Climate is a strong predictor of the geographic distribution of tree species, and thus climate change may trigger shifts in the distribution of a tree species and/or its demographic structure. In the ...study, we aim to comprehensively compare the distributions of four life stages of European beech (Fagus sylvatica) (i.e., regeneration, recruitment, young trees and mature trees) in forests in Slovenia, Central Europe, which are characterized by strong gradients of elevation (ELV), temperature (TEMP) and precipitation (PREC) to detect possible shifts in distribution and demography. Beech life stages were surveyed on 3366 plots. To depict disparities between ELV, TEMP and PREC distributions of beech life stages, we applied several non-parametric methods: basic statistical tests to study differences in medians, means, and 1st and 9th deciles; generalized additive models to study shifts in the optimum; and extreme value analysis to study shifts at the trailing and leading edges. A substantial shift in juvenile beech stages upward and toward colder sites was detected. However, the shift was not uniform along the distributions; the most significant shift was detected at the leading edge of ELV (+73 m) and TEMP (−2.6 °C), but surprisingly there was no beech movement identified at the trailing edge. The observed shift may be a result of the interplay between climate change, high spatial variability in microclimate, unexceptional droughts in the recent past, changes in forest use and possible limitations in the migration ability of beech and its adaptation capacity.
Disentangling the relative influence of background versus disturbance related mortality on forest demography is crucial for understanding long‐term dynamics and predicting the influence of global ...change on forests. Quantifying the rates and drivers of tree demography requires direct observations of tree populations over multiple decades, yet such studies are rare in old‐growth forest, particularly in the temperate zone of Europe. We use multi‐decade (1980–2020) monitoring of permanent plots, including observations of mode of mortality and disturbance events, to quantify rates and drivers of tree demography across a network of old‐growth remnants in temperate mountain forests of Slovenia. Annual rates of mortality and recruitment varied markedly among sites and over time; census intervals that captured intermediate severity canopy disturbances caused subtle peaks in annual mortality (e.g., >2%/year), while rates of background mortality in non‐disturbed intervals averaged about 1%/year. Roughly half of the trees died from modes of mortality associated with disturbance (i.e., uprooting or snapped‐alive). Results of a Bayesian multilevel model indicate that beech (Fagus sylvatica) had a higher likelihood of disturbance related mortality compared to fir (Abies alba), which mainly died standing, and there was a notable increase in the odds of disturbance mortality with increasing diameter for all species. Annual recruitment rates were consistently low at sites (<0.5%) that lacked evidence of disturbance, but often exceeded 3% on sites with higher levels of past canopy mortality. Recruitment was dominated by beech on sites with more diffuse background mortality, while the less shade tolerant maple (Acer pseudoplatanus) recruited following known disturbance events. Our study highlights the important role of stand‐scale, partial canopy disturbance for long‐term forest demography. These results suggest that subtle climate‐driven changes in the regime of intermediate severity disturbances could have an important influence on future forest dynamics and warrant attention.
We use multi‐decade monitoring of permanent plots to quantify rates and drivers of tree demography across a network of old‐growth remnants in temperate mountain forests. Annual rates of mortality and recruitment varied markedly among sites and over time, and roughly half of all trees died from disturbance related mortality. Our study highlights the important role of stand‐scale, intermediate severity disturbance for long‐term forest demography.
The aim of the article is to assess the potential impacts of climate change on Slovenian forests in the period 2080–2100 based on two climate scenarios: SSP1-2.6 (optimistic) and SSP5-8.5 ...(pessimistic) using the MaxEnt software. Slovenian forests are divided at the ecological community level into thirteen forest vegetation types. Analyses of changes in ecological niche areas, distances of vectors between centroids of present areas and future ecological niches, and general spatial changes are carried out. In addition, changes in the altitudinal zones of forest vegetation types were investigated. The results indicate significant changes for Thermophilous beech forests and Thermophilous hop-hornbeam, sessile oak, downy oak, Scots pine and black pine forests. The potential changes in the altitudinal zones of forest vegetation types indicate a clear trend of forest vegetation types moving to higher altitudinal zones.
V prispevku je predstavljen razvoj postopka proučevanja potencialnih vplivov podnebnih sprememb na slovenske gozdove v obdobju 2081–2100. Razvoj metodologije temelji na modeliranju ekoloških niš z ...uporabo metode maksimalne entropije. V raziskavi smo upoštevali dva podnebna scenarija smeri skupnega družbenogospodarskega razvoja (optimističnega SSP1-2,6 in pesimističnega SSP5-8,5). Slovenske gozdove smo razdelili na trinajst gozdnih vegetacijskih tipov. Statistični rezultati so pokazali, da je razvita metodologija primerna za namene tovrstnega proučevanja.
•Altered mixture and structure of Alpine mixed forests delays natural regeneration.•We studied optimal gap spatiotemporal dynamics for natural regeneration.•Results indicate gap and microsite ...partitioning between Norway spruce and beech.•Spruce seedlings were associated with diffuse light and thick organic horizons.•Higher topsoil moisture content, proximity of seed trees favoured beech seedlings.
Mixed mountain forests composed of Picea abies, Abies alba and Fagus sylvatica represent one of the most important alpine ecosystems with respect to economics, environmental effects and social functions. However, many stands are characterised by even-aged forest structure and altered tree species composition, making them more prone to disturbances and less effective in protection against natural hazards. Changes to the forest microclimate and nutrient cycling delay natural regeneration and favour the successional development of ground vegetation. In this study we hypothesized that the creation of gaps of appropriate size and shape would facilitate natural regeneration and forest conversion. In 2003, we selected 15 gaps, ranging in size from 0.01 to 0.62 ha and more than 50 years in age, and three areas below closed canopy on a south facing P. abies dominated mixed mountain forest (1380–1480 m a.s.l.). Within the gaps we established 542 systematically distributed research plots (1.5 × 1.5 m) and analysed regeneration attributes according to height classes, ground vegetation coverage, light climate, topsoil moisture, microsite relief and soil features. Measurements were repeated after five vegetation seasons and indicated minimal changes in vegetation structure and the slow development of regeneration overall. Vegetation ordination and generalized linear mixed models showed a positive association of P. abies seedling abundance with diffuse light, thickness of the organic horizons, presence of CWD and moss coverage and a negative association with ground vegetation cover, soil water content, Landolt indication value for nutrients and direct light. Fagus sylvatica seedlings were more abundant closer to seed trees, on less acidic soils with higher moisture content and on concave microrelief. The results indicate that P. abies and F. sylvatica seedlings may successfully establish under slightly open forest canopies, but in a few years the former require amounts of diffuse light comparable with that in the medium sized gaps in this study (0.15 ha). Due to the negative association between direct light and regeneration, gaps should be elliptical with the long axis oriented east-west. Recruitment of all species was significantly retarded by overbrowsing.
Using hierarchical clustering with unweighted pair-group method with arithmetic mean (UPGMA) we arranged 603 phytosociological relevés of beech forests on the present upper forest line, mainly from ...the Julian Alps and the Trnovo Forest Plateau (we also included the relevés from the Karawanks and the Kamnik Alps), into 32 clusters. Based on their analysis and comparison with previously described similar (alti)montane-subalpine beech communities we classified most of the relevés into the association
and its new subassociations
,
,
and several new variants. The altitude of the studied stands is predominantly 1400 to 1550 m (the upper line is at 1660 m); they occur at all aspects, frequently on steep and very steep slopes, mainly on limestone and dolomite limestone, the predominant soil type is rendzina. These stands are species rich (on average 61 species per relevé, altogether more than 500 vascular plants) and have many species in common with the stands of associations
and
•We studied regeneration dynamics in temperate forests disturbed by windthrows.•Higher seedling densities were at lower altitudes and on northerly exposed slopes.•Disturbed micro-sites, proximity of ...forest-edge favoured sapling survival.•Sapling survival was negatively associated with low sapling height and browsing.•Favouring of planted saplings decreased density of spontaneous regeneration.
We studied regeneration dynamics in forests disturbed by three different windthrow events in 2008 in Slovenia to assess the success of natural regeneration vs planting and subsequent silvicultural treatments. Fifty-three plots with planted saplings of Norway spruce and sycamore maple and 50 plots with dominant naturally regenerated saplings were selected in a randomly stratified manner. Sapling characteristics (height, height increment, root collar diameter, free-to-grow score, browsing and micro-site) were assessed in 2012 and 2014. Herbs and seedling establishment were studied in two subplots within each plot. Average seedling density was 13,074 and 14,674 ha−1 four and six years after the windthrows, respectively. Seedlings were irregularly distributed, which suggests micro-site differences in regeneration dynamics. The results indicated lower seedling success on sites that were southerly exposed, farther from the forest edge and seed trees, on undisturbed micro-sites and at higher altitudes. On such sites planting was justified. While seedling density indicated a positive relation to herb coverage, sapling survival was negatively associated with it as well as with browsing. Initial sapling height was the strongest predictor of survival. Spruce saplings had the lowest mortality, while shade-tolerant silver fir and beech experienced high mortality. The study indicated a high density and species diversity of naturally regenerated seedlings within windthrow areas, which was reduced by planting, mowing of competing vegetation and protection measures favouring planted saplings. Recommendations for the improvement of silvicultural operations for post windthrow restoration are given.
► We studied tree regeneration and vegetation in medium-sized gaps over a decade. ► Decrease in diffuse light (11.0–5.7%) indicated importance of several gap releases. ► Gap partitioning among herbs, ...beech and sycamore maple regeneration was observed. ► Beech advance regeneration under closed canopy was hindered by Allium ursinum. ► In similar conditions gap periphery seems advantageous for beech establishment.
Canopy gap recruitment in beech (Fagus sylvatica L.) old-growth forests is influenced by the interplay of the canopy gap disturbance regime, site factors, and stand history. Persistent seedling and sapling banks of beech and other shade tolerant species often play a major role in canopy gap closure. To gain more insight into interactions between medium-sized gaps and pre-gap ground vegetation patterns, we studied beech regeneration over a 10-year period on a site rich in wild garlic (Allium ursinum L.) in a Dinaric beech old-growth forest. In 1999 we selected the five largest newly created gaps (∼200m2) and systematically established 13 permanent plots (1×2m) in each gap. In 1999, 2004, and 2009, we sampled tree species regeneration (density, cover, and growth), ground vegetation (composition and cover), and light climate. Beech regeneration slowly increased in density and cover despite an overall decrease in light (11.0–5.7%). The same was not true for maple. While beech was present in all regeneration classes, dominant maple seedlings rarely reached 50cm. Beech also had a significantly greater height increment. Regeneration of both species was negatively affected by Allium cover, low light levels, and ungulate browsing. Gap partitioning was observed among shade tolerant Allium, which preferred microsites under closed canopy and low light levels, beech regeneration, which preferred gap periphery, and other less shade tolerant herbs, which favoured gap centres. The slow development of the regeneration indicated the importance of several gap releases. The high maple seedling density and less abundant beech advance regeneration in this study site compared to other beech sites suggests that Allium dominated managed forests might present an opportunity for growing less shade-tolerant species, if managed with a gap-oriented silvicultural system (e.g. irregular shelterwood).
•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.
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