ЗБЕРЕЖЕННЯ ГЕНОФОНДУ СТАРОВІКОВИХ ДЕРЕВ ДУБА ЗВИЧАЙНОГО В УМОВАХ EX SITU

Анотація

EX SITU CONSERVATION

OF ENGLISH OAK OLD-GROWTH TREES GENE POOL

Los S.A.

Ukrainian Research Institute of Forestry and Forest Melioration named after G.M. Vysotsky

Old-growth trees have great cultural, historical and ecological value. They provide continuity of sustainable development in a changing world and often associated with historical events or personalities, form the habitat of fungi, invertebrates, lichens, birds and animals. In many countries old-growth trees are taken under public protection. On the other hand, old-growth trees that have survived in good condition, despite the impact of unfavorable environmental factors for a significant number of years, represent a valuable genotypes and deserve attention in terms of forest breeding and preservation of the gene pool.

Selection of plus and best trees were started in Ukraine in the 50s of last century, under the leadership of S. S. Pyatnytskyi. In some forestries outstanding old-growth trees were involved in selection. Thus, in 1957 during selection of plus and best oak trees and harvesting of their acorns for the progeny test 14 outstanding trees aged 200 - 400 years were included. In particular, 9 of them were selected by N.I. Davidova in 74 - 83 forest plots of Merchansky forestry of Jovtnevy forest enterprise of Kharkiv region. Another five such trees aged 180 - 300 years were selected by V.V. Gursky on the territory of forest plot 5 of Neskuchansky forestry of Trostyanets forest enterprise of Sumy region. The plot is on territory of Trostyanetsky park, which has the status of the park-monuments of landscape art of national importance. The trees were growing in groups in younger English oak forest (80-120 years at time of selection). Forest growing conditions – D_2-3, forest types - fresh and wet lime-maple oak forest. In 1958 acorns of these trees were used to create the progeny test in forest plot 98 of Pivdenne forestry of Danylivska Experimental enterprise (now - Kharkiv Forest Research Station). As a control acorns from total harvest of forestry were sown.

Objective: to analyze the features of growth and development of progenies of old growth oak trees in the progeny test and their clones in clonal seed orchard and evaluate the possibility of such trees gene pool ex situ conservation and perspectives of their use in breeding research.

Material and methods.  The research were carried out in the progeny test in forestry plot 98 of Pivdenne forestry of Danylivska Experimental enterprise, created in 1958 by N.I.Davidova under the supervision of S. S. Pyatnytskyi. Forest growing conditions – D _2-3. During their creation acorns from 313 best trees oak, selected in 6 regions of Ukraine (Kharkiv, Sumy, Donetsk, Mykolaiv, Poltava and Vinnytsia) were used, and among them 14 are aged 180 - 400 years. During studies of growth and development of progenies in the test plantations for each tree  the folowing indices were determined; height, stem diameter at a height of 1.3 m, stem straightness, condition, presence of defects and damage. Data was processed by variation statistics methods using the software package MS Excel. Average arithmetic indexes of options were compared with each other and with the control. The significance of differences was determined by t-test.

Another object of the research was clonal seed orchard (CSO) of English oak in forest plot 129 of Pivdenne forestry of Danylivska Experimental enterprise, created by N.I.Davidova in 1979 in D2 condition, by planting of seedlings with closed root system. CSO is used for acorns collecting, and for study of growth, phenology, morphology and reproductive of plus trees clones. Among 56 clones of plus and best trees there are two clones of old-growth trees. The diagrams of clone reproduction intensity during 20-year period were constructed. The intensity of flowering and fruiting of clones were determined visually on a six-point scale minimum for three ramets of each clone.

Results and discussion. The trees selected in Neskuchanske forestry were distinguished by outstanding trunk diameters and wide lowered crowns. Branchless part of stem some of them was 3 m height. The trees selected in Merchanske forestry also distinguished by significant values of stem diameter and lowered crown. However, these trees have more narrow crown. At that time criteria for plus trees selection were under development. Under actual criteria selection by phenotype all these trees do not meet the requirements for plus trees. Therefore, in the following years they were excluded from the State Register.

Breeding evaluation of plus trees is determined on the results of their progeny testing. Analyse of growth characteristics of 50-year-old progenies of different ages plus and best trees in the test of the Pivdenne forestry, showed that the progeny of the tree №5 from Octyabrsky forest enterprise grew better than control, and by height - significantly. Among the four trees from Trostyanets origin one essentially exceeded control in both indicators, and two - significantly lag by diameter. The ratio between the best and worst progenies among the progeny of younger trees is similar.

Comparison of average heights and diameters of progenies of 180 - 300 years old trees and younger trees shows slight advantage of old-growth trees progeny. The part of straight among the progeny of younger best trees insignificant higher than from older trees.

Except of growth intensity an important characteristic of plus trees are their reproductive capacity, which is important when used their clones to create of clone seed orchards. Clones of plus trees selected without regard to this indicator, often don’t fruit at CSO for many years. Dynamics of reproduction intensity of old-tree clones M-4 and Tr-2 for the 20-year period shows quite significant fluctuations, due to changes in weather conditions. There were several harvest years (1996, 2005 and 2013).

On the other hand, the graph shows the difference between these clones. Almost throughout the observation period M-4 clone was distinguished by low flowering and fruiting intensity levels, while the clone Tr-2 fruiting intensity was assessed about 3 points or more for this period.

Summarizing the above, it should be noted that old-growth oak trees can be a valuable starting point for forest breeding and seed production. In addition to stability and longevity some of them are characterized by intensive growth and reproduction. So important and actual is the trees gene pool conservation and their involvement in the selection process.

Conclusions. The old-growth trees progeny are characterized by growth and reproduction intensity on level of younger trees progenies. Significant effect of age of plus and the best trees on growth and reproductive development of the progenies was not found. The presence among progenies of old-growth trees of variants with intensive growth indicates on prospect of these trees involvement into selection process, on condition of their progeny testing.  Reproductive capacity of old-growth trees depends on the genotype, and its implementation - on the weather conditions. The trees that have found a sufficient level of fruiting can be used to establish a permanent seed base provided high growth intensity of progeny in test. The old-growth trees gene pool conservation in ex situ conditions, for example in the progeny tests and clone archives, is important and necessary.

 Key words: gene pool ex situ conservation, English oak, old trees, growth, development.