Technical guidelines for genetic conservation and use Scots pine Pinus sylvestris

Csaba Mátyás1, Lennart Ackzell2 and C.J.A. Samuel3 1 University of West Hungary, Faculty of Forestry, Sopron, Hungary 2 National Board of Forestry, Jönköping, Sweden EUFORGEN 3 Forest Research, Northern Research Station, Roslin, Midlothian, United Kingdom

These Technical Guidelines are intended to assist those who cherish the valuable Scots pine, genepool and its inheritance, through conserving valuable seed sources or use in practical forestry. The focus is on conserving the genetic diversity of the species at the European scale. The recommendations provided in this module should be regarded as a commonly agreed basis to be complemented and further developed in local, national or regional conditions. The Guidelines are based on the available knowledge of the species and on widely accepted methods for the conservation of forest genetic resources.

Biology and ecology

Scots pine (Pinus sylvestris L.) is a pioneer species that readily regenerates after major natural or human disturbances, if weed competition and grazing pres- sure are low. Natural stands are often pure and fairly even-aged. The species grows predominant- ly on poorer, sandy soils, rocky outcrops, peat bogs or close to the forest limit. On fertile sites, Scots pine is outcompeted by other—usually spruce or broad-leaved—tree species. The species is wind-pollinated and has both male and female flowers on the same tree. Flower- ing is frequent; female flowering starts at the age of 15 years on solitary trees (on grafts, as early as 6–8 years) or 25–30 years in closed stands. Abundant male flowering appears some years later. Mast years are relatively frequent but at the boreal forest limit seed maturation is impeded by the short growing season; mast years may occur as seldom as once or twice in 100 years. Pinusnus sylvestrisScots pinePinus sylvestrissylvestrisScots pinePinus sylvestrisScots pinePinus Pin sylvestrisSc

Distribution Genetic knowledge conditions in the vegetation peri- od. Northern and continental populations need less heat sum Scots pine has a wide distribu- Taxonomic status and to complete phenophases and tion across the whole Eurasian hybridization reach hardiness. Southern and continent, ranging in latitude There have been numerous coastal provenances have longer from 37°N to 70°20’N. At the attempts to subdivide the vegetation cycles and are less boreal forest limit it survives with immense distribution area into hardy. Intensive geneflow also less than 100 frost-free days/yr various subspecies, which maintains high within-population and 300 mm annual rainfall. are rather unconvincing diversity in both adaptive and Towards the steppe plains of owing to the lack of any neutral traits. Central Asia its occurrence is clear discontinuities in the Stem form, crown form limited by the length of the contiguous range. Isolated and branchiness show drought period. In southern southern occurrences, great variability within the Europe and Asia Minor, isolated regarded as glacial relics, area of distribution. Only the occurrences are confined to the were occasionally described provenances of northern montane zone (up to 2200 m in as separate species, such as P. Europe/Siberia and those from altitude in the Balkans and hamata (Stev.) Sosn., P. armena higher elevations are straight- Spain, and 2700 m in the Cau- Koch and P. sosnowskyi Nakai stemmed with an ideal conic casus). for the Caucasus region. crown form and fine branches. Under natural conditions Certain regional populations (e.g. Importance and use Scots pine is not readily inter- southeastern Baltic coast popu- fertile with other pine species. lations) show superior growth Spontaneous hybrids with P. traits and high phenotypic stabil- Scots pine is a commercially nigra, P. densiflora and P. mugo ity, while in other areas growth important tree species in Europe. have been reported. Towards and stem form are typically poor, Its wood is easily workable, with other taxa, the species shows a possibly indicating improper sil- good mechanical properties, and robust hybrid incompatibility. vicultural practices in the past has many uses, primarily as con- (e.g. in Germany or in the struction timber and pulpwood. Intraspecific variability Carpathian Basin). Its moderate site demands The high migration potential of In accordance with growth render Scots pine an ideal both pollen and seed results in and stem form, mechanical species for artificial regeneration. effective geneflow with- properties of Scots pine timber Accordingly, its seed has been in the contiguous range, show differences according to traded and used across Europe causing a dis- origin. This also includes the for centuries. Indiscriminate tinct, clinal pat- chemical composition, e.g. the planting from seed of uncon- tern of variation extractive and oleoresin content trolled origin sometimes result- within the species, of wood. ed in blatant quality loss, trig- at least for adaptive Intraspecific variation in gering provenance research traits. This is typically resistance traits has also been well before present-day the case with growth recorded. Resistance to fungal genetic knowledge was and phenology charac- pathogens such as Lophodermi- available. ters, which are determined um spp. is higher in the western, primarily by temperature coastal parts of the range, while nuscots pinePinus sylvestris sylvestrisScots pinePinus sylvestrisScots pinePinus sylvestris PinuScots pinePinu

southeastern forest steppe pop- land, although most sources Threats to ulations are especially suscepti- matched the west-central Euro- genetic diversity ble. Geographic variation in sus- pean grouping, the Italian mito- ceptibility to insect pests has type was present. Overall, The main threats to sur- been proven for a number of molecular studies support the vival lie at the extremes insects; for instance Central existence of three evolutionary of its distribution, in European populations are sus- routes within Europe for Scots particular, the north- ceptible to root collar weevil and pine and the higher variability in western and southwest- pine moths, but more resistant to Spanish populations suggests ern fringes (Scotland and pine shoot borer and pine weevil. that this area may have been an southern Spain). Here the Biochemical and molecular original centre of diversity. distribution of the species studies have clearly indicated has become discontinuous that there is high diversity in and fragmentation into isolat- Scots pine throughout Europe, ed populations is common. with most variation occurring In extreme circumstances, within rather than between popu- this has left several rem- lations. Monoterpenes and nant populations with fewer than isozymes have been used to 100 trees. Regeneration at the group the remnant areas in Scot- boreal forest limit is also prob- land. Both approaches identified lematic. In patches of the distri- one region lying at the extreme bution browsing damage has led northwest of the species’ distri- to a change of species. Mea- bution with distinctive character- sures such as fencing or reduc- istics. These approaches have tion of game populations have been superseded by DNA-based been used to safeguard Scots markers for the chloroplast, pine populations, achieve suc- mitochondrial and nuclear cessful natural regeneration, genomes. increase stocking levels and Variation in mitochondrial expand the areas concerned. In DNA (maternally inherited in a number of instances, the need pines) has indicated that the for grafted seed orchards to sup- three major mitotypes present in ply seed representing individual, Spanish populations encompass highly vulnerable sources has all the variability found in the rest been recognized. of Europe. However, their individ- In the core area of European ual occurrence throughout distribution, where large-scale Europe separated Italian, west- artificial regeneration has taken central European and place for a long time, loss of Fennoscandian populations into locally adapted, autochthonous three clear groupings. At the populations may have occurred extremes of the natural range, in many areas. In regions where only one mitotype occurred in the species has been cultivated the isolated populations in outside its natural range (e.g. southern Spain whereas in Scot- Germany, France, Hungary) usus sylvestrisScots sylvestris pinePinus sylvestrisScots pinePinus sylvestris ScotsPinus pinePinus sylvestrisSc

Guidelines for genetic on such sites. Native stands conservation and use selected for gene conservation will also serve as ‘population Conservation priorities standards’ when compared with Because Scots pine is a species man-made forests. with an extremely wide distribu- As with populations on tion and occupying a broad range extreme sites, isolated outliers of habitats, genetic conservation might have been exposed to seems to be a task of low priori- specific selection pressures or ty. However, the need to address drift and may carry rare alleles. genetic resources of Scots pine Such populations should be is supported by the widely carefully protected and steps proven genetic diversity between taken to collect forest reproduc- populations, the effects of tion material at the sites. Local century-long cultivation and the material should be used for expected environmental changes regeneration and material from Scots pine stands are often of at the margins of the distribution. endangered sites should also be poor quality. Planted stands of As Scots pine is one of established in ex situ conserva- unknown origin may exert a Europe’s most important tree tion stands. genetic pollution threat to natural species under forest manage- Expected climate change will populations in the surroundings. ment, the anthropogenic influ- first affect the populations at the Expected climatic changes ence is obvious. Both survey and southern fringes of the distribu- will prolong droughts in conti- recording of native local tional range. These populations nental SE Europe and in the (autochthonous) stands are are often remarkably vigorous Mediterranean region; this must important for gene conservation. and tolerant and may be of value be recognized as a potential These records could include vari- for future breeding. Here also ex threat not only to populations at ous identification data; molecular situ measures should be applied the southern limits of the distri- markers become increasingly to safeguard long-term survival. bution area but also to high- useful for this task. The long tradition of artificial elevation populations. This is Long-term provenance tests regeneration may have developed likely to cause a northward shift have proved the value and landraces that could also be tar- of the area where the species importance of locally adapted gets for gene conservation can be successfully cultivated. populations. This is valid primari- efforts. These populations usually ly for extreme site conditions represent diverse, rather plastic (higher altitudes, coastal environ- genetic resources, valuable for ments, extreme boreal condi- future breeding and reproduction. tions, rocky or semiarid sites). Preserved populations on these Establishment and sites exhibit less plasticity when management of gene transferred to other conditions, conservation units but are usually superior locally. When selecting gene conserva- Special care should be taken, tion units along a continuous therefore, to select representa- cline, ecological information tive populations for conservation should be preferred to neutral Pinus sylvestrisScots pinePinus sylvestris sylvestrisScots pinePinus sylvestrisScots pinePinus sylP

Distribution range of Scots pine

markers. In the absence of drift, numerous adjoining stands of complex stand structure, but in a contiguous distribution various age, provided their origin this is not necessary as even- range adaptively different popu- is the same. In areas of scattered aged stands may hold equal lations may be expected at dis- occurrence, initial size may be 10 diversity. Regeneration felling tances where annual mean tem- ha as a minimum, which can be should be carried out stepwise, perature differs by a minimum of increased during successive allowing for recruitment from 1.0–1.5°C (equal to ca. 200 km regenerations. numerous seed years. Scots in a flat landscape). In many instances the pioneer pine is genetically rather insensi- The size of gene conserva- character of Scots pine demands tive to the type of regeneration tion units of Scots pine should human interaction to prevent eco- cutting used. However, if the be sufficiently large to compen- logical succession. As far as pos- influx of outside pollen were sate for and buffer against out- sible, natural regeneration minimized (a goal which can be side geneflow: 100 ha should be should be applied; this is less met with only partial success), considered the minimum. Nearby problematic on drier or poorer shelterwood cutting would be occurrences of genetically sites. Regeneration of admixed preferred to other regeneration degraded or otherwise unsuit- species should be tolerated for regimes. Fencing of the unit has able stands should be either ecological reasons. The light to be considered where high avoided or removed. A conser- demand of the species does not game density threatens natural vation unit should consist of allow the development of a very regeneration processes. PinuslvestrisScots pinePinus sylvestris sylvestrisScots pinePinus sylvestrisScots pinePinus sylvestris PScots EUFORGEN

These Technical Guidelines were In certain cases artificial regeneration may be necessary (e.g. for ex produced by members of the situ conservation). To sample genetic resources properly, cones from 50 EUFORGEN Conifers The objec- or more well-distributed trees should be collected (preferably in a good tive of the Network is to identify seed year). The quantity of seed from each tree must be equal in order minimum genetic conservation to get a balanced participation in the final seed lot. Mixing of repeated requirements in the long term in seed harvests is beneficial, and no seed sorting or grading must be Europe, in order to reduce the applied. overall conservation cost and to Direct sowing should be preferred to planting. If possible, planting improve the quality of standards should be carried out with higher density than usual to allow for more in each country. natural selection. Intermediate low-intensity fellings and management should main- tain a relatively dense stand structure. Selective removal of trees should be confined to malformed individuals; otherwise a broad vari- ation of phenotypes should be allowed. In summary, priorities for specific gene conservation measures will Citation: Mátyás, C., L. Ackzell differ regionally. Preservation of genetic resources of Scots pine and C.J.A. Samuel. 2004. should be visualized in the context of locally applied forest manage- EUFORGEN Technical Guidelines ment practices (especially control of seed sources for artificial regen- for genetic conservation and use eration), the extent of protected or unmanaged areas and the occur- for Scots pine (Pinus sylvestris). rence, density or fragmentation of the species at the landscape level, International Plant Genetic together with actual threats and risks. The urgency to set up gene Resources Institute, Rome, Italy. conservation units will be much higher in an area with fragmented 6 pages. remnants of local populations surrounded by planted forests of uncontrolled origin than in a region where sustainable forestry relying Drawings: Pinus sylvestris, Clau- on natural regeneration and local seed sources is practised. dio Giordano. © IPGRI, 2003. Selected bibliography ISBN 92-9043-661-1

Giertych, M. and Cs. Matyas, eds. 1991. Genetics of Scots pine. Develop- ments of Plant Genetics and Breeding, Vol. 3. Elsevier, Amsterdam. Sarvas, R. 1962. Investigations on the flowering and seed crop of Pinus sylvestris. Comm. Inst. For. Fenniae 33.4, Helsinki Scots pine breeding and genetics. 1994. Proc. IUFRO Symp. Lithuania, Lithuanian Forest Research Institute, Kaunas/Girionis. Silviculture and Biodiversity of Scots pine forests in Europe. 2000. Proc. EU EUFORGEN secretariat c/o IPGRI Concerted Action meeting, Valsain, Spain, June 1999. Investigación Via dei Tre Denari, 472/a Agraria, Sistemas y Recursos Forestales, Fuera de Serie No. 1, Madrid. 00057 Maccarese (Fiumicino) Rome, Italy Tel. (+39)066118251 More information Fax: (+39)0661979661 www.euforgen.org [email protected]