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ŠUMARSKI LIST 9-10/2020 str. 22     <-- 22 -->        PDF

Belgium, Netherlands, Portugal, Spain and United Kingdom (Shaw et al., 2017), and recently in Chile (Loewe et al., 2013) and New Zealand (Praciak et al., 2013). The species is characterised by rapid growth (Ducci and Tani, 2009), and lives in symbiosis with nitrogen-fixing bacteria Actinomyces alni (Frankia alni) /Woronin 1866/ Von Tubeuf 1895/ (Benson et al., 2004) thus improving soil fertility (Chiti et al., 2007; Innangi et al., 2017). For this reason, it is recommended as ideal for afforestation and reforestation (Innangi et al., 2017). It was used in windbreak plantations where better results were observed compared to poplars and willows (Praciak et al., 2013). The species is used as ornamental since it is considered to be one of the most decorative Alnus species (Mitchell 1979; Krüssmann 1984). In Croatia, A. cordata is recorded as decorative tree species (Ettinger 1892; Vidaković 1986; Karavla 1994; Đurasović 1997). The first report of Italian alder in Serbia is from a linear plantation at Fruška Gora (Bobinac et al., 2015a).
Italian alder is a broadleaved tree species that can reach a height of more than 25 m in natural forests (Ducci and Tani 2009), or up to 28 m in favourable conditions (Shaw et al., 2017) with diameter at breast height of more than 65 cm (Ducci and Tani, 2009). The species can grow over 15 m high in 20 years (Mitchell 1979; Shaw et al., 2017). According to Clark et al. (2008), the species can grow over 5 m tall until the age of 6 years.
Compared to other Alnus species, the Italian alder is less dependent on permanent standing water (Shaw et al., 2017) and grows well on calcerous soil (Russel et al., 2007). Within its range, the species prefers damp soils, but can adapt to different soils and can even be found on dry sites in lowland areas or mountains (Burnie and Foulis, 2004; Shaw et al, 2017).
Italian alder can be managed both as high and coppice stands (Ducci and Tani, 2009; Praciak et al., 2013). According to Praciak et al. (2013), suggested rotation is 25–30 years in coppice management. It is used as ancillary species in mixed plantations for timber production of high quality, and for biomass production (Caudullo and Mauri, 2016). Main tree species in mixed plantations supported by ancillary nitrogen-fixing species show higher diameter (Corazzesi et al., 2010; Bianchetto et al., 2013; Testaferri et al., 2019) and height increment (Corazzesi et al., 2010; Testaferri et al., 2019). In mixed plantations, Italian alder integrates well with Juglans regia (Tani et al., 2006; Cutini and Giannini, 2009) and pedunculate oak (Buresti and Frattegiani, 1992; Corazzesi et al., 2010; Battipaglia et al., 2017).
The aim of this paper is to point out the growth characteristics and the structure of the Italian alder linear plantation at age 11 and 16 years and contribute to the knowledge of adaptive and productive potential of the species in the available plantation in Serbia.
MATERIALS AND METHODS
MATERIJALI I METODE
Research object – Objekt istraživanja
The research was conducted in the plantation of Italian alder established at the end of 2005 in Erdevik, National park “Fruška Gora’’ (j = 45°07’N, l = 19°21’E). The seedlings used for the plantation were 1.5–2.0 m tall and two years old. The seedlings were produced from seed and donated by a forestry engineer, nurseryman and collector Đura Jorgić. The seeds were collected in the arboretum Lisičine (Croatia) where this species was previously recorded (Vidaković 1986). The plantation establishment was performed in the form of linear plantation — in some parts there was one, and in other two rows of seedlings with 7 m spacing between them (200 trees per hectare).
The plantation was established in the coastline of the reservoir Bruje at 125 m above sea level where zonal plant community is Carpino betuli-Quercetum roboris /Anić 59/ Rauš 1971 (Tomić 2013). The coastline is characterised by a pioneer shrub community of grey willow (Alliance: Salicion cinereae Th. Müller & Görs 1958.).
The mean annual air temperature is 11.3°C (absolute minimum −29.5°C; absolute maximum 43.6°C) according to weather station Sremska Mitrovica. Around 60% of the mean annual precipitation (614.2 mm) falls during the growing season (data from Republic Hydrometeorological Service of Serbia for the period 1981–2010, Source: http://www.hidmet.gov.rs/).
Measurements and data analysis of growth – Premjer i analiza podataka o rastu
The sample used for the dendrometric measurements at age 11 and 16 years was comprised of 35 numbered trees. The trees were solitary until age of 8 years when branches of adjacent trees were touching. Tree vitality was assessed according to Visual Tree Assessment guide described by Mattheck and Breloer (1994). Diameter at breast height (DBH) was calculated from circumference of trees measured at breast height with accuracy ±1 mm. The total height was measured with Vertex III (Haglöf Sweden AB, Långsele, Sverige) with accuracy ±0.1 m. Basic descriptive statistics – arithmetic mean (x9), standard deviation (sx), coefficient of variation (CV), minimum (min), maximum (max), skewness and kurtosis — were calculated for every of the measured (diameter and height) and calculated growth characteristics (basal area, volume) as well as h/DBH ratio and periodic annual increments (PAI) calculated as the difference between two successive growth element measurements of each tree divided by amount of years between measurements (Pretzsch, 2009).
On the basis of the collected data, the mean quadratic diameter (dg), the mean diameter of 20% thickest trees (Ddom),