediterranean area the crowns are denser. The stands south east of Bursa have an acceptable stem form. The inland stands (Uşak - Hopus) are rather open and of bad form.

The best stands are found in the Mediterranean area. The variation seems to be a function of altitude. Thus it is possible to distinguish between:

1. Low altitude coastal provenances of relatively poor form: stem crooked to fairly straight, branches coarse and long, branch angle rather acute, crown rather wide and thin. The greatest part of the populations between Marmaris and Antalya are of poor form which seems to improve going west from Gazipasa. Coastal provenances of good form are rare. The provenance at Gelibolu deserves a special mention: the trees have a straight stem, relatively fine, long branches at a right angle and good self-pruning ability. The form of the trees is also good at Antakya - Kizildağ (straight stem, relatively fine branches), but only fair at Silifke - Sehitlar (straight stem but coarse, acute-angled branches, bad self-pruning ability, strong taper);

2. Provenances at medium altitudes (500–900 m) of excellent form: straight stem, generally fine, rather short branches with wide branch angles and a more or less narrow, conical, rather dense crown.

Notwithstanding the large areas concerned the characteristics in form seem to vary only little along the Mediterranean coast.

Large, almost continuous, forest areas are found in the areas of Bucak and Pos. Narrow-crowned trees can be found in these regions but they are more frequent in the stands around Gündoğmus, especially at Eskibağ and Güzelbağ. This remote region around Taurus is characterized by broken topography and narrow valleys. Thus some degree of isolation and genetic differentiation may be present.

At Eskibağ (Tespihli Sérisi, 950 m) the population can probably be considered a distinct ecotype with very narrow crowns. Some hundred metres form this stand there is a stand of Pinus nigra which is amazingly similar in form. This seems to indicate that form is a characteristic associated with altitude.

At Güzelbağ (Bayir Serisi, 700 m) the crowns are still narrow, but it looks as if differentiation had occurred at higher altitudes and that the populations later migrated downwards. The same theory seems to be valid for the Anamur - Bakara population, where the stands resemble high-altitude stands (straight stem, good self-pruning ability, apparently knot-free wood, rather narrow crown and fine, short branches) although they are growing at only about 300 m, close to the Mediterranean coast, with a cool micro-climate and high in humidity, caused by a river running through the valley.

Although the influence of the genotype should be recognized, one should also attach importance to environmental factors. At Mersin - Fundikpinari (800 m) the bad stem form of the trees in some parts of the population, which is not a general characteristic of this area, is probably caused by the environment: the coarse branches could be caused by excessive soil fertility, persistence of dead branches by high humidity of the air and forking by Evetria attack.

Two populations visited in the interior of the Mediterranean area (Maras - Suçati, Gölhisar - Evciler) are growing in very difficult conditions: shallow soil and continental climate (low winter temperatures and low rainfall). The trees in these stands are relatively short, the stands are open and the self-pruning ability of the trees is rather poor. However, the other morphological characteristics, especially straightness of stem, are as good as in stands growing at medium altitudes, in optimum conditions (Maras - Suçati: fine branches, conical and relatively narrow crown; Gölhisan - Evciler: medium-sized branches, apparently wider crown). Thus it seems as if the very satisfactory form of the Mediterranean medium-altitude populations is under rather rigid genetic control.

The relatively isolated populations in the north-east (Black Sea Coast, Yesilirmak Valley) merit special mention. Only one stand was visited (Bafra - Camgolü). It is a good, dense stand with vigorous trees of relatively good form: slender, somewhat sinuous stems, many long coarse branches with a wide branch angle and a wide, rather dense crown. The persistence of dead branches is probably due to high humidity of the air. The general look of the trees in this area resembles that of Pinus pithyusa (U.S.S.R., northern coast of the Black Sea).

Another comparison which may be made is that between the generally indifferent form of the Turkish Aegean area and the stands Rhodos and Thassos. The question arises whether the beautiful stands on the Isle of Crete (700 – 1200 m) are in actual fact of the same origin as those at Taurus?

3.2.2 Growth

Growth is very much affected by site, thus it is difficult to estimate the genetic component of this characteristic. Also, because of the small number of trees measured in each stand (5 dominants), the figures presented in Table 3 cannot be considered very reliable. As can be seen the mean width of the annual rings between the age of 20 and 50 years is between 1.7 and 3.4 mm. Growth is generally most vigorous when the trees are between 20 and 30 years of age. It should also be noted that although the trees in the marginal populations in the inland areas (Uşak - Hopus, Gölhisar - Koças, Maras - Sucati) are lower in height growth, they do not exhibit a very much smaller diameter growth than the trees in the populations growing in optimum ecological conditions at medium elevation. The best diameter growth was found in the low altitude occurrences in Bafra - Çamgolü (3.4 mm) and Marmaris (3.0 mm). In the eastern parts of the Mediterranean area certain stands growing at medium altitude have a big diameter growth, comparable to the low altitude stands in the same region (this is especially true for the stands at Mersin - Findikpinari, 2.7 mm, and Pos - Başpinar, 2.5 mm).

4. SEED COLLECTION FOR PROVENANCE RESEARCH

The following (in some cases contradictory) requirements should be met:

1. the collections should be representative of the natural variation;

2. the collections should form a good base population for further improvement, thus high priority should be given to phenotypically desirable stands;

3. the seed samples should only be big enough to meet the needs of research plots, in order to minimize costs.

In view of the above 16 populations were proposed for inclusion in the provenance collections: 3 from the Aegean Sea area, 10 from the Mediterranean area (of which 4 from low altitude stands), 1 from the Black Sea area and 2 from the inland occurrences (see Table 1). These are thought to cover satisfactorily the phenotypic variability of the species (both good and less satisfactory stands). Several provenances are from low altitudes as Pinus brutia will probably be important as a reforestation species mainly at low altitudes. The Aegean Sea area is purposely underrepresented as compared to the Mediterranean area as the stands there are less variable and of relatively poor form. No provenance has been included from the Sea of Marmara area, since the populations there appear very similar to that at Sindirgi - Seydan. Two provenances (Bucak - Melli and Silifke - Şehitler) are proposed as standards in the provenance trials.

Twenty-five representative trees in each stand were marked for seed collection. The trees selected are somewhat better than average in form. They have a well-developed crown and had at the time of selection a relatively good cone crop for collection in the spring of 1972. In general a minimum spacing of 50 m between seed trees was allowed.

The collections should be done in good seed years to ensure that the seed collected from the 25 seed trees is broadly representative of the stand in which they are situated. P. brutia flowers every years, with higher than average seed years about every third year. The development of the cones takes 3 years. The cones stay on the tree for several years after maturation of the seed.

Seed collection of P. brutia in Turkey is traditionally carried out in May, except for in the inland and in the Black Sea area where it is done somewhat later (May/June). As the seeds probably mature in March, and as there is a possibility to allow for post-maturation in the cone, the collections could be stretched over the period April – June.

Thirty to fifty cones per tree (= 1000 cones per provenance) should be collected. With a germination percent of 70, this would yield 53 000 seedlings per provenance, covering the needs of the international provenance trials. In some areas it will be desirable to collect additional seed for the use of the Turkish Forest Service.

Simultaneously with the provenance trials experiments should be established to estimate heritabilities and genetic correlations of the species. This work should start with one low-altitude provenance (Marmaris - Gelibolu) and one medium altitude provenance (Bucak - Melli). Single-tree collections with seed from each tree kept separately should be made for this purpose.

Table 1 - STANDS VISITED

The number in column 1 refers to the distribution map on p. 33
The number in parenthesis in columns 10 and 11 indicates number of trees measured
Provenances suggested to be included in the forthcoming provenance trials are marked with an asterisk (*)

Table 2 - CLIMATIC DATA
(data supplied by the Meteorologic Service of Turkey)

Table 3 - WIDTH OF ANNUAL RINGS BETWEEN AGE 20 AND 50

Mean = mean width (figure in parentheses indicates the number of trees sampled)
m and M = minimum and maximum of the individual trees (width of annual rings)

Map 1 - WESTERN AND CENTRAL TURKEY

Map 2. DISTRIBUTION OF PINUS BRUTIA IN TURKEY¹

¹ Shaded areas indicate distribution of Pinus brutia in Turkey;
Numbers (1–23) indicate stands mentioned in table 1, p.