engleski

Distribution, habitat and population variability of green alder (Alnus alnobetula (Ehrh.) K.Koch subsp. alnobetula) in Croatia

Alnus alnobetula (Ehrh.) K.Koch (Betulaceae) is a monoecious and wind-pollinated, relatively short-lived, medium-sized deciduous shrub with a circumpolar distribution. The green alder comprises five subspecies, of which subsp. alnobetula (= A. viridis (Chaix) DC.) is native to Central, Southern and Eastern Europe. In Croatia, at present it can be found at only one locality on the Žumberak Mt (NW Croatia). The area of its distribution is restricted to the right slope above the Sušik brook, where it grows on moist soil alongside the Sekulići-Sv. Gera road. In this study, we evaluate the morphological variability of the green alder in Croatia. In October 2017, plant samples, i.e. leaves from two different types of shoots (short and long), male catkins, and infructescences (fruiting catkins), were collected for morphometric analysis. Descriptive and multivariate statistical methods were used to examine the diversity. The mean values of characters describing the size and shape of the leaves, as well as those describing male and fruiting catkins are similar to those reported in literature. In addition, our analyses have shown that the leaves from short shoots in comparison with the leaves from long shoots have a smaller leaf blade area, shorter petioles, and more rounded leaf base. Morphological variability is moderate, and significant intra-population variability has been observed for all analysed traits. Nevertheless, the low number of individuals, and large‐scale habitat changes (i.e. vegetation succession caused by abandonment of traditional land use and possible changes in water supply) would lead to the decline of the green alder population in Croatia. Because of its rarity, uniqueness, and scientific and conservational importance, the green alder in Croatia deserves special conservational measures and protection. Ecosystem management practices required to ensure the conservation of this rare and locally threatened woody plant species in Croatia are discussed in this paper.

conservation ; ecosystem management ; green alder ; morphology ; variability

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