itAliAn Alder (Alnus cordAtA/loisel./ desf.) – new species for Allochtonous dendroflora of serbiA

: The foreign tree species, Alnus cordata /Loisel./ Desf. (Italian alder), ( Betulaceae / Loisel./ Duby), not previously recorded in the dendroflora of Serbia, is described in this paper. Italian alder trees in an experimental plot in the area of Erdevik, aged 11 years, show good vitality and fast growth, and bear fruits since their 10 th year. Tree heights are in range from 10.4 to 16.2 m, and diameters at the breast height range from14.6 to 34.9 cm. The morphological properties of leaves, fruiting organs (“cones”) and male catkins are in concordance with the values in literature sources, although they show great variability. Since the time of plantation establishment, the absolute minimum air temperature in the nearby meteorological station of Sremska Mitrovica was –26.50C, so it can be assumed that the species is frost hardy. On the basis of the researched properties of Italian alder, it can be concluded that this species can be cultivated in Serbia as an ornamental in urban areas and as a fast growing species in forest plantations for biomass production.

У периоду гајења констатована је апсолутна минимална температура ваздуха на оближњој Abstract: The foreign tree species, Alnus cordata/Loisel./ Desf. (Italian alder), (Betulaceae/ Loisel./ Duby), not previously recorded in the dendroflora of Serbia, is described in this paper. Italian alder trees in an experimental plot in the area of Erdevik, aged 11 years, show good vitality and fast growth, and bear fruits since their 10 th year. Tree heights are in range from 10.4 to 16.2 m, and diameters at the breast height range from14.6 to 34.9 cm. The morphological properties of leaves, fruiting organs ("cones") and male catkins are in concordance with the values in literature sources, although they show great variability. Since the time of plantation establishment, the absolute minimum air temperature in the nearby meteorological station of Sremska Mitrovica was -26.50C, so it can be assumed that the species is frost hardy. On the basis of the researched properties of Italian alder, it can be concluded that this species can be cultivated in Serbia as an ornamental in urban areas and as a fast growing species in forest plantations for biomass production.
Italian alder (Alnus cordata (Loisel.) Desf.) was not so far recorded in Serbia. It is a deciduous tree of middle height, 17-25 m, аnd up to 28 m in favourable conditions, with a 65 cm diameter, and a maximum of 3 m. It is a fast growing species, that can reach more than 15 m height for 20 years. The crown is dense and elongated conical. The bark is lightly greyish brown, later dull brown, with numerous lenticels, smooth for a long time, later somewhat scally, with wide transversal and longitudinal fissures (Mitchell, 1979;Shaw et al., 2014). Twigs are reddish brown, smooth, with lenticels. Buds are ovate, up to 5 mm long with a 5 mm long peduncle, light green, ocassionally spotted reddish brown, sticky when young, otherwise glabrous (Mitchell, 1979;Krüssmann, 1984). Buds and fruiting organs (similar to small cones) are the biggest among all Alnus Gaertn. species (Ducci and Tani, 2009). Leaves are ovoid to round, with pointed tips, finely serrate on the margins, lustrous green on the upper side, light green and with rare tufts of rusty hair on the lower side by leaf nerves. They are 5-10 cm long аnd 5-7 cm wide. The leaf base is heart shaped (Russel et al., 2007;Shaw et al., 2014). The ends of leaf nerves are bifurcated (Eiselt and Schröder, 1977). The leaf peduncle is 2-3 cm long (Krüssmann, 1984). During autumn, leaves do not change colour and drop out green (Ducci and Tani, 2009). The flowers are unisexual, and the species is monoecious. It attains reproductive maturity at the age of 10-12 years. Male flowers consist of 5-6 catkins, yellowish green, 7-10 cm in lenght (Mitchell, 1979;Ducci and Tani, 2009). Female flowers are also catkins, upright, located above male flowers, red in colour. Their length is around 5 mm and they stand on 2-5 cm long peduncles (Mitchell, 1979;Shaw et al., 2014). Male catkins are either separate or positioned three in an inflorescence (other European alders have 3-8 female catkins in inflorescence) (Wall, 1964). Both male and female flowers form during winter, and open up next spring (Ducci and Tani, 2009). Italian alder flourishes in March and April (***2015). Female flowers produce fruiting organs which are the biggest among alders. They are ovoid, reddish brown in colour, their lenght is around 2,5 cm, аnd width around 1,8 cm (Ducci and Tani, 2009). Fruits are nutlets, very tiny, with corky additions, which serve for floating in water (Mitchell, 1979). It is an anemophilous species, whose pollen is distributed by wind (Russel et al., 2007).
Distribution of Italian alder is restricted, and it primarily grows in Italy, in the southern Apenines (provinces Basilicata, Calabria and Campania), and can also be found in the mountains of northeastern Corsica in France. It has an altitudinal amplitude ranging from 200 m to 1600 m a.s.l. (Ducci and Tani, 2009), (Picture 1).
In native stands it grows on various soils. It is less connected to wet sites than the majority of other species of this genus, and thrives on limestone. Italian alder is an intolerant to semitolerant species (Russel et al., 2007;Shaw et al., 2014). It prefers wet soils, rich in humus, but adapts itself to various soils and can also be found in dry forests in lowlands or highlands. It forms dense groves on poorly drained sites in depressions. It is frost hardy and can sustain the presence of sea salt in the air (***2004; Shaw et al., 2014). Italian alder is a pioneer species, and it can fastly colonize clearings created by the cutting of beech (Fagus sylvatica L.) or sweet chestnut (Castanea sativa Mill.) stands. In that way it forms pure stands. It is also capable of colonizing Austrian pine (Pinus nigra Arn.) stands in moister conditions. Epicormic buds usually survive on stumps after forest fires and they are capable of forming shoots rapidly (Ducci and Tani, 2009).  (Ducci and Tani, 2009) Italian alder is a fast growing and a pioneer species. In the same manner as the other species of the genus Alnus Gaertn., it increases soil fertility, firstly through symbiotic activity with the nitrogen fixing bacterium Actinomyces alni (Frankia alni), which is present on alder roots, and secondly by leaf litter which improves humus composition (Benson et al., 2004).
Its timber has reddish-orange colour, with wide growth rings, which is a consequence of fast growth. Wood quality is similar to that of hybrid poplars, but Italian alder wood is heavier, shrinks more, and has a high modulus of rupture. It breaks down rapidly when exposed to air, but is durable when immersed in water. It was used for the foundations of houses and bridges in Venice. Italian alder timber is used in carpentry, for turning and carving as well as for the production of furniture, plywood and panelling. It is also used as firewood (Ducci and Tani, 2009;Shaw et al., 2014). This species is cultivated in forest plantations in France and Italy (Mitchell, 1979). In central Italy it is used to a massive scale for the afforestation of poorly drained and wet soils, in agroforestry and for soil erosion control in mountain areas. Nowadays it is widely used for the protection of plantations of walnut (Juglans regia L.), sweet cherry (Prunus avium L.), as well as other valuable hardwoods (Shaw et al., 2014). It is also planted as an ornamental species, because it represents one of the most decorative species of this genus. It differs markedly from other alders by the appearance of the crown, bark, leaves, as well as by its bigger flowers and fruits (Mitchell, 1979;Krüssmann, 1984).
In this paper, interpopulation morphological characteristics of leaves, fruiting organs and female catkins are researched in a linear experimental plot in the area of Erdevik, on the basis of the average values of 10 individuals. The growth elements of height and width were also analyzed, on the basis of the average values of 40 measured individuals.

reseArch object
The Italian alder experimental plot was established with two-year-old seedlings (2+0) at the end of 2005, in the Erdevik area, at the locality Banja (National park "Fruška gora"). The seedlings were produced and donated by the collector Đura Jor-gić, forestry engineer. The seed originates from a cultivated tree from the arboretum "Lisičine" in Voćin (Croatia) (Vidaković et al., 1986). At the moment of planting, the height of seedlings was 1.5-2.0 m, аnd they had a high survival rate after planting. The seedlings were mostly planted in one row and partially in two rows, with a spacing of around 7 m between individuals. The plantation was established in the aim of revegetation of the coastal area of the artificial lake Bruje, and it represents an example of individual collector's initiative towards foreign flora gene pool development in Serbia, because Italian alder (Alnus cordata/Loisel/Desf.) was not so far recorded in the present allochtonous dendroflora of Serbia. In the National park "Fruška gora", according to the tree inventory during the preparation of forest management plans, there are 54 recorded foreign tree species (***2002), аnd in the Erdevik area, various findings of rare foreign tree species were recorded (Petrović, 1950;Bobinac et al., 2007) and unique record of a one hundred-year-old horse chestnut (Aesculus hиppocastanum L., var. 'Baumannii' Schn.) was ascertained (Bobinac et al., 2012).
The plantation of Italian alder was established in the western part of the national park "Fruška gora", at the elevation of 125 m a.s.l, in the coastal area of Bruje artificial lake, in the site of a pioneer shrubby community of grey willow (Alliance: Salicion cinereae Th. Müller & Görs 1958.).
According to its geographic position, the whole area is located in the temperate continental climate zone. On the basis of the records from the meteorological station of Sremska Mitrovica for the period 1981-2010, mean annual air temperature is 11.30C, mean air temperature in January is 0.10C and the lowest recorded temperature was -29.50C, which occurred in January of 1987. The vegetation period has a small number of frosty days. During the 2004-2014 period, the lowest recorded temperatures were between -5.6 and -26.50C. The mean annual precipitation level is 614.2 mm, of which 60% occurrs in the vegetation period (Таble 1).

working method
Tree measurement was performed on 40 dominant Italian alder individuals aged 11 years (at the  (Sremska Mitrovica 1981-2010 elevation=82 m a.s.l). I  II  III  IV  V  VI  VII  VIII  IX  X  XI XII Annual

Record low
Tree vitality was assessed by visual inspection, according to the VTA (Visual Tree Assessment) procedure, described by Mattheck and Breloer (1994).

Morphological properties of leaves, fruiting bodies and male catkins in the Italian alder plantation in the Erdevik area.
The results of conducted descriptive statistical analyses for the measured morphological properties of leaves, fruiting organs and male catkins are presented in Table 2. The average leaf length is 120 mm, the average leaf width is 69 mm and the average peduncle length is 27 mm. The leaves have average values within the limits for this species stated in literature (Krüssmann, 1984;Russel et al., 2007;Shaw et al., 2014). However, the leaves show a pronounced variability and when all measured morphological parameters are calculated, the variability coefficient of 10 analyzed trees is 20%, аnd for leaf length from peduncle to top (L1), leaf length from the point of maximum width to top (L5) and leaf width 2 cm from the top (L7), the variability coefficient is in the range from 25.4 to 31.9% (Picture 2).
Trees in the experimental plot fructified when they were 10 years old, аnd in the 11th year all trees abundantly fructified. The average length of fruiting organs is 25.0 mm, the average width is 15.3 mm, аnd the average peduncle length is 18.1 mm. Fruiting bodies have average values which are within the limits for this species mentioned in literature (Mitchell, 1979;Ducci and Tani, 2009;Shaw et al., 2014). Fruiting organs on individual trees usually occur in groups, with more than 3 in a group, аnd up to 15 "cones" were recorded on ramified flowering-fruiting branches (Picture 3). This phenomenon is not in accordance with the statement of Wall (1964), that female catkins occur solitary or up to 3 in an inflorescence, and it can be related to ramified flowering-fruiting branches in case of abundant seed production.    Because of that, the highest variability of all measured fruiting body parameters was recorded for peduncle length (35.7%). Closed male catkins (right before opening) are reddish-brown, and they are located on branch tips 2-8 together (Picture 4). In some trees in the experimental plot, male catkis released pollen already at the end of December 2014. Average male catkin length is 55.5 mm, аnd their span is 25-90 mm. The length of male catkins is within the limits for this species stated in literature (Mitchell, 1979;Ducci and Tani 2009). The average peduncle lenght of male catkins is 11.9 mm, аnd because of the ramified flowering branches the length of male catkins shows great variability (40.4%).

Tree growth elements of Italian alder in the plantation in the area of Erdevik
In the research plantation of Italian alder, trees aged 11 years have monopodial growth and pronounced ramification, which aldready starts at the height of around 2 m, as a consequence of age and poorly pronounced tree competition for growth space in a linear plantation (Picture 4). Since planting distance between the trees is 7m, crowns began to interlock at the age of eight years. The vitality of all trees in the plantation was marked with the highest grade.
Tree heights were between 10.4-16.2 m, and mean annual height increament had values ranging from 0.95 to 1.47 m. Mean tree height (hs) was 12.7 m (Таble 3).
Tree diameter at breast height ranged from 14.6 to 34.9 cm, аnd the mean diameter (ds) was 24.3 cm (Таble 3). Tree height structure shows a pronounced positive asymmetry, with an asymmetry coefficient of 0.414, while diameter structure shows a poorly defined positive asymmetry, with an asymmetry coefficient of 0.119. Both structures have platycurtic flatness (Таble 3). The variability of height structure is two times lower than the variability of diameter structure, which is a characteristic of fast growing species plantations (Andrašev, 2008).

conclusions
The presence of Italian alder (Alnus cordata/ Loisel/ Desf.), which represents a new species for the allochtonous dendroflora of Serbia, was first recorded in the experimental plot near Erdevik.
Trees are 11 years old, they have excellent vitality and grow fast, and since their 10 th year they bear fruits. Tree height ranged from 10.4 to 16.2 m, аnd the diameter ranged from 14.6 to 34.9 cm.
Morphological properties of leaves, fruiting organs and male catkins are within the limits of this species noted in literature, but show great variability.
Since the moment of plantation establishment, the lowest recorded air temperature in the nearby meteorological station of Sremska Mitrovica was -26.50C. Therefore, it can be assumed that this species can withstand low temperatures well. Further monitoring of the acclimatization of this foreign and potentially applicable species is recommended.
On the basis of the researched properties, this species could be cultivated in Serbia as an ornamental in urban areas and as a fast growing species in forest plantations for biomass production.
Acknowledgements: This research was realized within project "Forest plantations in the function of increasing forest cover of Serbia" (31041) financed by Ministry of education and science of the Republic of Serbia within the program technological development for the period 2011-2014.