Search results for "Forestry"
showing 10 items of 1998 documents
Rays hamper intrusive growth of vessel elements
2021
Key message In some circumstances vessel elements, both broad and narrow, enlarge only symplastically in tangential direction. Rays play a special role in regulating intrusive enlargement of vessel elements. Abstract The aim of this study was to analyse relations occurring between vessel elements and surrounding cells, i.e. susceptibility to separation of walls of cells occurring in the vicinity of vessel elements, with regard to their type—cells of the axial/radial system. On the basis of separation/lack of separation of cell walls, and thus change in cell contacts/lack of change in cell contacts, we have estimated the contribution of particular types of growth—intrusive and symplastic—in …
Mechanical properties of natural fiber composites produced using dynamic sheet former
2018
Composites formed from wood fibers and man-made cellulosic fibers in PLA (polylactic acid) matrix, manufactured using sheet forming technique and hot pressing, are studied. The composites have very low density (due to high porosity) and rather good elastic modulus and tensile strength. As expected, these properties for the four types of wood fiber composites studied here improve with increasing weight fraction of fibers, even if porosity is also increasing. On the contrary, for man-made cellulosic fiber composites with circular fiber cross-section, the increasing fiber weight fraction (accompanied by increasing void content) has detrimental effect on stiffness and strength. The differences …
Living and Dead Aboveground Biomass in Mediterranean Forests: Evidence of Old-Growth Traits in a Quercus pubescens Willd. s.l. Stand
2017
For a long time, human impact has deeply simplified most of the forest ecosystems of the Mediterranean Basin. Here, forests have seldom had the chance to naturally develop a complex and multilayered structure, to host large and old trees and rich biological communities, approaching old-growth conditions. Also for this reason, limited information is currently available about Mediterranean old-growth forests, particularly with regard to deadwood. The main aim of this work is to help fill this critical knowledge gap. In Sicily (Italy), we identified a Quercus pubescens forest that seemed to show some typical old-growth features. Total living volume (360 m3 ha−1) and basal area (34 m2 ha−1) wer…
Holocene history of Aleppo pine (Pinus halepensis Mill.) woodlands in the Ebro Basin (NE Spain). Climate-biased or human-induced?
2020
Abstract This paper reviews the past distribution of Aleppo pine woodlands in the Ebro Basin, Northeastern Iberia, from the Mesolithic to Modern times based on wood charcoal data. The aim is to detail the chronological timing and the drivers explaining the long-term presence of Aleppo pine woodlands and associated thermophilous flora. The available charcoal data support the early spread of Pinus halepensis during the Mesolithic (ca. 9000 cal BP) accompanied by Mediterranean trees and shrubs like Quercus sp. evergreen, Juniperus sp., Arbutus unedo, Pistacia lentiscus, Rhamnus/Phillyrea, Cistaceae, and Rosmarinus officinalis, as a local response to global climate change in the Early Holocene.…
The ongoing naturalisation of Eucalyptus spp. in the Mediterranean Basin: new threats to native species and habitats
2019
The genus Eucalyptus has been widely introduced into many regions of the world outside its native range and has become invasive in some Mediterranean biomes (e.g. in southern Africa and California). In the Mediterranean Basin and Europe, eucalypts were introduced at the end of the 18th century. However, natural regeneration events in these regions are recent in time and limited in terms of affected areas, except for the Iberian Peninsula. An updated overview about the natural spread of Eucalyptus species in Italy is still lacking. This paper aims to fill this knowledge gap, using both published data and unpublished field data regarding naturalisation events, with a specific focus on Sicily.…
Agro-ecological benefits of faba bean for rainfed Mediterranean cropping systems
2017
This paper reviews the main results from a set of experiments carried out in a semiarid Mediterranean environment during the past 25 years on faba bean (<em>Vicia faba</em> L.), a crop traditionally grown in southern Italy and Sicily under rainfed conditions. These experiments focused on the residual effects of faba bean on subsequent crop(s) and assessment of the nitrogen (N) balance during the crop cycle, paying attention to both the environmental release of N (losses via volatilisation and denitrification) and estimates of N2 fixation as influenced by tillage system, intercropping, and presence/absence of mycorrhizal inoculum. Faba bean relied on N2 fixation more than other g…
Contribution to the knowledge of Mediterranean wetland vegetation: Lemnetea and Potamogetonetea classes in Western Sicily
2021
The freshwater aquatic vegetation of the Lemnetea and Potamogetonetea classes in Western Sicily was surveyed and analyzed. 85 lakes and small pools were investigated collecting 147 phytosociological unpublished relevés to integrate the very scarce available data (only 3 relevés). By applying statistical analyses on abundances data and on the bases of physiognomy and dominant species, two alliances (Lemnion minoris and Stratiotion) and four different coenoses have been identify for the Lemnetea class; while 11 associations, assigned to two orders (Potamogetonetalia pectinati and Callitricho hamulatae-Ranunculetalia aquatilis) and four alliances (Potamogetonion, Nymphaeion albae, Ranunculion …
The critical period of weed control in faba bean and chickpea in Mediterranean areas
2013
Weeds are often the major biological constraint to growing legume crops successfully, and an understanding of the critical period of weed control (CPWC) is important for developing environmentally sustainable weed management practices to prevent unacceptable yield loss. Therefore, we carried out two field experiments to identify the CPWC for two grain legume crops traditionally grown in Mediterranean areas: chickpea and faba bean. The experiments were conducted at two sites both located in the Sicilian inland (Italy). In chickpea, when weeds were left to compete with the crop for the whole cycle, the grain yield reduction was on average about 85% of the weed-free yield, whereas in faba bean…
Heat requirements for loquat fruit development may be assessed with a Beta model approach
2018
In Mediterranean areas, loquat trees (Eriobotrya japonica Lindl.) typically bloom in fall and fruits develop during the winter period, reaching their ripening in spring. So far, little interest has been driven towards models capable of estimating heat requirements for the accomplishment of fruit development in the winter period. In this work, we verified whether in Mediterranean areas the heat accumulation (GDH) needed for loquat fruit growth, may be precisely described using a Beta model, a flexible mathematical function which, in the past, has been successfully used in peach. BBCH phenological stages of ‘Algerie’ trees were recorded in two experimental sites: Palermo, Italy (38°04’N, 13°2…
A ricardian analysis of the impact of climate change on permanent crops in a mediterranean region
2019
This is the first study which explores the impact of climate change in Sicily, a small Mediterranean region of Southern Europe. According to research, Mediterranean area has shown large climate shifts in the last century and it has been identified as one of the most prominent “Hot-Spots” in future climate change projections. Since agriculture is an economic activity which strongly depends on climate setting and is particularly responsive to climate changes, it is important to understand how such changes may affect agricultural profitability in the Mediterranean region. The aim of the present study is to assess the expected impact of climate change on permanent crops cultivated in Sicilian r…