Scots pine (Pinus sylvestris L.) isa pioneer species that readilyregenerates after major naturalor human disturbances, if weedcompetition and grazing pres-sure are low. Natural stands areoften pure and fairly even-aged.The species grows predominant-ly on poorer, sandy soils, rockyoutcrops, peat bogs or close to

the forest limit. On fertile sites,Scots pine is outcompetedby other—usually spruce

or broad-leaved—tree species.The species is wind-pollinated

and has both male and femaleflowers on the same tree. Flower-ing is frequent; female floweringstarts at the age of 15 years onsolitary trees (on grafts, as earlyas 6–8 years) or 25–30 years inclosed stands. Abundant maleflowering appears some yearslater. Mast years are relativelyfrequent but at the boreal forestlimit seed maturation is impededby the short growing season;mast years may occur as seldomas once or twice in 100 years.

Pinus sylvestris

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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 practicalforestry. 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 basisto be complemented and further developed in local, national or regional conditions. TheGuidelines are based on the available knowledge of the species and on widely acceptedmethods for the conservation of forest genetic resources.

Scots pine

Csaba Mátyás1, Lennart Ackzell2 and C.J.A. Samuel31 University of West Hungary, Faculty of Forestry, Sopron, Hungary2 National Board of Forestry, Jönköping, Sweden3 Forest Research, Northern Research Station, Roslin, Midlothian,United Kingdom

Technical guidelines for genetic conservation and use

Biology and ecology

Scots pine has a wide distribu-tion across the whole Eurasiancontinent, ranging in latitudefrom 37°N to 70°20’N. At theboreal forest limit it survives withless than 100 frost-free days/yrand 300 mm annual rainfall.Towards the steppe plains ofCentral Asia its occurrence islimited by the length of thedrought period. In southernEurope and Asia Minor, isolatedoccurrences are confined to themontane zone (up to 2200 m inaltitude in the Balkans andSpain, and 2700 m in the Cau-casus).

Scots pine is a commerciallyimportant tree species in Europe.Its wood is easily workable, withgood mechanical properties, andhas many uses, primarily as con-struction timber and pulpwood.

Its moderate site demandsrender Scots pine an idealspecies for artificial regeneration.Accordingly, its seed has beentraded and used across Europefor centuries. Indiscriminateplanting from seed of uncon-trolled origin sometimes result-ed in blatant quality loss, trig-gering provenance researchwell before present-daygenetic knowledge wasavailable.

Taxonomic status andhybridizationThere have been numerousattempts to subdivide theimmense distribution area intovarious subspecies, whichare rather unconvincingowing to the lack of anyclear discontinuities in thecontiguous range. Isolatedsouthern occurrences,regarded as glacial relics,were occasionally describedas separate species, such as P.hamata (Stev.) Sosn., P. armenaKoch and P. sosnowskyi Nakaifor the Caucasus region.

Under natural conditionsScots pine is not readily inter-fertile with other pine species.Spontaneous hybrids with P.nigra, P. densiflora and P. mugohave been reported. Towardsother taxa, the species shows arobust hybrid incompatibility.

Intraspecific variabilityThe high migration potential ofboth pollen and seed results in

effective geneflow with-in the contiguous range,

causing a dis-tinct, clinal pat-

tern of variationwithin the species,

at least for adaptivetraits. This is typically

the case with growthand phenology charac-

ters, which are determinedprimarily by temperature

conditions in the vegetation peri-od. Northern and continentalpopulations need less heat sumto complete phenophases andreach hardiness. Southern andcoastal provenances have longervegetation cycles and are lesshardy. Intensive geneflow alsomaintains high within-populationdiversity in both adaptive and

neutral traits.Stem form, crown form

and branchiness showgreat variability within thearea of distribution. Only the

provenances of northernEurope/Siberia and those from

higher elevations are straight-stemmed with an ideal coniccrown form and fine branches.Certain regional populations (e.g.southeastern Baltic coast popu-lations) show superior growthtraits and high phenotypic stabil-ity, while in other areas growthand stem form are typically poor,possibly indicating improper sil-vicultural practices in the past(e.g. in Germany or in theCarpathian Basin).

In accordance with growthand stem form, mechanicalproperties of Scots pine timbershow differences according toorigin. This also includes thechemical composition, e.g. theextractive and oleoresin contentof wood.

Intraspecific variation inresistance traits has also beenrecorded. Resistance to fungalpathogens such as Lophodermi-um spp. is higher in the western,coastal parts of the range, while

Distribution

Importance and use

Genetic knowledge

Pinus sylvestris Pinnus sylvestrisScots pinePinus sylvestrisScots pinePinus sylvestrisScots pinePinus sylvestrisSc

southeastern forest steppe pop-ulations are especially suscepti-ble. Geographic variation in sus-ceptibility to insect pests hasbeen proven for a number ofinsects; for instance CentralEuropean populations are sus-ceptible to root collar weevil andpine moths, but more resistant topine shoot borer and pine weevil.

Biochemical and molecularstudies have clearly indicatedthat there is high diversity inScots pine throughout Europe,with most variation occurringwithin rather than between popu-lations. Monoterpenes andisozymes have been used togroup the remnant areas in Scot-land. Both approaches identifiedone region lying at the extremenorthwest of the species’ distri-bution with distinctive character-istics. These approaches havebeen superseded by DNA-basedmarkers for the chloroplast,mitochondrial and nucleargenomes.

Variation in mitochondrialDNA (maternally inherited inpines) has indicated that thethree major mitotypes present inSpanish populations encompassall the variability found in the restof Europe. However, their individ-ual occurrence throughoutEurope separated Italian, west-central European andFennoscandian populations intothree clear groupings. At theextremes of the natural range,only one mitotype occurred inthe isolated populations insouthern Spain whereas in Scot-

land, although most sourcesmatched the west-central Euro-pean grouping, the Italian mito-type was present. Overall,molecular studies support theexistence of three evolutionaryroutes within Europe for Scotspine and the higher variability inSpanish populations suggeststhat this area may have been anoriginal centre of diversity.

The main threats to sur-vival lie at the extremesof its distribution, inparticular, the north-western and southwest-ern fringes (Scotland andsouthern Spain). Here thedistribution of the specieshas become discontinuousand fragmentation into isolat-ed populations is common.In extreme circumstances,this has left several rem-nant populations with fewer than100 trees. Regeneration at theboreal forest limit is also prob-lematic. In patches of the distri-bution browsing damage has ledto a change of species. Mea-sures such as fencing or reduc-tion of game populations havebeen used to safeguard Scotspine populations, achieve suc-cessful natural regeneration,increase stocking levels andexpand the areas concerned. Ina number of instances, the needfor grafted seed orchards to sup-ply seed representing individual,highly vulnerable sources hasbeen recognized.

In the core area of Europeandistribution, where large-scaleartificial regeneration has takenplace for a long time, loss oflocally adapted, autochthonouspopulations may have occurredin many areas. In regions wherethe species has been cultivatedoutside its natural range (e.g.Germany, France, Hungary)

nus sylvestris PinuThreats togenetic diversity

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Scots pine stands are often ofpoor quality. Planted stands ofunknown origin may exert agenetic pollution threat to naturalpopulations in the surroundings.

Expected climatic changeswill prolong droughts in conti-nental SE Europe and in theMediterranean region; this mustbe recognized as a potentialthreat not only to populations atthe southern limits of the distri-bution area but also to high-elevation populations. This islikely to cause a northward shiftof the area where the speciescan be successfully cultivated.

Conservation prioritiesBecause Scots pine is a specieswith an extremely wide distribu-tion and occupying a broad rangeof habitats, genetic conservationseems to be a task of low priori-ty. However, the need to addressgenetic resources of Scots pineis supported by the widelyproven genetic diversity betweenpopulations, the effects ofcentury-long cultivation and theexpected environmental changesat the margins of the distribution.

As Scots pine is one ofEurope’s most important treespecies under forest manage-ment, the anthropogenic influ-ence is obvious. Both survey andrecording of native local(autochthonous) stands areimportant for gene conservation.These records could include vari-ous identification data; molecularmarkers become increasinglyuseful for this task.

Long-term provenance testshave proved the value andimportance of locally adaptedpopulations. This is valid primari-ly for extreme site conditions(higher altitudes, coastal environ-ments, extreme boreal condi-tions, rocky or semiarid sites).Preserved populations on thesesites exhibit less plasticity whentransferred to other conditions,but are usually superior locally.Special care should be taken,therefore, to select representa-tive populations for conservation

on such sites. Native standsselected for gene conservationwill also serve as ‘populationstandards’ when compared withman-made forests.

As with populations onextreme sites, isolated outliersmight have been exposed tospecific selection pressures ordrift and may carry rare alleles.Such populations should becarefully protected and stepstaken to collect forest reproduc-tion material at the sites. Localmaterial should be used forregeneration and material fromendangered sites should also beestablished in ex situ conserva-tion stands.

Expected climate change willfirst affect the populations at thesouthern fringes of the distribu-tional range. These populationsare often remarkably vigorousand tolerant and may be of valuefor future breeding. Here also exsitu measures should be appliedto safeguard long-term survival.

The long tradition of artificialregeneration may have developedlandraces that could also be tar-gets for gene conservationefforts. These populations usuallyrepresent diverse, rather plasticgenetic resources, valuable forfuture breeding and reproduction.

Establishment andmanagement of geneconservation unitsWhen selecting gene conserva-tion units along a continuouscline, ecological informationshould be preferred to neutral

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Guidelines for geneticconservation and use

markers. In the absence of drift,in a contiguous distributionrange adaptively different popu-lations may be expected at dis-tances where annual mean tem-perature differs by a minimum of1.0–1.5°C (equal to ca. 200 kmin a flat landscape).

The size of gene conserva-tion units of Scots pine shouldbe sufficiently large to compen-sate for and buffer against out-side geneflow: 100 ha should beconsidered the minimum. Nearbyoccurrences of geneticallydegraded or otherwise unsuit-able stands should be eitheravoided or removed. A conser-vation unit should consist of

numerous adjoining stands ofvarious age, provided their originis the same. In areas of scatteredoccurrence, initial size may be 10ha as a minimum, which can beincreased during successiveregenerations.

In many instances the pioneercharacter of Scots pine demandshuman interaction to prevent eco-logical succession. As far as pos-sible, natural regenerationshould be applied; this is lessproblematic on drier or poorersites. Regeneration of admixedspecies should be tolerated forecological reasons. The lightdemand of the species does notallow the development of a very

complex stand structure, butthis is not necessary as even-aged stands may hold equaldiversity. Regeneration fellingshould be carried out stepwise,allowing for recruitment fromnumerous seed years. Scotspine is genetically rather insensi-tive to the type of regenerationcutting used. However, if theinflux of outside pollen wereminimized (a goal which can bemet with only partial success),shelterwood cutting would bepreferred to other regenerationregimes. Fencing of the unit hasto be considered where highgame density threatens naturalregeneration processes.

Pinus sylvestris PPinus sylvestrisScots pinePinus sylvestrisScots pinePinus sylvestrisScots pinePinus syl

Distribution range of Scots pine

In certain cases artificial regeneration may be necessary (e.g. for exsitu conservation). To sample genetic resources properly, cones from 50or more well-distributed trees should be collected (preferably in a goodseed year). The quantity of seed from each tree must be equal in orderto get a balanced participation in the final seed lot. Mixing of repeatedseed harvests is beneficial, and no seed sorting or grading must beapplied.

Direct sowing should be preferred to planting. If possible, plantingshould be carried out with higher density than usual to allow for morenatural selection.

Intermediate low-intensity fellings and management should main-tain a relatively dense stand structure. Selective removal of treesshould be confined to malformed individuals; otherwise a broad vari-ation of phenotypes should be allowed.

In summary, priorities for specific gene conservation measures willdiffer regionally. Preservation of genetic resources of Scots pineshould be visualized in the context of locally applied forest manage-ment practices (especially control of seed sources for artificial regen-eration), the extent of protected or unmanaged areas and the occur-rence, density or fragmentation of the species at the landscape level,together with actual threats and risks. The urgency to set up geneconservation units will be much higher in an area with fragmentedremnants of local populations surrounded by planted forests ofuncontrolled origin than in a region where sustainable forestry relyingon natural regeneration and local seed sources is practised.

www.euforgen.orgMore information

Pinus sylvestris PThese Technical Guidelines wereproduced by members of theEUFORGEN Conifers The objec-tive of the Network is to identifyminimum genetic conservationrequirements in the long term inEurope, in order to reduce theoverall conservation cost and toimprove the quality of standardsin each country.

Citation: Mátyás, C., L. Ackzelland C.J.A. Samuel. 2004.EUFORGEN Technical Guidelinesfor genetic conservation and usefor Scots pine (Pinus sylvestris).International Plant GeneticResources Institute, Rome, Italy.6 pages.

Drawings: Pinus sylvestris, Clau-dio Giordano. © IPGRI, 2003.

ISBN 92-9043-661-1

EUFORGEN secretariat c/o IPGRIVia dei Tre Denari, 472/a00057 Maccarese (Fiumicino)Rome, ItalyTel. (+39)066118251Fax: (+39)0661979661euf_secretariat@cgiar.org

lvestrisScots pinePinus sylvestrisScots pinePinus sylvestrisScots pinePinus sylvestrisScots

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Selected bibliography

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 Pinussylvestris. 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. EUConcerted Action meeting, Valsain, Spain, June 1999. InvestigaciónAgraria, Sistemas y Recursos Forestales, Fuera de Serie No. 1, Madrid.