This paper presents the Environmental Concern Kuznets Curve (ECKC) theory about decreasing environmental concern in the most developed and protected area-rich countries. We analyzed the relationship ...between the protected area (PA) coverage, environmental concern and GDP per capita in the 42 most developed countries in the 1990s, 2000s and 2010s. Our conclusion is that 1) as countries develop, environmental protection becomes less dependent on economic development; 2) at high levels of economic development, environmental concern decreases; 3) environmental concern reaches a maximum at 20–30% of PA coverage and decreases beyond this point. The influence of human values and factors at the local level was determined by a national survey (n = 999) on public attitudes toward greater conservation of forests in Slovenia. The results comply with the ECKC theory; the higher the naturalness of forests in the surroundings of a respondent's home, the lower the support for greater conservation. However, the study suggests that human values play a prominent role. Support for conservation largely depended on the respondents' general attitude toward forest cover and growing stock, harvesting intensities, satisfaction with the level of control in forests and concern for the population of protected brown bears. The general belief that ecosystems are fragile and there are limits to growth increased support for conservation by 33%. We conclude that the environment in the most developed countries is likely to experience increasing pressure due to decreasing environmental concern and its decoupling from objective problems.
•At high levels of economic development environmental concern decreases.•Environmental concern reaches a maximum at 20–30% of protected area coverage.•Detailed analysis for the world's best performing country in biodiversity protection.
Silver fir (Abies alba Mill.) is one of the most valuable conifer trees in Europe for historical and economic reasons. Growing interest in the species, along with the recognition that silver fir was ...subjected to inappropriate silvicultural measures during the 20th century due a lack of understanding of its ecology, have spurred recent studies from various disciplines which have yielded new insights into the gene ecology, history, ecology, structure and dynamics of fir populations. In this paper, we provide a multidisciplinary, synoptical review discussing the prospects for silver fir forestry in the 21st century. We describe the main characteristics of the history and ecology of silver fir, with a particular emphasis on gene ecology and the structure and dynamics of fir populations with respect to mixed stands and fir management. Fir is a fundamental species for maintaining high biodiversity in forested ecosystems because of its shade tolerance, plasticity to environmental conditions and ability to coexist with many tree species. Silver fir ecotypes show remarkable variation in features such as frost hardiness, drought resilience and shade tolerance. Fir can create stands of heterogeneous stand structure, from one-storied through to multi-storied structure and finally to selection structure. Natural regeneration of fir will be scarce if fir stands are managed inappropriately through the application of clear cutting, a short regeneration period and abrupt removal of shelter trees. Climate change is expected to reduce the abundance and distribution range of silver fir. Improvements in forest management treatments are recommended to improve silver fir conservation.
•Recruitment of beech, spruce and fir in uneven-aged stands studied on 200 m2 plots.•Optimal and critical levels of 18 influential factors determined with the Tobit model.•Stand basal area and the ...proportion of target tree species are key factors.•Stocking control is efficient for regulating recruitment of spruce and beech.•Fir recruitment is weakly limited by stand density and largely stochastic.
Tree recruitment models are important for predicting the dynamics of uneven-aged forests. Previous studies of recruitment of European beech, Norway spruce and silver fir have shown different ecological amplitudes of these species. However, recruitment in uneven-aged stands and the values of environmental factors at which the greatest and poorest recruitment can be expected remain poorly explained. The main objectives of this study were to 1) explain how 39 stand, site and climatic factors and their interactions influence the number of recruited trees in uneven-aged forests; 2) determine the optimal and critical ranges of influential factors, including stand basal area, number of trees, proportion of tree species, shade casting, soil pH, site productivity, temperature and precipitation; and 3) estimate the maximum expected response of recruitment to changes in stand density while controlling for the effect of other limiting factors. A Tobit censored regression model was used to consider that the observed range of the number of recruited trees is censored at zero. The models were parametrized and validated using 30,963 forest inventory plots (200 m2 each) in uneven-aged forests in Slovenia. The models, which used 9 stand, 6 site and 3 climatic factors, explained 15 %, 10 % and 8 % of the total variation of the number of recruited spruce, fir and beech, respectively. Stand structure was the most important factor, with stand basal area (BA) and the proportion of the studied species having the greatest effect. Site factors including soil pH and rockiness were important for fir recruitment. The number of recruited beech and spruce was positively influenced by decadal precipitation. Higher temperatures decreased recruitment of spruce. Beech was the only species sensitive to shade casting. Recruitment of beech was higher if shade was imposed by tree species other than beech. The optimal and critical ranges of limiting factors differ between species. The model suggests that the optimal stand basal area for recruitment of beech is ≤ 19 m2/ha, which is higher than that for spruce (≤ 16 m2/ha) but lower than that for fir (≤ 28 m2/ha). The maximum predicted response of the studied species to changes in stand basal area shows that stand density control is efficient for regulating recruitment of spruce and beech, but not for fir. The suggested sensitivities and threshold values may be used in individual tree growth models or simulation–optimization studies in support of forest management decisions.
•Self-thinning models were developed for several types of uneven-aged forests.•Pure stands are denser than mixed stands but their maximum stand density lines are steeper compared to mixed ...stands..•The proportion of beech increases the intercept and slope of the maximum stand density line.•Single-tree selection stands have the greatest intercept and the steepest slope of the maximum stand density line.•Quantile Regression and Stochastic Frontier Analysis predictions are congruent.
The self-thinning law describes the progressive mortality of growing trees in crowded even-aged stands because of competition. In uneven-aged stands, however, density-dependent mortality is relatively poorly known. We developed density-dependent self-thinning models for mono-species and multi-species uneven-aged stands. Three models for mono-species Picea abies, Abies alba and Fagus sylvatica stands, four models for mixed conifer/broadleaf stands and a model for single tree selection stands as a specific type of uneven-aged forest were parametrized by Quantile Regression (QR) and Stochastic Frontier Analysis (SFA) using data from n = 31,612 forest inventory plots in Slovenia. The average slope of the self-thinning line in uneven-aged stands of −1.422 was statistically significantly lower than Reineke’s slope. Maximum stand density was higher in mono-species stands than in multi-species stands. The higher the proportion of beech in a stand, the higher the intercept and slope of the maximum stand density line. In single tree selection stands, the intercept and the slope of the maximum stand density line were highest and statistically different from all other types of uneven-aged forests. Species mixture had an impact on the slope and intercept of the self-thinning line. The slopes of the self-thinning lines differed between the studied types by up to 36% and 69% in the SFA and QR models, respectively, while the intercepts differed by up to 13% and 24%, respectively. However, maximum stand densities differed significantly only between compositionally very dissimilar stand types, such as Fagus sylvatica- or Picea abies-dominated mixtures versus other broadleaf mixtures (e.g., Quercus petraea, Carpinus betulus). The SFA predictions of maximum stand densities were systematically lower and less varying than the QR predictions, but not statistically different. The models can be used to constrain individual tree growth models in uneven-aged forests and to estimate the onset of inter-tree competition in irregular stands.
The main objectives of the study were to (1) determine the response of the diameter growth of silver fir, Scots pine, and black pine in Central European seminatural forests to tree, stand, and ...environmental factors and (2) test for differences in their growth rate on different soils. Based on 26,291 permanent sampling plots (500 m² each), we developed a linear mixed-effects model of the diameter increment for each of these tree species. The models explained 32%–47% of the total diameter increment variability. The models differ in the set of predictors. All models suggested a non-linear effect of tree diameter on diameter increment. Nine predictors were common to all three models (stand basal area, quadratic mean diameter, basal area of overtopping trees, the proportion of beech in the stand volume, inclination, elevation, mean annual temperature, mean diurnal range, and soil unit), and six predictors were specific for one or two models (tree diameter, logarithm of tree diameter, proportion of other broadleaves, site productivity, rockiness, eastness index). Tree diameter was the most important variable for fir growth, while climatic variables explained most of the variability in pine diameter growth. The soil unit contributed from 5.3% to 7.5% to the explained diameter increment variability. Although the developed models are only locally accurate and cannot be used outside the study area without validation, the model predictions can be compared to those in other stand growth simulators and other geographical regions.
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.
•In Central European forestry the concept of »forest functions« (FF) was developed quite earlier compared to the general concept of ecosystem services.•FF are a spatially explicit tool for dealing ...with forest areas with high societal value.•FF maps are important for adapting management regime, collaborating in land-use planning and subsidizing measures for providing desired services.•The current varieties of the concept of FF indicate important differences among the Central European countries.
Forest functions (FF) are a constituent part of the concept of sustainable and multifunctional forestry in Central Europe (CE). We describe the origins and development of the current concept of FF in CE forestry and assess FF as a spatially-based tool for multi-objective forest management and policy based on a framework of six dimensions (purpose, type, legal status, mapping procedure, management and implementation). Designated FF areas indicate areas of relatively higher importance for public interests. In CE forestry, five specific purposes of FF can be identified: i) a tool for an adapted management regime, ii) the allocation of public money to subsidize services, iii) land use planning, iv) identification of ‘valuable’ locations in forest areas and v) a basis for dialog between the forestry sector and the public. Three main FF types are defined: productive (economic, supply), protective (ecological, environmental) and social (well-being, recreational), which are all further classified. One or more (or no) FF can be designated and overlapped in the same forest area. The public forestry administration has the main authority in the designation of FF, but several public services, NGOs, forest owners and the public may or must be involved in the designation process. Mapping FF areas is usually an essential part of forest planning at the landscape or regional spatial scale. The management regime in the designated areas, if compared to that used in general forests, is either the same, slightly adapted, strongly modified or restricted so as to ensure the provision of the target services. Management arrangements for providing desired FF on non-state forest land can be supported by financial instruments. The main advantage of FF is that they are a spatially-explicit tool for dealing with forest areas with high societal value. Three main criticisms of FF can be identified depending on how they are implemented: lack of operationalization, inadequate monitoring of management effectiveness and normative designation and mapping of FF.
Questions
What is the long‐term impact of deer browsing on the diversity of the herbaceous layer and tree species regeneration? Which parameters of regeneration of the tree species regeneration and ...the herbaceous layer best indicate browsing impact?
Study site
Dinaric Mountains, Slovenia.
Methods
We studied the long‐term impact of red deer on mixed temperate forests by comparing the tree species regeneration and herbaceous layer vegetation under two treatments: deer present, no deer. We analyzed the regeneration of trees older than one year up to a diameter at breast height of 10 cm (categorized into five height classes) and the cover abundance of plant species in the herbaceous layer (<50 cm).
Results
There were no significant differences between the treatments in the number of tree species regeneration. Browsing impact on the most abundant tree species—European beech, silver fir and sycamore—varied, indicating differences in palatability. When deer were present, the number of silver fir regenerating was significantly lower in all height classes, and regeneration of European beech specimens shorter than 50 cm was more abundant, while for sycamore shorter seedlings (<20 cm) were more abundant, and regeneration of taller specimens (≥50 cm) was significantly less abundant. The reduction of tree species diversity during natural regeneration is evident. There were no significant differences between the treatments in the number and diversity of plant species in the herbaceous layer; however, the abundance of 13 plant species differed significantly between the treatments. Deer reduce the density of tree species saplings due to long‐term browsing and thus indirectly increase tree species diversity in the regeneration up to 20 cm in height and plant species diversity in the herbaceous layer.
Conclusions
We documented the direct and indirect impact of deer on the diversity of tree species regeneration, but only found an indirect influence on the diversity of the herbaceous layer. The height structure of palatable tree species regeneration appears to be the most appropriate indicator of browsing impact. The observed browsing impact leads to the complete dominance of European beech in the tree species composition of forest stands.
Naturally regenerating tree species showed different, size‐dependent responses to the impact of red deer. Deer prevented recruitment of palatable tree species above the browse layer. No plant species in the herbaceous layer went locally extinct because of deer; however, deer influenced the abundance of some plant species. Deer indirectly increased plant species diversity in the herbaceous layer by reducing the density of tree saplings.
•Soil is a stronger driver of forest productivity than climate or topography.•Stand and tree growth rates differ significantly between soil units.•The soil unit is a more important variable in tree ...growth than in stand growth.•Most tree species exhibit the highest and the lowest growth on different soil units.•Most of the studied tree species grow most poorly on calcareous Leptosols.
We determined the size of differences in stand and tree growth in semi-natural forests with respect to 16 reference soil groups. The forest area of Slovenia (11.8 thousand km2) was used as the study area, and reference soil units were derived from the national soil map at a 1:25,000 scale consisting of 10,781 polygons with an average size of 117.95 ha. Stand growth was defined as periodic stand basal area increment, while the growth of Norway spruce, silver fir, Scots pine, European beech and sessile oak trees was estimated by the periodic diameter increment of 238,349 dominant trees on 67,061 permanent sampling plots. A linear fixed-effects model and linear mixed-effect models were used for studying stand and tree growth in different site, stand and tree conditions. The soil unit was the dummy variable with Dystric Cambisols set as the reference category. Soil contributed 4.3 % to the explained variability of basal area increment and 4–27 % to the explained variability of the diameter increment of the five tree species. Soil was a stronger driver of stand and tree growth than climate or topography. Stand and tree species production rate on soil units was in the interval of −28 % to +5 % and −47 % to +14 % of that on the reference soil unit, respectively. Stand growth was the highest on Eutric Gleysols and the lowest on Histosols, and tree species generally exhibited the highest and the lowest growth rates on different soil units. We suggest that soil should be considered in growth models and studied interrelatedly with climatic, site and stand variables.
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