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Context: Land use legacies of human activities and recent post-abandonment forest expansion have extensively modified numerous forest landscapes throughout the European mountain ranges. Drivers of forest expansion and the effects of changes on ecosystem services are currently debated. Objectives: (i) To compare landscape transition patterns of the Alps and the Apennines (Italy), (ii) to quantify the dominant landscape transitions, and (iii) to measure the influence of climatic, topographic and anthropogenic driving factors. Methods: Land cover changes and landscape pattern modifications were investigated at the regional (over 28 years, Alps and Apennines, Corine Land Cover dataset) and landscape scale (over 58 years, 8 Alpine and 8 Apennine sites, aerial images). The main driving factors of post-abandonment forest landscape dynamics were assessed with a statistical modeling approach. Results: Forest expansion was the dominant landscape transition at both Italian mountain ranges, with an annual overall rate of 0.6%. Forest expansion was more extensive at lower elevations in the Apennines where climate is less limiting and extensive abandoned croplands and pastures were available throughout the study period. Distance from pre-existing forest edges in the Alps and elevation in the Apennines emerged as the most important predictors. Conclusions: Forest expansion is most rapid where areas of recent agricultural abandonment coincide with favorable climatic conditions. Thus the prediction of forest landscape dynamics, in these mountain forests with a long history of cultural use, requires knowledge of how the magnitude and timing of land use changes intersect spatially and temporally with suitable conditions for tree establishment and growth. [ABSTRACT FROM AUTHOR]

• Roe deer browsing impact was investigated in temperate hardwood coppice forests. • Browsing effects were monitored for 11 years in an exclusion experiment. • High browsing impact in the early years after coppicing on more palatable species. • Coppice forests showed significant post-browsing recovery in the medium term. • Long-term monitoring is key to assess browsing impact and management implications. In southern European temperate forests, coppicing is a traditional form of forest management that shaped the present cultural landscape, providing multiple ecosystem services. Roe deer densities have been growing notably during the last decades mainly due to the abandonment of rural areas, changes in human land use and restocking. The impact of roe deer on coppice forests can affect the resprouting and, in turn, compromise the products and ecosystem services provided by these forests. During coppicing, stems are cut down close to the ground, where the growing shoots are exposed to deer browsing, especially during the early years following cutting. In this study, using a browsing exclusion experiment, we investigated the impact of browsing on temperate mountain hardwood coppice forests in the western Italian Alps over a period of eleven years following coppicing. We found that the impact of browsing was highest in the first two years following coppicing, with Quercus pubescens and Castanea sativa being the most affected tree species. The height of shoots was the variable that showed the biggest difference between fenced and unfenced areas. A significant negative effect of browsing on shoot height was found at the beginning of the experiment, with shoots growing in unfenced area showing the lowest height increments. After the third year, when the browsing intensity diminished, we observed the opposite trend, with shoots growing in unfenced areas showing higher height increments compared with fenced areas. A similar trend was observed also for the diameter of shoots over the course of the experiment. Eleven years after coppicing, however, the structural characteristics of the natural regeneration converged at all sites and in both fenced and unfenced areas. This study shows that coppice forests are resilient to browsing and are capable to recover growth loss within a few years after browsing has naturally diminished and stopped. The research conducted also points out the importance of medium- to long-term monitoring to assess post-disturbance dynamics and evaluate implications for management. [ABSTRACT FROM AUTHOR]

Abstract: Insect outbreaks and wind storms are the most common natural disturbances affecting the northern slopes of montane Norway spruce (Picea abies (L.) H. Karst.) forests in the European Alps. The combined effects on stand dynamics, including tree regeneration, of these natural disturbances and an anthropogenic (i.e., salvage logging) disturbance were studied to assess the role of post-disturbance management practices. The study areas were in two adjacent inner valleys of the Aosta Valley Autonomous Region (western Italian Alps). Les Combes study area experienced an insect (Lymantria monacha L.) outbreak that affected 91ha in 1984–1990, while a wind storm impacted 70ha in the other valley (Parriod study area) in 1990. Salvage logging took place in both study areas 2years after the natural disturbance occurrence (i.e., in 1991–1992 in Les Combes, and in 1992–1993 in Parriod), and only dead trees were salvaged. Site characteristics, overstory and understory trees, and coarse woody debris (CWD) data were collected during the summer of 2010 in 90plots randomly distributed within disturbed portions and in control stands of the two study areas. The variability of natural regeneration structure and composition in relation to environment, forest structure, type of disturbance, and salvage logging were analyzed by univariate (i.e., ANOVA and correlations) and multivariate (i.e., MRPP, PCA, and RDA) analyses. Regeneration structure and composition were clearly different for the two disturbance types. Individuals originated mainly from seed after the insect outbreak, while an important role was played by advance regeneration in the windthrow area. Regeneration was more abundant and rich in shade tolerant species (i.e., Abies alba Mill.) after the insect outbreak, while Larix decidua Mill. and light demanding broadleaves were dominant after the windthrow. The two major factors influencing post-disturbance regeneration were the amount of the residual overstory and the amount and distribution of CWD. The presence of residual forest patches facilitated regeneration establishment by reducing herb and shrub competition, and regulating the light that penetrates to the ground. Woodpiles had a negative influence on regeneration in terms of abundance and also influenced composition. On the contrary, scattered CWD facilitated the establishment of new individuals by reducing competition with herbs and shrubs, reducing the impact of browsing, and improving substrate moisture, especially for Norway spruce. [Copyright &y& Elsevier]

In the European Alps, subalpine forests are important for lichen diversity conservation at multiple levels. However, the potential role of coarse woody debris (CWD) has been only marginally considered in the previous literature. The aims of this case study are (i) to provide a first evaluation of the effects of different types of CWD (stumps, logs, and snags) and wood decay on lichen diversity in Pinus-Larix forests in the Italian Alps, and (ii) to increase the knowledge of the lichen biota on CWD in Italy. Seventy-eight species were found, including 12 nationally rare and 10 calicioid species; Placynthiella hyporhoda is new to Italy. Different types of CWD in different decay stages had significantly different lichen communities. Snags seem to be particularly effective for conservation, since they host the highest number of nationally rare species. Our survey suggests that CWD could be an important substratum for several nationally rare species, indicating that further surveys at a regional scale are urgently required in order to evaluate the role of CWD for lichen diversity conservation in the Alps. [ABSTRACT FROM PUBLISHER]

1. The tree-ring growth response of stone pine ( Pinus cembra L.) to climatic variability was studied in the Alps. The aims were (i) to assess tree-ring growth patterns at different spatial-temporal scales; (ii) to identify the climate parameters that explain most of the variability in radial growth at different time domains; and (iii) to study past and current trends in radial growth and climate–growth relationships at different locations. 2. High- and low-frequency stone pine chronologies were compiled for 30 treeline sites on the French and Italian Alps. We used gridded climate data computed from 200 years of instrumental records from an extensive Alpine network. Climate–growth relationships were computed with bootstrap correlation functions and their stationarity and consistency over time assessed with moving correlation. 3. No spatial patterns were detected in stone pine chronology statistics despite the regional clustering observed in tree-ring series and climate responses. This can be attributed to (i) local weather variability; (ii) different biophysical conditions caused by soil moisture, solar radiation, snowmelt dynamics and growing season length; and (iii) forest stand history and age structure, the expression of long-term land use and disturbances. 4. The exceptionally long-term climate records allowed significant stone pine growth response changes to be assessed at both annual and decadal time scales. Winter conditions and spring–summer temperatures mainly affected the growing season length, in addition to site carbon and water balance. Most of these limiting factors varied spatially and temporally along the latitudinal and longitudinal gradients in response to the corresponding changes in local conditions. 5. Our results show evidence of a clear response variability of Pinus cembra to climate limiting factors, at both spatial and temporal scale. Such knowledge extended to other species and regions will provide better estimates of the effect of climate variability on species distribution and dynamics within global change scenarios and more accurate past climate reconstruction and forest ecosystem modelling. [ABSTRACT FROM AUTHOR]

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 (R 2 > 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. • We mapped burn severity using Sentinel-2 paired images and reflectance composites. • Bi-temporal indices benefit from a reduction in non-fire induced spectral changes. • Reflectance composites exhibit spectral consistency in space and time. • Our approach increased the overall classification accuracy up to 5.2%. • Gaining contrast between healthy and burnt vegetation improves burn severity maps. [ABSTRACT FROM AUTHOR]

Abstract: Regeneration of non fire-adapted conifers following crown fires on the European Alps is often delayed or unsuccessful. Fire may limit establishment by eliminating seed trees, altering soil properties, or modifying microsite and soil conditions via disturbance legacies. However, the effect of soil legacies on post-fire establishment has rarely been discussed. We analyzed the abundance of Scots pine regeneration in a 257ha wildfire in an inner-alpine forest. Our aims were (1) to model fire intensity at the soil surface and topsoil heating along a gradient of increasing fire severities; (2) to assess the differences in soil properties along the fire severity gradient; (3) to model the effect of disturbance and soil legacies on the density of pine seedlings. We reconstructed fire behavior and soil heating with the First Order Fire Effects Model (FOFEM), tested the effect of fire severity on soils by nonparametric distributional tests, and modeled seedling density as a function of site, disturbance and soil legacies by fitting a GLM following a variable selection procedure. Topsoil heating differed markedly between the moderate and high severity fires, reaching temperatures high enough to strongly and permanently alter soil properties only in the latter. High fire severity resulted in decreased soil consistency and wet aggregate stability. Burned soils had lower organic matter and cations than those unburned. Pine seedlings favored low-fertility, eroded, and chemically poor sites. Establishment was facilitated by the presence of coarse woody debris, but hampered by increasing distance from the seed source. These results suggest that in dry, inner-alpine valleys, fire residuals and soil legacies interact in determining the success of Scots pine re-establishment. High severity fire can promote favorable soil conditions, but distance from the seed source and high evaporation rates of bare soils must be mitigated in order to ensure a successful restoration. [Copyright &y& Elsevier]