•The suggested procedure enables estimation of tree species composition alteration.•The alteration was primarily the result of past land use and forest management.•The alteration decreased along the ...gradients of rockiness, inclination and elevation.•Greater alteration appeared in areas closer to forest edge.•The alteration increased the susceptibility of forest stands to natural disturbances.
The alteration of natural tree species composition is defined as the deviation of the current tree species composition from that of the natural state. It can be used as a measure of human influence on forest vegetation, and thus as an indicator of the naturalness of forest vegetation. The aim of the study was to develop a standard procedure for estimating the alteration of natural tree species composition, to explain factors driving alteration and to examine its significance for susceptibility of forest stands to natural disturbances. The alteration of natural tree species composition was estimated for the Dinaric region (5556km2, Slovenia) by the Robič Index of Dissimilarity (RID), ranging from 0 (completely natural) to 100 (completely altered). The index was calculated on the compartment level (24ha each on average) with data on current and potential natural forest vegetation. The influence of human activities on tree species alteration was examined by using topographic and accessibility variables. The susceptibility of forest stands to natural disturbances was analysed with data on sanitary felling. In the study area, the natural tree species composition of forest stands is moderately preserved; the average value of RID was 50.05, ranging from 1.76 to 100, and the coefficient of variation was 0.49. The alteration of the natural tree species composition of forest stands is primarily the result of forest management and past land use, conditioned either by topography or accessibility of forests. The degree of alteration of tree species composition decreased along the gradients of rockiness, inclination and elevation. A greater degree of alteration appeared on the slopes of intermediate and south facing aspects than on north facing slopes, and in areas that were closer to the forest edge. A higher level of alteration significantly increases the susceptibility of forest stands to natural disturbances. The procedure represents a novel approach in modelling the alteration (naturalness) of tree species composition of forest vegetation. It is applicable at different spatial scales and fosters an understanding of the patterns of tree species composition under the influence of human activity across forest landscapes.
•We examined successional trajectories in fenced and unfenced salvaged stands.•Spruce’s share in regeneration density decreased over time.•Fencing accelerated successional development and favoured ...broadleaves.•Regeneration niche partitioning was affected by meso-relief and forest edge.•Shorter distances to seed trees favoured spruce and anemochorous broadleaves.
Management of Norway spruce monocultures in Europe is becoming increasingly difficult due to frequent natural disturbances. Their transformation could be especially challenging if several disturbances interact. In 2003 a spruce bark beetle outbreak damaged large tracts of spruce bottomland successional forest in southeast Slovenia where overabundant ungulate populations are present. In openings (5.4–7.5ha in size) in four salvaged forest compartments, we studied the effects of meso-relief, forest edge, seed trees and fencing on vegetation succession and tree regeneration. In 2005 and 2013 we sampled seedling density on 240 plots according to height class and species. In the second inventory we also assessed distance to seed trees and on a subsample of the plots the coverage of vascular plants. The results indicated sufficient natural regeneration and niche partitioning among species groups, with Norway spruce seedlings being more successful at stand edges, pioneers and anemochorous broadleaves in gap centres, and zoochorous broadleaves on plateaus as opposed to sinkholes. Seedling density of all anemochorous broadleaves was higher closer to seed trees. Spruce seedling abundance was negatively associated with the cover of herbaceous vegetation and that of pioneer trees with shrubs. Fencing resulted in significantly greater density, height and coverage of seedlings as well as a higher share of broadleaves. While bark beetle outbreak triggered regeneration of broadleaves, overbrowsing acted in the opposite direction by facilitating spruce. Thus, to accelerate successional development and to prevent a spruce dominated alternative ecosystem state, a significant reduction in deer abundance is needed. To safeguard seed sources, promote seed dispersal by encouraging perches and shelters, and preserve potential habitats, some damaged trees should be retained during salvaging operations.
We have expanded our knowledge of the localities, sites and distribution of the Amelanchiero ovalis-Pinetum mugo association in the Slovenian Alps. Based on phytocenological analyses, the shrub ...association belonging to the forest vegetation type Alpine mountain pine scrub was divided into two subassociations: peucedanetosum oreoselini and hylocomiadelphetosum triquetri. We also described four variants within the latter association.
Questions
We investigated the influence of protracted mortality of a dominant canopy tree (Abies alba) on long‐term understorey dynamics. We ask (a) how tree regeneration and understorey species ...diversity and composition changed over 32 years; and (b) whether the observed changes were mainly driven by mortality of A. alba.
Location
Three old‐growth forest reserves dominated by A. alba and Fagus sylvatica in the Dinaric Mountains of Slovenia.
Method
Tree layer and understorey regeneration and herbs were surveyed in 147 plots across the three forest reserves in 1983 and 2015. Soils were also sampled in 2015. The study period coincides with a protracted period of increased A. alba mortality in the canopy layer associated with anthropogenic emissions.
Results
Between 1983 and 2015, the decline in canopy layer A. alba caused a recruitment pulse of F. sylvatica regeneration to the subcanopy tree layer across the three reserves. These changes were accompanied by a significant decline in plot level herb species richness. A model‐based analysis of beta‐diversity revealed significant community convergence during the study period, mainly caused by the loss of rare species. Ellenberg values indicate that these changes were mainly driven by loss of understorey light, while an increase in soil pH may have played a role also.
Conclusions
This observational study suggests that the long‐term decline of A. alba resulted in a cascade of processes — widespread F. sylvatica recruitment that impeded penetration of light to the forest floor, and possibly a change in soil conditions due to the decline of coniferous litter. These changes caused a significant loss of herb diversity and homogenization of the understorey community across the three sites. This study sheds light on the potential cascading consequences triggered by episodes of increased tree mortality resulting from global‐change‐type drivers.
We examined how long‐term mortality of a foundation conifer tree influenced understorey vegetation dynamics. Canopy mortality caused a recruitment pulse of broad‐leaf regeneration, which resulted in a significant loss of herb diversity and homogenization of the understorey community. This study sheds light on the potential cascading consequences triggered by episodes of increased tree mortality resulting from global‐change‐type drivers.
Based on hierarchical classification of more than 300 phytosociological relevés of basophilic black and (or) Scots pine communities in the Southern, Eastern and Southeastern Alps we described a new ...association
, into which we classify stands that have until now been discussed in the framework of subassociations
and (partly)
, and are floristically slightly similar also to certain forms of the association
. The stands of the new association are for now classified into Natura 2000 habitat type Southeastern-European
forests (91R0), within it we propose a special habitat subtype Southeastern-Alpine Scots pine forests, and into a new forest site type Southeastern-Alpine Scots pine forest. At the contact of the Julian and Dinaric Alps we described a new subassociation
which comprises also a Natura 2000 species
Since the mid-19th century, Pinus nigra plantations have played a key role in the restoration of degraded European landscapes. Nowadays, these plantations are aging and prone to natural disturbances, ...insect infestations, and diseases. For their successful gradual conversion, knowledge of optimal gap spatiotemporal dynamics is crucial. We studied herb and natural regeneration patterns along with site factors on 477 subplots within 44 plots distributed over four stand types: closed stand (14% diffuse light), open stand (21%), gap edge (23%), and gap (57%). Despite the abundant Quercus petraea, Q. cerris, and Q. pubescens mast year, no one-year seedlings were recorded, which is likely due to the summer drought. Short seedlings (h < 20 cm) of Quercus sp., Fraxinus ornus and Ostrya carpinifolia were more successful within closed stands. Short Quercus seedlings were positively associated with soil depth and negatively associated with soil nutrients, distance to seed trees, and Sesleria autumnalis coverage. Taller Quercus seedlings required more light than both of its strongest competitors and were positively related to humid soils and less rocky sites. Ungulate overbrowsing significantly impeded natural regeneration. The results indicate a satisfactory Quercus density for conversion and the importance of advanced regeneration, which should be gradually, but persistently, released by progressively widening gaps.
As the Slovenian language is one of the rare common identity shared by all Slovenian nationals, Slovenians are unduly sensitive to the influence of foreign tongues on their own language. This is the ...reason behind the great divide between the actual Slovenian language and its idealized image. By advocating the use of “correct” Slovenian in films – where it does not belong due to the nature of the medium – the Slovenian linguistic establishment damaged the Slovenians’ relationship to their own cinema.
This paper provides phytosociological tables that describe scrub and forest communities with Alnus viridis in the Slovenian Alps. We described three new associations: Rhododendro hirsuti-Alnetum ...viridis (a green alder community on calcareous bedrock in the Eastern and Southeastern Alps), Huperzio selagi-Alnetum viridis (a green alder community in the silicate rocks under Mt. Komen in the eastern Savinja Alps) and Alno viridis- Sorbetum aucupariae (a successional stage of mountain ash and green alder on potential beech sites in the foothills of the southern Julian Alps; similar stages are known also elsewhere in the Alps), and presented additional three associations (Polysticho lonchitis-Fagetum, Rhodothamno-Laricetum and Rhododendro hirsuti-Pinetum mugo) whose stands comprise green alder.
V članku s fitocenološkimi tabelami opisujemo grmiščne in gozdne združbe, v katerih v slovenskih Alpah uspeva vrsta Alnus viridis. Opisali smo tri nove asociacije: Rhododendro hirsuti-Alnetum viridis (združba zelene jelše na karbonatni podlagi v vzhodnih in jugovzhodnih Alpah), Huperzio selagi-Alnetum viridis (združba zelene jelše v silikatnem skalovju pod goro Komen v vzhodnih Savinjskih Alpah) ter Alno viridis-Sorbetum aucupariae (sukcesijski stadij jerebike in zelene jelše na potencialno bukovih rastiščih v prigorju južnih Julijskih Alp, podobne stadije poznajo tudi drugod v Alpah) ter predstavili še tri druge asociacije (Polysticho lonchitis-Fagetum, Rhodothamno-Laricetum in Rhododendro hirsuti-Pinetum mugo), v čigar sestojih uspeva zelena jelša.
PDF
