Technical guidelines for genetic conservation and use Norway spruce Picea abies Tore Skrøppa EUFORGEN Norwegian Forest Research Institute, Ås, Norway These Technical Guidelines are intended to assist those who cherish the valuable Norway spruce 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 Norway spruce (Picea abies (L.) Karst) is monoecious, having both male and female flowers on the same individuals, but on sep- arate organs. The reproduc- tive buds are initiated during the previous year’s growth season. The temperature condi- tions play an important role in both floral initia- tion and development of reproductive buds, and in seed development and matura- tion. Unfavourable temperature conditions may explain why seed crops are both rare and irregular far north and at high altitudes. In seed orchards, flowering has occurred less fre- quently than was expected. The highest proportion of spruce seeds is produced by cross-fertilization, both between neighbouring trees and among distant individuals in the same or in nearby stands. Spruce pollen is able to move over long dis- tances, a fact that can cause Piceaorway sprucePicea abiesNorway abies sprucePicea abiesNorway PiceasprucePicea abiesNorway considerable gene flow among Distribution Importance and use populations. The actual rate of self-fertilization in natural popu- lations may vary consid- The total natural distribution of Picea abies is the most econom- erably between trees, P. abies covers 31 degrees of lat- ically important conifer tree but estimates show itude from the Balkan Peninsula species in Europe. It has shown that only a small pro- (latitude 41°27’N) to its northern- good yield and quality perform- portion of filled seeds most extension near the Chatan- ance on very different site condi- (less than 1%) may ga River, Siberia (latitude tions, and this favoured the originate from self-fertil- 72°15’N). Longitudinal range is species over a long period. The ization. Inbred spruce trees from 5°27’E in the French Alps species has a long history of cul- generally have reduced fitness to 154°E at the Sea of Okhotsk in tivation in Central Europe and compared with their outbred rel- Eastern Siberia. The vertical dis- has been seeded atives. tribution is from sea level and to and planted very Norway spruce trees undergo altitudes above 2300 m in the intensely since a rather long juvenile period dur- Italian Alps. Outside the natu- the middle of ing which they will not flower and ral distribution the species the 19th centu- set seeds. In the open canopy, has been widely planted, in ry. This has sexual maturity will generally be particular in Central Europe changed natural reached at an age of 20- and in Scandinavia. forests into artifi- 30 years, while it occurs later in The natural Euro- cial forests and has closed stands. Most spruce pean range of P. abies led to the introduc- seeds are dispersed close to the can be divided into tion of the species mother tree, but some also over three major regions far outside its natu- longer distances. Under natural as the result of post- ral range, both in regeneration the access to soil glacial re-coloniza- countries where it moisture seems to be the most tion: the Nordic- occurs naturally, e.g. critical factor for germination and Baltic-Russian, in Germany and Nor- establishment. Natural regenera- the Hercyno- way, and in new tion is also dependent on the Carpathian and countries such as species composition of the bot- Alpine regions Denmark, Belgium tom and field layer. The most and Ireland. To some productive spruce forests seem extent, Norway spruce to be the most problematic for also has been planted natural regeneration. in North America. Picea abies is a shade-toler- Picea abies pro- ant tree species that can grow on duces high-quality timber a variety of site types, in both dry and its long fibres make it and wet habitats. It reaches its important for the pulp and best growth on deep nutritious paper industry. The species soils with enough fresh moisture. also has high ecological It can grow in single stands or in importance, being a key mixtures with other conifers or species in northern regions of deciduous trees. Europe. aspruce abiesPicea abiesNorway spruce PiceaPicea abiesNorway sprucePicea abiesabieNorway spruc Genetic knowledge proper choice of reforestation Threats to materials. At the same time there genetic diversity is large variability for the same The genetic variability in P. abies traits within natural populations. In some areas where maladapted has been studied in provenance In Central Europe, the regional provenances of P. abies have and progeny trials, often planted variation patterns are less clear, been planted, damage and at several sites, and by genetic owing to a long history of plant- reduced yield have occurred. markers such as isozymes and ing and provenance transfers. During the last two decades the DNA markers. The neutral mark- species has suffered severely ers reveal a great genetic vari- with the forest decline in Central ability within populations. Europe, resulting in stands with Some differentiation occurs high percentages of trees with between populations derived needle loss, or completely from different glacial refugia, destroyed stands. The health and appears to reflect their problems of the Central Euro- post-glacial evolutionary his- pean spruce forest and the tory. Central European reduced possibilities for recre- provenances appear to ation in young spruce stands have somewhat reduced have to some extent reduced its genetic diversity com- popularity in reforestation, in par- pared with those from East- ticular outside its natural range. ern Europe and Scandi- Fragmentation of former continu- navia. ous forest areas is another threat The most pronounced for the genetic diversity of the adaptive patterns that have been species, and its response demonstrated in provenance tri- to global warming is als relate to the populations’ uncertain. The most serious responses to the climatic condi- biotic threats to P. abies are tions. In northern Europe these root rot (Heterobasidion anno- patterns of variability often can sum) and bark beetles (Ips be related to latitude and longi- typographus). tude, and with degree of conti- nentality, and will sometimes vary clinally. They are expressed by variation in the timing and duration of the annual growth period and the corresponding release and development of frost-hardiness in spring and autumn, respectively. These annual growth patterns have implications for frost-hardiness, growth potential and wood qual- ity traits, and are important for escePicea abies NorwayPicea sprucePicea abiesNorway abies sprucePicea abiesNorway sprucePiPice Guidelines for genetic for successful regeneration. The Clonal archives are static gene conservation and use objective is to maintain the conservation units, with no natu- potential for continuous future ral regeneration intended in the Genetic conservation of P. abies evolution of the population. It plantation. They often contain is done by proper use of refor- has been suggested that gene members of breeding popula- estation materials and by specific reserve forests should cover tions that are characterized in situ and ex situ conservation areas of at least 100 ha, but genetically and are used to pro- activities. In reforestation, the smaller areas can also serve the vide scions to be grafted in seed minimum requirement should be purpose. Such forests may orchards or to make controlled that the origin of the reproductive consist of a mixture of dif- crosses. All populations belong- material is known, and its adap- ferent species, if that is ing to a breeding programme, tive properties should be appro- their natural species com- such as seed orchards and prog- priate for the ecological condi- position. In areas where eny tests, are important gene tions at the regeneration site. A P. abies is not a native conservation units as they con- system for the control of repro- species, it may be desirable tain materials with known genet- ductive materials should be to conserve the genetic varia- ic properties that can be used to established and recommen- tion of well-adapted “landraces” generate new populations with dations for proper use of dif- in gene reserve forests. known adaptive and wood-pro- ferent materials should be devel- Establishment of ex situ con- duction characteristics. Breeding oped. The OECD Scheme and EU servation plantations of P. abies populations organized in a sys- regulations provide basic defini- may be necessary in order to tem of multiple populations at tions of different categories of conserve the genetic variability different sites have particular val- reproductive materials. The of threatened populations that ue for conserving genetic vari- P. abies seed samples of recom- cannot be maintained at the orig- ability both mended seed lots for practical inal site. The objective will be to within and reforestation should be harvested establish a new population that between in years with abundant flowering maintains as much as possible of popula- and seed production and be the original genetic variability tions. stored in sufficient amounts in and allows for long-term adapta- seed banks. tion to the local conditions at the In situ conservation of planting site. It can be estab- P. abies is often successfully lished by planting of seedlings, done in protected areas. In sev- but also by direct sowing or veg- eral countries, however, protect- etative propagules. Sizes of ed areas alone do not fulfil the 2–5 ha are generally recom- actual needs and requirements mended.