1,721,110 research outputs found
The synchronicity of masting and intermediate severity fire effects favors beech recruitment
No full textThe fire ecology of European beech (Fagus sylvatica L.) is poorly understood. We analyzed beech recruitment after a mast year in recently burnt and unburnt stands to answer to the questions: (i) Does post-fire mast seed production and recruitment in beech depend on fire severity, and (ii) which are the processes by which fire and the environment affect beech seed production, germination and seedling emergence and establishment in the first year after masting?
We selected three beech stands in the Southwestern Alps, burnt in either the winter of 2012 or 2013 but before the 2013 beech mast year. In the summer of 2013, at each stand, we established 30 sampling plots stratified by fire severity based on the percent basal area loss of beech (low; intermediate; high). Another 10 plots per stand were assigned to a control (unburnt) group. In the spring of 2014, we counted cupules, seeds, germinated seeds, and emergent seedlings (i.e., rooted in mineral soil) in four squares (0.4 × 0.4 m) at each plot. In the summer of 2014, at each plot, we measured stand characteristics (i.e., a circular area of 12-m in a planar radius) and counted established seedlings in 12 squares (1 × 1 m).
Control stands had 448 ± 38 cupules m−2 and 489 ± 44 seeds m−2 with a germination rate of 11%. In comparison to the control, production of cupules and seeds was significantly lower only under high fire severity (−75% and −63%, respectively). At intermediate and low severity sites, cupule and seed production were similar to unburnt sites, while seed germination and seedling emergence were higher. At intermediate severity sites established seedlings (86,000 ± 10,574 seedlings ha−1) were significantly more frequent than the control. Generalized linear and additive models demonstrated that intermediate disturbance of litter and canopy cover favored beech regeneration.
Mixed severity fires are an important ecological factor for the natural regeneration of beech. Such insights in beech disturbance ecology can help improve silviculture and post-fire restoration of Alpine forests. The synergy between fire and masting raises new questions concerning the role of fire in temperate beech forests
Historical Floras: addressing their genesis in order to be viewed from a modern-day perspective. A case study from Northern Italy
Full text linkHistorical Floras are biodiversity-oriented textual sources, which refer to times when scientific methods were far different compared to the present. They are also geographical documents, as the entire work is referred to a focal region explored by certain collectors and following certain principles, since the taxa recorded are usually accompanied by a description of the locality of the observation. Retrospective georeferencing, as well as taxonomic revision, of the records in Historical Floras are, however, very challenging processes, which are usually not taken into account. As a result, very few global overviews of Historical Floras exist to date. In this article we present the analysis of the 7767 floristic records of the late XIX century Flora of the province of Bologna (N-Italy) compiled by Girolamo Cocconi. We processed these records by georeferencing them, whenever possible, to 659 pairs of coordinates and coupling them with the analysis of the collectors involved besides the author, as to provide the spatial and temporal dimension that permits us to further understand the taxonomic information given by the species listed. This allowed us to detect a bias in the exploration of the territory, which depended on accessibility and/or attractivity of the areas for fieldwork and shifted through time as function of the available collaborators who influenced the definition of the floristic pattern of the territory. Finally, we provided a diachronic analysis with the present flora to document the most significant land use changes based on selected floristic target groups
Assessing the influence of roads on fire ignition. Does land cover matter?
No full textIn human-affected fire environments, assessing the influence of human activities on the spatial distribution of wildfire ignitions is of paramount importance for fire management planning. Previous studies have shown that roads have significant effects on fire ignition. However, since different land cover classes are subject to different levels of ignition risk, roads in different land cover classes may differently affect fire ignition. The aim of this paper is thus to assess the influence of roads on fire ignition in selected land cover classes subjected to different levels of anthropogenic pressure in Sardinia (Italy). Our results show that fires are preferentially ignited close to roads in all land cover classes. However, the influence of roads is much stronger in less impacted land uses, where the availability of human-induced ignitions highly depends on the accessibility networks. Our approach represents a first step towards the systematic integration of interacting fire ignition drivers such as roads and land cover into fire risk analysis
Indagini paleobotaniche sulla storia della vegetazione e degli incendi forestali durante l'Olocene al Lago di Origlio (Ticino Meridionale)
No full textFerro e fuoco: una ricostruzione paleoecologica dell'approccio territoriale nella Regione Insubrica in età preistorica
No full textWhat makes soil landscape robust? Landscape sensitivity towards land use changes in a Swiss southern Alpine valley
Full text linkLandscape sensitivity is a concept referring to the likelihood that changes in land use may affect in an irreversible way physical and chemical soil properties of the concerned landscape. The objective of this study is to quantitatively assess the sensitivity of the southern Alpine soil landscape regarding land use change-induced perturbations. Alpine soil landscapes can be considered as particularly sensitive to land use changes because their effects tend to be enhanced by frequent extreme climatic and topographic conditions as well as intense geomorphologic activity. In detail, the following soil key properties for soil vulnerability were analysed: (i) soil texture, (ii) bulk density, (iii) soil organic carbon (SOC), (iv) saturated hydraulic conductivity (Ksat), (v) aggregate stability and (vi) soil water repellency (SWR). The study area is characterized by a steep, east-west oriented valley, strongly anthropized in the last centuries followed by a progressive abandonment. This area is particularly suitable due to constant lithological conditions, extreme topographic and climatic conditions as well as historic land use changes. The analysis of land use change effects on soil properties were performed through a linear mixed model approach due to the nested structure of the data. Our results show a generally high stability of the assessed soils in terms of aggregate stability and noteworthy thick soils. The former is remarkable, since aggregate stability, which is commonly used for detecting land use-induced changes in soil erosion susceptibility, was always comparably high irrespective of land use. The stability of the soils is mainly related to a high amount of soil organic matter favouring the formation of stable soil aggregates, decreasing soil erodibility and hence, reducing soil loss by erosion. However, the most sensitive soil property to land use change was SWR that is partly influenced by the amount of soil organic carbon and probably by the quality and composition of SOM
Seed regeneration of sweet chestnut (Castanea sativa Miller) under different coppicing approaches
Full text linkNatural seed regeneration in chestnut coppices: a key factor in planning silvicultural management.
No full textOver the last 50 years, many unfavourable factors have led to the abandonment of the traditional management of many chestnut
coppices. This generated a general aging of the stands and a related reduction of the slope stability, emphasizing the importance of natural
regeneration for future forest management.
Natural regeneration from seed contributes to the increase of the stem density, provides new stools for future coppice generations and promotes
the proper development of the stand in terms of specific and structural diversity.
In this study we tested the effect of different silvicultural treatments in coppice stands on the seed regeneration potential of the chestnut tree. The
chestnut seed regeneration resulted to be influenced by: I) the age of the stand at felling time (increasing age was related to a greater presence
of regeneration from seed), II) the cover of released over-aged trees (light conditions on the soil), III) microclimatic conditions (drought stress in
particular).
Overall, the natural regeneration dynamics in chestnut coppices revealed to be a useful reference to identify some general guidelines for
sustainable interventions aiming to foster chestnut regeneration, while maintaining biodiversity in an effort to improve the quality of timber
assortments
Complementing daily fire-danger assessment using a novel metric based on burnt area ranking
No full textUnderstanding the relationship between fire and weather has important implications for fire danger evaluations, firefighting and fire management. Fire weather indices are mathematical representations of a suite of meteorological variables that are often used as decision-support tools for evaluating the likelihood of fire on a given day. However, these indices are seldom evaluated for their ability to express a probability in terms of final burnt area, which is a very important fire danger component. We propose a new approach for selecting fire weather indices that represent good proxies for both the probability of fire occurrence on a particular day and of the related final burnt area. The novel performance metric was applied to historical data (11 to 31 years) from four European regions with different fire regimes in Switzerland (Canton Ticino) and Italy (Cilento in Campania, Chilivani and Campidano in Sardinia). The results confirm the suitability of the approach for selecting an appropriate fire weather index for a particular region and for providing insight into the regional meteorological control patterns of fire ignition and spread. For three of the six fire regime types analyzed (Campidano, Cilento and winter fire season in Ticino), the prediction power for burnt area of most indices was generally in accordance with estimates of fire ignition risk. For the remaining case studies, fire ignition and burnt area appear to be controlled by different meteorological or non-climatic drivers. In these cases, the selection of the most suitable index should be based on a cutoff that optimizes the two selection criteria according to local needs. From an operational point of view, this novel approach that includes the burnt area aspect can strongly support decisions on firefighting alert and preparedness as well as requested firefighting strategies
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