Sensitivity of ground layer vegetation diversity descriptors in indicating forest naturalness

Abstract

Different diversity measures of forest floor assemblages were evaluated in order to check if they can be used as indicators of forest naturalness. We compared vascular and bryophyte vegetation of two habitat types in an unmanaged beech-dominated reserve and five managed stands of different ages. We used systematically collected data characterizing four spatial scales obtained by successively aggregating neighbouring quadrats. Species richness did not always differentiate near natural sites from managed sites, and the observed difference depended very much on the spatial scale used. The behaviour of Shannon-Wiener diversity function can only be understood if both the species richness and the evenness components are considered. Near natural plots had high Shannon-Wiener diversity values even at the finest spatial scale not only because of high number of species, but also because of high evenness. We found that a simple measure of pattern diversity-spatial variation of species importance-was the most effective in differentiating the diversity of plots with different levels of naturalness. The absolute values of pattern diversity in the forest floor vegetation were the highest in those plots where the characteristics of important limiting ecological factors were generated by natural disturbance. Vascular and bryophyte species responded differently to tree stand structural characteristics. The diversity of vascular vegetation was determined mainly by the spatial variation of light availability, whereas that of bryophyte vegetation responded to the amount and spatial heterogeneity of appropriate substrates (dead wood, rock). The use of pattern sensitive diversity measures is necessary to reveal diversity-naturalness relationships. We suggest that all diversity descriptors should be calculated for different spatial scales, since their change with spatial scale was as informative as their actual values.

Examination the health state with instrumental measurements and the diversity of sessile oak stands in Zemplén mountains

“…The herbaceous taxa play an important role in the diversity of forests, as they take part in the carbon storage and nutrient supply; moreover have a great impact on the primary production (Whigham 2004). In addition these species are proved to be appropriate indicators of the environmental changes because of their relative quick life cycle (Standovár et al 2006). The different types of disturbance have direct or indirect influences on the species composition and on the structure of the given layers (Brunet et al 1996, Decocq et al 2004, Van Calster et al 2008, von Oheimb & Härdtl 2009).…”

The effects of stand characteristics on the understory vegetation inQuercus petraeaandQ. cerrisdominated forests

“…The relationship between the overstory and the understory is better revealed in mesic forests (Burrascano et al 2011, Graae and Heskajer 1997, Härdtle et al 2003, Kelemen et al 2012, Standovár et al 2006. In case of dry, oak dominated forests, our knowledge is more incomplete, in spite of their economic and conservational significance.…”

The effect of contrasting management types on two distinct taxonomic groups in a large-scaled windthrow

“…Estimated species richness should also be treated with caution when used as an important factor of habitat value: the estimated species richness of scuttle flies and birds was higher for the managed windthrow when compared to the natural windthrow. Again, this result suggests that species richness is not a universal indicator of the natural state of the habitat (Standovar et al 2006). On the basis of the result, one may conclude that natural disturbances are not necessarily associated with higher species richness and species diversity relative to anthropogenic forest transformations.…”