SILVER FIR (ABIES ALBA) RESOURCES IN ALBANIA AND THEIR CONSERVATION

by
G. Zeneli²⁵²⁶, M. Dida²⁶, F. Ducci²⁷ and D. Habili²⁶

INTRODUCTION

Silver fir (Abies alba Mill.), an ecologically significant tree species native to many European mountain forests, is currently one of the most economically important conifers in Albania. It occupies an area of about 16060 ha and represents 9.3 percent of conifer forests. It is one of the tallest trees growing on the mountain regions of the country. Natural Silver fir forests comprise pure forests and forests mixed with other conifers, such as black pine (Pinus nigra Arn.), or broadleaf trees such as beech (Fagus sylvatica L.) and maple (Acer pseudoplatanus L.) (Habili, 1985). Silver fir populations show very high variability in Albania, as in most the species’ distribution range. This variation is correlated with the changes in physiographic conditions. Despite high levels of intrapopulation genetic variation, increased use of the forests, climate change and disease outbreaks undoubtedly affect the species’ resources and requires intensified genetic conservation. The first measures for the protection of targeted samples of Silver fir genetic variability are being implemented.

DISTRIBUTION

Forest resources in Albania cover approx. 1.028.060 ha or 35.7 percent of the national territory (Anonymous, 2000). Silver fir shows the highest average annual increment among forest trees (2.92 m³/ ha) compared with other economically important trees as beech (2.14 m³/ ha) or black pine (1.45 m³/ ha).

On the basis of physical, climatic and geographical characteristics, the country can be divided into four main regions (Mitrushi 1966). Silver fir forests are found in three of the four regions (the Western lowland region excepted). The natural distribution range includes (Map 1 and Table 2) (Habili 1985; Dano 1996):

• the northern mountain region (Albanian Alps) between 42º 10' N - 42º 34' N and 19º 41' - 20º 04' E. Only one percent of the species’ distribution range falls in this zone. Silver fir grows mainly on slopes facing east and northeast or in valleys where the climate is relatively milder. Long winters with severe freezing days are main limiting factors. Silver fir stands have the lowest increment and are not as developed as other areas.

• the central mountain region between 42º 12' N and 20º 03' - 20º 51' E. The largest area of fir forest is found in this zone (74 percent) where in most cases it forms mixed forests with beech (Fagus sylvatica), black pine (Pinus nigra), maple (Acer pseudoplatanus), and sometimes oak (Quercus spp). In this region, Silver fir shows tolerance to low temperatures and low annual rainfall, and is able to survive in several microclimates (Puke, Bulqiza, Mirdite, Mat, Tirane, Elbasan and Librazhd).

• the southern mountain region between 39º 46' N - 40º 20' N and 19º 31' - 20º 45' E. The majority of the pure Silver fir forests are located here, although the tree only covers 25 percent of the total area. Most stands are located on slopes facing southeast or northwest and are under the influence of the Adriatic Sea. The fact that Silver fir here achieves its maximum growth indicates its adaptability to drought conditions under a xerophytic ecotype.

In summary, stands of fir extend from Sotire - Koshovice, in the South (latitude 39° 46') to the northern borders of the country with Serbia & Montenegro (Vermosh - latitude 42° 38'); Llogara in the Western part (longitude 19° 31') to the Eastern part in Drenove - Bozdovec (longitude 20° 51') (Dano, 1996; Dano and Proko, 1998).

The altitudinal distribution varies greatly throughout the range. In the northern mountain region, because of frequent late frosts in spring, the species’ altitudinal range is limited to below 1500 m a.s.l. although, in rare cases, it grows up to 1800 m. Because of climatic limitations, the altitudinal limit in the central mountain region is more or less the same as in the Alps (1400 to 1600 m). The situation is different in the southern region, where it can be found from 450 m to 1700 m a.s.l. (Habili, 1985).

Table 1. Distribution of Silver fir (Abies alba) forest in Albania (Anonymous 2000)

ECOLOGY

Silver fir attains its best development in areas where there is comparatively high humidity, cold temperatures and high rainfall. A sheltered situation is adequate for its development. Both severe late frosts in spring and strong dry winds in winter jeopardize its growth and it is not found in regions with a marked continental climate (Habili, 1985). The major factor shaping its distribution is the amount of annual rainfall (1000-2 100 mm).

In regions with a temperate climate (eastern and northern mountain zone) with annual rainfall of 1800 to 2500 mm, the petrographic origin is not a limiting factor. The tree can grow on different bedrocks from magmatic to ultabasic formations. On the other hand, in the southern and southeastern parts of its range, which are characterized by long and dry summers, fir requires deep soils rich in CaCO₃.

Silver fir can achieve its optimum growth in soils derived from limestone or dolomite limestone. In areas where fir is associated with beech (Fagus sylvatica), the soil pH is acid to neutral, while in its associations with black pine (Pinus nigra), oak (Quercus spp) and maple (Acer pseudoplatanus) soil acidity ranges from 6.7 to 7.7. Fir prefers loamy or metamorphic soils with elevated hydric potential of deduction, but it grows well even on clay soils. Deep rich soil of sandy loam gives the best growth (Habili, 1985). Table 2 gives climatic and soil data for three major locations (Dano, 1996).

Within the range of distribution, Silver fir is more scattered and associated with other trees including both conifers and broadleaf trees. Pure forests account for 18 percent of its total area while the percentage of Silver fir compared with other trees in mixed forest is variable depending on local conditions.

In mixed forests Silver fir is found with other conifers as black pine (Pinus nigra Arn.), Norway spruce (Picea abies L. (Karst) (one association in Valbona - Northern Albania) or with broadleaf trees such as European beech (Fagus sylvatica L.), oak (Quercus spp) or Ostrya carpinifolia L (Paparisto et al, 1988). Based on climatic conditions, Silver fir achieves its optimum growth in the phytoclimatic zone Fagetum (hot subzone) and Castanetum (cold subzone). In particular cases, it can be grow in the cold subzone of Lauretum (Habili, 1985).

Table 2. Climatic and soil characteristics of Silver Fir locations in Albania (Dano, 1996)

Map 1. Natural distribution of Abies alba in Albania

TAXONOMY AND SPECIATION OF ALBANIAN FIRS

The taxonomy of Albanian firs still raises many questions. Hypotheses concerning the alleged occurrence of Abies alba Mill., Abies cephalonica Loud. and Abies borisii regis Mattf., either based on morphological and anatomical criteria (Mitrushi, 1955; Mitrushi, 1966; Habili, 1985), ecological surveys (Dano, 1996; Dano and Proko, 1998; Misiri, 1999), isosyme analyses (Misiri, 1999) or biochemical characters (Zeneli et al, 2001) are often contradictory because studies are generally based on single traits. Albanian fir populations show high variability in connection with their microclimatic niches (Habili, 1985; Dano, 1996; Dano and Proko, 1998).

Margraft (1932) was the first to study and describe the variations in Albanian fir populations and on the basis of morphological traits, recognized three species: Abies alba, Abies cephalonica and Abies borisii regis.

Referring to Margraft, Svoboda (1953) classified Albanian fir stands into two climatic types; fir populations north of the Shkumbin river were included in a "Illyrica" climatic type, while fir populations south of the Shkumbin river were referred to a "Macedonica" type. Mitrushi (1955) mentioned the same three species as Margraf, although later (1966), he only recognized two species, namely A. alba and A. borisii regis.

An extensive study of morphological and anatomical characters on samples collected over the Albanian distribution range (Habili, 1985) showed considerable variation between and within populations. Some traits appeared to vary along latitudinal and/or longitudinal gradients. Habili (1985) concluded that in some southern populations morphological features of A. cephalonica could be found, but the author excluded this species from Albania: A. cephalonica grows up to 38º 50' (Mattfeld, 1930), while Albania lies between 39º 38'- 42º 39'N.

Even Atlas Florae Europea (1988) displays contradictions on fir species distribution in Albania. While on map No 152 the distribution of A. alba covers all the national territory, on map No 154 firs in southern Albania are referred to as A. borissi-regis. Misiri (1999) concluded that southern firs are different from those in the central and northern regions and inherit a number of features of A. cephalonica , therefore belonging to A. borisii-regis.

More recently, Zeneli et al (2001) investigated fir terpene variation in needle oil and cortical oleoresin from different geographical regions. It was found that the terpene composition of the Drenova population (southeast) is as different from northern Albania populations as from the Greek fir reported by Fady et al. (1992). The geological characteristics of the Bosdovec-Drenova mountains are very varied (flysh and phyllites dominate) and a few populations of Silver fir may have been able to constitute glacial refuge. The existence of central resin channels in a radial section of fir trunk is reported as a characteristic of the Drenova fir, helping to differentiate it from other provenances (Habili, 1985).

To explain the patterns of variation of fir in Albania, it is necessary to consider the migration routes during the last glaciation. One often assumes the existence of a refuge in the Balkan Peninsula (Schiefele, 1970). The southern migration of A. alba before and during the last Ice Age and contacts with A. cephalonica in small refuges probably led to the development of Abies borisii regis hybrid populations. The introgression between the species may have been secondary, i.e it may have originated, to a large extent, from the natural hybridization of preexisting species A. alba and A. cephalonica (Mitsopoulos and Panetsos, 1987). Frequent contact between the two species during the Pleistocene could have contributed to the particular morphology of southeastern ecotypes of A. alba, including Albanian populations. (Fady and Conkle, 1993). After the end of the glaciation, fir has migrated northwards from the Balkan Peninsula (Southern Bosnia, Macedonia) (Horvat-Marolt and Kramer, 1982).

Another introgression zone has been in the Slovenian Alps, where Silver fir from the southern Balkans met populations from central Italy during their migration along the East Alpine route (Konnert and Bergmann, 1995). Silver fir may have been subject to genetic impoverishment during the re-migration from the refuges where it survived the glaciation period.

The present range of Silver fir in Albania and the existence of introgression (hybrid) zones appear to be the result of different migration routes after the end of the last glaciation from the Balkans and Central Italy (Konnert and Bergmann, 1995). Various factors, such as geographic isolation, gene flows, selective harvesting, soil mosaic, climatic and altitudinal variations, as well as forest fires, may have contributed to the present complex genetic structure.

In conclusion, it can be assumed that two Abies alba ecotypes, instead of two taxa, can be found in Albania. The first ecotype grows in Korca, Koshovica, Gjirokaster, Permet and Leskovik, while the second ecotype covers the mountains of Korca to the northern part of the country (Habili, 1985; Dano, 1996; Zeneli et al., 2001).

CONSERVATION

Abies alba has an extensive natural range and shows considerable morphological and physiological variation especially in its southern limit (Habili, 1985; Mitsopoulos and Panetsos, 1987; Wolf et al., 1994). Climatic changes are alleged driving forces in its expansion and regression phases. In Albania several populations are severely threatened by increased harvesting; forest fragmentation, climate change and insect and disease outbreaks. These threats highlight the urgent need for conservation and sustainable management of fir resources, and protection of appropriate amounts of genetic variability.

The first measures aimed at conserving Silver fir genetic resources are being implemented in the country. Parts of the Albanian territory have designated as protected areas (Vangjeli et al., 1997) and will play an important role in in situ conservation:

• the Forest Management Unit of Kardhiq (Southern Albania), where Silver Fir forms mixed forest with oak species is now a Strict Nature Reserve/Wilderness Area (Category I IUCN);

• fir stands at Hotova (approx. 2000 ha) are under a National Park (Category II in IUCN’s classification);

• Sotira, which represents the southern extension of fir in Albania (approx. 980 ha) has been designated a natural monument (Category III of IUCN);

• Shelegura (approx. 980 ha) is now a Habitat/Species Management Area (Category IV IUCN).

Seed stands have also been classified. They cover an area of 569 ha and are distributed in three major regions (from 39°49'00'' to 42°35'00'' N and 19°34'10'' to 20°25'00'' E), including 57 ha in the northern mountain region, 175 ha in the central mountain region and 337 ha in the southern mountain region. Seed orchards have already been established in two areas and may be extended to other ecogeographic zones, pending the availability of resources. Developing science-based conservation strategies and maintaining minimum viable populations will represent other important challenges towards the conservation of Albanian fir genetic resources.

ACKNOWLEDGEMENTS

This work has been partly financed by the Albanian Ministry of Agriculture and Food, Forest and Pasture Research Institute. We are also grateful to Jim Tokuhisa (Max Planck Institute for Chemical Ecology, Jena) for useful discussions.

REFERENCES

Anonymous. 2000. Annual report. Forest and Pasture Research Institute. Tirana.

Atlas Flora Europea. 1988. Distribution of vascular plants in Europe. 2^nd edition, Volume I, pp.10, map 152-154. Jalas,S and Suominen, J (eds).

Dano, K. 1996. Genetic resources of some important forest tree species and their conservation. Ph.D Thesis. Agriculture University of Tirana. 131pp. (in Albanian).

Dano, K. & Proko, A. 1998. The evidence of fir genetic resources and their conservation. The Bulletin of Agriculture Sciences 3: 113-116 (in Albanian).

Dida, M., Ducci, F. & Zeneli, G. 2001 Black pine (Pinus nigra Arn.) resources in Albania, Forest Genetic Resources No. 29, pp 43-46. FAO, Rome.

Dida, M. 2003. State of forest genetic resources in Albania. Forest Genetic Resources Working Papers, Working Paper FGR/62E. Forest Resources Development Service, Forest Resources Division. FAO, Rome.

Fady, B., Arbez, M. & Marpeau, A. 1992. Geographic variability of terpene composition in Abies cephalonica Loud. and Abies species around the Aegean: hypotheses for their possible phylogeny from the Miocene. Trees: Structure and Function, 6: 3, 162-171.

Fady, B. & Conkle, M.T. 1993. Allozyme variation and possible Phylogenetic implication in Abies cephalonica Loudon and some related Eastern Mediterranean Firs. Silvae Genetica 42, 6:351-359.

Habili, D. 1985. Botanical and Dentrometrical Study of Fir in Albania. Ph.D Thesis. Agriculture University of Tirana (in Albanian).

Horvat-Marolt, S. & Kramer, W. 1982. Die Weistanne (Abies alba Mill.) in Jugoslavien. Forstarchiv, 53, 172-180.

Konnert, M. & Bergmann, F. 1995. The geographical distribution of genetic variation of silver fir (Abies alba Mill. Pinaceae) in relation to its migration history. Plant Systematics and Evolution. 196, 19-30.

Margraft, F. 1932. Pflanzengeographie von Albanien. Ihre Bedentung für vegetation und flora des mittelmeerlondez. Stutgart. Biblioteka botanica, Heft 105.

Misiri, M. 1999. The taxonomic diversity of the fir in South Albania based on the biometrics, morphologic, structural, fitosociologic, and isozyme analysis. Ph.D thesis. Agricultural University of Tirana. (in Albanian)

Mitrushi, I. 1955. Trees and shrubs of Albania. Albanian Academy of Science. 604 pp (in Albanian)

Mitrushi, I. 1966. Dendroflora of Albania. Albanian Academy of Science. 358 pp (in Albanian)

Mitsopulos, D.J. & Panetsos, K.P. 1987. Origin of variation in Fir forest of Greece. Silvae genetica 36, 1: 1-15.

Paparisto, K., Demiri, M., Mitrushi, I. & Qosja, Xh. 1988. Flora of Albania. Albanian Academy of Science.

Schiefele, M. 1970. Die Tannen von aude. Allg. Forstzeitung 49, 1039-1041.

Svoboda, P. 1953. Lesni dreviny a jejech porosty. Prague.

Vangjeli, J., Habili, D. & Bego, F. (eds) 1997. Ecological Survey of High forest in Albania. World Bank. 331 pp.

Wolf, H., Ruetz, W.F. & Franke, A. 1994. Der Süddeutsche Weisstannen-Provenienzversuch der Baumschulpase und Anglage der Versuchschflächen. In: Weisstannen - Herkünften: Neue resultate zur Provenienzversuch bei Abies alba Mill., pp. 107-130. Wolf.H (ed.)

Zeneli, G., Tsitsimpikou, C., Petrakis, P.V., Naxakis, G., Habili, D. & Roussis, V. 2001. Foliar and cortex oleoresin variability of Silver fir (Abies alba Mill) in Albania. Zeitschrift fur Naturforschung C. 56(7-8): 531-539.

²⁵ Forest and Pasture Research Institute., Tirana, Albania

²⁶ Currently: Max Planck Institute for Chemical Ecology, Jena, Germany

²⁷ Coord. IUFRO WG 20213- Istituto Sperimentale per la Selvicoltura, Arezzo, Italy