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Abstract

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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... Besides economic and logistic reasons, a major barrier to implementing natural dynamics silviculture has been the lack of comprehensive understanding of the ranges of variability (whether historic, contemporary, or future) in natural disturbance regimes, including frequencies, spatial attributes, and severities (Kulakowski et al. 2017). Moreover, the distribution, composition, and dynamics of European forest landscapes have been fundamentally altered by millennia of human influence (Kaplan et al. 2009, Keeton et al. 2013, Pretzsch et al. 2017. ...
... However, in recent decades great progress has been made in describing the disturbance regimes of European forests, by applying long-term observational data (e.g. Thom et al. 2013, Nagel et al. 2017a, statistical (Seidl et al. 2014), and dendrochronological data analysis (Nagel et al. 2014(Nagel et al. , Čada et al. 2020, literature review , Thom and Seidl 2016, Kulakowski et al. 2017, conceptual approach Jentsch 2001, Kulakowski et al. 2017), as well as analysis of remote sensing data (Senf and Seidl 2020 ...
... This framework must acknowledge the alteration of disturbance regimes caused by centuries of human influence as well as shifting boundary conditions associated with climate change (Seidl et al. 2014, Kulakowski et al. 2017, Thom et al. 2017, Senf and Seidl 2020. It must also consider the broad range of forest management approaches and harvesting intensities in Europe, varying by region, forest type, ownership and subsidy programs, local conditions and accessibility, importance of non-timber services, and other factors (Schelhaas et al. 2018). ...
Article
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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.
... These depart from and challenge the conventional 'command and control' approaches to conservation and forest management, focused on suppressing disturbances and controlling natural dynamics to preserve and maintain specific habitats and species (Callicott et al., 1999;Dandy & Wynne-Jones, 2019;Holling & Meffet, 1996). It is argued, for instance, that these approaches will become increasingly difficult to implement in a rapidly changing world, where the frequency, extent and severity of forest disturbances such as fires, droughts, insect and disease outbreaks are likely to increase in light of projected warming (Dale et al., 2001;Kulakowski et al., 2017;Potter & Urquhart, 2016;Seidl et al., 2017;Turner, 2010). On the contrary, proactive approaches to conservation and forest management are geared towards promoting lively ecosystems and anticipating emergent futures that cannot always be predicted. ...
... Such is the case of rewilding, mentioned above, where disturbance regimes are encouraged, reintroduced and sometimes emulated (Fuhlendorf et al., 2009;Kulakowski et al., 2017;Navarro et al., 2015). For Andrea Perino and collaborators, rewilding is about releasing ecosystems "from continued and controlled anthropogenic disturbances to allow for natural variability and sources of stochasticity," thus enhancing spatial and temporal heterogeneity (Perino et al., 2019; see also Kulakowski et al., 2017). ...
... Such is the case of rewilding, mentioned above, where disturbance regimes are encouraged, reintroduced and sometimes emulated (Fuhlendorf et al., 2009;Kulakowski et al., 2017;Navarro et al., 2015). For Andrea Perino and collaborators, rewilding is about releasing ecosystems "from continued and controlled anthropogenic disturbances to allow for natural variability and sources of stochasticity," thus enhancing spatial and temporal heterogeneity (Perino et al., 2019; see also Kulakowski et al., 2017). ...
Thesis
In recent years, there has been a rethinking of the role of disturbance regimes in nature conservation: from exceptional and destructive events to be controlled and/or avoided, to key ecological processes to be nurtured and choreographed. These regimes concern the spatiotemporal dynamics of ecological disturbances, understood here as events that disrupt the structure of an ecology, community or population, causing profound changes in an ecosystem. The rethinking of their role precedes but resonates with current enthusiasms for proactive and experimental modes of conservation, such as rewilding. This thesis draws on three case studies (the New Forest, Knepp Castle Estate and Dundreggan Estate) to explore the ontological, epistemic and socio-political implications of rewilding for the governance of forest disturbance regimes in the UK, particularly through the use of large herbivores. Drawing upon relational understandings of nature, space and time, it develops an understanding of disturbance regimes as process and practice. It first examines how rewilding departs from orthodox biopolitical modes of governing life and the ontological politics at the interface between these various modes. To this end, it attends to the ways in which disturbances have been historically understood and how these understandings have come to shape their governance. Second, it explores the knowledge practices through which ecologists and forest managers know and enact disturbances, comparing a traditional 'prescriptive' approach with rewilding. It argues that in practice rewilding is multiple, in contrast to rewilding discourse. Finally, it maps the different and sometimes conflicting social, economic and cultural values associated with working with natural processes, exploring the political ecologies of governing disturbance regimes. It argues that controversies around forest management pertain to a large extent to contrasting perceptions of different types of 'work' within the idea of working landscape and how they are 'naturalised'. In the conclusion, the thesis explores three empirical and conceptual contributions of these findings for those seeking to understand the logics of rewilding and the processes, practices and dynamics by which nonhuman forms and processes are governed in a post-Natural and uncertain future. First, by deploying a relational approach to the governance of disturbance regimes and by focusing on a long-term disturbance, I draw out the relevance of temporality for thinking through and with disturbances as social and ecological processes. Second, by drawing attention to the intertwining of bio- and socio-political regimes, I propose a reframing of (European) rewilded landscapes as working landscapes. Finally, by attending to the intricacies of practice, I argue that rewilding praxis is multiple and hybrid. It often involves compromises and is shaped by past governance histories and the broader political and social context.
... At the same time, disturbances can also have a positive effect on biodiversity (Thom and Seidl, 2016). The expected intensifying disturbance regime will thus pose important new challenges for forest managers (Kulakowski et al., 2017;Nikinmaa et al., 2020), and the degree to which forest managers should interfere in the forests' natural disturbance regime is increasingly disputed Thorn et al., 2020). Combining information about disturbance risk with ES assessment could therefore help to identify priority areas for intervention or non-intervention and support forest management decisions (Lecina-Diaz et al., 2021;Seidl et al., 2018). ...
... Here, we modelled the short-term effects of natural disturbances, which are the currently the most visible effect of climate change in mountain forests (Kulakowski et al., 2017). However, on the long-term, climate change is likely to have other effects on mountain forests, such as an upward shift in the treeline, which may lead to an increase in carbon sequestration and avalanche protection (Grêt-Regamey et al., 2013b). ...
... However, this relationship is not homogeneous in space, and less pronounced for other ES. Mapping the risks to ES is therefore important information for forest managers under a changing disturbance regime, who face decisions about where to control and where to embrace the effects of natural disturbances (Kulakowski et al., 2017;Seidl et al., 2018). In this study, we mapped the ES and risk to ES at a 100 m resolution, which allows us to identify patterns at the landscape scale while limiting the computational time needed to run the models, and which corresponds to the grid size of available validation data. ...
Article
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Ecosystem service (ES) mapping has been developed with the aim of supporting ecosystem management, but ES maps often lack information about uncertainty and risk, which is essential for decision-making. In this paper, we use a risk-based approach to map ES in mountain forests, which are experiencing an increasing rate of natural disturbances, such as windthrow, bark beetle outbreaks, and forest fires. These disturbances affect the capacity of forests to provide essential ecosystem services, such as protection from natural hazards, wood production, and carbon sequestration, thus posing a challenge for forest management. At the same time, disturbances may also have a positive effect on certain services, e.g. by improving habitats for species that rely on dead wood. We integrate forests' susceptibility to natural disturbances into probabilistic Bayesian Network models of a set of ES (avalanche protection, carbon sequestration, recreation, habitats, and wood production), which combine information from remote sensing, social media and in-situ data, existing process-based models, and local expert knowledge. We use these models to map the level of the services and the associated uncertainties under scenarios with and without natural disturbances in two case study areas in the Swiss Alps. We use clustering to identify bundles of risk to ES, and compare the patterns of risk between the non-protected area of Davos and the strictly protected area of the Swiss National park with its surroundings. The spatially heterogeneous pattern of risk to ES reflects topographic variability and the forest characteristics that drive disturbance susceptibility, but also the demand for ecosystem services. In the landscape of Davos, the most relevant risks to ES are related to decreases in the protection against avalanches and carbon sequestration, as well as some risk to wood production and recreation. In the strictly protected Swiss National Park, the overall level of ES risk is lower, with an increase in habitat quality under the disturbance scenario. This risk-based approach can help identify stands with high levels of ES that are particularly susceptible to disturbances, as well as forests with a more stable ES provision, which can help define priorities in forest management planning.
... Natural disturbances create high structural heterogeneity as a result of diverse biological legacies left after a disturbance (Swanson et al., 2011). Forest disturbances create a resource pulse of deadwood over a short period of time (Kulakowski et al., 2017), increase light availability and change microclimatic conditions (Swanson et al., 2011;Wohlgemuth et al., 2019). Natural disturbances can affect the provision of water by altering hydrological regimes and by increasing soil erosion and leaching of soil nutrients into streams (Mikkelson et al., 2013). ...
... Forest stands affected by windstorms often enable the rapid growth of bark beetle populations (Seidl, Schelhaas, et al., 2014), which accounted for 8% of the total damage in European forests between 1950 and 2000 (Schelhaas et al., 2003). Although the interactions between windthrow and bark beetle outbreaks are well understood (Kulakowski et al., 2017), those between windthrow and post-disturbance logging have been rarely investigated, especially through the use of long time series . ...
Thesis
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Owing to climate change, natural forest disturbances and consecutive salvage logging are drastically increasing worldwide, consequently increasing the importance of understanding how these disturbances would affect biodiversity conservation and provision of ecosystem services. In chapter II, I used long-term water monitoring data and mid-term data on α-diversity of twelve species groups to quantify the effects of natural disturbances (windthrow and bark beetle) and salvage logging on concentrations of nitrate and dissolved organic carbon (DOC) in streamwater and α-diversity. I found that natural disturbances led to a temporal increase of nitrate concentrations in streamwater, but these concentrations remained within the health limits recommended by the World Health Organization for drinking water. Salvage logging did not exert any additional impact on nitrate and DOC concentrations, and hence did not affect streamwater quality. Thus, neither natural forest disturbances in watersheds nor associated salvage logging have a harmful effect on the quality of the streamwater used for drinking water. Natural disturbances increased the α-diversity in eight out of twelve species groups. Salvage logging additionally increased the α-diversity of five species groups related to open habitats, but decreased the biodiversity of three deadwood-dependent species groups. In chapter III, I investigated whether salvage logging following natural disturbances (wildfire and windthrow) altered the natural successional trajectories of bird communities. I compiled data on breeding bird assemblages from nine study areas in North America, Europe and Asia, over a period of 17 years and tested whether bird community dissimilarities changed over time for taxonomic, functional and phylogenetic diversity when rare, common and dominant species were weighted differently. I found that salvage logging led to significantly larger dissimilarities than expected by chance and that these dissimilarities persisted over time for rare, common and dominant species, evolutionary lineages, and for rare functional groups. Dissimilarities were highest for rare, followed by common and dominant species. In chapter IV, I investigated how β-diversity of 13 taxonomic groups would differ in intact, undisturbed forests, disturbed, unlogged forests and salvage-logged forests 11 years after a windthrow and salvage logging. The study suggests that both windthrow and salvage logging drive changes in between-treatment β-diversity, whereas windthrow alone seems to drive changes in within-treatment β-diversity. Over a decade after the windthrow at the studied site, the effect of subsequent salvage logging on within-treatment β-diversity was no longer detectable but the effect on between-treatment β-diversity persisted, with more prominent changes in saproxylic groups and rare species than in non-saproxylic groups or common and dominant species. Based on these results, I suggest that salvage logging needs to be carefully weighed against its long-lasting impact on communities of rare species. Also, setting aside patches of naturally disturbed areas is a valuable management alternative as these patches would enable post-disturbance succession of bird communities in unmanaged patches and would promote the conservation of deadwood-dependent species, without posing health risks to drinking water sources.
... The newly grown forest may not have the same species composition as that of the pre-disturbance system, but its ecological function can be similar to the previous one. It is thought that such a capacity for resilience is high with respect to a disturbance that repeatedly occurs in the forest (Kulakowski et al. 2017). In the case of Japanese forests, climatic hazards, such as typhoons and heavy snow, and repeated fuelwood gathering by rural residents can function as the inherent disturbance regimes of a regional forest (Hiura 1995;Iida and Nakashizuka 1995). ...
... Light but frequent damage caused by native herbivores, in combination with rare but intensive disturbances (whether natural or non-natural), affect the development and maintenance of the forest systems. From this perspective, both the system-inherent disturbance regime and the corresponding resilience are the goals of forest conservation (Kulakowski et al. 2017). Such target setting is not new and is becoming a global trend in forest management, especially in Europe and North America (Ghazoul et al. 2015). ...
Chapter
There are major challenges in restoring forest vegetationForest vegetation that has accumulated damage by deer, and it is unlikely that such vegetation will recover on its own. In this chapter, we detail an experiment to recover forest vegetation that had been severely affected by cumulative damage from sika deer (Cervus nippon). The experimental site consisted of clear-cut plots, simulating canopy gapsGap, and control plots, which were closed canopyClosed canopy. One half of both the treatment (gap) plots and uncut plots were enclosed by fencing to exclude deer, leaving the other half of the plots under the effect of deer. Over the next 10 years, the fenced closed-canopy plots did not show remarkable recoveryRecovery; in contrast, the gap plots came to be covered by rapidly growing, light-demanding plantsLight-demanding plants, even with the presence of deer in the unfenced plots. The gap-and-fenceFence plots gradually recovered forest vegetation. However, each of the gap-and-no-fence plots came to be covered by different plants that were unpalatableUnpalatable to deer. Based on these results, effective restorationRestoration strategies and future management protocols are discussed.
... 14Comparison of the volume calculated from our Forest Structure Data versus the mean of the volumes for the period 2000 to 2010 as reported in State of Europe's Forest 2015[3] (Ind 1.2B Change in growing stock on forests). Forest Structure Data refers to the values calculated by combining the gap-filled maps with land cover information to calculate country totals (seeFigure 7). ...
... Remote Sens. 2022,14, 395 ...
Article
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Today, European forests face many challenges but also offer opportunities, such as climate change mitigation, provision of renewable resources, energy and other ecosystem services. Large-scale analyses to assess these opportunities are hindered by the lack of a consistent, spatial and accessible forest structure data. This study presents a freely available pan-European forest structure data set. Building on our previous work, we used data from six additional countries and consider now ten key forest stand variables. Harmonized inventory data from 16 European countries were used in combination with remote sensing data and a gap-filling algorithm to produce this consistent and comparable forest structure data set across European forests. We showed how land cover data can be used to scale inventory data to a higher resolution which in turn ensures a consistent data structure across sub-regional, country and European forest assessments. Cross validation and comparison with published country statistics of the Food and Agriculture Organization (FAO) indicate that the chosen methodology is able to produce robust and accurate forest structure data across Europe, even for areas where no inventory data were available.
... Disturbances that are natural in frequency and intensity promote spatial and temporal heterogeneity of habitats and the complexity of their structure (Turner, 1998;Kulakowski et al., 2017;Perino et al., 2019). Typical disturbances are, for instance, those created by large herbivores through their foraging, defecation and trampling (Navarro et al., 2015;Ripple et al., 2015). ...
... Depending on the landuse legacy and the naturalness of the broader landscape, the abandoned land is vulnerable to significant degradation until the natural disturbance regimes are restored. Restoring natural disturbance regimes is, therefore, key in rewilding management (Torres et al., 2018) including to increase the resilience of the ecosystems to current and projected climate change (e.g., Kulakowski et al., 2017). ...
Article
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Human influence extends across the globe, from the tallest mountains to the deep bottom of the oceans. There is a growing call for nature to be protected from the negative impacts of human activity (particularly intensive agriculture); so-called “land sparing”. A relatively new approach is “rewilding”, defined as the restoration of self-sustaining and complex ecosystems, with interlinked ecological processes that promote and support one another while minimising or gradually reducing human intervention. The key theoretical basis of rewilding is to return ecosystems to a “natural” or “self-willed” state with trophic complexity, dispersal (and connectivity) and stochastic disturbance in place. However, this is constrained by context-specific factors whereby it may not be possible to restore the native species that formed part of the trophic structure of the ecosystem if they are extinct (e.g., mammoths, Mammuthus spp., aurochs, Bos primigenius ); and, populations/communities of native herbivores/predators may not be able to survive or be acceptable to the public in small scale rewilding projects close to areas of high human density. Therefore, the restoration of natural trophic complexity and disturbance regimes within rewilding projects requires careful consideration if the broader conservation needs of society are to be met. In some circumstances, managers will require a more flexible deliberate approach to intervening in rewilding projects using the range of tools in their toolbox (e.g., controlled burning regimes; using domestic livestock to replicate the impacts of extinct herbivore species), even if this is only in the early stages of the rewilding process. If this approach is adopted, then larger areas can be given over to conservation, because of the potential broader benefits to society from these spaces and the engagement of farmers in practises that are closer to their traditions. We provide examples, primarily European, where domestic and semi-domestic livestock are used by managers as part of their rewilding toolbox. Here managers have looked at the broader phenotype of livestock species as to their suitability in different rewilding systems. We assess whether there are ways of using livestock in these systems for conservation, economic (e.g., branded or certified livestock products) and cultural gains.
... Thus, we use resilience to refer to the capacity of a system to recover from and tolerate perturbations without shifting to a different state controlled by different processes (Holling, 1973). We also note that the term 'state' can refer to forest area, structure (e.g., unevenaged stand, or forest stands with individuals originating from multiple years), species composition and/or additional, broader attributes (Hart et al., 2019;Kulakowski et al., 2017). Thus, the exact definition of state will also contribute to whether a particular system is understood to be resilient . ...
... In various ecosystems globally, post-fire conifer regeneration is influenced by topography and post-fire climate (González et al., 2020;Hansen et al., 2018;Hoecker et al., 2020;Kulakowski et al., 2017;Luo et al., 2021;Rammig et al., 2006;Stevens-Rumann et al., 2018;Thom & Seidl, 2016). As climate warms, regeneration is expected to be more robust in biophysical settings that are cooler and have greater available moisture, including those on cooler aspects (e.g. ...
Article
Increased wildfire activity and climate change have intensified disturbance regimes globally and have raised concern among scientists and land managers about the resilience of disturbed landscapes. Here we test the effects of climate, topographic variation, and pre‐fire stand structure on regeneration in lodgepole pine (Pinus contorta var. latifolia) forests following high severity fire over the past decades. We surveyed lodgepole pine regeneration 8‐72 years after eight high‐severity fires in western Colorado and southern Wyoming. We used dendroecological methods and machine learning to (1) identify temporal trends in post‐fire regeneration and (2) examine influences of climate on post‐fire regeneration, with focus on post‐fire establishment, initial post‐fire density, and radial growth. All burned sites reached a median stocking density of ≥ 150/seedlings ha, but there was a large range of spatial heterogeneity, with many plots having an absence or scarcity of regeneration, implying a trend of increasing patchiness, with likely cascading effects on subsequent patterns and processes. Our analysis indicated that (1) post‐fire regeneration is influenced by pre‐fire stand structure (stand age and density), elevation, and post‐fire minimum temperature; (2) pre‐fire densities of > 14,000 stem/ha promoted successful stocking (≥150 seedlings/ha) and reduced lag between the disturbance and initial regeneration; (3) minimum post‐fire temperatures > ‐1.6 °C reduced lag of initial regeneration and promoted initial radial growth. Synthesis: Our study demonstrates lodgepole pine in high‐elevation forests are regenerating following fires under recent climactic trends, but that regeneration is affected by post‐fire climatic conditions. Importantly, forest patchiness may be increasing in a way that may affect future ecological dynamics and may compromise resilience of these systems.
... Temperate forests of the Northern Hemisphere were always under the influence of numerous disturbance factors (Boucher et al., 2012;Firm et al., 2009;Kulakowski et al., 2017;Vera, 2000) that had profound effects on their spatial structure and species composition (Bouget & Duelli, 2004;Muscolo et al., 2014;Vera, 2000). ...
Article
European forests are facing a rapid decline of light‐demanding biota. This has prompted active interventions to re‐establish and maintain partial habitat openness in protected areas. Managers of protected areas, however, need substantially more scientific evidence to support their decisions on where, when, and how to intervene. We investigated the importance of spatial continuity of open forest habitats in different years of succession, using six pairs of experimental clearings established in the formerly open, oak‐dominated forests of the Podyji National Park (Czech Republic). In each pair, one clearing was connected to the forest edge, while the other was isolated in closed forest. We sampled butterflies (74 spp.), moths (435 spp.), saproxylic beetles (465 spp.), and vascular plants (567 spp.) on the 12 clearings during the first five years of succession. We then compared species richness, abundance, and composition of the four taxa between the two clearing types and along the succession. All studied insect groups were substantially more species‐rich and more abundant in connected than in isolated clearings. Species composition of plants, moths, and butterflies differed between the clearing types. The number of species of all studied taxa generally increased from the first to the second or third year after cutting; species composition of all taxa differed among years. This suggests rapid changes in habitat quality and thus limited time for colonisation by light‐demanding organisms. Synthesis and applications: Our results offer an evidence that spatial connectivity and rapid temporal dynamics are important habitat features for light‐demanding insects. Attempts to create or restore habitats for light‐demanding forest biota should take into account that: (i) Insects benefit from direct connection of new open patches to open habitats or flight corridors such as forest edges. (ii) Considering plants, the optimal solution is to connect newly created open forest habitats to existing habitats with established biota of high conservation value. (iii) Interventions should be carried out within short time intervals, i.e. within years rather than decades. (iv) A fine mosaic of interconnected, open woodland patches in various successional stages is more beneficial than a single large patch with a single successional stage.
... Over the last two centuries, mountain forests have been intensively managed and have frequently lost their structural heterogeneity and natural biodiversity (Moning and Müller, 2009;Jiménez-Alfaro et al., 2018;Kaufmann et al., 2018;Stiers et al., 2018). One important means of regaining these attributes is applying silvicultural methods which preserve the key structures and processes of natural ecosystems (Seymour et al., 2002;Lindenmayer et al., 2006;Kulakowski et al., 2017). However, pristine forests directly or indirectly unaffected by man have disappeared in Europe, and nowadays only relic old-growth stands which are believed to retain the structural attributes and dynamics of primeval forests exist in several locations in the Alps, Balkans and Carpathians Sabatini et al., 2018;Veen et al., 2010). ...
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.
... Although generally perceived as negative phenomena by society and policy makers, windstorms play a pivotal ecological role. Several studies (Zielonka & Malcher, 2009;Dobrowolska, 2015;Kulakowski et al., 2017Kulakowski et al., , 2019Szwagrzyk et al., 2017;Meigs & Keeton, 2018) have highlighted that catastrophic windstorms, far from representing a threat to forest ecosystem integrity and functioning, actually make up an integral component of this ecosystem and trigger important forest dynamics. Due to the considerable changes they generate in the overall structure of forest stands, and consequently, in micro-environmental conditions, windstorms represent stimulators of forest regeneration (Long et al., 1998;Panayotov et al., 2011;Bolte et al., 2014;Dobrowolska, 2015), enhance diversification of forest stands in terms of age, height and structure (Dobrowolska, 2015) and provide a chance for shade-intolerant and early-successional species to take advantage of the canopy opening created by tree falling (Bormann & Likens 1979;Peterson & Pickett, 1995). ...
Article
Catastrophic wind disturbance affects not only forest structure and regeneration, but also functional and compositional dynamics of the herbaceous layer. However, the issue of changes in functional diversity and functional trait values of the understory layer in response to wind disturbance has not been addressed so far. This study aims at investigating the patterns of variations in functional diversity, trait values and species richness of herbaceous species following wind disturbance. The study was carried out in the Piska Forest, a woodland complex in northern Poland, which was almost completely destroyed by a windstorm in 2002 and part of which was successively set aside to study the effects of natural disturbance on forest ecosystems. Vegetation surveys were conducted at 112 sample plots between 2014 and 2015. Four forest habitat types were identified and individually examined. The degree of disturbance severity was assessed as percentage of dead trees on all trees per surface unit. A set of twelve functional traits was assigned to the recorded species. Three functional diversity metrics (richness, evenness and divergence) were calculated based on the selected functional traits. We assessed the relationship between each of such metric and disturbance severity for each habitat type. The relationship between species richness and disturbance severity was also determined. We then estimated the relative importance of habitat type and disturbance severity on both functional diversity and species richness. Lastly, we examined the response of functional trait values to both disturbance severity and habitat type. Our results showed that wind disturbance effects on functional diversity are not univocal and that they strongly depend on habitat type. In fact, while in coniferous stands disturbance determined a decrease of functional divergence and left functional richness unaltered, in mixed-coniferous habitats it enhanced functional richness and did not affect functional divergence. In mixed-deciduous habitats, both functional richness and divergence decreased. In swamp habitats no major changes in functional diversity were observed. Changes in functional evenness were not significant. At the same time, disturbance significantly enhanced species richness in all forest habitats, but the coniferous one. It was not possible to clearly disentangle the relative contribution of disturbance and habitat type, since the two are strictly correlated. Out of the tested functional traits, only SLA, seed releasing height and share of stress-tolerant species exhibited significant response along the tested disturbance gradient. Most of the other traits reacted only to variations in the habitat type.
... In many cases, piedmonts represent the interface between large urban centers and mountain ecosystems (Kulakowski et al., 2017), which makes piedmont regions sources of provisioning and regulating ES, such as prevention of natural disasters, food supply, water and raw materials, tourism, and CES related to recreational activities (cycling, bird watching and trekking) (Gret-Regameya et al., 2008). The Andean piedmont of Santiago is in central Chile, which has been classified as a biodiversity hotspot of global relevance due to the exceptional concentration of endemic species experiencing habitat loss (Myers et al., 2000). ...
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Large cities are both centers of demand for cultural ecosystem services (CES) and a source of environmental impacts. Assessing CES yields information to reduce the vulnerability of these services to such environmental impacts as well as to strengthen them in order to improve human well-being in cities. The Andean piedmont of Santiago is a natural mountainous area adjacent to the largest city in Chile and a source of CES, which are threatened as a result of the urbanization and weak territorial management instruments. A model was constructed to represent the provision of CES in the piedmont. The model integrated participatory techniques and geographic information analyses, making it possible to quantify and map the CES provision, which was represented by ecosystem attributes. CES are provided according to the weight that different stakeholders afford to these attributes. Attributes were characterized and then represented in space, resulting in a spatially explicit index constructed as the weighted sum of the previously established attributes. Our results show that the most relevant variables for the visitors when they come to enjoy the CES of the piedmont are accessibility and scenic beauty. In general terms, this means that the highest CES provision level is concentrated in the mid-altitude zone of the piedmont (away from the city but still accessible). We conclude that the piedmont areas close to large cities are relevant in terms of provision of CES and their protection is a priority to maintain the flow of CES towards the inhabitants of these cities.
... F I G U R E 1 Overview of the steps of the site-specific risk assessment to assess risks and management options associated with non-native tree species; NNT, non-native tree species; RA, risk assessment; SSRA, site-specific risk assessment change, disturbances, or land-use changes (Kulakowski et al., 2017). In addition, dynamics of the NNT may vary during the invasion process, as some populations may successfully establish or spread while others may fail to become invasive, depending on prevailing site conditions and NNT-specific plasticity or fitness (Blackburn et al., 2011). ...
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Non-native tree species (NNT) are used in European forestry for many purposes including their growth performance, valuable timber, and resistance to drought and pest or pathogen damage. Yet, cultivating NNT may pose risks to biodiversity, ecosystem functioning, and the provisioning of ecosystem services, and several NNT have been classified as invasive in Europe. Typically, such classifications are based on risk assessments, which do not adequately consider site-specific variations in impacts of the NNT or the extent of affected areas. Here, we present a new methodological framework that facilitates both mitigating risks associated with NNT and taking advantage of their ecosystem services. The framework is based on a stratified assessment of risks posed by NNT which distinguishes between different sites and considers effectiveness of available management strategies to control negative effects. The method can be applied to NNT that already occur in a given area or those NNT that may establish in future. The framework consists of eight steps and is partly based on existing knowledge. If adequate site-specific knowledge on NNT does not yet exist, new evidence on the risks should be obtained, for example, by collecting and analyzing monitoring data or modeling the potential distribution of NNT. However, limitations remain in the application of this method, and we propose several policy and management recommendations which are required to improve the responsible use of NNT.
... Such differences between the two systems can be explained by the modification of both the belowground (soil properties) and the above-ground resources due to change in the forest structure. Forest management involves a set of human activities and disturbances (Van der Maarel 1993; Kulakowski et al., 2017) and is a key factor affecting the environmental factors controlling changes in plant diversity. For example in our study, thinning and frequent cuttings in CWS has increased light availability (Ford and Newbould 1977;Strubelt et al., 2019) and access to soil water and nutrients (Parsons, Knight and Miller 1994). ...
Article
Air pollution from industrial areas is environmental stress on trees that can seriously endanger the future of forests. Ancient Persian oak trees (Quercus brantii Lindl.) in the semi-arid forests of the Zagros are exposed to various environmental stresses such as air pollution from the Ilam gas refinery, which causes many challenges in forest regeneration and afforestation, thus jeopardizing forest sustainability or restoration. This study aimed to investigate the effect of toxic pollutants emitted from a gas refinery operation on seed germination and morphological characteristics of seedlings from maternal trees that are located at different distances (1000, 1500, 2000, 2500, and 10000 m) and directions (east and west) from the facility. The results showed that oak seedlings grown from acorns collected at a distance of 10000 m had the highest values in various seed germination and seedling developmental measures and morphological traits such as leaf and root mass, number and length compared to other distances of 1000, 1500, 2000 and 2500 m from the gas refinery. The highest values in seed germination and seedling emergence and growth occurred at distances furthest from the refineries. Also, direction from the refinery significantly (p <0.05) affected root growth, with larger seedlings occurring from acorns collected west of the refinery. The results of principal component analysis and discriminate analysis showed that various seed germination traits were most sensitive to gaseous toxic pollutants emitted from this source. Based on all studied traits, seedlings from acorns collected at 10,000 m from the facility were easily distinguished from seedlings of acorns collected at closer distances. It can be concluded that refinery toxic pollutants caused significant adverse changes in germination and seedling growth from acorns collected from oak trees located near (less than 10000 m) to the source of air pollution. It is recommended that such pollution sources should be established far away from forest areas, and if constructed, be equipped with appropriate technologies such as flare gas recovery (FGR) to reduce emission of toxic pollutants and other emissions such as sulfur dioxide (SO2) and hydrogen sulfide (H2S) from the gas refinery. It is also strongly recommended that acorns collected for restoration measures come from maternal trees growing at a distance >10000 m, and especially to the west of gas refineries.
... Fire is one of the major natural disturbance agents in European Alpine forests (Bebi et al., 2017;Kulakowski et al., 2016). Current fire regimes in the European Alps exhibit significant heterogeneity in terms of fire frequency, spatial extent and seasonality, according to the variability in climatic, environmental and anthropogenic drivers (Bebi et al., 2017;Conedera et al., 2018;Wastl et al., 2013;Zumbrunnen et al., 2011). ...
Article
Deriving burn severity from multispectral satellite data is a widely adopted approach to infer the degree of environmental change caused by fire. Burn severity maps obtained by thresholding bi-temporal indices based on pre- and post-fire Normalized Burn Ratio (NBR) can vary substantially depending on temporal constraints such as matched acquisition and optimal seasonal timing. Satisfying temporal requirements is crucial to effectively disentangle fire and non-fire induced spectral changes and can be particularly challenging when only a few cloud-free images are available. Our study focuses on 10 wildfires that occurred in mountainous areas of the Piedmont Region (Italy) during autumn 2017 following a severe and prolonged drought period. Our objectives were to: (i) generate reflectance composites using Sentinel-2 imagery that were optimised for seasonal timing by embedding spatial patterns of long-term land surface phenology (LSP); (ii) produce and validate burn severity maps based on the modelled relationship between bi-temporal indices and field data; (iii) compare burn severity maps obtained using either a pair of cloud-free Sentinel-2 images, i.e. paired images, or reflectance composites. We proposed a pixel-based compositing algorithm coupling the weighted geometric median and thematic spatial information, e.g. long-term LSP metrics derived from the MODIS Collection 6 Land Cover Dynamics Product, to rank all the clear observations available in the growing season. Composite Burn Index data and bi-temporal indices exhibited a strong nonlinear relationship (R² > 0.85) using paired images or reflectance composites. Burn severity maps attained overall classification accuracy ranging from 76.9% to 83.7% (Kappa between 0.61 and 0.72) and the Relative differenced NBR (RdNBR) achieved the best results compared to other bi-temporal indices (differenced NBR and Relativized Burn Ratio). Improvements in overall classification accuracy offered by the calibration of bi-temporal indices with the dNBR offset were limited to burn severity maps derived from paired images. Reflectance composites provided the highest overall classification accuracy and differences with paired images were significant using uncalibrated bi-temporal indices (4.4% to 5.2%) while they decreased (2.8% to 3.2%) when we calibrated bi-temporal indices derived from paired images. The extent of the high severity category increased by ~19% in burn severity maps derived from reflectance composites (uncalibrated RdNBR) compared to those from paired images (calibrated RdNBR). The reduced contrast between healthy and burnt conditions associated with suboptimal seasonal timing caused an underestimation of burnt areas. By embedding spatial patterns of long-term LSP metrics, our approach provided consistent reflectance composites targeted at a specific phenological stage and minimising non-fire induced inter-annual changes. Being independent from the multispectral dataset employed, the proposed pixel-based compositing approach offers new opportunities for operational change detection applications in geographic areas characterised by persistent cloud cover.
... In particular, forests have a huge carbon sequestration function and play an important role as a buffer for climate change and maintaining ecological security [2,3]. However, forest ecosystems often suffer from various human and natural disturbances, including forest pests and diseases, multiple fires, and artificial logging [4][5][6]. Forest fire is a natural disaster with such strong suddenness and destructive power that it is not easy to rescue the forests. Forest fires damage the structure, composition, and function of virgin forests to a certain extent, and can even threaten the safety of human beings and affect the region's carbon cycle in severe cases. ...
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With the increasingly severe damage wreaked by forest fires, their scientific and effective prevention and control has attracted the attention of countries worldwide. The breakthrough of remote sensing technologies implemented in the monitoring of fire spread and early warning has become the development direction for their prevention and control. However, a single remote sensing data collection point cannot simultaneously meet the temporal and spatial resolution requirements of fire spread monitoring. This can significantly affect the efficiency and timeliness of fire spread monitoring. This article focuses on the mountain fires that occurred in Muli County, on 28 March 2020, and in Jingjiu Township on 30 March 2020, in Liangshan Prefecture, Sichuan Province, as its research objects. Multi-source satellite remote sensing image data from Planet, Sentinel-2, MODIS, GF-1, GF-4, and Landsat-8 were used for fire monitoring. The spread of the fire time series was effectively and quickly obtained using the remote sensing data at various times. Fireline information and fire severity were extracted based on the calculated differenced normalized burn ratio (dNBR). This study collected the meteorological, terrain, combustibles, and human factors related to the fire. The random forest algorithm analyzed the collected data and identified the main factors, with their order of importance, that affected the spread of the two selected forest fires in Sichuan Province. Finally, the vegetation coverage before and after the fire was calculated, and the relationship between the vegetation coverage and the fire severity was analyzed. The results showed that the multi-source satellite remote sensing images can be utilized and implemented for time-evolving forest fires, enabling forest managers and firefighting agencies to plan improved firefighting actions in a timely manner and increase the effectiveness of firefighting strategies. For the forest fires in Sichuan Province studied here, the meteorological factors had the most significant impact on their spread compared with other forest fire factors. Among all variables, relative humidity was the most crucial factor affecting the spread of forest fires. The linear regression results showed that the vegetation coverage and dNBR were significantly correlated before and after the fire. The vegetation coverage recovery effects were different in the fire burned areas depending on fire severity. High vegetation recovery was associated with low-intensity burned areas. By combining the remote sensing data obtained by multi-source remote sensing satellites, accurate and macro dynamic monitoring and quantitative analysis of wildfires can be carried out. The study’s results provide effective information on the fires in Sichuan Province and can be used as a technical reference for fire spread monitoring and analysis through remote sensing, enabling accelerated emergency responses.
... European forests currently face changes in ecosystem functionality and resilience due to climate change (e.g., increased severity of disturbances such as hazard risk, storms with consequent insect attacks, fires, drought, etc.) (Schelhaas et al. 2015;Kulakowski et al. 2017). Apart from reducing GHG emissions, Millar et al. (2007) proposed forest management adaptation via behavior change, promoting the resilience of forests and increasing the adaptive capacity of forest users to climate change. ...
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In this volume, the concept of climate-smart forestry (CSF) has been introduced as adaptive forest management and governance to address climate change, fostering resilience and sustainable ecosystem service provision. Adaptive forest management and governance are seen as vital ways to mitigate the present and future impact of climate change on forest. Following this trajectory, we determine the ecosystem services approach as a potential adaptive tool to contribute to CSF. Ecosystem services as public or common goods face the traditional social dilemma of individual versus collective interests, which often generate conflicts, overuse, and resource depletion. This chapter focuses on the ecosystem servicegovernance approach, especially on incentive tools for behavioral change to CSF in the long term, which is a basic precondition for the sustainability of ecosystem integrity and functions, as well as ensuring the continuous delivery of ecosystem goods and services, as per the CSF definition. Payments for ecosystem services (PES) are seen as innovative economic instruments when adding a social dimension by involving local communities and their values to ensure the long-term resilience and adaptation of forest ecosystems to climate change. We argue that tackling climate changeadaptation requires the behavioral change of ecosystem service providers to a collaborative and integrated PES approach, as also emphasized by the Sustainable Development Goals (SDGs) of the Agenda 2030.
... Additionally, Mediterranean forests show fundamentally different structural characteristics from temperate mesic forests, due to the highdrought stress Mediterranean forests experience during the summer and due to fire disturbance (Karavani et al., 2018). These conditions may hinder the development of structural features typically associated with old-growth stages, as dense forest, unfragmented as was assumed in this work (Burrascano et al., 2013;Kulakowski et al., 2017). This is a limitation found in other studies for modelling Mediterranean forest characteristics on large scale (Sabatini et al., 2018). ...
Article
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Forest condition, biodiversity, and ecosystem services are strongly interlinked. The biodiversity levels depend to a large extent on the integrity, health, and vitality of forests at the same time as losses of forest biodiversity lead to decreased forest productivity and sustainability. Under this conceptual framework, this study presents a methodology for mapping forest condition at European scale supporting the attainment of the 2020 Aichi Biodiversity Target 5 “the rate of loss of all natural habitats, including forests, is at least halved and where feasible brought close to zero, and degradation and fragmentation is significantly reduced” and the implementation of Sustainable Development Goals (SDG), as well as the EU forest strategy since the sustainable forest management is oriented to support the provision of forest services and to enhance the condition of biodiversity forests’ host. The work presents the developments of an operational indicator at European scale. This spatially explicit information on forest condition can be the baseline map with a 1 km resolution to monitor the state and changes of condition by exposition to pressures and threats. This condition indicator considers structural, functional, and compositional aspects of forest with relevance for health and vitality of species and habitats hosted by forest ecosystems. The methodology implemented used harmonized, published and open datasets. It provided confident results for the assessment of the condition within hemiboreal, temperate and alpine forests, showing the Carpathian, Dinaric Alps and Alps, among others, as hotspots with pre-dominantly good condition. The results were validated with data derived from the reporting for the EU Habitat Directive and explicit dataset on known primary forests in Europe. However, this method underestimated the forest condition in the Mediterranean and Boreal forest types due to data gaps, regional specific characteristics, and design limitations. This study illustrates an operational and transferable approach for addressing the assessment of ecosystem forest condition at European scale being considered as a support tool for European countries when mapping and assessing their national territory, as potential common approach to map forest ecosystems that allows for consistent aggregation and comparisons across scales.
... This study contributes to the conception that bark beetle outbreaks, even in their unprecedented magnitude, are acting as a natural disturbance agent in temperate conifer mountain forest (e.g., Kulakowski, 2016). On a longer time scale, such bark beetle outbreaks would likely be one of the drivers to promote a dynamic ecological system typical for temperate conifer ecosystems, with higher tolerance to our current climate (Kulakowski et al., 2017). Therefore, the stakeholders of Tatra National Park and any other national park in Central Europe would be advised to adopt other management practices than salvage logging as reactions to bark beetle outbreaks. ...
Article
Temperate mountain forests have experienced an increase in frequency and severity of natural disturbances (e.g., droughts, fires, windstorms and insect outbreaks) in recent decades due to climate and environmental change. Outbreaks of bark beetles have caused significant dieback of conifer forests in Central Europe and it is essential to model and predict the potential severity of future bark beetle outbreaks. However, to predict future bark beetle activity, historical baseline information is required to contextualize the magnitude of current and potential future outbreaks. A fossil beetle record from a forest hollow in the Tatra Mountains, Slovakia; one of the best-preserved national parks in Central Europe, was produced to identify insect outbreaks during the last millennia. Sub-fossil bark beetle re-mains were compared with parallel pollen and charcoal to assess whether peaks in conifer bark beetle remains correspond with indications of disturbance documented in historical or sedimentary fossil records. Three peaks in bark beetle remains were detected (1) post-2004, (2) AD 1140-1440, and (3) AD930-1030. The abundance of speciesPityogenes chalcographusandPityophthorus pityographus in the two top samples can be linked directly to large bark beetle outbreaks in the High Tatra Mountains after 2004. P. chalcographus and P. pityographus are also the abundant species in the second peak (AD 1140e1440) while the third peak (AD 930e1030) consists of the species Polygraphus poligraphus. The most prominent conifer bark beetle in Central Europe, Ips typographus, was found to be present in most of the samples but always at very low numbers. It is plausible that P. chalcographus and P. pityographus fossils might be useful proxies for past conifer bark beetle outbreaks in Central Europe, as they occur together with fossils of I. typographus but appear to be well-preserved. A significant correlation was found between primary bark beetles and macroscopic charcoal densities in the sediment, highlighting the complex interactions between disturbance agents, bark beetles and fire, in this long-term regime of natural disturbances. Our 1400-year disturbance record shows how bark beetle outbreaks have been an important component of the regional natural disturbance regime for over a millennium and have intensified with increasing anthropogenic activity. Bark beetle outbreaks are likely one of the drivers promoting the future ecological stability of the temperate conifer ecosystem over decades to centuries.
... Norway spruce (Picea abies (L.) Karst.) is one of the most important tree species of the Carpathian Mountains, Alps, and the Balkan Mountains (Panayotov et al., 2011). Unmanaged Norway spruce mountain forests are limited in quantity in continental Europe and the majority of these forests are located in the Carpathian Mountains (Panayotov et al., 2011), which represents one of the largest mountain forest ecosystem in Europe Kulakowski et al., 2017). Because the Carpathian Mountains span greater than 1,500 km, the extensive forests within the Carpathian Mountains offer an ideal opportunity to study forest dynamics of Norway spruce forests as impacted by past disturbances. ...
Article
Natural disturbances strongly influence forest structural dynamics, and subsequently stand structural heterogeneity, biomass, and forest functioning. The impact of disturbance legacies on current forest structure can greatly influence how we interpret drivers of forest dynamics. However, without clear insight into forest history, many studies default to coarse assumptions about forest structure, for example, whether forests are even or unevenly aged. The aim of this study was to analyze the effects of past disturbances on the current diameter distributions of Norway spruce (Picea abies (L.) Karst.)-dominated landscapes throughout the Carpathian Mountains. Our dendroecological dataset comprises tree cores from 339 plots (7,845 total tree cores), nested within 28 primary forest stands, known to vary greatly in the severity of historical disturbances. Our analyses revealed that historical disturbances had a strong and significant effect on the current diameter distribution shapes at the plot level. We demonstrated that mixed-severity disturbance regimes were more frequent and create a complex pattern of diameter distributions at the plot and stand scale. Here, we show that high severity disturbance was associated with unimodal diameter distributions, while low and moderate severity was associated with the reverse J-shaped distribution. This is a result of complex disturbance patterns, with structural biological legacies. Our results will have important management implication in the context of tree size heterogeneity, biomass storage, and productivity as influenced by natural disturbances. Lastly, these results demonstrate that structural changes may arise as consequences of changing disturbance regime associated with global change.
... Natural disturbances heavily impact carbon sequestration in forests (e.g., Thom and Seidl 2016). Storms, avalanches, insect outbreaks, and fires (in terms of their frequency, severity, and unpredictability) threaten the resilience and stability of mountain forest landscapes and inherently affect their carbon sequestration potential (e.g., Kulakowski et al. 2017). In particular, natural disturbances have negative effects on carbon uptake through reducing forest cover and subsequently living biomass, changing species composition, altering the carbon flows among pools and between the pools and the atmosphere (Pilli et al. 2016). ...
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The European Union (EU) aims at reaching carbon neutrality by 2050. Within the land use, land-use change, and forestry (LULUCF) sector, forestry will contribute to this target with CO 2 sink, harvested wood products (HWP), and use of wood for material or energy substitution. Despite the fact that the forest sink currently offsets about 9% of the total EU GHG emissions, evaluating its future mitigation potential is challenging because of the complex interactions between human and natural impacts on forest growth and carbon accumulation. The Regulation (EU) 2018/841 has improved robustness, accuracy, and credibility of the accounting of GHG emissions and removals in the LULUCF sector. For the forest sector, the accounting is based on the Forest Reference Level (FRL), i.e., a projected country-specific value of GHG emissions and removals against which the actual GHG emissions and removals will be compared. The resulting difference will count toward the EU GHG target for the period 2021–2030. Here, we provide an overview of the contribution of forests and HWP to the EU carbon sink for the period 2021–2025 (proposed FRLs) and focus on the contribution of mountain forests to the EU carbon sink, through exploring co-benefits and adverse side effects between climate regulation and other ecosystem services.
... The action of many agents causing the mortality of overstory trees may induce the formation of aggregated distribution patterns of canopy gaps. In European montane forests formed by European beech (Fagus sylvatica L.), silver fir (Abies alba Mill.) and Norway spruce (Picea abies (L.) H. Karst.), these agents include wind, heavy snowfall in the autumn and spring when deciduous trees are leaved, ice storms and, among the biotic factors, insects and pathogenic fungi (Nagel et al., 2016;Kulakowski et al., 2017;Nagel et al., 2017;Orman and Dobrowolska, 2017). All these factors are known to cause disturbances frequently characterized by an aggregated spatial distribution. ...
Article
The action of many agents causing the mortality of overstory trees may potentially induce the formation of an aggregated distribution of canopy gaps. In this study we tested the hypothesis that natural stand dynamics generates an aggregated pattern of canopy openness in old-growth forests formed by Fagus sylvatica L., Abies alba Mill. and Picea abies (L.) H. Karst. We compared canopy openness and its spatial heterogeneity in five stands in the Western Carpathians (Central Europe) and three stands in the Dinaric Mountains (Southeast Europe). The stands were between 4.48 and 9.24 ha in size. In each stand we took hemispheric photographs in a regular 20 × 20 m grid in the leafless period to minimize coverage by the understory. Tree species and the dbh of live trees of dbh ≥7 cm were recorded on circular plots with a radius of 7 m centered at the grid points. At the stage of picture processing, understory trees of dbh <25 cm and polar coordinates recorded during field measurements were removed from the pictures, and for every grid point the local canopy openness of the overstory layer was determined in the sky region defined by a zenith angle of 15°. We characterized the spatial pattern of canopy openness by using variograms and Moran’s I coefficients and tested the spatial dependence in the distribution patterns of grid points characterized by different levels of canopy openness. Depending on the stand, mean canopy openness varied between 17.5 and 41.0%, with the greatest values recorded in the Carpathian stands with a considerable proportion of Norway spruce and a more severe disturbance regime. Relationships between canopy openness and the overall number, basal area or volume of trees forming the overstory were strongly modified by variation in the density and species percentage in the mid-canopy zone. In all the stands small-scale variation determined for inter-point distances of 20 m accounted for the majority of the total variation in canopy heterogeneity and ranged between 61 and 100%. We found a tendency to form random patterns of canopy openness in the Dinaric stands, which were characterized by a greater basal area and probably also lower frequency of severe disturbances, and aggregated patterns in the Carpathian stands, which were characterized by a smaller basal area driven by more severe disturbances. The revealed spatial dependence in canopy openness may suggest that in the studied ecosystem canopy gaps are not only a legacy of the mortality of canopy trees but also self-organizing structural elements which, under a more severe disturbance regime, can affect the mortality rate in their neighbourhood. Nonetheless, the percentage of spatially structured variability in canopy openness observable at scales larger than the grid spacing used in our study was insignificant (83% on average). The close-to-random pattern of canopy heterogeneity may weaken the spatio-temporal synchronization of the juvenile growth, maturation and senescence of neighbouring trees and counteract the formation of coarse-grained patch mosaics.
... Forest stands affected by windstorms often enable the rapid growth of bark beetle populations (Seidl et al., 2014), which accounted for 8% of the total damage in European forests between 1950 and 2000 (Schelhaas et al., 2003). Although the interactions between windthrow and bark beetle outbreaks are well understood (Kulakowski et al., 2017), those between windthrow and postdisturbance logging have been rarely investigated, especially through the use of long time series . ...
Article
Forests host most terrestrial biodiversity and provide important ecosystem services, including the provision of drinking water. Increasing frequency and intensity of natural disturbances and subsequent salvage logging may impact both biodiversity and drinking-water quality. However, empirical evidence and particularly that generated from long-term studies, is scarce. Using data obtained from the monitoring of streamwater between 1985 and 2018 and mid-term data on biodiversity of twelve species groups, we quantified the combined effects of natural disturbances and salvage logging. We used generalized additive models to test the effects of cumulative disturbed and salvage-logged areas on annual maximum nitrate and dissolved organic carbon (DOC) concentrations. We used generalized mixed-effects models to test the effect of management (disturbed unlogged, disturbed logged and undisturbed, intact forest) on species numbers of studied taxa. We found that forest disturbances led to a temporal increase of nitrate concentration in streamwater, yet remaining far below 50 mg L − 1 , the limits recommended by the World Health Organization. Salvage logging did not exert any additional impact on nitrate and DOC concentrations, and hence did not affect streamwater quality. Natural disturbances increased the biodiversity in eight out of twelve species groups. Salvage logging additionally increased the biodiversity of five species groups related to open habitats, but decreased the biodiversity of three deadwood-dependent species groups. We conclude that neither natural forest disturbances in watersheds nor associated salvage logging have a harmful effect on the quality of the streamwater, which is used for drinking water. Setting aside naturally disturbed areas would promote the conservation of deadwood-dependent species.
... The combination of these two factors gradually intensified in the early 20th century. The abandonment of mountainous and semi-mountainous areas and the establishment of these populations in cities and urban areas allowed the intensification of agriculture and stock breeding and production increase [2]. This phenomenon was further intensified during the second half of the 20th century and, in the decade 1990-2000, involved the abandonment of 20 Mha in 20 European countries, marking significant changes in land cover and use [3]. ...
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While deforestation is a major environmental issue in the tropics, with thousands of hectares converted to agricultural land every year, in Europe the opposite trend is observed, with land abandonment in mountainous and semi-mountainous areas allowing the afforestation of former agricultural and pastoral land. This trend allows semi-natural ecosystems to recover after a prolonged period of exploitation and often over-exploitation, but it may also lead to significant loss of landscape heterogeneity with potentially detrimental effects on biodiversity. The current study aims to monitor changes in the vegetation coverage across a period of 35 years (between 1984 and 2019) in the Rhodopi Mountains range National Park in northern Greece. A time series of LANDSAT TM (16 images), LANDSAT ETM + (1 image) and LANDSAT 8 OLI/TIRS (4 images) were employed. One data transformation method was applied (TCT), and five vegetation indices (NDVI, NDWI, SAVI, EVI2 and BSI) were calculated to capture the land cover transition during the study period. The obtained results and all used indices suggest that over the study period there was a continuous trend of vegetation cover increasing, with open areas decreasing. The observed trend was further confirmed using Object Oriented Image Analysis on two pairs of images sensed in 1984 and 2019, respectively. The results suggest that almost 22.000 ha of open habitats have been lost to broadleaved and conifer woodlands, while the former also appear to be advancing into conifer-covered areas. This trend has led to significant loss of landscape heterogeneity and to a broadleaf-dominated landscape. The results are discussed in relation to their driving forces, the potential implications on biodiversity and the risk of wildfires in the near future.
... El piedemeonte, por otro lado, se refiere a la bajada o pedestal de las montañas, y corresponde a una superficie en el margen de la montaña que desciende gradualmente. En muchas ciudades -como en el caso de Santiago-, el piedemonte corresponde a una interfaz entre centros urbanos y ecosistemas de montaña (Kulakowski et al., 2017), y es una zona que provee importantes contribuciones a las personas en aspectos culturales (Álvarez-Codoceo et al., 2021), pero que se encuentra usualmente degradada y bajo amenazas de cambio de uso de suelo debido a la expansión urbana. El piedemonte podría representar una importante zona para actividades de restauración con especies nativas, con miras a potenciar la captura de carbono en biomasa vegetal y suelos. ...
... The underlying premises of our experimental design were (a) to simulate the exact same scenarios with both models (which required the harmonization of some elements of the design, for example, with regard to the different time steps of iLand and LandClim, see also Petter et al., 2020) and (b) to focus on the diversity effects of interest here while controlling for other potential drivers of forest dynamics (e.g. legacy effects from past disturbances and land use; Kulakowski et al., 2017). Specifically, we initialized four levels of tree species diversity (gamma diversity) in two spatial configurations (alpha and beta diversity), see Figure 2a. ...
Article
Single species forest systems often suffer from low resistance and resilience to perturbations. Consequently, fostering tree species diversity is discussed as an important management approach to address the impacts of changing climate and disturbance regimes. Yet, the effect of the spatial grain of tree species mixtures remains unknown. We asked whether increasing tree species diversity between stands (beta diversity) has the same effect as increasing tree species diversity within stands (alpha diversity) at similar overall levels of richness (gamma diversity). We conducted a multi‐model simulation experiment under climate change, applying two forest landscape models (iLand, LandClim) across two contrasting landscapes of Central Europe. We analyzed the effect of different levels and configurations of diversity on the disturbance impact and the temporal stability of biomass stocks and forest structure. In general, increasing levels of diversity decreased disturbance impacts. Positive diversity effects increased with increasing severity of climate change. Beta diversity buffered disturbance impacts on landscape‐level biomass stocks more strongly than alpha diversity. The effects of the spatial configuration on forest structure were more variable. Diversity effects on temporal stability were less pronounced compared to disturbance impacts, and mixture within and between stands had comparable effects on temporal stability. Diversity effects were context‐dependent, with patterns varying between landscapes and indicators. Furthermore, we found a strong species identity effect, with increasing diversity being particularly beneficial in conifer‐dominated systems of the European Alps. The two models agreed on the effects of different levels and configurations of tree species diversity, underlining the robustness of our findings. Synthesis and application: Enhancing tree species diversity can buffer forest ecosystems against increasing levels of perturbation. Mixing tree species between stands is at least as effective as mixing tree species within stands. Given the managerial advantages of between‐stand mixtures (e.g., reduced need to control competition in order to maintain diversity, higher timber quality, lower logistic effort), we conclude that forest management should consider enhancing diversity at multiple spatial scales.
... Similarly, at the global or regional level, numerous other papers analyse spatial differences in forest ecosystems resilience (e.g. Krumhansl et al., 2016;Kulakowski et al., 2017), spatial and temporal variation of the ecosystems resilience to marine heatwave (Frölicher et al., 2018), similar variations in plant water behaviour in the context of ecosystems resilience to drought (Konings & Gentine, 2017), in-stream conditions and ecosystems (Lake, 2000;Lake et al., 2007) or in refuge spots for organisms during extreme events (Krause et al., 2017). A prerequisite to reorganise ecosystems after large disasters, spatial resilience takes sometimes the form of ecological memory, which corresponds, in the case of socialecological systems, to place identity. ...
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This study offers a literature review and bibliometric analysis aiming to enhance our understanding of the actual contribution of resilience approaches to spatial and territorial development and planning studies. Using citation link-based clustering and statistical text-mining techniques (in terms of prevalence of topics, over time, extraction of relevant terms, keywords frequencies), our study maps scientific domains that include the spatial dimension of resilience thinking. It offers a systematic assessment of modern approaches by connecting profoundly theoretical views to more instrumental and policy-oriented approaches. Firstly, the theoretical background of spatial resilience used in numerous studies in various fields is analysed from the viewpoint of the type of embedded resilience (engineering, ecological, social-ecological, economic, social etc.). Secondly, we review and discuss the significance of three main and consistent research directions in terms of different scales and political/institutional contexts that matter from the viewpoint of spatial and territorial planning. Our findings show that spatial resilience debates are far from being settled, as according to many scientists, resilience measurements are often based on technical-reductionist frameworks that cannot comprehensively reflect the complex systems and issues they address. Our conclusions highlight the necessity of a harmonized framework and integrated perspective on resilience in sustainable territorial planning and development, in both theoretical and empirical contexts.
... The more frequent disturbance at a particular plot in the past, a higher variability of biological legacies (e.g. deadwood decay stage diversity) and environmental conditions can be expected (Kulakowski et al., 2017). Some studies suggest that for fungal species richness, the diversity and variability of deadwood is more significant than the amount of deadwood (Abrego & Salcedo, 2013;Thorn et al., 2018a). ...
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Understanding the processes shaping the composition of assemblages at multiple spatial scales in response to disturbance events is crucial for preventing ongoing biodiversity loss and for improving current forest management policies aimed at mitigating climate change and enhancing forest resilience. Deadwood-inhabiting fungi represent an essential component of forest ecosystems through their association with deadwood decomposition and the cycling of nutrients and carbon. Although we have sufficient evidence for the fundamental role of deadwood availability and variability of decay stages for fungal species diversity, the influence of long-term natural disturbance regimes as the main driver of deadwood quantity and quality has not been sufficiently documented. We used a dendroecological approach to analyse the effect of 250-years of historical natural disturbance and structural habitat elements on local (plot-level) and regional (stand-level) species richness of deadwood-inhabiting fungi. We used data collected from 51 study plots within nine best-preserved primary spruce forest stands distributed across the Western Carpathian Mountains. Historical disturbances shaped the contemporary local and regional species richness of fungi, with contrasting impacts of disturbance regime components at different spatial scales. While local diversity of red-listed species has increased due to higher disturbance frequency, regional diversity of all species has decreased due to higher severity historical disturbances. The volume of deadwood positively influenced the species richness of deadwood-inhabiting fungi while canopy openness had a negative impact. The high number of observed rare species highlights the important role of primary forests for biodiversity conservation. From a landscape perspective, we can conclude that the distribution of species from the regional species pool is-at least to some extent-driven by past spatiotemporal patterns of disturbance events. Natural disturbances occurring at higher frequencies that create a mosaic forest structure are necessary for fungal species-especially for rare and endangered taxa. Thus, both the protection of intact forest landscapes and forest management practises that emulate natural disturbance processes are recommended to support habitats of diverse fungal communities and their associated ecosystem functions.
... Since the severity of insect outbreaks varies as a function of stand structure, land management actions that lead to a homogenization of ecosystems in which all trees are equally susceptible may intensify potential impacts. On the other hand, natural disturbances that generate structural and functional heterogeneity, from the scale of individual trees to landscapes, will likely promote future ecological resilience and adaptation in the face of climate and environmental change (Kulakowski et al., 2017). ...
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Plant traits are an expression of strategic tradeoffs in plant performance that determine variation in allocation of finite resources to alternate physiological functions. Climate factors interact with plant traits to mediate tree survival. This study investigated survival dynamics in Norway spruce (Picea abies) in relation to tree-level morphological traits during a prolonged multi-year outbreak of the bark beetle, Ips typographus, in Central Europe. We acquired datasets describing the trait attributes of individual spruce using remote sensing and field surveys. We used nonlinear regression in a hypothesis-driven framework to quantify survival probability as a function of tree size, crown morphology, intraspecific competition and a growing season water balance. Extant spruce trees that persisted through the outbreak were spatially clustered, suggesting that survival was a non-random process. Larger diameter trees were more susceptible to bark beetles, reflecting either life history tradeoffs or a dynamic interaction between defense capacity and insect aggregation behavior. Competition had a strong negative effect on survival, presumably through resource limitation. Trees with more extensive crowns were buffered against bark beetles, ostensibly by a more robust photosynthetic capability and greater carbon reserves. The outbreak spanned a warming trend and conditions of anomalous aridity. Sustained water limitation during this period amplified the consequences of other factors, rendering even smaller trees vulnerable to colonization by insects. Our results are in agreement with prior research indicating that climate change has the potential to intensify bark beetle activity. However, forest outcomes will depend on complex cross-scale interactions between global climate trends and tree-level trait factors, as well as feedback effects associated with landscape patterns of stand structural diversity.
... Our modelling results indicate a predominately positive effect of dead wood after natural disturbances without salvage 305 logging. In addition to the medium-term rockfall protection studied here, advanced decay stages of deadwood is beneficial for the biodiversity in particular of saproxylic organisms (Lachat et al., 2013;Sandström et al., 2019), improves biogeochemical cycles and edaphic conditions, provides favourable conditions for tree regeneration and results in greater heterogeneity and functional resilience at different spatial scales (Bače et al., 2012;Shorohova and Kapitsa, 2015;Kulakowski et al., 2017). For the conservation of saproxylic biodiversity Lachat et al. (2013) recommend in their review deadwood densities above 30 m 3 · 310 ha −1 for mixed mountain forests, but highlights that certain saproxylic species are just found with deadwood densities ≥ 100 m 3 ·ha −1 . ...
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How deadwood mitigates rockfall hazard in mountain forests is a key scientific question to understand the influence of climate induced disturbances on the protective capacity of mountain forests. To address this question both experimental quantification combined with numerical process modelling are needed. Modelling provides detailed insights into the rock-deadwood interaction and therefore can be used to develop effective forest management strategies. Here, we introduce an automatic deadwood generator (ADG) to assess the impact of fresh woody storm debris on the protective capacity of a forest stand against rockfall. The creation of deadwood scenarios allows us to directly quantify their mitigation potential. To demonstrate the functionality of the proposed ADG method, we compare genuine deadwood log patterns, their effective height, and ruggedness at two natural windthrow areas at Lake Klöntal, Switzerland, to their generated counterparts. We perform rockfall simulations for the time a) before, b) directly after and c) 10 years after the storm. The results are compared to scenario d) a complete clearing of the thrown wood, in other words a no forest scenario. We showcase an integration of deadwood in rockfall simulations with realistic, deadwood configurations alongside with a DBH- and rot fungi dependent maximal deadwood breaking energy. Our results confirm the mitigation effect of deadwood significantly reducing the jump heights and velocities for 400 kg rocks. Our modelling results suggest that even after a decade, deadwood has a stronger protective effect against rockfall compared to standing trees. An ADG can contribute to the decision making in forest and deadwood management after disturbances.
... Forests are complex socio-ecological systems (SES), where environmental and ecological functions interrelate and are shaped by human needs, e.g., [1][2][3][4][5]. However, in the last few decades, these systems and the multiple services they provide are increasingly triggered by-among others-the growth in frequency and intensity of disturbances, including extreme climatic events [6][7][8]. These threats are becoming particularly relevant for the European forests whose vulnerability has been increasing in the last years, mainly due to the expansion of the growing stock and increased exposure to climate change effects [9,10]. ...
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Windstorms are considered among the most impacting natural events for European forests and related Socio-Ecological Systems (SES). Given that their intensity and frequency are increasing , an in-depth understanding of their impacts is crucial to mitigate risks and potential negative effects. However, so far, scientific research on windstorm impacts has mainly focused on environmental dimensions, while socioeconomic and institutional ones are rarely taken into consideration. Our analysis aims at enriching the current scientific knowledge on windstorm impacts on forest SES by providing an overview of the state-of-the-art academic investigations on windstorm impacts on socioeconomic and institutional dimensions. Overall, 46 papers were reviewed to identify the most recurrent post-windstorm dynamics and drivers that influence resilience and adaptation of socioeconomic , institutional and related governance dimensions of European forest SES. Results show that the current scientific knowledge on socioeconomic impacts of windstorms mainly concentrates on forest-related stakeholders and sectors, paying little attention to the broader social, cultural and institutional drivers that contribute to forest SES resilience. Further, cascade effects linking environmental , social and institutional dimensions are poorly analyzed. This restricted focus could lead to an incomplete understanding of the dynamics shaping socioeconomic adaptability to windstorms, affecting long-term and sustainable recovery from extreme natural events. To correctly frame effective , intersectoral and coordinated recovery strategies gaining a deeper understanding of human-environment interactions is needed, as well as acknowledging the positive influence of causal relationships in improving forest-related SES resilience.
... Disturbances play a fundamental role in forest dynamics and in combination with environmental factors, they shape forest ecosystems, particularly spatial and age structures, quantity of biomass, species composition, and overall biodiversity (White and Pickett, 1985). Historically, complex mixed-severity disturbance regimes have prevailed in European mountain forest ecosystems (Seidl et al. 2011a, Meigs et al. 2017, Kulakowski et al. 2017. However, climate change has increased disturbance frequency and severity during recent decades (Seidl et al. 2011b, Turner 2010, Raffa et al. 2008, Schurman et al. 2018, which has in turn increased their effects on forest understories and biodiversity (Stevens et al. 2015, Dietz et al. 2020, Zellweger et al. 2020. ...
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... Such differences between the two systems can be explained by the modification of both the belowground (soil properties) and the above-ground resources due to change in the forest structure. Forest management involves a set of human activities and disturbances (Van der Maarel 1993; Kulakowski et al., 2017) and is a key factor affecting the environmental factors controlling changes in plant diversity. For example in our study, thinning and frequent cuttings in CWS has increased light availability (Ford and Newbould 1977;Strubelt et al., 2019) and access to soil water and nutrients (Parsons, Knight and Miller 1994). ...
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The oak (Quercus brantii Lindl.) semiarid forests of western Iran are among the oldest and host a remarkable diversity. However, the originally high forests were largely converted to coppices and submitted to a long history of traditional management and human disturbances. We investigated the effect of past management and forest structure on soil properties and vegetation diversity on two forest systems: coppice‐withstandards stands abandoned after an intense period of exploitation (CWS) and high forest stands (HF) submitted to a low intensity of management. We selected in each system three 1-2 ha stands and sampled 30 plots to measure vegetation diversity, forest structure using structural indices and, main soil factors including bulk density, nutrients, organic carbon and porosity. We found a higher species diversity in HF than in CWS with respectively 7 woody species in the former and only 4 in the latter as well as a higher structural complexity. Plant composition differed also between the two systems and multivariate analyses revealed clear associations between vegetation composition and soil factors in particular soil nutrients, soil porosity for HF and bulk density and texture for CWS. In fact, contents in soil nutrients were higher in HF than in CWS for total nitrogen (0.28 vs 0.15 %), available phosphorus (22.82 vs 15.47 ppm), available nitrogen (0.28 vs 0.15 ppm), and organic matter (2.58 vs 1.61 %) whereas soils of CWS showed a higher bulk density (1.39 vs 1.29) and a lower porosity (47.66 vs 51.50 %). This study thus revealed the legacy of the past forest management actions on the different components of the forest ecosystem. We concluded that the conservative management in high forests was more favourable for the protection of soil and vegetation diversity than in the traditional coppicing system.
... Beside windthrows (Feser et al., 2015), bark beetle outbreaks (Jönsson et al., 2009) and forest fires (Mozny et al., 2021;Jain et al., 2020) are also likely to increase in frequency or amplitude due to climate change and land-use legacies. Allowing natural processes without salvage logging after windthrow and without sanitary felling after bark beetle outbreaks are increasingly promoted as an adequate management option (Kulakowski et al., 2017;Sommerfeld et al., 2021). In rockfall protection forests, it is decisive to know more about the short-and long-term effects of piled stems on rockfalls after natural disturbances or management interventions. ...
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Silver fir Abies alba was once an abundant tree species in the Karkonosze Mts. in Poland but its population has decreased. The aim of our study was to assess 1) the impact of canopy trees on the growth dynamics of silver fir saplings and 2) the relationship between the growth rate of silver fir saplings and the soil properties, with special regard to the soil enzyme activity. The study was conducted in the Karkonoski National Park on five experimental plots. Silver fir seedlings were planted in Scots pine, European larch, Norway spruce, silver birch and European beech stands in 1999. In 2016, we measured the diameter at breast height (DBH) and height of the canopy trees and the height, DBH, height increments, needle width and length of 100 silver fir saplings. The dehydrogenase, urease, phosphatase and asparaginase activity was analysed in organic and humus soil horizons. The height, diameter and needle dimensions of young silver fir trees were significantly different under different canopies. The urease and asparaginase activity was the highest under the larch and spruce canopy in both soil horizons. Phosphatase activity was also the highest under larch canopy but only in organic soil horizon. Young silver fir (thicket) has grown under the canopy of all tested tree species but found best growth conditions under larch and pine canopies. The relative growth of silver fir is therefore a function of both stand canopy and soil properties.
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Ecosystem services (ESs) of mountain areas may be impacted by cumulative and interactive effects of multiple disturbances including insect infestations, wildfires, timber harvesting, and building construction. However, the impacts of natural and human disturbances on ESs and the trade-offs/synergies among ESs are poorly known, particularly in mountain ecosystems with diverse landscapes. Here, we used the Qilian Nature Reserve in northwestern China as a case study, for which we quantified mountain disturbances with a BEAST algorithm and three critical ESs (carbon sequestration, water yield, and habitat quality) with the CASA and InVEST models. We then simulated ESs using the BN model, and estimated the impacts of disturbances on ESs and their trade-offs in different environment conditions through multi-scenario analysis. Our results suggested that BEAST could effectively capture the patterns and dynamics of small-scale disturbances, which were previously difficult to predict with normal land use/cover products. The established BN model could simulate the spatio-temporal dynamics of carbon sequestration, water yield, and habitat quality with an average classification error of 17.8, 12.7 and 4.5% for each ES, respectively. Significant synergy existed between carbon sequestration and habitat quality at the regional scale, while trade-off existed between water yield and the other two ESs. Specifically, these trade-offs/synergies among ESs tended to be weak at medium value of ESs, but stronger at higher and lower states. Thus, significant differences existed in the “win-lose” solutions between water yield and the other two ESs, further resulting the limited space to simultaneously improve three ESs. Disturbances at medium frequency and low-medium intensity were beneficial for the maintenance and improvement of three ESs. The BN model is a promising decision support tool to integrate small-scale disturbances into ES evaluation and identify the most suitable management solutions for mountain ecosystems; this could provide critical information for decision-makers and guidance for sustainable development.
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Forests are rockfall-protective ecological infrastructures, as a significant amount of kinetic energy is absorbed during consecutive rock-tree impacts. Although many recent works have considered rock impacts with standing trees, the effect of lying deadwood in forests has not yet been considered thoroughly, either experimentally or numerically. Here, we present a complete examination of induced rockfall experiments on a forested area in three different management stages. The trilogy is conducted in a spruce forest stand (i) in its original state, (ii) after a logging operation with fresh, lying deadwood and (iii) after the removal of the deadwood. The tests allow us to directly quantify the effect of fresh deadwood on overall rockfall risk for the same forest (slope, species) under three different conditions. The study yields quantitative results on the barrier efficiency of the deadwood logs as only 3.6 % of the rocks surpass the deadwood section. The mean runout distance is reduced by 42 %. Conversely, the runout distance increases by 17 % when the cleared stand is compared to the original forest. These results quantitatively confirm the benefits of nature-based mitigation measures integrated into forestry practice and we show how modern rockfall codes can be extended to incorporate such complex, but realistic forest boundary conditions.
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Windstorms are one of the most important disturbance factors in European forest ecosystems. An understanding of the major drivers causing observed changes in forests is essential to improve prediction models and as a basis for forest management. In the present study, we use machine learning techniques in combination with data sets on tree properties, bioclimatic and geomorphic conditions, to analyse the level of forest damage by windstorms in the Sudety Mountains over the period 2004–2010. We tested four scenarios under five classification model frameworks: logistic regression, random forest, support vector machines, neural networks, and gradient boosted modelling. Gradient boosted modelling and random forest have the best predictive power. Tree volume and age are the most important predictors of windstorm damage; climate and geomorphic variables are less important. Forest damage maps based on forest data from 2020 show lower probabilities of damage compared to the end of 20th and the beginning of 21st century.
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Species richness, abundance and biomass of insects have recently undergone marked declines in Europe. We metabarcoded 211 Malaise-trap samples to investigate whether drought-induced forest dieback and subsequent salvage logging had an impact on ca. 3000 species of flying insects in silver fir Pyrenean forests. While forest dieback had no measurable impact on species richness, there were significant changes in community composition that were consistent with those observed during natural forest succession. Importantly , most observed changes were driven by rare species. Variation was explained primarily by canopy openness at the local scale, and the tree-related microhabitat diversity and deadwood amount at landscape scales. The levels of salvage logging in our study did not explain compositional changes. We conclude that forest dieback drives changes in species assemblages that mimic natural forest succession, and markedly increases the risk of catastrophic loss of rare species through homogenization of environmental conditions.
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Large-scale bark beetle outbreaks in spruce dominated mountain forests have increased in recent decades, and this trend is expected to continue in the future. These outbreaks have immediate and major effects on forest structure and ecosystem services. However, it remains unclear how forests recover from bark beetle infestations over the long term, and how different recovery stages fulfil the capacity of forests to protect infrastructures and human lives from natural hazards. The aim of this study was to investigate how a bark beetle infestation (1992–1997) in a spruce dominated forest in the Swiss Alps changed the forest structure and its protective function against snow avalanches. In 2020, i.e. 27 years after the peak of the outbreak, we re-surveyed the composition and height of new trees, as well as the deadwood height and degree of decay in an area that had been surveyed 20 years earlier. With the help of remote sensing data and avalanche simulations, we assessed the protective effect against avalanches before the disturbances (in 1985) and in 1997, 2007, 2014 and 2019 for a frequent (30-year return period) and an extreme (300-year return period) avalanche scenario. Post-disturbance regeneration led to a young forest that was again dominated by spruce 27 years after the outbreak, with median tree heights of 3–4 m and a crown cover of 10–30%. Deadwood covered 20–25% of the forest floor and was mainly in decay stages two and three out of five. Snags had median heights of 1.4 m, leaning logs 0.5 m and lying logs 0.3 m. The protective effect of the forest was high before the bark beetle outbreak and decreased during the first years of infestation (until 1997), mainly in the case of extreme avalanche events. The protective capacity reached an overall minimum in 2007 as a result of many forest openings. It partially recovered by 2014 and further increased by 2019, thanks to forest regeneration. Simulation results and a lack of avalanche releases since the infestation indicate that the protective capacity of post-disturbance forest stands affected by bark beetle may often be underestimated.
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West Kalimantan has great potential of forests and indigenous people. Therefore, it is crucial to study on forest management by indigenous people. The study is aimed at analyzing the forest management carried out by the Dayak Katab Kebahan community; and the condition of the forest ecosystem. The research area is in Melawi Regency, West Kalimantan. Observations and in-depth interviews were conducted to explore the customs in managing forests. A vegetation survey using purposive sampling was performed. The fauna study was conducted by the exploration method. Vegetation data analysis was carried out by calculating the importance value and diversity indices. One-way ANOVA analysis was done to determine the presence of forest ecosystem differences between two forests. The findings showed forest managed by the Dayak Katab Kebahan community has a core zone which is a zone that should not be disturbed, and a cultivation zone which can be utilized and can be intercropped with plantation crops; and the forest ecosystem managed by the Dayak Katab Kebahan community has a higher fauna richness, vegetation diversity index and the importance value index of each species. It is suggested that the government be involved in supporting the customary law of local communities in forest conservation.
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Disturbance of forest watersheds has numerous effects on up and downstream environments, including erosion and reduction in productivity in disturbed areas, removal of nutrients, and deposition of pollutants on the land surface by runoff contamination of water resources. Little research has been conducted on forest ecosystems despite the environmental problems induced by nutrient transport. Therefore, the present study was conducted to quantitatively compare sediment yield, surface runoff, and nutrient and organic matter (OM) loss from undisturbed and disturbed forest areas during rain events in the Research and Educational Forest Watershed of Tarbiat Modares University in northern Iran. The study involved two treatments with three replications using 6-m² plots. Results verified the significant effects of forest degradation (P < 0.05) on hydrological components and nutrient and OM loss. The surface runoff volume, runoff coefficient, sediment concentration, and sediment yield from plots located in the disturbed forest area were 5, 7, 5.5, and 18 times more, respectively than those measured in the undisturbed area. Also, the loss of carbon, nitrogen, phosphorus, and potassium in the disturbed area was more than in the undisturbed forest by 5, 10, 16, and 19 times. The maximum rate of loss of nutrients was 25 kg.ha⁻¹. Enrichment ratios for carbon, nitrogen, phosphorus and potassium in the undisturbed area were 1.38 ± 0.33, 1.13 ± 0.11, 0.25 ± 1.86 and 1.24 ± 0.20, respectively, and 0.36 ± 1.59, 0.37 ± 1.57, 0.22 ± 1.98 and 0.29 ± 1.008, respectively, in the disturbed area. The study results should be applied to improve the management of Iranian forest ecosystems.
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ContextGrowing evidence suggests that climate change could substantially alter forest disturbances. Interactions between individual disturbance agents are a major component of disturbance regimes, yet how interactions contribute to their climate sensitivity remains largely unknown. Objectives Here, our aim was to assess the climate sensitivity of disturbance interactions, focusing on wind and bark beetle disturbances. Methods We developed a process-based model of bark beetle disturbance, integrated into the dynamic forest landscape model iLand (already including a detailed model of wind disturbance). We evaluated the integrated model against observations from three wind events and a subsequent bark beetle outbreak, affecting 530.2 ha (3.8 %) of a mountain forest landscape in Austria between 2007 and 2014. Subsequently, we conducted a factorial experiment determining the effect of changes in climate variables on the area disturbed by wind and bark beetles separately and in combination. ResultsiLand was well able to reproduce observations with regard to area, temporal sequence, and spatial pattern of disturbance. The observed disturbance dynamics was strongly driven by interactions, with 64.3 % of the area disturbed attributed to interaction effects. A +4 °C warming increased the disturbed area by +264.7 % and the area-weighted mean patch size by +1794.3 %. Interactions were found to have a ten times higher sensitivity to temperature changes than main effects, considerably amplifying the climate sensitivity of the disturbance regime. Conclusions Disturbance interactions are a key component of the forest disturbance regime. Neglecting interaction effects can lead to a substantial underestimation of the climate change sensitivity of disturbance regimes.
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Disturbance and succession have long been of interest in ecology, but how landscape patterns of ecosystem structure and function evolve following large disturbances is poorly understood. After nearly 25 years, lodgepole pine (Pinus contorta var. latifolia) forests that regenerated after the 1988 Yellowstone Fires (Wyoming, USA) offer a prime opportunity to track the fate of disturbance-created heterogeneity in stand structure and function in a wilderness setting. In 2012, we resampled 72 permanent plots to ask (1) How have postfire stand structure and function changed between 11 and 24 yr postfire, and what variables explain these patterns and changes? (2) How has landscape-level (among-stand) variability in postfire stand structure and function changed between 11 and 24 yr postfire? We expected to see evidence of convergence beginning to emerge, but also that initial postfire stem density would still determine trajectories of biomass accumulation. After 24 yr, postfire lodgepole pine density remained very high (mean = 21,738 stems/ha, range = 0-344,067 stems/ha). Stem density increased in most plots between 11 and 24 yr postfire, but declined sharply where 11-yr-postfire stem density was >72,000 stems/ha. Stems were small in high-density stands, but stand-level lodgepole pine leaf area, foliage biomass, and live aboveground biomass increased over time and with increasing stem density. After 24 yr, mean annual lodgepole pine aboveground net primary production (ANPP) was high (mean = 5 Mg.ha(-1).yr(-1), range = 0-16.5 Mg.ha(-1).yr(-1)). Among stands, lodgepole pine ANPP increased with stem density, which explained 69% of the variation; another 8% of the variation was explained by environmental covariates. Early patterns of postfire lodgepole pine regeneration, which were contingent on prefire serotiny and fire severity, remained the dominant driver of stand structure and function. We observed mechanisms that would lead to convergence in stem density (structure) over time, but it was landscape variation in functional variables that declined substantially. Stand structure and function have not converged across the burned landscape, but our evidence suggests function will converge sooner than structure.
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Ice storms are important natural disturbances in temperate forests, yet have received little attention outside North America. Following an extreme ice storm in Slovenia, we examined patterns of ice damage within and among temperate forest sites and quantified differences in susceptibility to damage with respect to tree species and size across a gradient of storm intensity and site conditions. Based on a damage survey of 60 plots distributed across six unmanaged forest sites, ordinal logistic regression was used to examine patterns of ice damage as a function of storm intensity, species, tree size, and slope steepness. Our findings indicate that a complex interaction among these drivers gave rise to substantial variation in damage type and severity among species, plots, and stands. Fagus sylvatica, the most dominant species, was one of the most susceptible species to severe ice damage, while conifers (Abies alba and Picea abies) were least susceptible. Crown damage was the most common damage type at low storm intensity, while uprooting increased at higher intensity, particularly for large trees on steep slopes. Differences in species susceptibility to ice damage, combined with variation in storm intensity and site conditions, gave rise to heterogeneous damage patterns that have the potential to alter successional pathways. Based on an analysis of historical records, moderate-to-severe ice storms recur relatively frequently in the region, suggesting that they play a more important role in forest dynamics than previously thought.
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Afforestation and forest management are considered to be key instruments in mitigating climate change. Here we show that since 1750, in spite of considerable afforestation, wood extraction has led to Europe’s forests accumulating a carbon debt of 3.1 petagrams of carbon. We found that afforestation is responsible for an increase of 0.12 watts per square meter in the radiative imbalance at the top of the atmosphere, whereas an increase of 0.12 kelvin in summertime atmospheric boundary layer temperature was mainly caused by species conversion. Thus, two and a half centuries of forest management in Europe have not cooled the climate. The political imperative to mitigate climate change through afforestation and forest management therefore risks failure, unless it is recognized that not all forestry contributes to climate change mitigation.
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Rapid and ongoing change creates novelty in ecosystems everywhere, both when comparing contemporary systems to their historical baselines, and predicted future systems to the present. However, the level of novelty varies greatly among places. Here we propose a formal and quantifiable definition of abiotic and biotic novelty in ecosystems, map abiotic novelty globally, and discuss the implications of novelty for the science of ecology and for biodiversity conservation. We define novelty as the degree of dissimilarity of a system, measured in one or more dimensions relative to a reference baseline, usually defined as either the present or a time window in the past. In this conceptualization, novelty varies in degree, it is multidimensional, can be measured, and requires a temporal and spatial reference. This definition moves beyond prior categorical definitions of novel ecosystems, and does not include human agency, self-perpetuation, or irreversibility as criteria. Our global assessment of novelty was based on abiotic factors (temperature, precipitation, and nitrogen deposition) plus human population, and shows that there are already large areas with high novelty today relative to the early 20th century, and that there will even be more such areas by 2050. Interestingly, the places that are most novel are often not the places where absolute changes are largest; highlighting that novelty is inherently different from change. For the ecological sciences, highly novel ecosystems present new opportunities to test ecological theories, but also challenge the predictive ability of ecological models and their validation. For biodiversity conservation, increasing novelty presents some opportunities, but largely challenges. Conservation action is necessary along the entire continuum of novelty, by redoubling efforts to protect areas where novelty is low, identifying conservation opportunities where novelty is high, developing flexible yet strong regulations and policies, and establishing long-term experiments to test management approaches. Meeting the challenge of novelty will require advances in the science of ecology, and new and creative conservation approaches.
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Context Natural disturbances can have a considerable negative impact on the productivity of forest landscapes. Yet, disturbances are also important drivers of diversity, with diversity generally contributing positively to forest productivity. While the direct effects of disturbance have been investigated extensively it remains unclear how disturbance-mediated changes in diversity influence landscape productivity. Considering that disturbances are increasing in many ecosystems a better understanding of disturbance impacts is of growing importance for ecosystem management. Objectives Here, our objectives were to study the effect of disturbance on tree species diversity at different spatial scales (α and β diversity), and to analyze how a disturbance-mediated variation in tree species diversity affects forest productivity. Methods To account for long-term interactions between disturbance, diversity, and productivity and test a range of disturbance scenarios we used simulation modeling, focusing on a temperate forest landscape in Central Europe. Results We found an overall positive effect of disturbance on tree species diversity both with regard to α and β diversity, persisting under elevated disturbance frequencies. Productivity was enhanced by within- and between-stand diversity, with the effect of α diversity decreasing and that of β diversity increasing through the successional development. Positive diversity effects were found to be strongly contingent on the available species pool, with landscapes containing species with different life-history strategies responding most strongly to disturbance-mediated diversity. Conclusions We conclude that, rather than homogenizing disturbed areas, forest managers should incorporate the diversity created by disturbances into stand development to capitalize on a positive diversity effect on productivity.
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The dynamics, structure, and landscape heterogeneity of the lodgepole pine and spruce-fir forests of the Rocky Mountains in the western United States are shaped by wildfires, outbreaks of insects, and the potential interactions between these disturbances. Outbreaks of bark beetles create habitat heterogeneity in forests that can benefit numerous wildlife species. While important questions remain, the best available science indicates that outbreaks of bark beetles do not increase the risk of high-severity fires in lodgepole pine and spruce-fir forests of the Rocky Mountains. Furthermore, the effects of outbreaks are much less important to fire risk than are weather and climate. By contrast, severe wildfires can reduce subsequent susceptibility to outbreaks in both forest types, although the modulating effect of fires on susceptibility to outbreaks may be contingent on current and future climate influences on beetle populations and tree resistances. The current state of knowledge does not support the common assumption that increases in bark beetle activity have resulted in increased wildfire activity. Therefore policy discussions should focus on societal adaptation to the effects of the underlying driving factor of increased tree mortality from insects and from burning: climate warming. © 2015 by Dominick A. DellaSala and Chad T. Hanson. Published by Elsevier Inc. All rights reserved.
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Naturaldisturbances,orthelackthereof,contributedtoshapeEarth’sland- scapes and maintain its diversity of ecosystems. In particular, natural fire dynamics and herbivory by wild megafauna played an essential role in defining European land- scapes in pre-agricultural times. The advent of agriculture and the development of complex societies exacerbated the decline of European megafauna, leading to local and global extinctions of many species, and substantial alterations of fire regimes. Those natural phenomena were over time gradually and steadily replaced by anthro- pogenic disturbances. Yet, for the first time since the Black Death epidemic, agri- cultural land-use is decreasing in Europe. Less productive marginal areas have been progressively abandoned as crop and livestock production has become concentrated on the most fertile and easier to cultivate land. With little or no substitute for the anthropogenic disturbances associated with these abandoned agricultural practices, there is growing concern that disturbance-dependent communities may disappear, along with their associated ecosystem services. Nonetheless, rewilding can give an opportunity to tackle the issue of farmland abandonment. This chapter first depicts the historical European landscapes and the role of two natural disturbances, herbiv- ory and fire. The importance of disturbance-dependent habitats is then highlighted by drawing attention to the alpha and beta diversity that they sustain. Finally, the chapter investigates options for rewilding abandoned land to maintain disturbance- dependent and self-sustained habitats for which we suggest active restoration in the early stages of abandonment. This may be achieved via prescribed burning and sup- port or introduction, when necessary, of populations of wild mammals.
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In many parts of the world forest disturbance regimes have intensified recently, and future climatic changes are expected to amplify this development further in the coming decades. These changes are increasingly challenging the main objectives of forest ecosystem management, which are to provide ecosystem services sustainably to society and maintain the biological diversity of forests. Yet a comprehensive understanding of how disturbances affect these primary goals of ecosystem management is still lacking. We conducted a global literature review on the impact of three of the most important disturbance agents (fire, wind, and bark beetles) on 13 different ecosystem services and three indicators of biodiversity in forests of the boreal, cool- and warm-temperate biomes. Our objectives were to (i) synthesize the effect of natural disturbances on a wide range of possible objectives of forest management, and (ii) investigate standardized effect sizes of disturbance for selected indicators via a quantitative meta-analysis. We screened a total of 1958 disturbance studies published between 1981 and 2013, and reviewed 478 in detail. We first investigated the overall effect of disturbances on individual ecosystem services and indicators of biodiversity by means of independence tests, and subsequently examined the effect size of disturbances on indicators of carbon storage and biodiversity by means of regression analysis. Additionally, we investigated the effect of commonly used approaches of disturbance management, i.e. salvage logging and prescribed burning. We found that disturbance impacts on ecosystem services are generally negative, an effect that was supported for all categories of ecosystem services, i.e. supporting, provisioning, regulating, and cultural services (P < 0.001). Indicators of biodiversity, i.e. species richness, habitat quality and diversity indices, on the other hand were found to be influenced positively by disturbance (P < 0.001). Our analyses thus reveal a 'disturbance paradox', documenting that disturbances can put ecosystem services at risk while simultaneously facilitating biodiversity. A detailed investigation of disturbance effect sizes on carbon storage and biodiversity further underlined these divergent effects of disturbance. While a disturbance event on average causes a decrease in total ecosystem carbon by 38.5% (standardized coefficient for stand-replacing disturbance), it on average increases overall species richness by 35.6%. Disturbance-management approaches such as salvage logging and prescribed burning were neither found significantly to mitigate negative effects on ecosystem services nor to enhance positive effects on biodiversity, and thus were not found to alleviate the disturbance paradox. Considering that climate change is expected to intensify natural disturbance regimes, our results indicate that biodiversity will generally benefit from such changes while a sustainable provisioning of ecosystem services might come increasingly under pressure. This underlines that disturbance risk and resilience require increased attention in ecosystem management in the future, and that new approaches to addressing the disturbance paradox in management are needed. © 2015 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.
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Disturbances are fundamental components of ecosystems and, in many cases, a dominant driver of ecosystem structure and function at multiple spatial and temporal scales. While the effect of any one disturbance may be relatively well understood, multiple interacting disturbances can cause unexpected disturbance behavior (e.g., larger extents), altered return likelihoods, or reduced ecosystem resilience and regime shifts. Given the long-lasting implications of such events, and the potential for changes in disturbance rates driven by climate change and increasing anthropogenic pressures, developing a broad conceptual understanding and some predictive ability regarding the likelihood of interactions between disturbances is crucial. Through a broad synthesis of the literature, and across multiple biomes, disturbance interactions are placed into a unified framework around the concept of changing ecosystem resistance ("linked interactions," alterations to likelihood, extent, or severity) or ecosystem resilience ("compound interactions," alterations to recovery time or trajectory). Understanding and predicting disturbance interactions requires disaggregating disturbances into their constituent legacies, identifying the mechanisms which drive disturbances behavior (or ecosystem recovery), and determining when and where those mechanisms might be altered by the legacies of prior disturbances. The potential for cascading effects is discussed, by which these interactions may extend the reach of anthropogenic or climate change-induced alterations to disturbances beyond what is currently anticipated. Finally, several avenues for future research are outlined, as suggested from the current literature (and areas in which that literature is lacking). These include the potential for cross-scale interactions and changing scale-driven limitations, further work on cascading effects, and the potential for cross-biome comparisons. Disturbance interactions have the potential to cause large, nonlinear, or unexpected changes in ecosystem structure and functioning; finding generality across these complex events is an important step in predicting their occurrence and understanding their significance.
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Although some ecosystem responses to climate change are gradual, many ecosystems react in highly nonlinear ways. They show little response until a threshold or tipping point is reached where even a small perturbation may trigger collapse into a state from which recovery is difficult (1). Increasing evidence shows that the critical climate level for such collapse may be altered by conditions that can be managed locally. These synergies between local stressors and climate change provide potential opportunities for proactive management. Although their clarity and scale make such local approaches more conducive to action than global greenhouse gas management, crises in iconic UNESCO World Heritage sites illustrate that such stewardship is at risk of failing.
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The relative importance of people and climate in shaping prehistoric fire regimes is debated around the world, and this discussion has helped inform our understanding of past and present ecosystem dynamics. Evidence for extensive anthropogenic burning of temperate closed-canopy forests prior to European settlement is geographically variable, and the factors responsible for this variability are not well resolved. We set out to explain the differences in the influence of prehistoric human-set fires in seasonally dry forest types in the Pacific Northwest, New Zealand, and northern Patagonia by comparing the fire traits of dominant taxa, postfire vegetation recovery, long-term climate trends, and human activities that may have motivated burning. Our analysis suggests that ecological and climatic factors explain much of the differences in how these mesic–dry forests responded to prehistoric anthropogenic burning. Understanding past human–environment interactions at regional scales is an important step for assessing the impact of biomass burning at all scales.