engleski

Plant diversity of climatogenic silver fir – beech forest in the Dinaric karst across several mesoscale gradients

Dinaric silver fir – beech forests, with almost continuous area of 3000 km2, are the most widely distributed altimontane climatogenic forests in the Croatian high karst. Parts of it contain virgin stands, while the majority of the area is composed of selectively logged stands with naturally grown forest. Despite many researches dealt on these forests in the past, the relationships between plant diversity and the very complex environmental gradients that occur in this landscape has not been done yet. Here, we present the results of a unified survey of 151 plots distributed throughout the entire distribution area of these forests in Croatia, including virgin and managed stands. Data on floristic composition, climate, and geomorphology were gathered for all plots. After TWINSPAN and PCoA analyses of floristic data, we identified six subassociations of the Omphalodo-Fagetum association: homogynetosum, galietosum, aceretosum, mercurialetosum, asaretosum and seslerietosum. RDA analysis revealed that elevation, precipitations and latitude were the most important variables explaining variance in species composition. Partial RDA analysis has shown that latitude and longitude had highest unique contribution, while highest shared effects upon the species composition was that of climatic and elevation data. Latitude was negatively correlated with the number of plant species, Shannon-Wiener index and Evenness, while longitude was positively correlated with all these indices. Stands belonging to -asaretosum and -mercurialetosum subassociations had the highest plant diversity, while -galietosum and -homogynetosum hosted the lowest. Differences in life form spectra across subassociations, additionally confirmed significant influence of latitudinal gradient on flora of these forests. Based on their floristic assemblage, virgin stands did not aggregate together apart from managed ones, but they grouped with managed stands in different subassociations across geomorphology, elevation, climatic and geographical gradients. The present results suggest that environmental conditions are prevailing driving forces influencing plant diversity of these forests, and that present management seem to preserve that diversity.

Omphalodo-Fagetum; variation partitioning; RDA; Croatia

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