Meta-analysis is used to compare the patterns of the tree and the herb layers in a Central-European deciduous hardwood forest. Vegetation patterns are represented by distance matrices and dendrograms. The significance of the relation between the patterns is evaluated through permutation (Mantel) tests and full randomization (Monte Carlo simulation) tests. The relationship between the two layers is significant but weak. When using ecological indicators as variables for characterising the herb layer, the relation is stronger. Distance matrices and dendrograms describe the vegetation pattern similarly. However, the results of pairwise tests of significance strongly depend on the “level” of comparisons, i.e., whether distance matrices or dendrograms are compared. This follows perhaps from the differences between permutation and full randomization tests.
Bryophyte vegetation on volcanic rock outcrops and dead wood is studied in a near-natural montane beech stand in northern Hungary. Substrate specificity of the species and the existing interspecific relationships are described. The most important species combinations and their diversity are evaluated using information theoretical functions and Monte-Carlo simulations. All analyses are based on presence/absence data of 33 species in 1508 100 cm2 microplots. Most species exhibit strong substrate specificity. Of the species that occurred with frequencies higher than 10, 8 are associated to rock, 5 to dead wood and 5 to both substrate types. Analyses of interspecific associations and agglomerative classification reveal that frequent species of species-poor bare rocks are separated from species-rich assemblages of humus-rich outcrops and coarse woody debris. Monte Carlo simulations reveal that many species combinations are significantly more frequent than expected under the assumption of random combining of species. Observed number, diversity and evenness of species combinations are significantly lower, whereas interspecific constraint (expressed as associatum) is significantly higher than under the neutral models even when data are stratified according to substrate type. The presence of coarse woody debris, not only provides habitat for wood inhabiting bryophytes, but also results in diverse rupicolous bryophyte assemblages on humus-rich outcrops.
This study investigated if ecological traits of forest floor vegetation could be used as indicators of naturalness of beech forest in Hungary, by comparing near-natural unmanaged stands with managed ones. Seventeen patches in the unmanaged Kékes Forest Reserve were compared with 11 subcompartments of different ages in the surrounding managed forest. In each stand, the character state distributions of 9 ecological species traits were calculated based on presence/absence data of plants. Averages for unmanaged versus managed stands were compared. Significant effects of management were shown. The characteristics of herbaceous plants with higher frequency in managed stands include late start and longer duration of flowering, overwintering canopy, and small epizoochorous seeds. Unmanaged stands are richer in plants that bear leaves from spring to autumn, start flowering early or flower very shortly, produce large seeds. Relevance of this method is discussed for Central Europe, where in large areas intensive forest management rather than fragmentation or break in forest continuity is the major human disturbance.
Authors:Zs. Mag, T. Szép, K. Nagy, and T. Standovár
In this study we (1) examined the applicability of the widely available CORINE land cover map of Europe in predicting several components of the richness of forest breeding bird community, and (2) analysed how different ecologically meaningful species groups respond to the differences in landscape composition and how these differences are reflected in the relationships between total species richness and richness of these species groups at the 2.5 × 2.5 km2 scale. We found that landscape composition had only moderate success in predicting the richness components of the forest bird community. The predictive power of the applied general linear models differed very much: roughly 60% of the observed variance was explained when the dependent variables (species richness and abundance) were calculated using data of all the 21 studied forest bird species or that of common forest birds. However, species richness and abundance of groups of more vulnerable species were predicted with much less success (30% variance explained), suggesting that CORINE is not an adequate tool in predicting the conservation status of these sensitive forest birds. Forest cover explicated 90 to 100% of the explained variance in the models suggesting that forest bird community was much less sensitive to the type of land cover occuring in the surroundings. We showed that richness and abundance of selected species groups had different non-linear relationships with total species richness, suggesting that — if used alone —, total species richness is a weak predictor of other richness components of the forest bird community.
Authors:K. Kenderes, R. Aszalós, J. Ruff, Zs. Barton, and T. Standovár
We analysed the role of topography, tree stand characteristics and management on the susceptibility of forest stands to abiotic natural disturbances. In 1996, stands of Börzsöny Mts, Hungary were hit by a severe ice storm, then by strong winds three years later. Affected areas were mapped on aerial photos, and we built a GIS database containing variables describing topography and tree stand characteristics. The role of variables in predicting ice break and windfall was investigated by non-parametric statistical tests and by a series of C&RT (Classification and Regression Tree) analyses. Elevation, aspect and slope proved to have strong statistical relationships with the distribution of both ice break and windfall, with misclassification error (MER) of 18% and 15%, respectively, if studied without stand descriptors. Mixing ratio and age of beech were the most important stand descriptors to explain the distribution of ice break (MER=15%), whereas that of windfall was best described by the age and height of the two dominant tree species (MER=11%). The explanatory power could be increased if all variables (topographic + stand descriptors) were considered, though the increase in explanatory power was higher in the case of ice break (MER decreased from 15% to 11%) than for windfall (MER decreased from 11% to 10%). Since management related stand variables (beech mixture ratio, age, height, amount of recently felled stock, slenderness) and susceptibility to disturbance events seemed to be related, our results suggest that the sensitivity of tree stands could be decreased by increasing compositional and structural heterogeneity.
Authors:T. Standovár, P. Ódor, R. Aszalós, and L. Gálhidy
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.
Authors:T. Standovár, F. Szmorad, B. Kovács, K. Kelemen, M. Plattner, T. Roth, and Zs. Pataki
A new forest state assessment methodology to complement existing conservation and forestry data has been developed. The aim is to provide tools for strategic planning including spatial distribution of conservation priorities. The method is point-based using a dense systematic sampling grid and provides more detailed information than vegetation maps or forest subcompartment descriptions, but requires less effort than forest inventories. Indicators include canopy composition and structure, deadwood, herbs, microhabitats, disturbances, shrubs and regeneration. The results can inform managers about the structural and compositional diversity of forest stands in the form of thematic maps and can provide the basis for analysis of habitat suitability for forest-dwelling organisms. A smartphone application has been developed to enable electronic data collection. PostGIS and Python scripts were used in the data flow. In this paper, we outline the development of the assessment protocol, and present the sampling design and the variables recorded. The main advantages of the survey methodology are also shown by case-studies based on data collected during the first field season in 2014. The protocol has been designed for low mountain forests in Hungary, but it can be modified to fit other forest types.