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After large and severe wildfires, the establishment of tree regeneration, particularly for species without specific fire-adaptive traits, can be challenging. Within harsh environments, the presence of favorable microsites, as those provided by deadwood, enhancing microclimatic conditions, is crucial to the re-establishment of forest cover and thus to foster recovery dynamics. Active restoration strategies can have an impact on these dynamics, altering or hindering them. The main hypothesis of this study is that manipulating deadwood in terms of quantity and spatial arrangement can result in differences in natural regeneration density and composition. Post-disturbance regeneration dynamics and the role played by deadwood over time in the creation of safe sites for seedling establishment were investigated in an area affected by a high-severity wildfire that underwent different post-fire restoration treatments along a gradient of increasing deadwood manipulation, spanning from salvage logging to non-intervention. Two inventories were performed 5 and 11 years after the fire. Ground cover proportion was significantly different among treatments, with lower values of lying deadwood in salvaged sites. A higher probability of regeneration establishment close to deadwood was found in both surveys, confirming the facilitating role of deadwood on post-fire forest regeneration. Microsite dynamics resulting from deadwood facilitation were highlighted, with establishment probability and anisotropic relationships between deadwood elements and seedlings changing over time, as recovery processes slowly improved environmental conditions. In dry mountain areas affected by stand-replacing wildfires, by removing deadwood, salvage logging reduces the number of safe sites for regeneration, further impairing the ecosystem recovery. Passive management should be the ecologically preferred management strategy in these conditions, although intermediate interventions (e.g., felling without delimbing, leaving deadwood on the ground) could be effective alternatives, accelerating snag fall dynamics and immediately increasing favorable microsite availability. [ABSTRACT FROM AUTHOR]

Copyright of Fire Ecology is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• Large high severity patches and salvage logging hinder post-fire tree regeneration. • Distance from seed trees was the most important driver of Scots pine regeneration. • Potential positive effects of AN and importance of site selection for plantation. • Integrating micro-scale site selection can improve the efficiency of plantation. Changes in disturbance regimes triggered by land use and climate change can significantly alter forest ecosystems by modifying the distribution of some species and hindering post-disturbance tree regeneration dynamics. Applied nucleation (AN) could be a valuable active restoration approach for promoting natural recovery in forest ecosystems affected by stand-replacing disturbances as it improves seed availability and microsite conditions. The study aimed to investigate the potential of AN under different scenarios in a mountain forest ecosystem of the Northwestern Italian Alps dominated by Scots pine (Pinus sylvestris L.). The area was affected by a large stand-replacing fire in 2005 and post-fire salvage logging that amplified ecosystem degradation and dampened natural tree regeneration. We assessed the main drivers guiding natural post-fire natural recovery and identified suitable sites for tree regeneration through a machine learning correlative model (Bayesian Additive Regression Tree, BART). Specifically, we used several environmental predictors (e.g., topography, wind direction, and distance from seed trees) to model the occurrence of natural tree regeneration. We predicted the probability of tree regeneration presence at landscape scale under the current situation (fire followed by salvage logging) and a set of AN scenarios characterized by an increase in nuclei density, since distance from seed trees emerged as the most important driver for natural tree regeneration. Starting from the situation 16 years after the fire, we reclassified the prediction raster into a binary map of intervention priority (priority and non-priority patches), using the probability value that maximized the model accuracy (true skill statistic; TSS) as threshold. Patches with scarce pine regeneration were considered as high intervention priority sites for AN. These predictions made it possible to assess the most efficient active management scenario in terms of promoting forest recovery. The simulations showed the positive effects of AN on natural tree regeneration and the importance of site selection for plantations, proving that AN could be a promising post-fire management technique that can minimize human interventions and their associated economic and ecological costs. To our knowledge, this work is the first AN simulation in a temperate mountain ecosystem. The selection of favorable sites can be further improved by considering fine-scale characteristics through field experiments and cross-scale integration. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Forest Research is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Treeline position, structure, and composition are shaped by natural and anthropogenic factors. At human-disturbed treelines, it is particularly difficult to disentangle the specific role of natural and anthropogenic drivers controlling tree recruitment dynamics following land abandonment. We tested for a possible common regeneration pattern of Pinus nigra Arn. at four upper treeline ecotones in the central Apennines (Italy). The sites were selected based on (1) the occurrence of natural encroachment of P. nigra above 1600 m a.s.l., and (2) the mountain top elevation higher than 2000 m a.s.l. We assessed structure and spatiotemporal patterns of P. nigra advancing regeneration using point and surface pattern analyses. We mapped, measured, and dated 845 trees sampled on a total surface area of 336 ha. P. nigra is the only tree species expanding at high altitude and features a scattered process that started 35-40 years ago, with a maximum recruitment frequency between 1995 and 2003. Pinus regeneration appeared over-dispersed along the slope at a scale range of 12-18 m. We found spatial segregation between saplings and young trees at intermediate distances (8-17 m) and small patches of young trees distributed along the treeline ecotone. The spatial pattern of P. nigra encroachment in the central Apennines revealed a replicable model independent of treeline topography and local disturbance histories. [ABSTRACT FROM AUTHOR]

Highlights: [•] Regeneration dynamics is a key factor in shaping high-altitude forests. [•] We used spatial statistics in three fully-mapped 1-ha plots on an elevation gradient in the Alps. [•] The spatial pattern of regeneration is surprising convergent among sites. [•] These similarities come out despite the species and stand features differences. [ABSTRACT FROM AUTHOR]

Objectives: We examined canopy gap structure and regeneration patterns at the landscape scale using a combination of remote sensing and field-based surveys. Methods: The study was carried out in the forest reserve of Lom, an old-growth Fagus-Abies-Picea forest located within the Dinaric Alps in the north-western part of Bosnia and Herzegovina. A high-resolution (1-m panchromatic and 4-m multispectral) Kompsat-2 satellite image was orthorectified and classified through an unsupervised pixel-based classification using an artificial neural network method. Results: This approach allowed the identification of 650 canopy gaps, ranging in size from 32 to 1,776 m. Only 20 intermediate to large gaps (>250 m) were identified, and they were mainly present near the perimeter of the reserve. The origin of these large openings was associated with past human-caused disturbances or topographic conditions. The species composition of regeneration within large, human-caused gaps differed markedly from small gaps and non-gap sites in the core area of the reserve. Shade-intolerant species dominated the seedling and sapling layers in large openings. The landscape approach employed in this study confirmed the hypothesis that small gaps predominate at Lom, especially within the core area of the reserve. [ABSTRACT FROM AUTHOR]

Abstract: It is frequently believed that a post-fire environment requires immediate actions in order to be restored. Salvage logging followed by plantation is a common post-fire restoration practice in many forests of the northwestern Italian Alps. The objectives of this study were to assess the impact of active and passive management techniques on the restoration of a burned area of the Aosta Valley and to determine which approach is the most suitable for enhancing Pinus sylvestris regeneration after stand replacing wildfires. The influence of five management options (no intervention; salvage logging; broadleaves plantation; Larix decidua plantation; P. sylvestris or Pseudotsuga menziesii plantation) and environmental variables on natural regeneration structure and composition was evaluated through direct gradient analysis. Pinus sylvestris and Populus tremula were the dominant tree species (40 and 29%, respectively) in the regeneration layer. Density, size, and structural diversity of natural regeneration were higher in the no intervention area. The proximity to forest edge was found to be the most important environmental variable. This study provided evidence that taking advantage of natural restoration processes may be a suitable alternative strategy to the active restoration practices adopted according to the Aosta Valley policy of post-fire management. [ABSTRACT FROM AUTHOR]

• Natural seed regeneration of chestnut is a key issue in recovering overaging chestnut coppices. • The establishment of seed regeneration was more than sufficient to guarantee a safe turnover of dead stools. • Chestnut trees released (standards) after coppicing do not play a relevant role as tree-seeders. • The presence of standards inhibited the growth of seedlings up to 10 m away. • An excessive presence of standards has promoted the settling of regeneration of shade-tolerant species. The management of Italian chestnut coppices has gradually been suspended after World War II, causing a widespread overaging of the concerned stands. In recent years, the renewed interest in coppice wood products increased the need of a solid knowledge on the most suitable restoration practices of overaged coppices. In this context, a key issue is assuring a qualitative and abundant seed regeneration of the chestnut tree (Castanea sativa Miller) in order to substitute overaged stools. Open questions still exist however on the role of the standards (trees released after coppicing) and, in particular, on their interaction with the post-coppicing establishment of seed regeneration. In order to clarify these aspects, we applied different coppicing systems in overaged chestnut coppices so as to create a gradient of residual coverage ranging from full coverage left (no intervention) to simple coppicing (all trees cut, no standards released). The impact of different treatments on chestnut regeneration has been then assessed through field surveys in the second and fifth year post-coppicing, respectively. Chestnut seed regeneration promptly and abundantly established to guarantee the replacement of dead stools also in the simple coppicing. The post-coppicing pulse of chestnut seed regeneration mostly originated from the existing annual seed bank and it was concentrated in the first two years after the intervention, whereas seed inputs by standards or by adult trees at the forest edge played a secondary or negligible role from the third post-coppicing year onwards. Thus, the presence of standards did not benefit regeneration. Rather, it displayed a marked depressive effect on the growth rate of young chestnut seedlings and, under significant shading conditions, enhanced the establishment of shade-tolerant tree species. From a silvicultural point of view, simple coppicing of overaged chestnut coppices represents a valuable management option combining a rapid establishment of natural seed regeneration of chestnut with the resprout and development of the most vigorous stools. [ABSTRACT FROM AUTHOR]

High severity stand-replacing wildfires can deeply affect forest ecosystems whose composition includes plant species lacking fire-related traits and specific adaptations. Land managers and policymakers need to be aware of the importance of properly managing these ecosystems, adopting post-disturbance interventions designed to reach management goals, and restoring the required ecosystem services. Recent research frequently found that post-fire salvage logging negatively affects natural regeneration dynamics, thereby altering successional pathways due to a detrimental interaction with the preceding disturbance. In this study, we compared the effects of salvage logging and other post-disturbance interventions (adopting different deadwood management strategies) to test their impact on microclimatic conditions, which potentially affect tree regeneration establishment and survival. After one of the largest and most severe wildfires in the Western Alps that affected stand-replacing behavior (100% tree mortality), a mountain forest dominated by Pinus sylvestris L., three post-fire interventions were adopted (SL-Salvage Logging, logging of all snags; CR-Cut and Release, cutting snags and releasing all deadwood on the ground; NI-No Intervention, all snags left standing). The differences among interventions concerning microclimatic conditions (albedo, surface roughness, solar radiation, soil moisture, soil temperature) were analyzed at different spatial scales (site, microsite). The management interventions influenced the presence and density of safe sites for regeneration. Salvage logging contributed to the harsh post-fire microsite environment by increasing soil temperature and reducing soil moisture. The presence of deadwood, instead, played a facilitative role in ameliorating microclimatic conditions for seedlings. The CR intervention had the highest soil moisture and the lowest soil temperature, which could be crucial for seedling survival in the first post-fire years. Due to its negative impact on microclimatic conditions affecting the availability of preferential microsites for regeneration recruitment, salvage logging should not be considered as the only intervention to be applied in post-fire environments. In the absence of threats or hazards requiring specific management actions (e.g., public safety, physical hazards for facilities), in the investigated ecosystems, no intervention, leaving all deadwood on site, could result in better microclimatic conditions for seedling establishment. A preferred strategy to speed-up natural processes and further increase safe sites for regeneration could be felling standing dead trees whilst releasing deadwood (at least partially) on the ground. [ABSTRACT FROM AUTHOR]

Large crown fires in the Aosta Valley mostly occur in south-facing slopes where xeric conditions favour the presence of highly flammable conifer stands dominated by Pinus sylvestris. North-facing slopes are less affected by the occurrence of wildfires but the availability of large fuel amounts and prolonged drought periods can raise the fire risk also in these areas. Although stand-replacing wildfires affected about 20% of the total burned forest area from 1989 to 2017, the scarce fire adaptations of Pinus sylvestris pose serious problems for the regeneration of this species and a suitable post-fire management strategy is thus required to enhance this process. Long and mid-term forest regeneration dynamics of Pinus sylvestris were explored using both field surveys and remote sensing techniques in 12 stand-replacing wildfires occurred between 1989 and 2006 in the Aosta Valley. Tree regeneration at different development stages was sampled during 2017 and its fractional cover was also assessed. Time series of Landsat derived spectral vegetation indices were employed to track forest regeneration over time and temporal trajectories were modelled using robust regression methods to assess the magnitude and the direction of spectral changes throughout the years. [ABSTRACT FROM AUTHOR]