Pedophysiographic Features and Heavy Metal Content (Pb, Zn, Cd and Cu) in Spruce Forests of Northern Velebit and tirova a

The largest and the most coherent complexes of natural spruce stands in Croatia are currently distributed in the altimontane and subalpine vegetation belt of Velebit over an area of 3165 ha and altitudes ranging from 1100 to almost 1600 m.Past phytocoenological research into spruce forests in northern Velebit distinguishes three different associations: frost valleys of tirova a and Apati anska Duliba support the altimontane spruce forest with bastard agrimony (Aremonio-Piceetum Horvat 1938), shallower sink holes and slopes descending from the surrounding tops contain the altimontane-subalpine spruce forest with Laserpitium krapfii (Laserpitio krapfii-Piceetum Vukeli et al. 2010), while rocky tops, hips, karrens and ridges feature the subalpine spruce forest with small-reed (Calamagrostio variae-Piceetum Bertovi 1975). These associations are distributed as azonal, microclimatically and edaphically conditioned associations, of which spruce forest with bastard agrimony occurs in the belt of Dinaric beech-fir forest (Omphalodo-Fagetum) while the two others grow in a higher belt of subalpine beech forest with buttercup (Ranunculo platanifoliae-Fagetum). Their mutual differences result from ecological factors which are decisive for their occurrence and distribution. Of these, the edaphic relationships which we explored in this work draw particular interest.Composite samples were taken from the top layer up to 5 cm deep (13 composite samples composed of 9 individual samples each), pedological profiles were opened (11 profiles), and soil samples were taken by pedogenetic horizons within pedological research in three spruce communities: altimontane spruce forest with bastard agrimony (Aremonio-Piceetum), altimontane-subalpine spruce forest with Laserpitium krapfii (Laserpitio krapfii-Piceetum), and subalpine spruce forest with small-reed (Calamagrostio-Piceetum) in the area of northern Velebit and tirova a. Composite samples, taken from the top soil layer up to 5 cm deep, consisted of 9 samples, each taken at a distance of 1 m in a cross pattern.Soil samples were analyzed by means of the following laboratory methods: determination of pH values (HRN ISO 10390:2005), determination of CaCO3 content (HRN ISO 10693:2004), determination of organic and total carbon and nitrogen with dry combustion (HRN ISO 10694:2004, HRN ISO 13878:2004), determination of concentrations of Pb, Zn, Cu and Cd (HRN ISO 11466:2004), and determination of the granulometric soil composition (HRN ISO 11277:2004). Descriptive statistics were made for all the samples by the investigated phyto