TEMPERATE ECOSYSTEMS / Spruces, Firs and Larches 1449 established using genetically modified P. tremula, Spruces, Firs and Larches P. tremuloides, P. deltoides,andP. alba  P. tremula selected varieties. The use of genetically modified H Wolf, State Board for Forestry (Saxony), Pirna, plants has raised concerns over the risk posed to Germany the fitness or future adaptability of wild relatives & 2004, Elsevier Ltd. All Rights Reserved. with whom transgenic plantations might repro- duce. Consequently, a major ongoing effort has been sterility transformation that would prevent Introduction completely the sexual reproduction of transgenic plantations. Together with the genera Pinus (subfamily Pinoi- deae), Cathaya, Pseudotsuga (subfamily Laricoideae), See also: Genetics and Genetic Resources: Propaga- and Cedrus, Keteleeria, Nothotsuga, Pseudolarix, tion Technology for Forest Trees. Tree Breeding, Tsuga (subfamily Abietoideae), the genera Picea Practices: Breeding for Disease and Insect Resistance; (subfamily Piceoideae), Abies (subfamily Abietoi- Genetics and Improvement of Wood Properties. Tree deae), and Larix (subfamily Laricoideae) belong to Breeding, Principles: A Historical Overview of Forest the family Pinaceae. The subfamilies are distinguished Tree Improvement; Breeding Theory and Genetic Testing; by cone and seed characters like the existence of an Conifer Breeding Principles and Processes; Economic umbo or the existence of resin vesicles on the seed. Returns from Tree Breeding; Forest Genetics and Tree Species of the genera Picea (spruce), Abies (fir), Breeding; Current and Future Signposts. and Larix (larch) are exclusively distributed in the northern hemisphere from 221 N in the south to 1 Further Reading 73 N forming the polar borderline of trees. Several species of these genera cover wide areas in boreal Dickmann DI and Stuart KW (1983) The Culture of Eurasia and North America. They contribute to a Poplars in Eastern North America. MI: East Lansing: major extent to the northern coniferous forests which Michigan State University Press. stretch from coast to coast across these latitudes and Dickmann DI, Isebrands JG, Eckenwalder JE, and form the greatest expanses of continuous forests. Richardson J (eds) (2001) Poplar Culture in North Many species of these genera are also found in America. Ottawa, Canada: NRC Research Press. Grant V (1975) Genetics of flowering plants. New York: mountainous regions of the more temperate zones Columbia University Press. often forming the alpine tree border line. International Union of Forest Research Organizations Picea, Abies, and Larix species occur in a wide (1995) International Poplar Symposium, abstracts. range of habitats with very different soil and climate Seattle, WA: University of Washington. conditions. They are associated with various tree International Union of Forest Research Organizations species depending on certain site conditions but they (1999) International Poplar Symposium II, abstracts. can also be found in pure stands under extreme site Orleans, France: INRA, Station d’Ame´lioration des conditions. Mainly reproducing sexually by wind Arbres Forestiers. pollination, vegetative reproduction is the dominant International Union of Forest Research Organizations mode of propagation if sexual reproduction is (2002) International Poplar Symposium III, abstracts. limited due to climatic limitations. Uppsala: Swedish University of Agricultural Sciences. Isebrands JG and Richardson J (comps.) (2000) 21st The lifetime of Picea, Abies, and Larix species Session of the International Poplar Commission (IPC- ranges variously from 150 to 900 years. Under 2000): Poplar and Willow Culture: Meeting the Needs of favorable conditions they grow to tall trees often Society and the Environment, 24–28 September 2000, forming dense forests with considerable growing Vancouver. Gen. Tech. Rep. no. NC-215. St. Paul, MN: stocks. Among populations of most species gene- US Department of Agriculture Forest Service, North tic differences can be observed in various traits. Due Central Research Station. to their wood characteristics, the timber of spruces, Lefevre, F. (2001) Managing the dynamic conservation firs, and larches can be used for a wide variety networks. In: Teissier du Cros, E. (ed.), Forest Genetic of purposes and is therefore of high economical Resources Management and Conservation: France as a importance. Case Study, pp. 23-27. Paris: Ministry of Agriculture and Fisheries, Bureau of Genetic Resources, Commission of Forest Genetic Resources. Spruces Stettler RF, Bradshaw HD Jr, Heilman PE, and Hinckley TM (eds) Biology of Populus and its Implications for The genus Picea (subfamily Piceoideae) is related Management and Conservation. Ottawa, Canada: NRC most closely to the genus Pinus (subfamily Pinoi- Research Press. deae), but differs significantly by, e.g., cone and 1450 TEMPERATE ECOSYSTEMS / Spruces, Firs and Larches seed characteristics, the absence of short shoots, or Table 1 The intragenetic classification and distribution of the period of cone maturing. Picea is a very uni- species of the genus Picea form genus, showing no significant differences within Distribution Botanical name Common name the genus allowing the delineation of subgenera. The genus Picea includes 34 species of cone-bearing, tall North America P. breweriana Brewer spruce P. chihuahuana — evergreen trees with straight stems and regularly P. engelmannii Engelmann spruce constructed crowns with columnar or pyramidal P. glauca White spruce habit. The horizontally arranged and usually rather P. mariana Black spruce short branches are whorled. On young trees, the bark P. pungens Blue spruce, is rather thin, on old trees scaly. The buds are conical Colorado spruce P. rubens Red spruce or ovate, resinous or without resin. The spirally P. sitchensis Sitka spruce arranged needles are either four-sided or flat on a Europe and Northern P. abies Norway spruce short petiole which remains on the shoot after needle Asia fall. Stomatal bands can be found on all four sides or P. obovata Siberian spruce in the case of flat needles on the lower surface. P. omorika Serbian spruce P. orientalis Oriental spruce Central Asia and P. schrenkiana Schrenk spruce Himalayas Natural Distribution P. smithiana Himalayan spruce Out of the 34 species of Picea, eight species occur P. spinulosa — East Asia including P. alcoquiana Alcock spruce naturally in North and Central America, and 26 islands species are distributed in Eurasia (Table 1). The P. glehnii Sakhalin spruce greatest species diversity is found in China and the P. jezoensis Hondo spruce, Himalayas often in single species stands. Yezo spruce Picea species are mainly distributed in the boreal P. koraiensis — P. koyamae Koyama spruce and subboreal zones of the northern hemisphere as P. maximowiczii — well as to a minor extent in the mountainous regions P. morrisonicola — of the more southerly zones where Picea can be P. torano Japanese spruce found up to the subalpine range forming the treeline Central China and P. asperata Chinese spruce (Figure 1). The species of the genus Picea can be South Asia P. aurantiaca — divided in a northern and a southern group, the P. brachytyla — differences between the groups are important from P. crassifolia — the ecological and genetical point of view. Picea P. farreri — species of the northern group occur mainly in large, P. likiangensis Purple spruce often overlapping natural distribution areas either P. meyeri — P. neoveitchii — from east to west only interrupted by the Atlantic P. purpurea — Ocean and the Bering Sea like Picea abies, P. glauca, P. retroflexa — and P. obovata or from north to south like P. wilsonii — P. engelmannii (Figure 1). In contrast, the species of the southern group grow in small, often isolated natural occurrences, for example P. omorika. Himalayas forming the most upper limit of closed The northern limit of distribution of Picea is forests in the world (P. asperata). reached at about 691 N in Norway (P. abies) and the Northwest Territory of Canada (P. glauca, Climate and Soils P. mariana). In the south, Picea stands can be found up to 231 to 271 N at the eastern (P. morrisonicola) Picea species can withstand extremely cold tempera- and up to 231 to 251 N at the western hemisphere tures down to À 601C. The amplitude of temperature (P. chihuahuana)(Figure 1). In warmer regions, the varies from À 601Cto351C. The mean annual water supply is the limiting factor of distribution. precipitation ranges from 230 to 4000 mm with the In the northern part of the distribution area, the maximum falling outside the vegetation period. The vertical occurrence of Picea reaches from sea level in vegetation period ranges from 26 to 175 days, the North America and Eurasia to 2250 m above sea shorter growing season in the north counterbalanced level in the Central Alps (P. abies) and about 3700 m by longer periods of daylight and the ability of spruces in the southern Rocky Mountains (P. engelmannii). to assimilate down to temperatures of À 6to À 71C. In the southern part, Picea species with upright Picea species are not very demanding of soil growth can be found in altitudes up to 4700 m in the conditions with the exception of the water supply. TEMPERATE ECOSYSTEMS / Spruces, Firs and Larches 1451 Figure 1 Natural distribution area of spruces (Picea spp.) Adapted with permission from Kruessmann G (1983) Handbuch der Nadelgehoelze. Berlin: Parey-Verlag. In the northern part of the distribution area, Picea Pollination is by wind over long distances