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Abstract

Primary forests are characterized by high vertical and horizontal stand diversity, which provides habitat for a diverse range of species with complex habitat requirements. Detailed knowledge of related ecological processes and habitat development of primary forest species are essential to inform forest management and biodiversity conservation decisions, but relationships are not well documented. We collected dendrochronological data and inventoried numerous structural elements in permanent plots throughout the primary temperate forests within the Carpathian Mountains. We fit and compared multiple predictive models to quantify the importance of 200 years of natural disturbance dynamics on the occurrence probability of an umbrella species – the capercaillie (Tetrao urogallus). We showed that a mixed-severity disturbance regime ranging from low through moderate to high severity disturbances is required to generate diverse forest habitats suitable for capercaillie. The variation in natural disturbance severity and its timing promoted key structural habitat elements, such as low natural regeneration density, low mature tree density, high ground vegetation cover, availability of forest gaps, and abundance of standing deadwood. This study demonstrates the importance of natural disturbance in maintaining the variety of conditions necessary to support primary forest specialist species. Managers of protected areas should be mindful that natural disturbances generate habitat for the capercaillie in mountain Norway spruce forests. Further intervention is unnecessary. Conservation planning and forest reserve design should shift focus to the large-scale spatial requirements needed to ensure that a wide range of forest developmental phases are represented in protected areas.

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... Capercaillie extinctions and population declines are both associated with habitat loss and fragmentation, as well as intensified land-use by people (e.g. in sport, tourism and recreation, and forest management) (Storch 2007(Storch , 2013Thiel et al. 2011;Moss et al. 2014;Coppes et al. 2017Coppes et al. , 2018. The major reasons for changes in the habitat of the species are considered to relate to the development of commercial forestry, where large areas are clear-felled (Saniga, 2003;Wegge and Rolstad, 2011;Mikoláš et al., 2015;Kämmerlea et al. 2020). ...
... Besides the direct influences (such as clearcutting in lek areas), modern forestry has affected populations of the capercaillie also in an indirect manner, namely through its tendency to cause change in forest structure, age, and stand composition (Broome et al. 2014;Braunisch et al. 2019). In forests which are managed, natural disturbancescharacteristic of unmanaged old-growth forests that do favour the formation of a forest structure suitable for the capercaillieplay only a minor role (Mikoláš et al. 2017). The widespread fencing of forest plantations results in grouse collisions. ...
... However, in line with the expectations, Key Areas which were further from roads were those still supporting capercaillies, while the negative influence of human disturbance on the species has been demonstrated with regard to other areas across the range (Summers et al. 2007;Storch 2013;Moss et al. 2014). It is not only forest works that are damaging to the capercaillie; human recreation also has a negative effect (Coppes et al. 2017(Coppes et al. , 2018. ...
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Background Forest management affects the habitat conditions for many forest-dwelling species. Among them, the capercaillie ( Tetrao urogallus ) is a rare forest grouse inhabiting old, mature forests. We compared the structure of forest habitat among 9 active and 9 abandoned leks in the Augustów Forest (North-Eastern Poland), within a radius of 1 km of the leks, defined as the Key Areas for the capercaillie in lowland temperate forest. Habitat measurements were conducted on 1779 circular plots. Assessments made on all plots related to 13 habitat variables measured or noted in the field, including stand structure, canopy closure, stand developmental stage, percentage of Scots pine ( Pinus sylvestris ), soil fertility and soil moisture, the share of undergrowth, the cover of shrubs, the cover of bilberry ( Vaccinium sp.), and the presence of certain habitat elements important to the capercaillie. Results To compare the still-occupied and the abandoned KAs for the capercaillie, a logistic regression model was developed. The variables best explaining differences between these two categories were: the occurrence of undergrowth layers, canopy closure in the second canopy layer, and stand age. According to the model, with the increase of the shrub-layer cover as well as the density of trees, the probability of the presence of the capercaillie decreased. The capercaillie in the area of the Augustów Forest occupy mainly dry and poor, middle-aged, pine-dominated forests, with a moderate extent of stand canopy closure and only weakly-developed layers of undergrowth. Conclusions The filling-in of mature stands with sub-canopy trees and shrubs (the process which is stimulated by climate change and site eutrophication) causes structural changes, which are unfavourable to the capercaillie. This might explain why in the course of the recent decades the capercaillie has abandoned the oldest stands, distinguished by the presence of bigger shares of undergrowth. The capercaillie has shifted to younger stands, which reveal a lesser extent of canopy closure and a more limited development of understorey vegetation.
... In terms of habitat, although traditionally the species was considered as dependent on mature or old forest (Angelstam, 2004;Storch, 1993;Swenson and Angelstam, 1993;Valkeajärvi and Ijäs, 1986) or even to forests in the old-growth stage (Rolstad andWegge, 1989a, 1987;Saniga, 2003), more recent studies have rather contradicted this (Miettinen et al., 2008;Mikoláš et al., 2017a;Rolstad et al., 2007;Sirkiä et al., 2011b). Other research has shown that while the capercaillie generally prefers mature forests (with more open canopies and ground vegetation present) it also uses younger stages with denser canopies as well (especially hens - (Rolstad et al., 1988;Storch, 1993); but also males - (Rolstad et al., 2007)) and sometimes even more open places (after harvesting and before canopy closure of the new stand - (Saniga, 2002)). ...
... Therefore, a more diverse and fine-grain mosaic-like habitat would be preferred by the species to contiguous, uniform forest cover (Bollmann et al., 2011;Jacquin et al., 2005;Sirkiä et al., 2011aSirkiä et al., , 2011b. Recent studies carried out in the Carpathians (Mikoláš et al., 2017a) have pointed out that mixed-severity natural disturbance regime (ranging from low to high severity) would produce in natural forests the diverse forest habitat conditions needed for capercaillie. However, as the species is present across the entire Carpathian chain (Simon, 2015), not only in protected areas, it is noteworthy to analyze the habitat resulting from disturbances produced by forest management as well. ...
... However, despite a high preference for such forests as habitat, our results showed that birds are using younger stages of development as well, in agreement with previous findings in other parts of Europe (Miettinen et al., 2005(Miettinen et al., , 2008Rolstad et al., 1988). This shows that the species is not dependent on the old-growth stage as previously considered (Rolstad andWegge, 1987, 1989a;Saniga, 2003) and agrees with findings from other studies (Miettinen et al., 2008;Mikoláš et al., 2017a;Rolstad et al., 2007;Sirkiä et al., 2011b). It also shows that capercaillie has favorable habitat on very large areas with managed forests across the Romanian Carpathians. ...
Article
Long term analyses on habitat dynamics are challenging when data from the past is scarce. In addition, large scale perspectives are difficult to attain without proper modelling of habitat conditions. These drawbacks were overcome in the case of capercaillie in Romania with the help of satellite-based information and by finding relevant environmental variables which influence the species habitat. We used MaxEnt software with four variables (spruce distribution, elevation, precipitation and temperature in June) and 750 presence points. The model had a high predictive ability (area under the curve over 95%), elevation and spruce distribution being the most important variables. A separate set of 902 presence points was used for model crosschecking. Most of the crosscheck points (98.6%) fell inside the predicted habitat confirming the model performance. To detect habitat preferences the vegetation mosaic in 90 circles (3 km-radius) was analyzed using both historical (Cold War) and recent satellite information. The modelled habitat across the Romanian Carpathians was a mosaic of stands of different ages. Moreover, a similar structure was found inside and outside the analyzed circles: forests between 65 and 120 yr. dominated, followed by the younger classes (20–65 yr. and forests <20 yr.). The oldest class (> 120 yr.) was the least common. The majority (i.e., 90%) of the presence points used for model crosscheck fell within actively managed forests, including former large clearcuts (revealed by the Cold War spy-satellite images). This suggests that the species was tolerant to forest management and also able to recolonize areas when habitat became favorable again. Therefore, controlled forest management maintains the habitat favorability at very large scales in a shifting steady-state mosaic. This management-driven habitat together with the one produced by natural disturbances in natural forests provides favorable conditions for a habitat continuum along the Romanian Carpathians.
... In most parts of its former central European range, population sizes have decreased and it is endangered or even extinct in many parts (Klaus et al. 1989). One of the relict capercaillie populations in Europe inhabits the patches of natural old-growth forests in the Carpathian Mountains (Saniga 2003;Mikoláš et al. 2017a), where a contact zone between the two main phylogenetic lineages has also been detected (Klinga et al. 2015). ...
... To identify areas suitable for capercaillie populations, we employed an environmental niche model (ENM), as constructed and presented by Mikoláš et al. (2017a). The ENM includes maximum entropy modelling (Maxent 3.3; Phillips et al. 2006) that is based on machine learning approach contrasting the distribution of environmental variables at the presence locations with those at randomly chosen background locations (Phillips and Dudík 2008;Warren and Seifert 2011). ...
... The annual mean temperature was determined to be the most important variable in the ENM (mean AUC = 0.942 ± 0.014 SE; for details see Mikoláš et al. 2017a). The average AUC value for the best CNM was 0.967 (± 0.011 SE), which indicates a strong fit and high predictive ability. ...
Article
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A major concern in conservation biology today is the loss of genetic diversity in structured populations, which is often a consequence of habitat contraction and restricted gene flow over time. These dynamic biological processes require monitoring with temporal environmental and landscape genetic data. We compared the spatial genetic variation of a relict, umbrella species, the capercaillie (Tetrao urogallus), in two different demographic periods, as represented by older museum specimens (1960–1990) and recent non-invasive samples (2011–2015) collected from the Carpathian Mountains, where habitat connectivity has dramatically decreased in the past decade. Using a combination of species distribution modelling and spatial genetic inference, we analysed how climatic and environmental constraints shaped population structures of the species. Environmental and climate niche models confirmed that relict Carpathian capercaillie populations are temperature sensitive, and they occur in a narrow range of mountain forest habitats at the highest altitudes. We found that the environmental and climatic constraints led to genetically isolated populations, but we also detected clusters that did not match relatively interrupted areas of niche habitats. We observed a similar disruption of gene flow in both periods; however, a stronger signal of genetic structuring in recent samples indicated that the processes negatively affecting connectivity are ongoing. The effective population size of the Carpathian population has declined in recent years, but it has been low for at least the last five decades in the Western Carpathians. This study demonstrates the importance of temporal ecological and genetic data as an effective warning tool for the conservation and management of wildlife species.
... This was not possible with this version of MASSIMO, but current revisions of the model that focus on regeneration will allow accounting for such effects (Zell et al. 2019). Including indicators that account for management-and disturbance-induced changes in habitat suitability of management-and disturbance-sensitive umbrella species may improve our assessment of biodiversity provision (Lexer and Seidl 2009;Mikoláš et al. 2017). ...
... In contrast, a reduction of beetle predisposition with more intensive management as under our energy scenario, was in a trade-off relationship with reduced old-growth features. Previous studies have shown positive effects of beetle disturbance on forest species diversity in the Bavarian forest and the Carpathians, due to increased stand structural diversity (Lehnert et al. 2013;Mikoláš et al. 2017). Others found host dilution with increased tree diversity to increase Engelmann spruce survival in spruce beetle affected forests in western North America (Conner et al. 2014). ...
... Together with our results, these studies suggest that there are various ways to realize synergies between the prevention of bark beetle disturbance and the promotion of biodiversity. Ideally they are combined to generate landscape heterogeneity and thus a broad range of different habitats on a small area, i.e. by promoting old-growth patches of non-host species (Bouget et al. 2014) and by timber harvesting that emulates patch-scale natural disturbances (Mikoláš et al. 2015(Mikoláš et al. , 2017. ...
Article
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Background Scenario analyses that evaluate management effects on the long-term provision and sustainability of forest ecosystem services and biodiversity (ESB) also need to account for disturbances. The objectives of this study were to reveal potential trade-offs and synergies between ESB provision and disturbance predisposition at the scale of a whole country. Methods The empirical scenario model MASSIMO was used to simulate forest development and management from years 2016 to 2106 on 5086 sample plots of the Swiss National Forest Inventory (NFI). We included a business-as-usual (BAU) scenario and four scenarios of increased timber harvesting. Model output was evaluated with indicators for 1) ESB provision including a) timber production, b) old-growth forest characteristics as biodiversity proxies and c) protection against rockfall and avalanches and 2) for a) storm and b) bark beetle predisposition. Results The predisposition indicators corresponded well (AUC: 0.71–0.86) to storm and insect (mostly bark beetle) damage observations in logistic regression models. Increased timber production was generally accompanied with decreased predisposition (storm: >−11%, beetle: >−37%, depending on region and scenario), except for a scenario that promoted conifers where beetle predisposition increased (e.g. + 61% in the Southern Alps). Decreased disturbance predisposition and decreases in old-growth forest indicators in scenarios of increased timber production revealed a trade-off situation. In contrast, growing stock increased under BAU management along with a reduction in conifer proportions, resulting in a reduction of beetle predisposition that in turn was accompanied by increasing old-growth forest indicators. Disturbance predisposition was elevated in NFI plots with high avalanche and rockfall protection value. Conclusions By evaluating ESB and disturbance predisposition based on single-tree data at a national scale we bridged a gap between detailed, stand-scale assessments and broader inventory-based approaches at the national scale. We discuss the limitations of the indicator framework and advocate for future amendments that include climate-sensitive forest development and disturbance modelling to strengthen decision making in national forest policy making.
... These results highlight a need for sufficiently large and adequately connected networks of strict reserves, more complex silvicultural treatments INTRODUCTION Inappropriate forest management that alters forest structures, compositions, or functions as a result of the replacement or alteration of historical disturbance patterns cause serious ecological harm, such as the loss of biodiversity or soil degradation (Achat et al. 2015, Mikol a s et al. 2017b. As characterized in the concept of the "historical range of variability" (Keane et al. 2009), specific variations of past disturbances were the primary drivers of forest conditions that native forest species had adapted to over long periods of time, and they are likely to benefit from similar conditions in the future (Drapeau et al. 2016, Mikol a s et al. 2017a, Betts et al. 2019. Using the historical range of variability (e.g., by emulating natural disturbances) to guide forest management will help sustain forest ecosystem structures, composition, and functions (Seymour et al. 2002, Long 2009, Kulakowski et al. 2017. ...
... Based on this suggestion, our analyses support a minimum reserve area on the order of hundreds of hectares. However, where stands are geographically isolated (far from other reserves or surrounded by a hostile environment) or structurally homogeneous (in terms of tree age structure), much larger reserves (possibly larger than 10,000 ha) could be required to guarantee viable populations of species under the moderatescale, mixed-severity disturbance regime (Lehnert et al. 2013, Mikol a s et al. 2017a. ...
Article
Estimates of historical disturbance patterns are essential to guide forest management aimed at ensuring the sustainability of ecosystem functions and biodiversity. However, quantitative estimates of various disturbance characteristics required in management applications are rare in longer‐term historical studies. Thus, our objectives were to: (1) quantify past disturbance severity, patch size, and stand proportion disturbed, and (2) test for temporal and sub‐regional differences in these characteristics. We developed a comprehensive dendrochronological method to evaluate an approximately two‐century‐long disturbance record in the remaining Central and Eastern European primary mountain spruce forests, where wind and bark beetles are the predominant disturbance agents. We used an unprecedented large‐scale nested design dataset of 541 plots located within 44 stands and 6 sub‐regions. To quantify individual disturbance events, we used tree‐ring proxies, which were aggregated at plot and stand levels by smoothing and detecting peaks in their distributions. The spatial aggregation of disturbance events was used to estimate patch sizes. Data exhibited continuous gradients from low‐ to high‐severity and small‐ to large‐size disturbance events. In addition to the importance of small disturbance events, moderate‐scale (25‐75% of the stand disturbed, >10 ha patch size) and moderate‐severity (25‐75% of canopy disturbed) events were also common. Moderate disturbances represented more than 50% of the total disturbed area and their rotation periods ranged from one to several hundred years, which is within the lifespan of local tree species. Disturbance severities differed among sub‐regions, whereas the stand proportion disturbed varied significantly over time. This indicates partially independent variations among disturbance characteristics. Our quantitative estimates of disturbance severity, patch size, stand proportion disturbed, and associated rotation periods provide rigorous baseline data for future ecological research, decisions within biodiversity conservation, and silviculture intended to maintain native biodiversity and ecosystem functions. These results highlight a need for sufficiently large and adequately connected networks of strict reserves, more complex silvicultural treatments that emulate the natural disturbance spectrum in harvest rotation times, sizes, and intensities, and higher levels of tree and structural legacy retention.
... These degraded capercaillie habitats largely corresponded to spruce-dominated forests, where Stăncioiu et al. (2018) assessed high connectivity levels based on a variety of tree species. Capercaillie requires specific habitat elements typical of mature and old-growth stages of forest development, such as semi-open forest habitats, presence of low-branched trees, high ground vegetation cover, snags, and uprooted trees (Bollmann et al., 2005;Mikoláš et al., 2017b). Those conditions are the result of forest development driven by natural disturbances, such as windthrow and bark beetle mortality, in unmanaged forests (Meigs et al., 2017). ...
... Forest specialist species, such as capercaillie, but even more importantly, a diverse assemblage of species dependent on deadwood (e.g., insects, fungi, lichens, bryophytes), require specific habitat structures (Mikoláš et al., 2017b;Zemanová et al., 2017;Nagel et al., 2017;Thorn et al., 2018). Estimates suggest that those species represent more than 30% of the forest biodiversity, and many of them are redlisted species that form a key component of many forest communities (Siitonen, 2001). ...
Article
Amidst rapid global climate change and at a time when many adaptive policies and strategies have been implemented , reductionism in forest management decisions may have detrimental effects on forest biodiversity. Stăncioiu et al. (2018) made an important contribution by assessing forest connectivity based on tree species populations in Romania. Their study concluded that current management policies and inherited guidelines from the past likely promoted the conservation of regional biodiversity. In this viewpoint paper, we present a different perspective on their conclusion. We show that current management policies are threatening biodiversity in Romania, and changes in forest management policies are urgently needed to halt the loss of habitats of protected species. Although recent management policies likely did lead to good tree species connectivity, habitats of protected species are becoming increasingly fragmented by logging. Adopting policies to protect forest habitats of protected species, limiting large-scale salvage logging within protected areas, and restricting road building to reduce forest fragmentation are crucial steps towards the long-term persistence of biodiversity hotspots in the Romanian Carpathians.
... The Capercaillie Tetrao urogallus is considered to be an indicator species for open, structurally diverse boreal and mountain forests, with well-developed ground vegetation (Picozzi et al. 1992, Storch 2002, Summers et al. 2004. Often associated with old growth (Swenson & Angelstam 1993) or even primary forests (Picozzi et al. 1992, Mikoláš et al. 2017, the species also uses younger forests if the structure is suitable (Picozzi et al. 1996, Rolstad et al. 2007). The Capercaillie is a large-bodied, precocial bird that occurs over an extensive geographic and altitudinal range in a wide range of forest habitats (Klaus et al. 1989). ...
... To ensure a long-term availability of gaps and open stands in the Black Forest, silvicultural practices should be adapted to include the creation of small clear-cuts within permanent forest cover systems. Additionally, allowing for natural processes, such as bark beetle infestations and storms, can also be a useful 'passive management tool' to lower the canopy cover and improve Capercaillie habitat suitability (Mikoláš et al. 2017, Kortmann et al. 2018, especially in protected forests. These practices are not only beneficial for Capercaillie but may also support a variety of other species inhabiting open forests (Niemelä et al. 1996, Forsman et al. 2010). ...
Article
Capsule Open forest stands with high levels of sunlight and Bilberry Vaccinium myrtillus cover are important for Capercaillie Tetrao urogallus broods. Aims To study the habitat use by Capercaillie broods in the Black Forest, Germany. Methods Habitat characteristics were mapped at locations where indirect signs and observations of Capercaillie broods were recorded along transects. These were compared to habitat characteristics at random locations along the transects using generalized linear mixed models. Results Capercaillie broods in the Black Forest preferred open forest stands with canopy gaps, long daily sun exposure on the ground and an intermediate cover of Bilberry. Stands with high levels of ground vegetation cover and Mountain Pine Pinus mugo shrubs were preferred by Capercaillie broods, while stands with high levels of regeneration cover were avoided. No effect of the horizontal stand layers, number of basal-branched solitary trees or anthills was found. Conclusions To improve habitats for Capercaillie broods, we advise that there should be active creation of structured open stands and forest gaps in areas with high levels of sun exposure (south-west facing) and where Bilberry or heather dominates the ground vegetation.
... Extensive natural forest disturbances are very common in various forest ecosystems (Szwagrzyk, 2000). Natural disturbances that have always been present in forest his− tory may play a positive role in forest ecology (Thorn et al., 2017), especially in primeval forests (Trotsiuk et al., 2014;Čada et al., 2016;Meigs et al., 2017;Mikoláš et al., 2017), which are pro− tected in Europe. Abundant natural regeneration of forests is often observed after various dis− asters, such as e.g. ...
Article
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Damages caused by external (biotic and abiotic) factors generally cause losses in forest manage− ment, negatively affect the continuity of providing various ecosystem services, and therefore play an important role in the management of forest resources. The aim of the study was to present the type and extent of natural damages of commercial forests in the temperate climate of north− −eastern Poland (Central and Eastern Europe). In addition, a relationship between the occurrence of damage of a given type and the site type of forest, the age of the stand and species composition was investigated. The necessary information was obtained from the documentation of the State Forests National Forest Holding through an interactive form. Nearly 8% of the stands in north− −eastern Poland were damaged. Vast majority of the damage were attributed to wild herbivores-65%, followed by pathogenic fungi-24% and insects-8%. The degree of damage to stands depends on the source of damage, species and age of trees. 60% of damaged stands were damaged in 20%, and 1/3 in 10%. Animals most often damaged oaks; fungi-alders; insects-spruce. Fires most often damaged juniper, pine and birch. The most frequently damaged pine, oak and birch stands were characterized by the highest average age of trees (73.1; 56.0; 56.5 years, respectively). On the other hand, the least frequently damaged linden stands were characterized by the lowest average age of trees-45.1 years. Taking into account the influence of the forest site on the probability of damage to stands caused by natural factors, there are no significant differences between most sites. A slightly higher probability of damage to stands occurs in the moist forest site type, but the importance of this site in the study area is small. The paper indicates the exis− tence of a serious problem of damage to the young generation of the forest by wild herbivores. This poses a real threat to the preservation of forest sustainability-the renewal of some tree species, in the study area, animals caused significant damage to oak regeneration. We suggest discussing the necessity to limit the number of wild herbivores in commercial forests. The cur− rently used felling age, adopted for individual tree species, also requires discussion. As we have shown, the higher age of the stands contributes to more frequent damage.
... For an evaluation of the most effective conservation strategy, we need well-designed studies aiming at disentangling the relative importance of habitat area, habitat quality, as well as spatial and temporal connectivity for biodiversity. Ultimately this may lead to the question whether or not conservation strategies in nature reserves should consider interventions shaping habitat heterogeneity, e.g. by considering the mixed disturbance severity concept (Mikoláš, Svitok, Bollmann, Reif, Bače et al., 2017), or enhancing the restoration of old-growth attributes (Bauhus, Puettmann & Messier, 2009) (Beese & Bryant, 1999). Current forest management guidelines and certification criteria (FSC Working Group Germany, 2012) promote land-use equalization by favouring a single management system, in Central Europe a fine-grained continuous cover forestry regime (Messier, Puettmann, Chazdon, Andersson, Angers et al., 2015). ...
Article
Fulltext Share Link (until December 15, 2018): https://authors.elsevier.com/c/1XybY57Eq07Kxc *** Abstract: Forests are under pressure from accelerating global change. To cope with the multiple challenges related to global change but also to further improve forest management we need a better understanding of (1) the linkages between drivers of ecosystem change and the state and management of forest ecosystems as well as their capacity to adapt to ongoing global environmental changes, and (2) the interrelationships within and between the components of forest ecosystems. To address the resulting challenges for the state of forest ecosystems in Central Europe, we suggest 45 questions for future ecological research. We define forest ecology as studies on the abiotic and biotic components of forest ecosystems and their interactions on varying spatial and temporal scales. Our questions cover five thematic fields and correspond to the criteria selected for describing the state of Europe’s forests by policy makers, i.e. biogeochemical cycling, mortality and disturbances, productivity, biodiversity and biotic interactions, and regulation and protection. We conclude that an improved mechanistic understanding of forest ecosystems is essential for the further development of ecosystem-oriented multifunctional forest management in the face of accelerating global change.
... In contrast, capercaillie occurs mostly in coniferous and mixed late seral forests that are characterised by a herb layer dominated by ericaceous plants and open areas that are utilized for courtship behaviour (Bañuelos et al., 2008). A lack of detailed information on disturbance-mediated changes in forest structures often hampers the quantitative analysis of the effects of disturbances and succession on capercaillie and hazel grouse (Mikolás et al., 2017). As the result of bark beetle infestations, mature spruce trees die, resulting in an opening of the canopy and in enhanced growth of regeneration and shrub layers (Swanson et al., 2011). ...
Article
Boreal and mountainous forests are a primary focus of conservation efforts and are naturally prone to large-scale disturbances, such as outbreaks of bark beetles. Affected stands are characterised by biological legacies which persist through the disturbance and subsequent succession. The lack of long-term monitoring data on post-disturbance forest structure precludes understanding of the complex pathways by which natural disturbances affect forest structure and subsequently species presence. We analysed the response of capercaillie (Tetrao urogallus) and hazel grouse (Tetrastes bonasia) to bark beetle infestations. We combined high-resolution airborne light detection and ranging (LiDAR) with a 23-year time series of aerial photography to quantify present-day forest structure and stand disturbance history. Species presence was assessed by collecting droppings of hazel grouse and capercaillie in a citizen science project. Structural equation models showed that the probability of hazel grouse presence increased with increasing disturbance, and the probability of both hazel grouse and capercaillie presence increased with succession. Indirect effects of bark beetle infestations, such as a reduced abundance of deciduous trees and an enhanced herb layer cover, were positively associated with capercaillie presence. Decreasing canopy cover increased the probability of hazel grouse presence. The high temporal and spatial heterogeneity of bark beetle infestations created forest structures that meet the contrasting habitat requirements of both, capercaillie and hazel grouse. This heterogeneity resulted from biological legacies such as decomposing snags, and the simultaneous regrowth of natural regeneration. A benign-neglect strategy towards bark beetle infestations could hence foster capercaillie and hazel grouse in mountainous forests.
... However, following a rapid increase in human densities and settlements (Demographic Research Centre 2017), the Western Carpathian capercaillie population has experienced more than a 70% decline since 1970 (SM- Fig. 1). Intact capercaillie habitats have been fragmented into isolated pockets due to the negative impact of human disturbances, including logging, expanding road networks, and ski resort developments (Mikoláš et al. 2017a). ...
Article
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Context A comprehensive understanding of how rapidly changing environments affect species gene flow is critical for mitigating future biodiversity losses. While recent methodological developments in landscape ecology and genetics have greatly advanced our understanding of biodiversity conservation, they are rarely combined and applied in studies. Objectives We merged multifaceted landscape habitat modelling with genetics to detect and design biological corridors, and we evaluated the importance of habitat patches to test corridor efficacy for gene flow in a fragmented landscape. We examined an isolated population of an endangered umbrella species, the capercaillie (Tetrao urogallus), in the Western Carpathians; they have experienced habitat deterioration and accompanying population declines in recent decades. Methods To detect spatial patterns of genetic distances, we combined and optimized resistance surfaces using species distribution modelling, structural and functional connectivity analyses, multivariate regression approaches, and Moran’s eigenvector maps at hierarchical scales. Results Larger habitat patches had better gene flow among them, and we confirmed a broken metapopulation network characterised by a pattern of isolation by the environment. Distance to human settlements explained landscape genetic patterns better than other environmental and landscape features, MaxEnt resistance, Conefor resistance surfaces, and the pairwise Euclidean distances among individuals. The closer individuals were to settlements, the more pronounced were the effects of logging and other negative factors on their connectivity. Conclusions Merging multifaceted landscape habitat modelling with genetics can effectively test corridor efficacy for gene flow, and it represents a powerful tool for conservation of endangered species.
... Natural disturbances are important drivers of primary forest dynamics, and they play an important role in maintaining biodiversity. Preventing natural disturbances and conducting salvage logging can cause habitat loss for many forest specialist species, and it has a detrimental effect on a broad array of forest communities, including birds, saproxylic beetles, springtails, wood-inhabiting fungi, and epixylic lichens Mikoláš et al., 2017b). Some forest specialist species are dependent on the continuous presence of primary forest habitat features, such as old trees, high amounts and diversity of deadwood, and natural dynamics often result in open to semi-open structure of the forest canopy (Miklin and Cizek, 2014;Zemanová et al., 2017). ...
Article
Given the global intensification of forest management and climate change, protecting and studying forests that develop free of direct human intervention-also known as primary forests-are becoming increasingly important. Yet, most countries still lack data regarding primary forest distribution. Previous studies have tested remote sensing approaches as a promising tool for identifying primary forests. However, their precision is highly dependent on data quality and resolution, which vary considerably. This has led to underestimation of primary forest abundance and distribution in some regions, such as the temperate zone of Europe. Field-based inventories of primary forests and methodologies to conduct these assessments are inconsistent; incomplete or inaccurate mapping increases the vulnerability of primary forest systems to continued loss from clearing and land-use change. We developed a comprehensive methodological approach for identifying primary forests, and tested it within one of Europe's hotspots of primary forest abundance: the Carpathian Mountains. From 2009 to 2015, we conducted the first national-scale primary forest census covering the entire 49,036 km 2 area of the Slovak Republic. We analyzed primary forest distribution patterns and the representativeness of potential vegetation types within primary forest remnants. We further evaluated the conservation status and extent of primary forest loss. Remaining primary forests are small, fragmented, and often do not represent the potential natural vegetation. We identified 261 primary forest localities. However, they represent only 0.47% of the total forested area, which is 0.21% of the country's land area. The spatial pattern of primary forests was clustered. Primary forests have tended to escape anthropogenic disturbance on sites with higher elevations, steeper slopes, rugged terrain, and greater distances from roads and settlements. Primary forest stands of montane mixed and subalpine spruce forests are more abundant compared to broadleaved forests. Notably, several habitat types are completely missing within primary forests (e.g., floodplain forests). More than 30% of the remaining primary forests are not strictly protected, and harvesting occurred at 32 primary forest localities within the study period. Almost all logging of primary forests was conducted inside of protected areas, underscoring the critical status of primary forest distribution in this part of Europe. Effective conservation strategies are urgently needed to stop the rapid loss and fragmentation of the remaining primary forests. Our approach based on precise, field-based surveys is widely applicable and transferrable to other fragmented forest landscapes.
... Obwohl durch die Erderwärmung langfristig vor allem in den Tieflagen von Gebirgsregionen eine Lebensraumverschlechterung für Auerhühner zu erwarten ist (Huntley et al. 2007;Braunisch et al. 2013;Moss 2015), könnte die Zunahme von Wetterextremen (z. B. Stürme, Trockenperioden; Dale et al. 2001) auch zu Lebensraumverbesserungen führen (Mikoláš et al. 2017;Kortmann et al. 2018). Der Klimawandel kann daher einen großen Einfluss auf die Entwicklung der Auerhuhnlebensräume haben. ...
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Capercaillie (Tetrao urogallus) are considered as indicator species of species rich, open conifer dominated forests and still occur over large parts of their natural range. In Western- and Central Europe populations are mainly restricted to mountain ranges, many of them are declining or became extinct. In the Black Forest, South-Western Germany, the population was first estimated based on lek counts across the entire mountain range in 1971, since 1983 this census was performed yearly. In addition, since 1988, all sightings of capercaillie are collated on a 5-year basis, to map the capercaillie distribution. The lek counts clearly reveal a negative population trend: While a total of 570 males were counted in 1971, only 167 males were counted in 2018. This decline is not evenly distributed across the Black Forest. The subpopulations in the Eastern Black Forest (Baarschwarzwald) and the Southern Black forest decreased most (from 48 males in 1993 to 8 males in 2018 and from 160 males in 1993 to 26 males in 2018, respectively). The Central Black Forest subpopulation remained stable with 11 lekking males. The Northern Black Forest subpopulation first increased (from 130 lekking males in 1993 to 197 in 2008) and decreased afterwards to 122 males in 2018. The distribution area decreased from 607 km2 in the period from 1989 to 1993 to 344 km2 from 2014 to 2018. The loss of distribution area was recorded for all subpopulations, but was largest for the Baarschwarzwald subpopulation. The causes of the decline still remain unclear and might include habitat deterioration due to changes in the forestry regime and an increase in growing stock, increasing predation pressure, climate change and an increase in anthropogenic disturbance.
... For example, species confined to the boreal or highaltitude forest (e.g. Siberian Jay (Perisoreus infaustus) or Capercaillie (Tetrao urogallus), Mikoláš et al., 2017) do not breed in tundra or alpine grasslands and vice versa (e.g. Snow Bunting (Plectrophenax nivalis) or Water Pipit (Anthus spinoletta), Melendez & Laiolo, 2014). ...
Article
The level of habitat specialization is informative in terms of animals’ population status and conservation concern. Therefore, identifying the areas where specialist species are aggregated and understanding the ecological constrains that might shape their distribution has become an important issue. In this sense, we tested whether specialist communities are more likely to succeed in milder and stable environments or in more extreme and less predictable environments. For that purpose, we used data from the EBCC atlas of European breeding birds and for each of 50 × 50 km grid cells calculated community specialization index (CSI). We expressed CSI in two ways: as a mean (CSIMEAN) and a standard deviation (CSISD) across species in a given cell. We used generalized least squares (GLS) models to relate these measures to geographic variables (latitude, longitude and altitude) and climatic variables (temperature and rainfall) across Europe controlling for possible confounding effects of habitat heterogeneity and human-induced land cover conversion. We identified two areas, Scandinavian Peninsula and the steppe regions north of Caucasus, where bird communities are highly specialised. GLS models showed that habitat specialization generally increased with altitude and this pattern was broadly shared by the CSIMEAN and CSISD. Concerning climatic variables, we found that specialist spatial distribution was significantly related to extreme temperatures and lower level of precipitation. Our results thus suggest that European specialist birds are found mostly in strongly seasonal, dry and cold environments. Thereby, preserving these sensible environments from further perturbations might be the key for the specialist conservation.
... Despite these controversial results, it has been suggested that the species needs a certain level of spatial heterogeneity (Canut et al., 2011). For instance, Mikoláš et al. (2017) showed that, in primary forests of the Carpathian Mountains, a disturbance regime of variable intensity is required to generate diverse habitats suitable for Capercaillie, and they conclude that natural disturbance should be mimicked as a conservation tool in protected areas. ...
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Long-term monitoring of endangered birds is essential to estimate population trends and to identify potential causes of population decline. This is particularly important for alpine birds inhabiting mountain areas at the boundaries of their range. Here we analyse the population trend of Capercaillie in the Spanish Central Pyrenees based on annual surveys carried out between 2000 and 2017. We found a significant population decline (around 58%) in the number of birds counted in leks. Most capercaillies inhabit coniferous forests of Black Pine with abundant Bilberry and Rhododendron understorey. The number of males declined at lower altitudes and in more exposed orientations, in a scenario consistent with the differential rate of loss of habitat quality due to climate change. We hypothesised that one of the main causes of the Capercaillie decline could be low breeding success (average annual productivity 0.67 chicks per female). In light of the decline rates observed, the Pyrenean population should be relisted as endangered in the Spanish National Catalogue of Endangered Species. Affording a higher degree of protection should guarantee the adoption of management measures to reverse or slow down the general trend of decline of the species in the south of its range.—Gil, J.A., Gómez-Serrano, M.Á. & López-López, P. (2020). Population decline of the Capercaillie Tetrao urogallus aquitanicus in the Central Pyrenees. Ardeola, 67: 285-306.
... old-growth forests) represent forest communities that have attained high age through natural development, largely untainted by direct human activity over time, while still exhibiting unique ecological features and offering a diverse range of ecosystem services (White and Lloyd, 1994;Mosseler et al., 2003;Mosseler et al., 2011;Kulakowski et al., 2017). They are characterized by a high degree of vertical and horizontal stand diversity, provide habitats for a diverse range of species, and generally contain a higher amount of accumulated biomass than managed forests, thereby playing an important role as a major global carbon sink (Gunn et al., 2014;Calfapietra et al., 2015;Nabuurs et al., 2016;Mikoláš et al., 2017). In recent decades, efforts have been made to quantify the impact of environmental change on forest stand dynamics (Black et al., 2008b;Bigler and Veblen, 2009;Di Filippo et al., 2015) in order to differentiate the importance and strength of various growth-affecting factors, along with their interactions (Castagneri et al., 2011;Primicia et al., 2015;Latte et al., 2015). ...
... The capercaillie in particular is considered an indicator species for species-rich, open, structurally diverse mature conifer-dominated forests (Suter et al., 2002;Pakkala et al., 2003) and is associated with the forest structures caused by natural disturbance events (i.e. wind throw, bark beetle; Mikoláš et al., 2017, Kortmann et al., 2018. Structural attributes typical of late successional stages and natural disturbance dynamics (i.e. ...
Article
The degradation of forest habitats in managed forests is a major threat to biodiversity. Accordingly, the conservation of forest-dwelling species has to be integrated with other goals and paradigms of production forestry. As those objectives may differ, it is crucial to quantify the potential effectiveness of habitat management for conservation to demonstrate its actual value. Here, we analysed detailed field-based distribution maps of a declining population of capercaillie (Tetrao urogallus), an indicator of open, structurally diverse conifer-dominated forests, in southwestern Germany to quantify the potential effect size of habitat management. We modelled range loss dynamics as a function of habitat structures obtained from high-resolution aerial stereo imagery, in order to estimate the potential increase in the probability of local capercaillie persistence under different management scenarios. Furthermore we identified situations in which habitat management would produce the largest conservation benefits. The probability of local capercaillie persistence during the study period was positively related to population connectivity, winter snow height and the availability of suitable forest structures. The positive effect of habitat management was largest at sites where persistence probability would otherwise be low to intermediate. Potential negative effects of decreasing snow load under climate change on local capercaillie persistence could be compensated more effectively by habitat improvement than a lack of population connectivity, implying that focusing habitat management on the edges of the distribution in addition to core areas would maximize conservation returns. Our results may thus contribute to an effective allocation of conservation investments where their leverage is highest.
... For example, in central Europe multi-aged (i.e. multi-cohort) stands originating from partial disturbances and subsequent pulse tree recruitment are common in some primary conifer forests (Mikoláš et al. 2017). ...
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In Europe, forest management has controlled forest dynamics to sustain commodity production over multiple centuries. Yet over‐regulation for growth and yield diminishes resilience to environmental stress as well as threatens biodiversity, leading to increasing forest susceptibility to an array of disturbances. These trends have stimulated interest in alternative management systems, including natural dynamics silviculture (NDS). NDS aims to emulate natural disturbance dynamics at stand and landscape scales through silvicultural manipulations of forest structure and landscape patterns. We adapted a “Comparability Index” (CI) to assess convergence/divergence between natural disturbances and forest management effects. We extended the original CI concept based on disturbance size and frequency by adding the residual structure of canopy trees after a disturbance as a third dimension. We populated the model by compiling data on natural disturbance dynamics and management from 13 countries in Europe, covering four major forest types (i.e., spruce, beech, oak, and pine‐dominated forests). We found that natural disturbances are highly variable in size, frequency, and residual structure, but European forest management fails to encompass this complexity. Silviculture in Europe is skewed towards even‐aged systems, used predominately (72.9% of management) across the countries assessed. The residual structure proved crucial in the comparison of natural disturbances and silvicultural systems. CI indicated the highest congruence between uneven‐aged silvicultural systems and key natural disturbance attributes. Even so, uneven‐aged practices emulated only a portion of the complexity associated with natural disturbance effects. The remaining silvicultural systems perform poorly in terms of retention as compared to tree survivorship after natural disturbances. We suggest that NDS can enrich Europe's portfolio of management systems, for example where wood production is not the primary objective. NDS is especially relevant to forests managed for habitat quality, risk reduction, and a variety of ecosystem services. We suggest a holistic approach integrating natural dynamics silviculture with more conventional practices.
... Contrarily, changes in species richness might be large while the turnover between communities in different habitat types is relatively small, i.e., a high number of species is shared 36 . Shared species can include species that utilize both forest types, for instance by roosting or breeding in unlogged disturbed forest and foraging in both unlogged and salvage-logged forests 37,38 . ...
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Forests are increasingly affected by natural disturbances. Subsequent salvage logging, a widespread management practice conducted predominantly to recover economic capital, produces further disturbance and impacts biodiversity worldwide. Hence, naturally disturbed forests are among the most threatened habitats in the world, with consequences for their associated biodiversity. However, there are no evidence-based benchmarks for the proportion of area of naturally disturbed forests to be excluded from salvage logging to conserve biodiversity. We apply a mixed rarefaction/extrapolation approach to a global multi-taxa dataset from disturbed forests, including birds, plants, insects and fungi, to close this gap. We find that 75 ± 7% (mean ± SD) of a naturally disturbed area of a forest needs to be left unlogged to maintain 90% richness of its unique species, whereas retaining 50% of a naturally disturbed forest unlogged maintains 73 ± 12% of its unique species richness. These values do not change with the time elapsed since disturbance but vary considerably among taxonomic groups.
... Contrarily, changes in species richness might be large while the turnover between communities in different habitat types is relatively small, i.e., a high number of species is shared 36 . Shared species can include species that utilize both forest types, for instance by roosting or breeding in unlogged disturbed forest and foraging in both unlogged and salvage-logged forests 37,38 . ...
Article
Full-text available
Forests are increasingly affected by natural disturbances. Subsequent salvage logging, a widespread management practice conducted predominantly to recover economic capital, produces further disturbance and impacts biodiversity worldwide. Hence, naturally disturbed forests are among the most threatened habitats in the world, with consequences for their associated biodiversity. However, there are no evidence-based benchmarks for the proportion of area of naturally disturbed forests to be excluded from salvage logging to conserve biodiversity. We apply a mixed rarefaction/extrapolation approach to a global multi-taxa dataset from disturbed forests, including birds, plants, insects and fungi, to close this gap. We find that 75 ± 7% (mean ± SD) of a naturally disturbed area of a forest needs to be left unlogged to maintain 90% richness of its unique species, whereas retaining 50% of a naturally disturbed forest unlogged maintains 73 ± 12% of its unique species richness. These values do not change with the time elapsed since disturbance but vary considerably among taxonomic groups.
... However, the literature is still lacking information on the long-term influence of particular traits of disturbance like severity, frequency and timing. Linking disturbance history to the habitat requirements of birds is a novel approach, successfully proposed and tested by Mikoláš et al. (2017), which allows the incorporation of data extending from tens to hundreds of years. ...
Article
Understanding the processes shaping the composition of assemblages in response to disturbance events is crucial for preventing ongoing biodiversity loss in forest ecosystems. However, studies of forest biodiversity responses to disturbance typically analyze immediate or short-term impacts only, while studies relating long-term disturbance history to biodiversity assemblage dynamics are rare. To address this important knowledge gap, we used a dendroecological approach to link natural disturbance history of 250 years (1750-2000) to structural habitat elements and, in turn, to breeding bird assemblages. We used data collected in 2017 and 2018 from 58 permanent study plots within 10 primary spruce forest stands distributed across the Western Carpathian Mountains of Europe. This dataset contained breeding bird counts and environmental variables describing forest density, tree diameter distribution, tree height, tree microhabitats, deadwood quantity and quality, and regeneration. Bird assemblages were significantly influenced by forest structure which was in turn shaped by disturbance dynamics (disturbance frequency, time since the last disturbance and its severity). Early successional species associated with more open habitats were positively influenced by disturbance-related structure (i.e. deadwood-related variables, canopy cover), while some species responded negatively. At the same time, overall abundance, species richness and Shannon diversity of the bird assemblage remained unchanged under variable disturbance histories. Our results support a view of primary spruce forests as a highly dynamic ecosystem, harbouring populations of bird species at all stages of succession despite significant structural changes and shifting patch mosaics over time due to natural disturbances.
... Here we demonstrate a spatiotemporal approach, and our result is fundamentally different with previous ones (Fig. 2). We believe that our findings provide an important empirical base for using phonological metrics over time to fit species distribution models, and is applicable to other regions where the majority of the conservation funds are directed toward a single charismatic species (Mikoláš et al., 2017). We found that the net habitat loss inside nature reserves is 200% higher for Asiatic black bear and 80% higher for forest musk deer than outside nature reserve, while all other species had higher net habitat increase in than outside nature reserves (Fig. 4). ...
Article
The use of a charismatic umbrella species as surrogate for sympatric species is often advocated as an efficient approach. However, comprehensive evaluations from a spatio-temporal perspective are few, leaving the long-term effectiveness of such practices remain uncertain. We modeled the habitat change for giant panda and eight sympatric mammalian species using observations from extensive camera trap surveys and remotely-sensed environmental predictors during two time periods, early 2000s and early 2010s. We found that the degree and spatial pattern of the habitat suitability change varied among species. The overall habitat suitability improved between the early 2000s and early 2010s for seven target species including giant panda Ailuropoda melanoleuca, suggesting positive effects of several recent conservation projects in restoring natural landscapes for certain species groups. However, the current nature reserve system designed for giant pandas did not adequately cover critical landscapes for several species, including the two species who experienced net habitat loss, Endangered forest musk deer Moschus berezovskii and Vulnerble Asiatic black bear Ursus thibetanus. To conserve multiple species simultaneously in this region, we recommend establishing nature reserves for other threatened species who share dissimilar habitat needs with giant panda, and adding a widely distributed omnivores, Asiatic black bear, as a surrogate species in central and southwest China. These findings reveal the risk of using umbrella species as a conservation shortcut in protecting animal communities in China, and have substantial implications for other regions where the majority of the conservation funds are directed toward a single charismatic species.
... Once spreading across the whole European continent, nowadays primary forests are found just in the form of small, disconnected remnants [21,22]. The Carpathian region is optimal for describing the structure and dynamics of these ecosystems because it includes a large and diverse (in terms of forest types) amount of primary forests [6]. ...
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Research Highlights: Past disturbances occurred naturally in primary forests in the Southern Carpathians. High-and moderate-severity disturbances shaped the present structure of these ecosystems, which regenerated successfully without forestry interventions. Background and Objectives: Windstorms and bark beetle outbreaks have recently affected large forest areas across the globe, causing concerns that these disturbances lie outside the range of natural variability of forest ecosystems. This often led to salvage logging inside protected areas, one of the main reasons for primary forest loss in Eastern Europe. Although more than two-thirds of temperate primary forests in Europe are located in the Carpathian region of Eastern Europe, knowledge about how natural disturbances shape the forest dynamics in this region is highly essential for future management decisions. Material and Methods: We established our study in a primary forest valley situated in the centre of the largest temperate primary forest landscape in Europe (Făgăras , Mountains). A dendrochronological investigation was carried out to reconstruct the natural disturbance history and relate it to the present forest structure. Results: The dendrochronological analysis revealed high temporal variability in the disturbance patterns both at the patch and stand level. Moderate severity disturbance events were most common (20-40% of canopy disturbed in 60% of the plots) but high severity events did also occur (33% of the plots). Regeneration was spruce-dominated and 71% of the seedlings were found on deadwood microsites. Conclusions: We conclude that the current structure of the studied area is a consequence of the past moderate-severity disturbances and sporadic high-severity events. The peak in disturbances (1880-1910) followed by reduced disturbance rates may contribute to a recent and future increase in disturbances in the Făgăras , Mts. Our findings show that these disturbance types are within the range of natural variability of mountain spruce forests in the Southern Carpathians and should not be a reason for salvage logging in primary forests from this area.
... In fact, sampling within fragments of primary forest throughout the Carpathians provided the rare opportunity to study a naturally occurring low-altitude range limit of Picea abies in Europe, where intense management has otherwise led to an artificial proliferation of Picea at low altitudes. The unique structural characteristics of these monospecific Picea forests, for example, disturbance patches generated by spruce beetle outbreaks, are crucial habitat elements for multiple species of high conservation value (Mikolaš et al. 2017). Critically, alpine areas conducive to monospecific Picea forests are shrinking, and the likely encroachment of low altitude tree species implies major changes to the variety of habitats found in these forests (Dirnböck et al. 2011). ...
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Adapting for competitiveness versus climatic stress tolerance constitutes a primary trade-off differentiating tree life-history strategies. This tradeoff likely influences where species’ range-limits occur, but such links are data-demanding to study and key mechanisms lack empirical support. Using an exceptionally rich dendroecological network, we assessed spatial variation in climate and competition effects on Picea abies and Fagus sylvatica throughout the Carpathian Ecoregion. Ring width synchrony aided in diagnosing how the prevalence of resource-limited (competition) and sink-limited (climate) growth changes with altitude and community composition. Contrasting growth patterns towards respective upper and lower range limits of Fagus and Picea reflected tradeoffs between competitive vs. cold-tolerant strategies. Fagus performance declined with altitudinal increases in climate sensitivity, but improved under interspecific competition. Picea growth increased towards the species’ lower range limit, but declined under interspecific competition. Warmer temperatures likely benefit competitively stronger species at mid elevations and thus imply range reductions for alpine conifers.
... A capercaillie is a ground-dwelling bird species that inhabits forest habitats characterized by open canopy (40-60%), structural heterogeneity, and rich ground vegetation [41]. Capercaillies typically inhabit primary forests in the study region [42], although habitat associations may differ in other parts of Europe. We thoroughly searched the study plots for signs of capercaillie occurrence (e.g. ...
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With accelerating environmental change, understanding forest disturbance impacts on trade-offs between biodiversity and carbon dynamics is of high socioeconomic importance. Most studies, however, have assessed immediate or short-term effects of disturbance, while long-term impacts remain poorly understood. Using a tree-ring-based approach, we analysed the effect of 250 years of disturbances on present-day biodiversity indicators and carbon dynamics in primary forests. Disturbance legacies spanning centuries shaped contemporary forest co-benefits and trade-offs, with contrasting, local-scale effects. Disturbances enhanced carbon sequestration, reaching maximum rates within a comparatively narrow post-disturbance window (up to 50 years). Concurrently, disturbance diminished aboveground carbon storage, which gradually returned to peak levels over centuries. Temporal patterns in biodiversity potential were bimodal; the first maximum coincided with the short-term post-disturbance carbon sequestration peak, and the second occurred during periods of maximum carbon storage in complex old-growth forest. Despite fluctuating local-scale trade-offs, forest biodiversity and carbon storage remained stable across the broader study region, and our data support a positive relationship between carbon stocks and biodiversity potential. These findings underscore the interdependencies of forest processes, and highlight the necessity of large-scale conservation programmes to effectively promote both biodiversity and long-term carbon storage, particularly given the accelerating global biodiversity and climate crises.
... The new structures that result from natural disturbances, like an increased amount of dead wood, open canopy, a diverse understory, vertical diversification. and spatial heterogeneity (Meigs et al., 2017;Senf et al., 2020;Swanson et al., 2011), can provide habitat for rare or endangered species (Bässler & Müller, 2010;Mikol as et al., 2017). For example, Aculeata, Syrphidae and Formicidae can benefit from open forests with warmer microhabitats (Beudert et al., 2015;Lehnert et al., 2013). ...
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Natural disturbances are increasing around the globe, also impacting protected areas. Although previous studies have indicated that natural disturbances result in mainly positive effects on biodiversity, these analyses mostly focused on a few well established taxonomic groups, and thus uncertainty remains regarding the comprehensive impact of natural disturbances on biodiversity. Using Malaise traps and meta-barcoding, we studied a broad range of arthropod taxa, including dark and cryptic taxa, along a gradient of bark beetle disturbance severities in five European national parks. We identified order-level community thresholds of disturbance severity and classified barcode index numbers (BINs; a cluster system for DNA sequences, where each cluster corresponds to a species) as negative or positive disturbance indicators. Negative indicator BINs decreased above thresholds of low to medium disturbance severity (20%-30% of trees killed), whereas positive indicator BINs benefited from high disturbance severity (76%-98%). BINs allocated to a species name contained nearly as many positive as negative disturbance indicators, but dark and cryptic taxa, particularly Diptera and Hymenoptera in our data, contained higher numbers of negative disturbance indicator BINs. Analyses of changes in the richness of BINs showed variable responses of arthropods to disturbance severity at lower taxonomic levels, whereas no significant signal was detected at the order level due to the compensatory responses of the underlying taxa. We conclude that the analyses of dark taxa can offer new insights into biodiversity responses to disturbances. Our results suggest considerable potential for forest management to foster arthropod diversity, for example by maintaining both closed-canopy forests (>70% cover) and open forests (<30% cover) on the landscape.
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The expected future intensification of forest disturbance as a consequence of ongoing anthropogenic climate change highlights the urgent need to more robustly quantify associated biotic responses. Saproxylic beetles are a diverse group of forest invertebrates representing a major component of biodiversity that is associated with the decomposition and cycling of wood nutrients and carbon in forest ecosystems. Disturbance-induced declines or shifts in their diversity indicate the loss of key ecological and/or morphological species traits that could change ecosystem functioning. Functional and phylogenetic diversity of biological communities is commonly used to link species communities to ecosystem functions. However, our knowledge on how disturbance intensity alters functional and phylogenetic diversity of saproxylic beetles is incomplete. Here, we analyzed the main drivers of saproxylic beetle abundance and diversity using a comprehensive dataset from montane primary forests in Europe. We investigated cascading relationships between 250 years of historical disturbance mechanisms, forest structural attributes and the taxonomic, phylogenetic and functional diversity of present-day beetle communities. Our analyses revealed that historical disturbances have significant effects on current beetle communities. Contrary to our expectations, different aspects of beetle communities, that is, abundance, taxonomic, phylogenetic and functional diversity, responded to different disturbance regime components. Past disturbance frequency was the most important component influencing saproxylic beetle communities and habitat via multiple temporal and spatial pathways. The quantity of deadwood and its diameter positively influenced saproxylic beetle abundance and functional diversity, whereas phylogenetic diversity was positively influenced by canopy openness. Analyzing historical disturbances, we observed that current beetle diversity is far from static, such that the importance of various drivers might change during further successional development. Only forest landscapes that are large enough to allow for the full range of temporal and spatial patterns of disturbances and post-disturbance development will enable long-term species coexistence and their associated ecosystem functions.
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Aim Natural disturbances influence forest structure, successional dynamics, and, consequently, the distribution of species through time and space. We quantified the long-term impacts of natural disturbances on lichen species richness and composition in primary mountain forests, with a particular focus on the occurrence of endangered species. Location Ten primary mountain spruce forest stands across five mountain chains of the Western Carpathians, a European hotspot of biodiversity. Methods Living trees, snags, and downed logs were surveyed for epiphytic and epixylic lichens in 57 plots. Using reconstructed disturbance history, we tested how lichen species richness and composition was affected by the current forest structure and disturbance regimes in the past 250 years. We also examined differences in community composition among discrete microhabitats. Results Dead standing trees as biological legacies of natural disturbances promoted lichen species richness and occurrence of threatened species at the plot scale, suggesting improved growing conditions for rare and common lichens during the early stages of recovery post-disturbance. However, high-severity disturbances compromised plot scale species richness. Both species richness and the number of old-growth specialists increased with time since disturbance (i.e. long-term uninterrupted succession). No lichen species was strictly dependent on live trees as a habitat, but numerous species showed specificity to logs, standing objects, or admixture of tree species. Main conclusions Lichen species richness was lower in regenerating, young, and uniform plots compared to overmature and recently disturbed areas. Natural forest dynamics and its legacies are critical to the diversity and species composition of lichens. Spatiotemporal consequences of natural dynamics require a sufficient area of protected forests for provisioning continual habitat variability at the landscape scale. Ongoing climatic changes may further accentuate this necessity. Hence, we highlighted the need to protect the last remaining primary forests to ensure the survival of regionally unique species pools of lichens.
Article
Disturbances have been recognized as a key factor shaping the species composition, structure and dynamics of natural forest ecosystems. In Europe, where forests driven by spontaneous processes have survived in relic form, knowledge about natural disturbance regimes is still fragmentary. To expand this knowledge, we reconstructed stand-level growth and analyzed the spatio-temporal pattern of release signals in the increment chronologies of individual trees as indicators of disturbance events in the Western Carpathians (Central Europe). The study was carried out in five old-growth forests formed by Fagus sylvatica L., Abies alba Mill. and Picea abies (L.) H. Karst. Depending on the stand, the analyses included tree-ring series of 84–193 trees sampled over areas of 5.9–13.6 ha and aimed at determining (1) the spatio-temporal pattern of disturbance severity over the last two centuries, (2) whether disturbances have been synchronized in time across the study sites and (3) whether disturbances have induced pulsed dynamics of stand development manifested as fluctuations in radial tree increment at the level of entire stands. In the period 1850–2010, the percentage of decades with the proportion of released trees < 10, 10–20, 20–30 or more than 30% was 38, 41, 14 and 7%, respectively, and no instances of severe disturbances simultaneously impacting an extensive area and releasing the vast majority of trees were found. The release events were only weakly synchronized at the between-stand level. The spatial distribution of released trees varied over the decades, with a shift toward spatial independence for the most severe disturbances. At the stand level, the interchanging periods of increasing/decreasing tree growth lasted between 24 and 36 years, with the exception of one stand in which this period lasted 54 years. The revealed fluctuations in tree growth attributable to changes in stand density were relatively small and accounted on average for 7% of the total variation in annual tree increments. This suggests that local level disturbances introduce structural heterogeneity and strongly modify tree growth, but at the stand level, their effect is dispersed and causes only minor fluctuations. An over-dispersion of decadal release frequencies compared to the random model and spatial correlation of disturbing events on the one hand, and the lack of extensive disturbances, frequent occurrence of multiple releases in tree life histories, and small fluctuations in the reconstructed growth at the stand level on the other hand, suggest a disturbance regime which goes beyond random processes in a strict sense and is thus not entirely compatible with the classical model of gap-phase stand dynamics.
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Old-growth forests around the world are vanishing rapidly and have been lost almost completely from the European temperate forest region. Poor management practices, often triggered by socioeconomic and institutional change, are the main causes of loss. Recent trends in old-growth forest cover in Romania, where some of the last remaining tracts of these forests within Europe are located, are revealed by satellite image analysis. Forest cover declined by 1.3 % from 2000 to 2010. Romania's protected area network has been expanded substantially since the country's accession to the European Union in 2007, and most of the remaining old-growth forests now are located within protected areas. Surprisingly though, 72% of the old-growth forest disturbances are found within protected areas, highlighting the threats still facing these forests. It appears that logging in old-growth forests is, at least in part, related to institutional reforms, insufficient protection and ownership changes since the collapse of communism in 1989. The majority of harvesting activities in old-growth forest areas are in accordance with the law. Without improvements to their governance, the future of Romania's old-growth forests and the important ecosystem services they provide remains uncertain.
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Ecology of capercaillie (Tetrao urogallus) was studied in the mountains of Central Slovakia (West Carpathians) in 1981-2003. In the studied area, the capercaillie population inhabited especially old natural forests (100-250 years old) in the spruce-beech-fir (850-1,270 m a.s.l.) and spruce (1,250-1,530 m a.s.l.) vegetation zones. The overstorey stand age ranged between 80 and 250 years with the mean of 128 years. The understorey stand age ranged from 10 to 60 years. The overstorey tree density ranged between 200 and 1,050 stems per ha (mean 725). The understorey tree density ranged from 5 to 650 trees per ha (mean 290). Both males and females preferred old forests throughout the year. The results demonstrate a marked decrease (> 50%) in the numbers of cocks and hens on twelve monitored leks (28%) and a slight decrease (< 50%) on ten display grounds (24%). During the study period, capercaillie cocks became extinct on seven (16%) leks and in their surroundings. More or less constant numbers were found on twelve leks only (28%) and a slight increase occurred on two leks only (4%). A statistically highly significant corre - lation was found between the area of old-growth forest and the number of cocks attending a lek. In addition to forest deterioration predation appeared to be of major importance in limiting the numbers of capercaillies. Key points for forest management in relation to capercaillie protection are suggested.
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Capercaillie (Tetrao urogallus L., 1758), the largest and most size-dimorphic species of grouse, is decreasing in number throughout its man-modified range in the boreal forests of the Palaearctic. Poor reproduction owing to direct and indirect effects of commercial forestry is considered a main cause of the decline. We studied brood habitats in a pristine forest in northwestern Russia to identify key elements in habitat selection in the natural environment of this species. We monitored the movement of 10 radio-marked broods during their first 7 weeks of life, and compared the abundance of insects and cover at their locations (N = 120) with nearby random control sites. The broods preferentially used moist spruce forest and the insect-rich herb spruce forest, but were most often located in the more abundant vaccinium spruce forest, which was richest in bilberry (Vaccinium myrtillus L.) and associated lepidopteran larvae. Brood locations were consistently richer in insects than random controls in 3 of the 4 habitat types studied. The most pronounced difference was in the density of lepidopteran larvae, a food source known to form an important part of the diet of young capercaille chicks. Broods continued to select insect-rich sites throughout the 7 week age period; in the preferred moist spruce forest, larval abundance increased at brood locations, while it remained constant at control sites. Compared to the distribution of insects, cover did not appear to be as an important determinant of brood habitat selection, possibly because the structural characteristics were rather similar among the most widely used habitat types. Shrub cover tended to be higher at brood locations than at controls, whereas vertical cover along the ground was not different. This relationship to cover factors may reflect an adaptation to avoid predation by goshawk (Accipiter gentilis (L., 1758)), the most important predator of grouse in this pristine boreal forest.
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Old-growth forests typically have complex structures, including heterogeneous spatial arrangements as well as a diversity of individual structures. Two aspects of this spatial complexity are discussed and illustrated: (1) vertical distribution of foliage, often apparent as multiple layers; and (2) horizontal heterogeneity, often evident as canopy gaps and dense reproduction patches. Shifts in mortality processes from competitive-based mortality in young stands to agent-based mortality (i.e., insects, diseases, and wind) in older stands play an important part in the development of structural heterogeneity. Old temperate forests can be viewed as fine-scale structural mosaics in which all stand development processes are simultaneously present within the stand. An additional definition of forest stand that incorporates the entire structural mosaic of old-growth is needed.
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Mixed-severity disturbance regimes are prevalent in temperate forests worldwide, but key uncertainties remain regarding the variability of disturbance-mediated structural development pathways. This study investigates the influence of disturbance history on current structure in primary, unmanaged Norway spruce (Picea abies) forests throughout the Carpathian Mountains of central and eastern Europe, where windstorms and native bark beetle outbreaks are the dominant natural disturbances. We inventoried forest structure on 453 plots (0.1 ha) spanning a large geographical gradient (\>1,000 km), coring 15–25 canopy trees per plot for disturbance history reconstruction (tree core total n = 11,309). Our specific objectives were to: (1) classify sub-hectare-scale disturbance history based on disturbance timing and severity; (2) classify current forest structure based on tree size distributions (live, dead, standing, downed); (3) characterize structural development pathways as revealed by the association between disturbance history and current forest structural complexity. We used hierarchical cluster analysis for the first two objectives and indicator analysis for the third. The disturbance-based cluster analysis yielded six groups associated with three levels of disturbance severity (low, moderate, and high canopy loss) and two levels of timing (old, recent) over the past 200 years. The structure-based cluster analysis yielded three groups along a gradient of increasing structural complexity. A large majority of plots exhibited relatively high (53\%) or very high (26\%) structural complexity, indicated by abundant large live trees, standing and downed dead trees, and spruce regeneration. Consistent with conventional models of structural development, some disturbance history groups were associated with specific structural complexity groups, particularly low-severity/recent (very high complexity) and high-severity/recent (moderate complexity) disturbances. In other cases, however, the distribution of plots among disturbance history and structural complexity groups indicated either divergent or convergent pathways. For example, multiple disturbance history groups were significantly associated with the high complexity group, demonstrating structural convergence. These results illustrate that complex forest structure – including features nominally associated with old-growth – can be associated as much with disturbance severity as it is with conventional notions of forest age. Because wind and bark beetles are natural disturbance processes that can induce relatively high levels of tree mortality while simultaneously contributing to structural complexity and heterogeneity, we suggest that forest management plans allow for the stochastic occurrence of disturbance and variable post-disturbance development trajectories. Such applications are especially appropriate in conservation areas where biodiversity and forest resilience are management objectives, particularly given projections of increasing disturbance activity under global change.
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In order to gauge ongoing and future changes to disturbance regimes, it is necessary to establish a solid baseline of historic disturbance patterns against which to evaluate these changes. Further, understanding how forest structure and composition respond to variation in past disturbances may provide insight into future resilience to climate-driven alterations of disturbance regimes.
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Mountain forests are among the most important ecosystems in Europe as they support numerous ecological, hydrological, climatic, social, and economic functions. They are unique relatively natural ecosystems consisting of long-lived species in an otherwise densely populated human landscape. Despite this, centuries of intensive forest management in many of these forests have eclipsed evidence of natural processes, especially the role of disturbances in long-term forest dynamics. Recent trends of land abandonment and establishment of protected forests have coincided with a growing interest in managing forests in more natural states. At the same time, the importance of past disturbances highlighted in an emerging body of literature, and recent increasing disturbances due to climate change are challenging long-held views of dynamics in these ecosystems. Here, we synthesize aspects of this Special Issue on the ecology of mountain forest ecosystems in Europe in the context of broader discussions in the field, to present a new perspective on these ecosystems and their natural disturbance regimes. Most mountain forests in Europe, for which long-term data are available, show a strong and long-term effect of not only human land use but also of natural disturbances that vary by orders of magnitude in size and frequency. Although these disturbances may kill many trees, the forests themselves have not been threatened. The relative importance of natural disturbances, land use, and climate change for ecosystem dynamics varies across space and time. Across the continent, changing climate and land use are altering forest cover, forest structure, tree demography, and natural disturbances, including fires, insect outbreaks, avalanches, and wind disturbances. Projected continued increases in forest area and biomass along with continued warming are likely to further promote forest disturbances. Episodic disturbances may foster ecosystem adaptation to the effects of ongoing and future climatic change. Increasing disturbances, along with trends of less intense land use, will promote further increases in coarse woody debris, with cascading positive effects on biodiversity, edaphic conditions, biogeochemical cycles, and increased heterogeneity across a range of spatial scales. Together, this may translate to disturbance-mediated resilience of forest landscapes and increased biodiversity, as long as climate and disturbance regimes remain within the tolerance of relevant species. Understanding ecological variability, even imperfectly, is integral to anticipating vulnerabilities and promoting ecological resilience, especially under growing uncertainty. Allowing some forests to be shaped by natural processes may be congruent with multiple goals of forest management, even in densely settled and developed countries.
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Disturbances shape forest structure and composition, but the temporal dynamics of disturbance patterns, their influence on dynamics of forest structural complexity, and the potential impacts of ongoing climate changes are not fully understood. We addressed these issues by focusing on (1) long-term, landscape level retrospective analysis of disturbance dynamics of mountain Norway spruce (Picea abies) forest; (2) testing for the prevailing disturbance agent; and (3) the detection of disturbance drivers, particularly site conditions, using a dendrochronological approach.
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Population structure and barriers to gene flow are important components for understanding the evolutionary history of a species. Here we study population structure and differentiation in the western capercaillie (Aves: Phasianidae) along the Carpathian Mountains. Further, we compared the levels of population differentiation among capercaillie from the Carpathian Mountains, Balkans (Bulgaria) and the boreal forest (Russia and Sweden) in order to reveal past and current processes which may influence population structure. Tissue samples, non-invasive faeces and feathers and toe pads from museum specimens were used for genetic analyses of mitochondrial (mtDNA) sequences and allelic variation at nine nuclear DNA (nDNA) microsatellite loci. Analyses of mtDNA sequences revealed a southern subclade within the northern clade. Within the northern clade, microsatellite data distinguished two groups: (1) Western Carpathian populations; and (2) Eastern Carpathian and boreal forest populations. Bulgarian populations constituted a third cluster corresponding to the southern phylogenetic subclade. The Western Carpathian populations showed a heterozygote deficiency. The analyses indicate that the abundant Eastern Carpathian populations share alleles with populations from the boreal forest suggesting a common origin of these populations since the last glacial period. On the other hand, the Western Carpathian populations have been isolated over a long period with only a few migrants from the east, thereby becoming differentiated from the eastern and northern populations. The southern populations have been isolated from the northern populations since the last glacial maximum. The molecular analyses did not support the currently recognised taxonomy at the subspecies level.
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Background: In forests subject to stand-replacing disturbances, conventional models of succession typically overlook early-seral stages as a simple re-organization/establishment period. These models treat structural development in essentially 'relay floristic' terms, with structural complexity (three-dimensional heterogeneity) developing primarily in old-growth stages, only after a closed-canopy 'self-thinning' phase and subsequent canopy gap formation. However, is it possible that early-successional forests can sometimes exhibit spatial complexity similar to that in old-growth forests - i.e. akin to an 'initial floristic' model of structural development? Hypothesis: Based on empirical observations, we present a hypothesis regarding an important alternative pathway in which protracted or sparse forest establishment and interspecific competition thin out tree densities early on - thereby precluding overstorey canopy closure or a traditionally defined self-thinning phase. Although historically viewed as an impediment to stand development, we suggest this process may actually advance certain forms of structural complexity. These young stands can exhibit qualities typically attributed only to old forests, including: (1) canopy gaps associated with clumped and widely spaced tree stems; (2) vertically heterogeneous canopies including under- and mid-stories, albeit lower stature; (3) co-existence of shade-tolerant and intolerant species; and (4) abundant dead wood. Moreover, some of these qualities may persist through succession, meaning that a significant portion of eventual old-growth spatial pattern may already be determined in this early stage. Implications: The relative frequency of this open-canopy pathway, and the degree to which precocious complexity supports functional complexity analogous to that of old forests, are largely unknown due to the paucity of naturally regenerating forests in many regions. Nevertheless, recognition of this potential is important for the understanding and management of early-successional forests.
Book
1. Introduction 2. Estimation 3. Hypothesis testing 4. Graphical exploration of data 5. Correlation and regression 6. Multiple regression and correlation 7. Design and power analysis 8. Comparing groups or treatments - analysis of variance 9. Multifactor analysis of variance 10. Randomized blocks and simple repeated measures: unreplicated two-factor designs 11. Split plot and repeated measures designs: partly nested anovas 12. Analysis of covariance 13. Generalized linear models and logistic regression 14. Analyzing frequencies 15. Introduction to multivariate analyses 16. Multivariate analysis of variance and discriminant analysis 17. Principal components and correspondence analysis 18. Multidimensional scaling and cluster analysis 19. Presentation of results.
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Disturbances from wind, bark beetles, and wildfires have increased in Europe's forests throughout the 20(th) century (1). Climatic changes were identified as a main driver behind this increase (2), yet how the expected continuation of climate change will affect Europe's forest disturbance regime remains unresolved. Increasing disturbances could strongly impact the forest carbon budget (3,4), and are hypothesized to contribute to the recently observed carbon sink saturation in Europe's forests (5). Here we show that forest disturbance damage in Europe has continued to increase in the first decade of the 21(st) century. Based on an ensemble of climate change scenarios we find that damage from wind, bark beetles, and forest fires is likely to increase further in coming decades, and estimate the rate of increase to +0.91·10(6) m(3) of timber per year until 2030. We show that this intensification can offset the effect of management strategies aiming to increase the forest carbon sink, and calculate the disturbance-related reduction of the carbon storage potential in Europe's forests to be 503.4 Tg C in 2021-2030. Our results highlight the considerable carbon cycle feedbacks of changing disturbance regimes, and underline that future forest policy and management will require a stronger focus on disturbance risk and resilience.
Book
Applied Predictive Modeling covers the overall predictive modeling process, beginning with the crucial steps of data preprocessing, data splitting and foundations of model tuning. The text then provides intuitive explanations of numerous common and modern regression and classification techniques, always with an emphasis on illustrating and solving real data problems. The text illustrates all parts of the modeling process through many hands-on, real-life examples, and every chapter contains extensive R code for each step of the process. This multi-purpose text can be used as an introduction to predictive models and the overall modeling process, a practitioner's reference handbook, or as a text for advanced undergraduate or graduate level predictive modeling courses. To that end, each chapter contains problem sets to help solidify the covered concepts and uses data available in the book's R package. This text is intended for a broad audience as both an introduction to predictive models as well as a guide to applying them. Non-mathematical readers will appreciate the intuitive explanations of the techniques while an emphasis on problem-solving with real data across a wide variety of applications will aid practitioners who wish to extend their expertise. Readers should have knowledge of basic statistical ideas, such as correlation and linear regression analysis. While the text is biased against complex equations, a mathematical background is needed for advanced topics. © Springer Science+Business Media New York 2013. All rights reserved.
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The Minimum Area Requirements (MAR) of species is a concept that explicitly addresses area and therefore can be highly relevant for conservation planning and policy. This study compiled a comprehensive database of MAR estimates from the literature, covering 216 terrestrial animal species from 80 studies. We obtained estimates from (a) Population Viability Analyses (PVAs) which explored a range of area-related scenarios, (b) PVAs that provided a fixed value – either MAR or the minimum viable population size (MVP) alongside other area-relevant information, and (c) empirical studies of occupancy patterns in islands or isolated habitat patches across area. We assessed the explanatory power of life-history traits (body mass, feeding guild, generation length and offspring size), environmental variables (average precipitation and temperature), research approach and phylogenetic group on MAR estimates. PVAs exploring area showed strong correlation between MAR and body mass. One to two additional variables further improved the predictive power. PVA reporting fixed MAR, and occupancy-based studies, were better explained by the combination of feeding guild, climatic variables and additional life history traits. Phylogeny had a consistent but usually small contribution to the predictive power of models. Our work demonstrates that estimating the MAR across species and taxa is achievable but requires cautious interpretation. We further suggest that occupancy patterns are likely sensitive to transient dynamics and are therefore risky to use for estimating MAR. PVA-based evaluations enable considering time horizon and extinction probability, two aspects that are critical for future implementation of the MAR concept into policy and management.
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In Scots pine (Pinus sylvestris) forests the composition of the ground flora can be affected by the amount of light reaching the forest floor, influencing the balance between the three common ericaceous shrubs bilberry (Vaccinium myrtillus), cowberry (Vacciniumvitis-idaea) and heather (Calluna vulgaris). A pinewood ground flora with more than 20% bilberry cover is considered good habitat for capercaillie (Tetrao urogallus), a large forest grouse of considerable conservation interest throughout Europe. Old, semi-natural Scots pine woodland is considered its prime habitat in Scotland, although this is limited in area compared to twentieth century planted forests. Action to manipulate environmental conditions within Scots pine plantations by altering light levels to favour bilberry through thinning and felling could potentially increase greatly the area of available capercaillie habitat in Scotland. We implemented a five year study to look at bilberry response to variable intensity thinning in two Scots pine plantations, where thinning followed management guidance for capercaillie available at the time. Bilberry was present in both forests but a positive response to thinning was not universal; although at both sites bilberry cover increased significantly over five years with levels >20% cover reached, this could only be attributed to the thinning treatment at one of the sites. A treatment of small patch clearfelling did not lead to losses in bilberry. Management guidance published after the trial had begun, identified the appropriate intensity of thinning for enhancing bilberry cover at our study sites, indicated by the relative increase of bilberry in the plots where the prescription had been followed. Although there was no significant treatment effect by year five, 42% average bilberry cover was reached at one site tested. However the format of this guidance, a range of stem density-tree height combinations, was difficult to apply using typical forest management data and we explore redefining the guidance as a post thinning stand basal area range. We suggest >22 to <31 m2 ha−1 basal area would be appropriate in Scots pine plantations established at normal spacing and subject to the commonest form of selective thinning regime. This range in basal area can be achieved without conflicting with management for timber production. Our results also support small patch clearfelling as a method of diversifying plantation age structure which is compatible with maintaining capercaillie brood habitat.
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Decaying logs form the major seedbed for trees in European subalpine Picea abies forests. However, many aspects related to seedling colonization pattern on logs remain unclear. The aim of this study was to analyze the relationships of P. abies (Norway spruce) seedling (height <15 cm) and sapling (height ⩾15 cm) densities on decaying logs in relation to stage of wood decay, log diameter, ground contact of decaying log, assumed cause of tree death, presence of species of wood-decaying fungi and coverage by surrounding plants in the subalpine old-growth forests of the Bohemian Forest and Ash Mountains, in the Czech Republic. We have focused on how logs with different origin differ in their properties and how these properties influence seedling abundance. Seedling densities peaked on the medium-decayed logs and decreased thereafter. Sapling densities continually increased as the decay progressed. Seedling and sapling densities followed negative binomial distributions, with many logs of all decay stages having low regeneration densities. The degree of ground contact, white-rot-causing Armillaria spp. presence, white-rot-causing Phellinus nigrolimitatus presence and log diameter were positively related to both seedling and sapling density. Also tree death as a result of wind uprooting was positively related to sapling density. Conversely, the presence of brown-rot-causing Fomitopsis pinicola and tree death as a result of bark beetle attack were negatively related to regeneration densities. The low cover of vegetation from sides positively affected seedling density; however, heavily covered logs were less occupied by seedlings. Our study provides evidence that large logs originating from wind uprooting or butt rot infection are most appropriate for retention to promote natural spruce regeneration in managed subalpine spruce forests.