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.
Ice storms are important natural disturbances in temperate forests, yet have received little attention outside North America. Following an extreme ice storm in Slovenia, we examined patterns of ice ...damage within and among temperate forest sites and quantified differences in susceptibility to damage with respect to tree species and size across a gradient of storm intensity and site conditions. Based on a damage survey of 60 plots distributed across six unmanaged forest sites, ordinal logistic regression was used to examine patterns of ice damage as a function of storm intensity, species, tree size, and slope steepness. Our findings indicate that a complex interaction among these drivers gave rise to substantial variation in damage type and severity among species, plots, and stands. Fagus sylvatica, the most dominant species, was one of the most susceptible species to severe ice damage, while conifers (Abies alba and Picea abies) were least susceptible. Crown damage was the most common damage type at low storm intensity, while uprooting increased at higher intensity, particularly for large trees on steep slopes. Differences in species susceptibility to ice damage, combined with variation in storm intensity and site conditions, gave rise to heterogeneous damage patterns that have the potential to alter successional pathways. Based on an analysis of historical records, moderate-to-severe ice storms recur relatively frequently in the region, suggesting that they play a more important role in forest dynamics than previously thought.
A long history of human presence in the Alps has made studies of natural forest structure, composition, and disturbance processes difficult. In the Slovenian Alps, we identified a mixed European ...beech (
Fagus sylvatica L.)-silver fir (
Abies alba Mill.)-Norway spruce (
Picea abies (L.) Karst.) stand with old-growth characteristics that escaped past cutting. We reconstructed the dynamics of the stand using a combination of stand and age structure analyses, dendroecological evidence of past canopy disturbance, and historical evidence of past human activities. The disturbance reconstruction revealed a stand-scale disturbance in the 1850s. Based on the presence of pit-and-mound topography throughout much of the stand and the absence of logging activities found in historical records, we assume this event was caused by strong winds. The current structure and composition of the stand are largely a result of this event. Post-disturbance forest development was dominated by the release of shade tolerant regeneration, especially
F. sylvatica. The windthrow also created appropriate conditions (i.e. increased light and exposed mineral soil) for recruitment of less shade tolerant species, including larch (
Larix decidua Mill.) and maple (
Acer pseudoplatanus L.). The results suggest that periodic, intermediate severity wind disturbances, similar to the event documented here, may have had an important influence on pre-settlement forest dynamics in mixed mountain forests of the Alps, and add to the limited available information regarding the historic range of natural variability of disturbance processes. This information may be useful for forest management that attempts to emulate natural processes.
Exploitation of natural forests forms expanding frontiers. Simultaneously, protected area frontiers aim at maintaining functional habitat networks. To assess net effects of these frontiers, we ...examined 16 case study areas on five continents. We (1) mapped protected area instruments, (2) assessed their effectiveness, (3) mapped policy implementation tools, and (4) effects on protected areas originating from their surroundings. Results are given as follows: (1) conservation instruments covered 3–77%, (2) effectiveness of habitat networks depended on representativeness, habitat quality, functional connectivity, resource extraction in protected areas, time for landscape restoration, “paper parks”, “fortress conservation”, and data access, (3) regulatory policy instruments dominated over economic and informational, (4) negative matrix effects dominated over positive ones (protective forests, buffer zones, inaccessibility), which were restricted to former USSR and Costa Rica. Despite evidence-based knowledge about conservation targets, the importance of spatial segregation of conservation and use, and traditional knowledge, the trajectories for biodiversity conservation were generally negative.
► Long-term influence of single-tree selection system on forest structure was analysed. ► High variability of harvest intensity during last 130
years was recorded. ► Species mixture was regulated by ...canopy closure, silviculture and SO
2 emissions. ► Improvement of the system is possible by spatiotemporal combination of diverse fellings.
The single-tree selection system is an important option for management of Norway spruce (
Picea abies (L.) Karst.) and silver fir (
Abies alba Mill.) forests because it provides continuous cover, requires low investments for tending, and promotes natural regeneration as well as high stand resistance and elasticity. It is often regarded as a very conservative system that usually results in only minor spatiotemporal changes in forest structure and composition. We studied management history, structural changes, regeneration dynamics, and light climate of a traditional single-tree farmer selection silver fir-Norway spruce forest (site typology
Bazzanio-Abietetum). Stand structure was analyzed on five 0.25
ha permanent plots in 1994, 2001, and 2008. Regeneration density and height growth, forest floor vegetation, and light climate were also assessed on 1.5
×
1.5
m regeneration subplots in 2001 and 2008. Tree cores extracted from dominant trees from both species in two plots were used for reconstructing stand history and age structure of the canopy layer. We documented the forest response to three types of selection management regimes: excessive, normal, and conservative. Excessive management with harvest intensity significantly above the increment was documented until the late 1950s, including two peaks of heavy fellings (diameter limit cut) in the 1880s and 1930s, which favoured establishment of Norway spruce and released regeneration. The period that followed was characterized by normal selection management, but was nevertheless marked by a decline of silver fir as a result of air pollution and several droughts. This led to sanitary fellings that were carried out from the late 1970s to the early 1990s. In the last two decades conservative management followed, which led to suppression and decline of regeneration, especially of Norway spruce, and loss of selection structure. Although we recorded lower regeneration potential of silver fir compared with Norway spruce within the seedling category, silver fir outcompeted Norway spruce within the small-sized tree category (1
cm
<
dbh
⩽
10
cm) because of its superior height growth in low light levels (diffuse light <6%) and occupied a greater share of the canopy. Nevertheless, we anticipate that over the long-term the low light regime will also cause regeneration decline of silver fir and broadleaves. Our research revealed significant structural changes in a single-tree farmer selection forest during the last 150
years. These were a result of variable management regime and environment. A farmer single-tree selection system could better mimic the natural disturbance regime if spatiotemporal combinations of diverse felling regimes would be used.
Integrative forest management attempts to simultaneously fulfill both wood production and biodiversity conservation in a given forest region, and presumably supplants the need for unmanaged forest ...reserves. This is the dominant management paradigm in the temperate zone of Europe, yet few studies have examined the validity of this approach. We used Slovenia as a test bed to examine how the long-term practice of integrative forest management has influenced two structural components of mature forest conditions, namely coarse woody debris (CWD) and large living trees, as well as the distribution of the White-backed Woodpecker, a species dependent on such conditions. Data were compiled from national inventory plots, coupled with separate surveys in 51 forest reserves. The mean volume of CWD and density of large beech trees across managed forests in Slovenia was 15m3ha−1 and 6ha−1, respectively; these mean values were significantly higher (165m3ha−1 and 55ha−1) in old-growth reserves. CWD was primarily comprised of small diameter pieces in managed forest, whereas large diameter pieces in multiple stages of decay represented most of the volume in reserves. These results, coupled with the limited distribution of the woodpecker across the country, suggest that integrative management practiced over a large scale may be insufficient for maintaining biodiversity dependent on mature forest conditions at current levels of wood extraction.
Free-ranging large herbivores are keystone species in terrestrial ecosystems, and have an important ecological role by affecting both the structure and the function of plant communities and other ...groups of organisms. Large herbivores often increase plant diversity especially in more productive grasslands such as temperate grasslands in Europe. Additionally, other important effects of ruminants are redistribution of nutrients by feeding and subsequent excretion of urine and dung, soil compaction and erosion via trampling and dispersal of seeds, respectively. In Europe, populations of several ruminants species are increasing both in number and geographical distribution, and problems connected with effects of grazing of red deer (Cervus elaphus L.) on grassland in some locations in Slovenia have been increasing as well. Several areas of the Inner Carniola and Kočevje regions have been overgrown with forest, and these areas have the highest density of red deer. Therefore, the pressure of red deer on the remaining grasslands is increasing and may cause important economic loss for land owners. Ungulates can affect the economic profitability of grasslands also indirectly, through the impact on species composition of grasslands and by altering the overall productivity of soil. For proper management of their populations both direct and indirect ecological impacts and value of free-ranging ungulates have to be known. Therefore, an overview of foreign and Slovene studies related to the impacts of free-ranging ruminants on grassland ecosystems is presented in the paper.
Aim
Old‐growth, mesic temperate forests are often assumed to be structured by gap‐phase processes, resulting in quasi‐equilibrial long‐term dynamics. This assumption influences management focused on ...simulation of natural disturbance dynamics and is embedded in most models of forest successional dynamics. We use multi‐decade monitoring of permanent plots in old‐growth forests to assess demographic assumptions directly with respect to tree mortality rates.
Location
Sixteen sites in mesic, temperate old‐growth forests in eastern North America and Europe with multi‐decade monitoring.
Time period
Variable across sites, spanning c. 20–78 years from 1936 to 2014.
Major taxa studied
Tree species of late‐successional, cool‐temperate forests of Europe and eastern North America.
Methods
We calculated and compared the annualized mortality rates (m), with confidence intervals, by species, size class and measurement interval, for tree species of sufficient abundance.
Results
Retrospective analysis shows dynamic and diverse demographic properties across populations and sites. Stand‐scale mortality rates of 0.7–2.5%/year average higher than previous estimates for old‐growth temperate forests. Variations among species, over time and among size classes, suggest that gap‐phase models are inadequate to explain stand dynamics, implying instead that rare disturbance events of moderate severity have long‐lasting effects in old‐growth forests and that indirect anthropogenic influences affect old‐growth, unlogged forests.
Main conclusions
Multi‐decade baseline data, essential for understanding community assembly and long‐term dynamics in these “slow systems,” are rare and poorly integrated. Our analysis demonstrates the value of the few long‐term, “legacy” data sets. Results suggest that differences in life history interact with complex disturbance histories, resulting in non‐equilibrial dynamics in old‐growth temperate tree communities, and that changes in disturbance patterns through anthropogenic climate change might, therefore, be an important driver of ecosystem change.
Slovenia has a small number of old-growth forest remnants, as well as many forest reserves approaching old-growth conditions. In this paper, we describe some of the basic characteristics of these ...old-growth remnants and the history of their protection in Slovenia. We then trace the long-term development of research in these old-growth remnants, with a focus on methodological changes. We also review some of the recent findings from old-growth research in Slovenia and discuss future research needs. The conceptual understanding of how these forests work has slowly evolved, from thinking of them in terms of stable systems to more dynamic and unpredictable ones due to the influence of natural disturbances and indirect human influences. In accordance with this thinking, the methods used to study old-growth forests have changed from descriptions of stand structure to studies that address natural processes and ecosystem functions.
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