A density management diagram for Norway spruce in the temperate European montane region

Norway spruce is one of the most important conifer tree species in Europe, paramount for timber provision, habitat, recreation, and protection of mountain roads and settlements from natural hazards. Although natural Norway spruce forests exhibit diverse structures, even-aged stands can arise after disturbance or as the result of common silvicultural practice, including off-site afforestation. Many even-aged Norway spruce forests face issues such as senescence, insufficient regeneration, mechanical stability, sensitivity to biotic disturbances, and restoration. We propose the use of Density Management Diagrams (DMD), stand-scale graphical models designed to project growth and yield of even-aged forests, as a heuristic tool for assessing the structure and development of even-aged Norway spruce stands. DMDs are predicated on basic tree allometry and the assumption that self-thinning occurs predictably in forest stands. We designed a DMD for Norway spruce in temperate Europe based on wide-ranging forest inventory data. Quantitative relationships between tree- and stand-level variables that describe resistance to selected natural disturbances were superimposed on the DMD. These susceptibility zones were used to demonstrate assessment and possible management actions related to, for example, windfirmness and effectiveness of the protective function against rockfall or avalanches. The Norway spruce DMD provides forest managers and silviculturists a simple, easy-to-use, tool for evaluating stand dynamics and scheduling needed density management actions.     

Natural development and regeneration of a Central European montane spruce forest

Montane Norway spruce forests of Central Europe have a very long tradition of use for timber production; however, recently there has been increasing concern for their role in maintaining biological diversity. This concern, coupled with recent severe windstorms that led to wide-spread bark beetle outbreaks, has brought the management of montane spruce forests to the forefront of public policy discussions in Central Europe. In order to shed light on the natural development and current structure of mature montane spruce forests, we established four 0.25 ha research plots in a semi-natural montane spruce forest in the Šumava Mountains (The Bohemian Forest), Czech Republic. We mapped all trees, extracted increment cores for age and growth-pattern analyses, and inventoried all current tree regeneration, including the substrates on which it was found. Stands were characterized by uni-modal tree diameter distributions and high basal areas (56.6 m² ha⁻¹ on average), indicating a natural transition from the stem exclusion phase towards the understory reinitiation phase. The stands showed largely single-cohort recruitment age structures, however, with recruitment spanning seven decades. Our analyses suggest that this cohort existed as advance regeneration prior to major disturbances in the late 1800s, which included post-bark beetle salvage logging. Spatial pattern analyses of living and dead stems combined, showed an increase in uniformity of living trees, pointing to the role of natural density-dependent mortality. However, past growth patterns and historical documentation suggest that low intensity canopy disturbances (wind and snow) also caused mortality and diversified canopy structure. Because the stands developed naturally over the past 120+ years and thus escaped thinning operations, high volumes of coarse woody debris (94 m³ ha⁻¹) and snag densities (546 stems ha⁻¹) have accrued. Advance spruce regeneration was quite abundant and existed primarily on deadwood substrates, even though these occupied only a small percent of stand area. Because of salvage logging in the late 1880s, these stands do not qualify, according to the traditional paradigm, as natural spruce forests. As a result, they are recently subject to active management practices including salvage logging that remove dead and dying trees. Given the importance of deadwood for forest regeneration and recovery from disturbance, as demonstrated in this study, we argue that dead wood removal may limit future natural regeneration in these stands. Thus, the purported benefits of removing dead and dying trees from semi-natural forests must be carefully weighed against the potential detrimental impacts on natural spruce forest regeneration and biodiversity.     

Individual-based analysis of tree establishment and forest stand development within 25?years after wind throw

Wind throw is a common disturbance in forest ecosystems. Because many forests are intensively used our knowledge on forest dynamics after such disturbances is limited. In the Bavarian Forest National Park/Germany after the wind throw event in summer 1983, we started our long-term observation in nearly natural Norway spruce forests within 5-year intervals up to 2010. A part of the affected stands was cleared, while another part was left untouched for natural development. Here, we focused on the tree species regeneration, using an individual-based approach. We expected that tree species regeneration in both management types would follow different succession pathways. Indeed, we found different regeneration characteristics, depending on whether the area had been cleared or left unmanaged. For example, for the target species Norway spruce, a chronic regeneration during the first two decades with low numbers, but a high survival rate of individuals, and for the pioneer species birch, pulse regeneration with high numbers of individuals only at the beginning and high individual loss during the following years occurred. Unmanaged and cleared wind throw areas, respectively, offer different quantities of micro-sites: the pit and mound structure as mineral soil disturbance was limited to less than 1/4 in the untouched area, whereas there was mineral soil disturbance more or less everywhere on the cleared parts. Type and intensity of disturbance allow a wide range of succession pathways after wind throw, based on the fundamental processes of germination and competition. Therefore, for protection area management as well as for forest management, the human activity immediately after the event is crucial. Because each management impact will change the succession pathway fundamentally any impact has to be omitted in protection areas with the main goal of natural vegetation succession. Also in managed forests abdication of any impact on small areas may improve the natural structures and biodiversity of forests.     

The ecology of tree regeneration in mature and old forests: combined knowledge for sustainable forest management

We focused our attention on quantifying the factor complex of forest regeneration in 423 mature and old stands with contrasting environmental conditions. We recorded the microhabitat selection of tree recruits, the frequency of tree seedlings, and evaluated the drivers of sapling abundance and diversity. The majority of forest regeneration was established on undisturbed forest floor. Dead wood was a frequent substrate in spruce-(co)dominated forests. Seedling frequency within a stand was related to the site-type specific productivity gradient of stands—pine seedlings were common in low-productivity and spruce in high-productivity boreal forests. Seedlings of temperate broad-leaved trees dominated in productive boreonemoral forests, except for oak, which showed a uniform distribution of abundance in all forest site-types. Sapling abundance was dictated by forest site-type, and facilitated by stand diversity, variability in stand closure, lying dead wood, abundant moss, and a thick organic layer. Only in boreal forests was sapling abundance suppressed by the abundant spruce and younger trees. Upon considering the relationship between sapling abundance and species richness, sapling diversity was dependent on forest site-type, suppressed by stand density and dead wood (old gap) abundance, and facilitated by stand diversity. In addition, boreonemoral stands, competition from herbs, and facilitation by mosses occurred. The observed pattern of tree recruitment points to the importance of top-down effects of the overstory, competing or facilitating interactions with forest floor vegetation, and availability of regeneration microhabitats, which in complex make their ecology comparable with forest herbs. Natural forest regeneration can be enhanced if silvicultural methods support mixed stands and enhance field layer diversity. Oak can provide the universal tree species to improve stand structure over a wide range of habitats.     

Storm legacies shaping post-windthrow forest regeneration: learnings from spatial indices in unmanaged Norway spruce stands

The anticipated increase in extreme disturbance events due to climate change is likely to expose Norway spruce (Picea abies (L.) Karst.) dominated forests in northern Europe to new conditions. Empirical data on the resilience of such natural (unmanaged) forests to disturbance and the long-term patterns of regeneration in its aftermath are currently scarce. We performed a quantitative assessment of natural forest stands in north–western Latvia to identify and characterise the patterns of stand structure 44 years after a stand-replacing disturbance and investigated the effects of legacies on regeneration. The spatial distribution of tree species and their dimensions were assessed in 71 circular sample plots (500 m² each) in natural forest areas, where Norway spruce dominated prior to the windthrow and salvage logging was not carried out. Spatial indices (species mingling index, size differentiation index, and aggregation index) were used to characterise stand structure and diversity. The different initial states (age and coverage of surviving trees) of stands affected eventual tree species dominance, size differentiation, degree of mingling and aggregation. Our results demonstrate a close relationship between disturbance legacies and spatial indices. The pre-storm understory and canopy survivors decreased species mingling, whereas survivors increased size differentiation. The size differentiation increased also with a higher degree of species mingling. Leaving differential post-storm legacies untouched promotes a higher structural and species diversity and therefore supports the management approach of preserving canopy survivors.

     

Long-term dynamics of a mixed conifer stand in Slovenia managed with a farmer selection system

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.     

Regeneration in windthrow areas in hemiboreal forests: the influence of microsite on the height growths of different tree species

Natural regeneration of windthrow areas is an important issue when planning forestry measures after forest disturbances. Seedling recruitment was investigated in storm-damaged hemiboreal mixed forests in eastern Estonia. The establishment and growth of seedlings from natural regeneration was registered for tree species in soil pits and in mounds of uprooted trees in stands that were either heavily or moderately damaged. Seedling growth is expected to be better in large but shallow soil pits created by uprooted Norway spruce [Picea abies (L.) Karst.] and poorer in small but deep pits created by the hardwoods in the area, silver birch (Betula pendula Roth.) and European aspen (Populus tremula L.). The most abundant regenerating species was birch. Pits hosted larger seedling numbers than mounds, due to soil instability in mounds. Rowan (Sorbus aucuparia L.) showed significantly faster growth than the other seedling species. Norway spruce pits were preferred to pits of other species by both birch and spruce seedlings. Black alder [Alnus glutinosa (L.) J. Gaertn.] did not show a preference for pits of a certain species of uprooted tree. Both spruce and rowan preferred hardwood mounds over spruce mounds. Storm severity also affected species composition: birch predominantly occurred on pits and mounds in heavily disturbed areas, while spruce was more abundant in the moderately damaged areas. The effects of advance regeneration and surrounding stands on seedling microsite preferences should be considered in future research and subsequent management recommendations.     

Tree recruitment in gaps of various size,clearcuts and undisturbed mixed forest of interior British Columbia,Canada

Tree seedling recruitment was monitored after various types of logging in mixed conifer and deciduous forests of northern British Columbia, Canada. Predicting tree seedling recruitment after disturbance is fundamental to understanding forest dynamics and succession and is vital for forest management purposes. Seedling recruitment success in multi-species northern latitude forests varied as a function of mature tree canopy cover, gap size and position in a gap. Recruitment was abundant within canopy gaps across a wide range of gap sizes (20–5000 m²), but recruit numbers dropped off rapidly under the closed forest canopy and in the open conditions of clearcuts. Inside canopy gaps, recruitment was similar by gap position in small gaps (<300 m²) but, in these northern latitude forests, exhibited a trend of increasing density from the sunny north to shady south end of larger gaps. This was true for all tree species regardless of their shade tolerance ranking. There was no evidence of gap partitioning by any of the tree species during the regeneration phase suggesting that adaptation to the subtleties of gap size during early recruitment are not well developed in these tree species. Favorable locations for emergence and early establishment of germinants were less favorable for growth and survival of established seedlings, i.e. the regeneration niches in these forests were discordant. Tree abundance and species diversity appears to be controlled more by differentiation among growth and survival niches than by the regeneration niches. From the perspective of forest management, abundant natural regeneration of all the dominant tree species of these mixed-species forests can be obtained after partial cutting.     

Long-term spruce forest continuity – a challenge for a sustainable Scandinavian forestry

Macroscopic charcoal and pollen analysis were used to study the disturbance history and development of a boreal Norway spruce (Picea abies (L.) Karst.) forest landscape in southeastern Norway. The sites studied were natural forests and the charcoal records showed no evidence of fire disturbance that could have broken the continuity in the spruce forests that were established ca. 1700 years ago. Consequently, true spruce forest ecosystem continuity was documented on a landscape level. However, fire disturbed the mixed pine-deciduous forest ecosystems that preceded the present spruce forests, suggesting a shift from fire-prone, to fire-free forest ecosystems.It is argued that the studied forest landscape has the potential to be an important natural reference for future forestry, that would be required to mimic natural forest dynamics to be biologically sustainable. A stereotypic promiscuous use of fire in the regeneration phase may cause serious damages in forest ecosystems that have developed without the impact of fire disturbance.     

Population dynamics of tree species in southern Quebec,Canada: 1970–2005

Over the last few decades, several phenomena contributed to modify the structure and composition of the eastern North American forests. Along with forest management, disturbances such as insect defoliation, global environmental changes, acid deposition, and rising atmospheric CO₂ concentrations, have been identified as phenomena that could affect forest structure and composition. Currently, there is very little quantitative information on the resulting effect of multiple disturbances on the main parameters of forest dynamics (growth, mortality, and recruitment). Using available data from the Quebec permanent sample plots network, we analyzed the ecological response of tree species populations to the combined effect of contemporary global environmental changes, disturbance regimes, and forest management practices over the last 30 years in southern Quebec. The results indicate that the main parameters of forest dynamics changed considerably over the last three decades. The last spruce budworm outbreak initiated a successional change in coniferous stands. The basal area of Abies balsamea and Picea glauca, the most abundant coniferous species, decreased by 29.7%, while pioneer species abundance increased. For late successional deciduous species, observed changes in forest dynamics appear to be mainly associated with global environmental changes rather than with natural disturbances or forest harvesting. The results indicate that inferring responses of tree population dynamics to global environmental changes can be very complex or even misleading considering the confounding effects of other disturbance agents. The results also suggest that the ecosystem-based management approach promoted by forest ecologists, aimed at maintaining landscape stand composition and structures similar to those characterizing natural environments, will not be easily achieved. Forest ecosystems are highly dynamic and disturbances other than tree harvesting appear to have been the major factors affecting their pattern of change over the last three decades. Forest managers should consider adaptive management approaches that will consider the contemporary evolution of forest ecosystems in a changing environment.     

Habitat fragmentation and structure and composition of tree populations in a agroforestry landscape (southern Québec,Canada)

A number of forests in agroforestry environments are at risk due to urban development or agricultural expansion. These forests often consist of patches of wooded areas scattered in the agricultural and urban grid, and often constitute green corridors that enable a flow between animal and plant species (migration corridors). This study evaluates the composition and structure of riparian forests in agroforestry areas that are subject to various natural and anthropogenic disturbances. This study aims to understand the dynamics of these riparian forest populations and evaluate the effects of the disturbances on the tree stands (e.g. floods, partial cutting), while taking into account their development over space and time based on a diachronic assessment from 1945 to 2010. Although these woodlands are subject to various disturbances, a fairly large diversity of tree species can be noted, and the regeneration of the saplings and small trees follows a normal growth curve (asymmetric) with a high contingency of young tree population comparable to a typical reverse-J distribution. However, lower densities are observed for riparian stands subject to frequent flooding, which could over time compromise recruitment and forest regeneration for some tree species (e.g. woody plants with weak adaptive strategies). The multivariate analyses (Redundancy Analysis and Canonical Correspondence Analysis) conducted over all the soil, environmental and forest data reveal that some variables are more strongly related to the composition of the forest populations, including pH, ground litter and soil drainage. However, these variables must still be considered as being part of a set of interacting soil conditions. Lastly, the future of these woodlands may appear uncertain because there are no government policies or measures to ensure their protection and preservation.     

Forest pasturing of livestock in Norway: effects on spruce regeneration

Forest pasturing of free-roaming livestock is a common practice in many parts of the world, but knowledge on how it affects tree regeneration in boreal forests is lacking. We mapped tree density, livestock site use and accumulated damage to young trees of commercial interest(Norway spruce, Picea abies L. Karst.) on 56 clearcuts inside and outside a fenced forest area used for livestock pasturing in Ringsaker, Norway. Inside the fence 56±1.8% of spruce trees were damaged compared to 37±3.4% outside. Proportion of damaged spruce trees was positively related to cattle use of the clearcut, but not so for sheep. On the most intensively used clearcuts, four out of five trees were damaged. The density of deciduous trees was five times lower inside compared to outside of the fence(varying with plant species). While livestock grazing may reduce resource competition in favour of spruce, the current animal density clearly is impeding forest regeneration in the study area.     

Effects of species and tree size diversity on recruitment in the Alaskan boreal forest: A geospatial approach

This study empirically evaluates and maps the relationships between recruitment and species and tree size diversity, as measured with the Shannon’s index, within mixed poplar/birch and mixed spruce stands across the boreal forest of Alaska. Data were collected from 438 permanent sample plots re-measured at a 5-year interval. Significant explanatory factors of recruitment, including species and tree size diversity were first identified using hierarchical partitioning. The effects of tree diversity on recruitment were then studied using generalized linear models and universal kriging to account for non-spatial factors and for spatial autocorrelation. We found a consistent positive relationship between recruitment and species diversity and a general negative relationship between recruitment and tree size diversity, indicating a tradeoff between species diversity and tree size diversity in affecting recruitment. These relationships however were not uniform across the landscape, presumably because they were subject to strong spatial autocorrelation attributable to natural disturbances and environmental stressors. In general, diversity had least effect on recruitment in stressful environments where stress, rather than competition, most likely governed recruitment.     

Dynamics and drivers of post-windthrow recovery in managed mixed mountain forests of Slovenia

Large and severe disturbances may erode the resilience of temperate forest ecosystems and alter their recovery dynamics, especially under global change. We investigated mid-term recovery in mixed mountain forests in Slovenia after three independent severe windstorms in 2008 created large disturbed patches. Across a network of 102 permanent plots and three inventories over the 11-year post-disturbance period, we monitored trends in density, composition, and structure of regeneration, which are key indicators of forest resilience. Ecological drivers of regeneration, including topography, microsites, and biotic interactions, were analysed using linear mixed models. We quantitatively assessed physiognomic recovery by comparing regeneration densities with the restocking target used in forest practice, and compositional recovery by comparison with pre-disturbance stand composition. Regeneration densities and structure tended to converge among post-disturbance treatments (planting vs. natural regeneration) 11 years post-disturbance, as density of natural regeneration substantially dropped between the second and third inventory. Some drivers of recovery (i.e. ground vegetation and distance to the forest edge) varied over time, while the effect of elevation on regeneration density was consistently negative. The results indicate that the forest sites generally show adequate resilience to large-scale wind disturbances, in terms of physiognomic recovery, but not in terms of rapid compositional recovery, as pioneer and light-demanding tree species increased in share compared to the pre-disturbance stands.

     

Western Carpathian mountain spruce forest after a windthrow: Natural regeneration in cleared and uncleared areas

A catastrophic windstorm called “bora” occurred in The Tatra National Park in Slovakia in 2004 and destroyed an extensive area of mountain spruce forests. Part of the windthrow area was left uncleared for natural development, but most of the area was cleared. We analyzed natural regeneration in cleared and uncleared windthrows, and in reference closed canopy forest in 2007 and 2008 with the aim of assessing the regeneration capability of the windthrown forests and proposing the best method for their restoration.     

A model describing natural regeneration recruitment of Norway spruce (Picea abies (L.) Karst.) in Austria

In the absence of reliable and representative data on the frequency of seed years, seed amounts, germination and survival of seeds, the data of the observation period 1992–1996 of the permanent national forest inventory of Austria are used to develop a model describing the probability for the occurrence, density and height of Norway spruce (Picea abies (L.) Karst) natural regeneration in the forests of Austria. The forest inventory provided data on natural regeneration (saplings between 10 and 130 cm height) on clusters within a 3.89 km square sampling grid. A logistic equation is used to predict the probability for natural regeneration occurrence. Input parameters for this equation are the variables that describe the site, with slope and azimuth as continuous variables, and growth districts and vegetation types as discrete variables; the crown competition factor describes density and the quadratic mean diameter describes the stage of development of the stand. The same equation type is used to predict the probability for the occurrence of Norway spruce, conditional on the occurrence of some regeneration. An additional variable in this species specific model is a dummy variable which is set to 1 if Norway spruce occurs in the overstory and otherwise zero. Additional site variables entering this model are elevation and vegetation types characterizing soil fertility and moisture. Because the density and height of spruce regeneration depends on the stand's susceptibility to browsing, the probability for browsing is also modelled as a logistic equation depending on elevation, vegetation type, and stand density. Finally the probability distribution for height and density of the regeneration is described by two bivariate Weibull-distributions, each one describing browsed and unbrowsed Norway spruce regeneration respectively.     

Understory dynamics after disturbance accelerate succession from spruce to beech-dominated forest—the Siggaboda case study

??Context

It is assumed that climate change will favour European beech (Fagus sylvatica L.) to Norway spruce (Picea abies [L.] Karst.) at its northern range margins due to climate change and induced disturbance events.

??Aims

An old-growth mixed forest of spruce and beech, situated near the northern beech margin, was studied to reveal effects of disturbances and response processes on natural forest dynamics, focussing on the understory.

??Methods

We carried out analyses on understory dynamics of beech and spruce in relation to overstory release. This was done based on a sequence of stand and tree vitality inventories after a series of abiotic and biotic disturbances.

??Results

It became apparent that beech (understory) has a larger adaptive capacity to disturbance impacts and overstory release (68 % standing volume loss) than spruce. Understory dynamics can play a key role for forest succession from spruce to beech-dominated forests. Disturbances display an acceleration effect on forest succession in the face of climate change.

??Conclusion

Beech is poised strategically to replace spruce as the dominant tree species at the study area. Due to an increasing productivity and a lower risk of stand failure, beech may raise into the focus of forestry in southern Sweden.     

Response of fungal and plant communities to management-induced overstorey changes in montane forests of the Western Carpathians

The effect of forest management on biodiversity is a crucial issue for sustainable forestry and nature conservation. However, the ways in which management affects macrofungal and plant communities and diversity of mountain temperate forests still remain poorly understood. We performed a random sampling stratified by stand age and stand type on the sites of temperate montane fir–beech forests. Diversity of macrofungi and the vascular plant understorey in beech- and spruce-dominated managed stands was investigated and compared to primeval forests located in the Po?ana Biosphere Reserve, Western Carpathians. Both the vascular plant and the macrofungal communities were altered by management, and the response of the macrofungal species (especially wood-inhabiting fungi) was more pronounced in terms of species composition change. Species turnover evaluation seems to be an important tool of forest natural status assessment, because alpha diversity did not change as much as species composition. Certain species of Carpathian primeval forests were confirmed as good indicators for natural forest change; others were proposed. Species pool and mean number of species per plot were the highest in unmanaged fir–beech forests, and species diversity significantly decreased in spruce plantations. The number of species decreased significantly due to the change of canopy tree species composition only in the macrofungal communities. As an outcome for forest management, we recommend keeping mixed forests involving all natural tree species and providing at least a minimal amount of dead wood necessary for wood-inhabiting organisms and leaving some area of unmanaged natural forests within complexes of managed stands.     

Legacies from natural forest dynamics: Different effects of forest management on wood-inhabiting fungi in pine and spruce forests

The species composition of wood-inhabiting fungi (polypores and corticoids) was investigated on 1138 spruce logs and 992 pine logs in 90 managed and 34 natural or near-natural spruce and pine forests in SE Norway.Altogether, the study included 290 species of wood-inhabiting fungi. Comparisons of logs with similar properties (standardized tree species, decay class, dimension class) in natural and managed forests showed a significant reduction in species number per log in managed spruce forests, but not in managed pine forests. The species number per log in managed spruce forests was 10-55% lower than on logs from natural spruce forests. The reduction was strongest on logs of large dimensions. A comparison of 200-400 spruce logs from natural and managed forests showed a 25% reduction in species richness corresponding to a conservative loss of ca. 40 species on a regional scale.A closer inspection revealed that species confined to medium and very decayed spruce logs were disfavored in managed forests, whereas species on early decay classes and decay generalists were unaffected. Similarly, species preferring large spruce logs were disfavored in managed forests. Forest management had strongest impact on low-frequent species in the spruce forests (more than 50% reduction), whereas common species were modestly affected. Corticoid fungi were more adversely affected than polypore fungi.These results indicate that wood-decaying fungi in pine forests are more adapted to forest disturbances than spruce-associated species. Management measures securing a continuous supply of dead wood are more important in spruce forests than in pine forests.     

Regeneration of Picea abies forests on highly productive peatlands—clearcutting or selective cutting?

The study was focused on severe forest regeneration problems that are typical for highly productive peatlands. The aim of the study was to give recommendations for practical forestry on how to renew the forests. Experiments with different forest regeneration methods on highly productive peatlands were set up in nine mature Norway spruce (Picea abies (L.) Karst.) forests in northern, central and southern Sweden. The treatments in the study were natural regeneration in shelterwoods (at densities of 140 and 200 stems ha^‐1), planting of bare‐root spruce seedlings after site preparation (mounding) in the shelterwoods and on clearcuts, and planting without site preparation on clearcuts.

Judging from the extent of windthrow in the denser shelterwoods and the stocking of natural regeneration under remaining shelter trees 4–5 years after final cut, shelterwood regeneration is a promising method. On clearcuts, planting without site preparation resulted in poor seedling survival, large extent of damage to the seedlings and small height increment. Planting in mounds on the clearcuts was much more successful. The best survival of planted seedlings was observed in the shelterwoods. Both the denser and the sparse shelterwoods seemed to give satisfactory protection to the seedlings.

Final recommendations on the most suitable forest renewal method(s) will be made in about five years after the removal of the shelter trees.