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ŠUMARSKI LIST 5-6/2013 str. 29     <-- 29 -->        PDF

reasons of ramet number variations (Kang et al. 2001a). It is generally known that actual seed orchards have often different numbers of ramets per clone. Both variation of ramet number per clones and fertility variation cause unequal gamete contributions in the orchards (Muona and Harju 1989, Kang et al. 2001b).
The aims of this study were (1) to estimate the effective clone numbers for seed orchards in each of the conifer species in Turkey, (2) to discuss the causes and implications of the variation in ramet number among the seed orchards, (3) to determine the relationship between effective clone number and gene diversity. It is expected that the results from this study will contribute establishment and management of present and future seed orchards.
Material and methods
Materijal i metode
Tree breeding studies were started in 1964 in Turkey. The National Tree Breeding and Seed Production Program (NTBSP) were implemented in 1994 (Koski and Antola 1993). Pinus brutia Ten., P. nigra Arnold, P. sylvestris L., Cedrus libani A. Richard and Fagus orientalis Lipsky were determined as target species. In different regions of Turkey, 172 seed orchards of seven major timber conifer species (P. brutia, P. nigra, P. sylvestris, P. pinea L., P. halepensis Mill., Picea orientalis (L.) Link. and C. libani) were established by Turkish Ministry of Forestry and Water Works, Forest Tree Seeds and Tree Breeding Research Directorate by 2011 (OATIAM 2011). Currently 159 Gene Conservation Forests for conifers have been set aside with about 25198.4 ha land area, by the Turkish Forest Tree Seeds and Tree Breeding Research Directorate for the conifer species in the country. In this study, variation in ramet number among clones in all clonal seed orchards of conifers in Turkey was estimated. The number of ramets per clone for the studied seed orchards was checked after establishment to determine whether thinning occurred or not.
Average number of ramets per orchards, average coefficient of variation for ramets in orchards (C.V%), average census number of clones in orchards (N), average effective number of clones based on variation in the number of ramets (Nc) and the relative effective number of clones (Nr) were calculated for all seed orchards according to Kang et al. 2001b. The effective number of clones, Nc, was calculated based on the variation of ramet numbers among clones;
               
where ntotal is the total number of ramets in the seed orchard; ni is the number of ramets of clone i; and N is the census number of clones in the seed orchard (Kang et al. 2001b).
The relative effective number of clones (Nr) was used to compare the census number (N) and the effective number of clones (Nc) in the seed orchards. Relationships between Nc and N and, between Nc and age of orchards were determined using Pearson’s correlation coefficient (r). The Nc in an orchard is equivalent to the status number of the seed orchard when clones are non-inbred and unrelated (Lindgren and Mullin 1998, Kang et al. 2001b). The estimated proportional gene diversity (GD = 1–1/2Nc) for all seed orchards were calculated according to Kang et al. (2001b).
Results
Rezultati
When all the seed orchards of conifers are considered, the clone number ranged from 8 [P. sylvestris seed orchard, National code (ND) 136] to 152 (P. sylvestris seed orchard, ND 160). Most of the seed orchards were established with about 30 clones. Large differences for total living number of ramets among orchards and number of ramets per clone were observed. The minimum ramet number was observed in a P. nigra seed orchard (ND 41), having 75 ramets from 10 clones on total of 0.2 ha area. The maximum ramet number was observed also in P. nigra seed orchard (ND 80 and 140) having 3225 ramets from 30 clone on 20.6 ha area. The average seed orchard size was 6.46 ha (ranging from 3.46 to 11.72 ha). The average number of ramets per orchards was 1141.6 (Table 1). Spacing between ramets in the seed orchards varies between 4x4 m and 10x10 m, most being 8x8 m spacing.
Pinus brutia: There were 64 seed orchards. The number of clones ranged from 10 (ND 22) to 146 (ND 155). The number of ramets in the seed orchards ranged from 229 (ND 33) to 2790 (ND 38). The smallest seed orchard (ND 2) was 1.0 ha in size whereas the largest one (ND 16) was 18.6 ha. The ages of seed orchards were between 7 and 36 years. Spacing between ramets in most seed orchards were 8x8 m (smallest 5x5 m, largest 10x10 m).
Pinus nigra: There were 56 seed orchards. The number of clones ranged from 10 (ND 41) to 120 (167). The number of ramets in the seed orchards ranged from 75 (ND 41) to 3225 (ND 80 and 140). The smallest seed orchard (ND 41) was 0.2 ha in size whereas the largest one (ND 73) was 20.7 ha. The ages of seed orchards were between 2 and 48 years. Spacing between ramets in most seed orchards were 8x8 m (smallest 4x4 m, largest 8x8 m).
Pinus sylvestris: There were 21 seed orchards. The number of clones ranged from 8 (ND 136) to 152 (ND 160). The number of ramets in the seed orchards ranged from 94 (ND 87) to 2287 (ND 178). The smallest seed orchard (ND 87) was 0.2 ha in size whereas the largest one (ND 160) was 9.9 ha. The ages of seed orchards were between 8 and 48 years. Spacing between ramets ranged between 5x5 m and 7x7 m.