engleski

Who’s afraid of altitude? – Bryophytes vs. vascular plants along the elevational gradients of Dinaric Alps (Western Balkans)

Species composition and species richness along the altitudinal gradients have been a topic of interest in biogeography and ecology for a long time. Comparison of different taxonomic groups along the same elevational gradients are extremely rare globally. A comparative study of the altitudinal distribution of bryophytes and vascular plants on littoral Dinarides was conducted along two complete, about 1600 m long elevational transects in Gorski Kotar and Velebit, embracing eight discrete forest elevational belts. Both taxonomic groups showed similar patterns of alpha diversity, best described by the cubic regression function with diversity maxima approximately between 1100 and 1200 m a.s.l. The total number of taxa of vascular plants and bryophytes is the lowest in the lowest belt of holm oak, and the highest in the complex of spruce communities. Vascular plants exhibit the highest species turnover (beta diversity) on the border of two phytogeographical regions, while the most prominent species turnover of bryophytes appears with evergreen boreal (spruce) and subalpine (pine krummholz) vegetation types. Bryophytes exhibit wider altitudinal ranges and a greater tendency toward exclusively higher elevations compared to vascular plants. Neither vascular plants nor bryophytes follow Rapoport’s rule of increment of the average altitudinal range of species with increasing elevation. Flora assemblages along the altitudinal gradients are ecologically primarily defined by gradients of climatic indicator values (temperature and humidity) for both taxonomic groups, while bryophyte assemblages are additionally defined by gradients of substrate characteristics (nitrogen amount and pH reaction). The indicator values for bryophytes exhibit weaker indicator potential in explaining floristic composition compared to indicator values for vascular plants, which proves that these two groups only partially describe the same ecological gradients. This research is one of the few studies of the altitudinal distribution of bryophytes in Europe and the first in the Dinaric Alps and the Balkan Peninsula.

Croatia, diversity, Gorski Kotar, richness, Velebit

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