Search

The uneven presence of the cork oak (Quercus suber L.) within its distribution range is not only determined by its climatic requirements but also by specific edaphic needs. Although most of the natural populations thrive in acidic soils deriving from metamorphic or volcanic rock outcrops, some cork oak populations are found growing in soils deriving from calcareous bedrock, which are considered less suitable. We carried out a multidisciplinary investigation at the south eastern edge of the Q. suber distribution range (Mountains of Palermo, NW Sicily), including soil, floristic, and vegetation surveys, aimed at: (i) assessing the native or introduced origin of some peculiar cork oak populations; (ii) describing the associated plant communities and soils; (iii) identifying the ecological factors which could explain the local adaptation to soils deriving from calcareous bedrock; (iv) discussing the ecological role played by this species in the study area and within its distribution range. The collected information suggest that the detected cork oak stands are native to these areas. We hypothesized that the co-occurrence of high fire frequency, high soil calcium content and erosion, which caused the intermixing of different parent materials, might favor its competitive interactions with other Mediterranean tree species, thus accounting for the local presence of Q. suber. The study of cork oak populations thriving in peculiar substrates at the driest end of the range could be of great importance for the future conservation of this species, which is expected to face growing threats in the coming decades.

The present study provides a critical review of the available historical data on the distribution of Abies nebrodensis, a fir tree endemic to Sicily. The only (somewhat ambiguous) references to its occurrence on Mount Etna date back to the 1st century bc and refer back to the 3rd century bc. Although the botanical and forestry literature and the very few surviving herbarium specimens do not prove that A. nebrodensis grew outside the Madonie mountain range, several indications suggest its past occurrence on other Sicilian mountain ranges such as the Erei, Nebrodi, and probably also Sicani mountains. The results of the most recent pollen investigations (still ongoing) point to the disappearance of Abies from most of Sicily by the 1st century bc, and at least since the Middle Ages A. nebrodensis had become extremely rare even on the Madonie mountains. Publications focused on the wooden artefacts from archaeological excavations and the restoration of architectural heritage have provided some information on the past use of fir wood in Sicily, but the species identity of the firs being used remain unresolved. The present review of the past occurrence and distribution of A. nebrodensis suggests that it may have previously occupied a wider ecological niche.

Pruning is an important horticultural practice for the management of olive orchards (Olea europaea L.) that generates a considerable amount of residues every year. Olive orchards are increasingly expanding beyond the Mediterranean Basin to new growing Countries (Australia, California, Argentina, Chile and Uruguay) and this will certainly lead to larger availability of pruning material. Currently, the interest in use of olive tree pruning residues for energy purposes is increasing but unfortunately, the information on the differences among organs of the tree, in terms of calorific value and ash content, is scarce. Another unknown aspect is the effect of cultivar vigour on dry matter partition among different tree organs, these are important traits to establish the energetic quality of pruning residues. The aim of this research was to study energetic aspects of six olive cultivars, largely grown in the Sicilian olive industry and characterized by different vigour. The trees taken into consideration in the study were selected in an experimental orchard to avoid any effect due to differences in environmental conditions and management. The energetic characteristics, calorific value and ash content, were evaluated for the various tree organs particularly shoots, leaves and branches; also root system was evaluated, although the roots can only be used once the trees are uprooted. Significant differences were observed in the calorific values among the different tree organs and the cultivars. Regarding the ash, shoots and leaves showed the highest content with respect to the other organs, thus causing a possible tendency in slagging with fouling and corrosion of boiler components.

Studying the genetic diversity and structure of the current forest populations is essential for evaluating the ability to survive to future biotic and abiotic changes and planning conservation strategies. Quercus trojana is an eastern Mediterranean tree species with a fragmented distribution range, and its westernmost outposts are located in southern Italy. The demand for timber and cropland over the centuries has severely reduced it s occurrence in this part of the range. We assessed the genetic diversity and structure of the extant Italian populations of Q. trojana and derived conservation guidelines. A total of 322 samples were genotyped with six polymorphic nuclear microsatellite markers. Our results reveale d a high genetic diversity in all populations, structured into two main gene pools, and a highly divergent single population. Based on the allelic richness and heterozygosity estimation, we identified populations which can be considered as valuable source material for conservation programs, and those requiring adequate measure to reestablish gene flow and reduce fragmentation. Finally, a comparison with a set of eastern Mediterranean samples indicated a relationship between the Italian and the Greek gene pool; different hypotheses on the Italian gene pool origin were discussed. The need to protect these marginal, disjunct populations was further reinforced. ` survivre aux changements biotiques et abiotiques futurs et planifier les stratégies de conservation. Quercus trojana Webb est une espèce arborescente de l’est de la région méditerranéenne caractérisée par une aire de distribution naturelle fragmentée. Ses avant-postes les plus a` l’ouest sont situés dans le sud de l’Italie. Au cours des siècles, la demande pour le bois et les terres destinées a` l’agriculture a sévèrement réduit son occurrence dans cette partie de son aire de distribution. Nous avons évalué la diversité génétique et la structure des populations actuelles de Q. trojana en Italie, afin d’en déduire des lignes directrices pour la conservation. Un total de 322 échantillons ont été génotypés pour six marqueurs nucléaires polymorphes de type microsatellite. Les résultats indiquent qu’il y a une grande diversité génétique dans toutes les populations, structurée en deux pools génétiques principaux, ainsi qu’une population unique très divergente. Sur la base des estimations de richesse allélique et d’hétérozygotie, les populations pouvant être considérées comme une source utile de propagules pour les programmes de conservation ont été identifiées, ainsi que les populations nécessitant des mesures adéquates pour restaurer le flux génique et réduire la fragmentation. Enfin, la comparaison avec un jeu d’échantillons provenant de l’est de la région méditerranéenne montre qu’il existe un lien entre le pool génétique de l’Italie et celui de la Grèce. Différentes hypothèses concernant l’origine du pool génétique italien sont abordées dans la discussion. La protection de ces populations marginales disjointes a encore besoin d’être renforcée.

Scarce information is available on the biological reasons why a small subset of introduced species can effectively establish within novel ecosystems. A comparison of early growth traits can help to explain the better performance of alien invasive species versus native co-occurring species. In one year-long experiment, we compared the early life stages of Ampelodesmos mauritanicus (Poir.) Dur. & Schinz (Amp), a native perennial Mediterranean grass, and Pennisetum setaceum (Forssk.) Chiov (Penn), an emerging invader grass in sub-arid and Mediterranean-climate areas. The Penn seedlings grew significantly faster and were approximately 2.5 times taller than the Amp seedlings, reaching a final average height of 90 cm. The shoot and root dry masses of the Penn seedlings were, respectively, more than 14 times and 4 times higher than those of the Amp seedlings. As a consequence, the shoot:root ratio was significantly higher in Penn, which resulted in a greater allocation of resources to the photosynthetic organs. Penn showed a more rapid life cycle compared with Amp. Penn produced seeds 9 months after sowing while no spikelet was produced by Amp until the end of the experiment. As a consequence, Penn may gain a reproductive advantage due to rapid seed dissemination. Ultimately, a suite of peculiar early growth traits makes Penn an aggressive competitor against Amp, which is an important floristic element of native Mediterranean grasslands. Penn seems better suited than Amp in colonizing frequently disturbed sites with fluctuating resource availability or irregular rainfall distribution and Penn is gradually replacing Amp.

Mediterranean plantations are the most suitable areas to assess vegetation dynamics and competitive interactions between native and exotic woody species. Our research was carried out in a coastal pine plantation (Sicily) where renaturalization by native species (Pistacia lentiscus L. and Olea europaea var. sylvestris) and invasion by Acacia saligna (Labill.) H.L.Wendl. simultaneously occur. The regeneration pattern of woody species in the pine understory was evaluated in six experimental plots along a stand density gradient, from 200 to approximately 700 pines per hectare. Both pine stand density and regeneration by native species had a significant negative relationship with Acacia natural regeneration. Olea regeneration was positively correlated with stand density, while Pistacia showed a non-significant relationship. Saplings of both native species were mostly less than 1 m high, whereas approximately 70% of Acacia individuals were higher than 1 m. We found that 400 pines per hectare should be considered a minimum stand density to keep Acacia under control, while favouring the establishment of native species in the understory. The successful control of Acacia requires an integrated management strategy, including different forest interventions according to stand density: thinning, control measures against Acacia, and renaturalization actions.

In order to invade new ecosystems, invasive alien plants need to cope with different microbial communities. Whilst the ability to avoid antagonists is well recognized, the opportunity to establish mutualistic associations is less known, even in widespread invasive species such as Ailanthus altissima (Mill.) Swingle. We sought to evaluate whether the beneficial effects of arbuscular mycorrhizal fungi (AMF) on Ailanthus seedlings are maintained over time, under prolonged pot limitation. We compared three-month-, three-year- and four-year-old mycorrhizal seedlings grown in natural forest soil (NT) with seedlings grown in sterilized (ST) and non-mycorrhizal (NM) soils, in pots of 3.4 L (22 &times, 15 cm). Growth parameters and leaf traits were assessed, including carbon (&delta, 13C) and nitrogen (&delta, 15N) stable isotope compositions. NT seedlings showed relatively higher vigor in the early stage but, subsequently, the benefits provided by AMF were lost. Interestingly, mycorrhizal seedlings consistently showed about 2&permil, &delta, 13C enrichment, relatively to the other treatments. Negative linear relationships between leaf &delta, 13C and N content were found. Higher photosynthesis rates and WUE are the likely causes of the early enhanced growth in mycorrhizal seedlings. The symbiotic relationship between AMF and Ailanthus could be driven by resource availability. Greater insights into such aspects could provide an improved perspective on the ecological limits of Ailanthus.

In this paper the populations of Pachydema Castelnau, 1832 (Coleoptera Melolonthidae) living in Lampedusa Island (Sicily Channel, Central Mediterranean Sea, Italy), so far attributed to P. hirticollis (Fabricius, 1787) of North Africa, are examined. The comparison of the main morphological characters between these two populations allowed to attribute those of Lampedusa to a new species that is described in the present work. Faunistic and biological observations on these species are provided.

Arbuscular mycorrhizal fungi (AMF) may promote plant invasion by enhancing plant performance and competitiveness. However, only a small number of studies have considered the interactions between local soil microbial communities and invasive plants, and even fewer have focused on alien trees. Ailanthus altissima is a serious problem in the Mediterranean Basin, where it has invaded many habitats. We investigated the symbiosis between A. altissima and indigenous AMF in two invaded, ecologically different Mediterranean woodlands. Mycorrhizal infection was high at both sites (> 60% of the root fragments were mycorrhizal), indicating that A. altissima roots may be infected by AMF under different ecological conditions. In a greenhouse experiment, A. altissima seedling growth was evaluated in untreated soil (natural soil containing the entire soil microbial community), in sterilized soil, and in sterilized soil containing the entire microbial community except AMF. Seedling growth was greater in the natural soil than in the other two soils. Seedlings in natural soil but not in the other two soils were extensively colonized by AMF, indicating that AMF may have been responsible for the greater growth in the natural soil. Growth was poorer in the sterile soil that had been inoculated with a soil suspension lacking AMF than in the sterile soil, suggesting that the natural soil also contained pathogens and that the AMF countered the effects of these pathogens. Overall, the results indicate that AMF are an important component of Mediterranean woodlands invaded by A. altissima and AMF may facilitate A. altissima's invasion in these woodlands.

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) were, respectively, about 6 and 3 times higher than the averages recorded in the regional forest inventory for this forest type. Deadwood was particularly abundant, exceeding the threshold of 30 m3 ha−1, mainly represented by lying dead elements. Dead to live wood ratio reached 9%, a value close to the threshold of 10% considered for Mediterranean old-growth forests. As the investigated forest showed some typical old-growth traits, it deserves to be fully protected and could be a permanent monitoring area for studying deadwood and stand dynamics in mature Mediterranean stands.

Key message: This work demonstrates that the Olive tree, which is managed and pruned as a fruit tree, can be treated as a forest tree using allometric equations, to estimate both biomass production and volumes. Abstract: The Olive tree (Olea europaea L.) is an evergreen tree that can grow and accumulate a relatively high amount of dry matter, even in dry environmental conditions common in the Mediterranean basin and typical of traditional rain-fed agriculture. The objective of this research was to develop a tool to predict woody biomass and tree component volume for the olive tree, to be used for different agricultural and environmental purposes. The study was carried out in six olive groves across three locations in Italy, collecting data on the “Leccino” cultivar, which is spread worldwide. Models for volume and biomass were developed for the whole tree and its different components. Basal diameter and a diameter of 80 cm of the trunk height were explored as independent variables for modeling. The results of this study demonstrate a high correlation between the two selected variables and total biomass, above and below-ground biomass and tree component volumes. The same variables show high correlation with total leaf area, but no correlation with the root/shoot ratio, and Leaf Area Index.

Sambucus nigra L. (Caprifoliaceae) is wide spread in temperate and sub-tropical zones. The consumption of its berries has been associated with health benefits especially for its high content of natural antioxidants such as polyphenols, in particular anthocyanins. In this work we investigated the polyphenolic composition and the in vitro antioxidant activities (ABTS, DPPH, BCB and FRAP-ferrozine (FRAP-FZ) assays) of S. nigra berries, collected in four different Sicilian areas (Italy). Elderberries are considered one of the fruits with highest anthocyanins content, the amount of phenolic compounds, other than anthocyanins, is approximately 1.5 times greater than the latter. The LC–MS analyses have revealed an opposite trend in the polyphenols pattern in Sicilian populations. Moreover, a statistical correlation was found between cyanidin-3- sambubioside-5-glucoside and antioxidant activity evaluated by FRAP-FZ and ABTS assays. In conclusion, Sicilian S. nigra berries are appealing for its antioxidant potential and for its particularly high content of anthocyanins.

The aim of this work was to investigate the effect of an experimental fire used for grassland management on soil organic carbon (SOC) stocks. The study was carried out on Hyparrhenia hirta (L.) Stapf (Hh) grassland and Ampelodesmos mauritanicus (Desf.) T. Durand & Schinz (Am) grasslands located in the north of Sicily. Soil samples were collected at 0–5 cm before and after the experimental fire, and SOC was measured. During the grassland fire, soil surface temperature was monitored. Biomass of both grasses was analysed in order to determine dry weight and its chemical composition. The results showed that SOC varied significantly with vegetation type, while it is not affected in the short term by grassland fire. Am grassland stored more SOC compared with Hh grassland thanks to lower content in the biomass of the labile carbon pool. No significant difference was observed in SOC before and after fire, which could be caused by several factors: first, in both grassland types the measured soil temperature during fire was low due to thin litter layers; second, in a semiarid environment, a higher mineralization rate results in a lower soil carbon labile pool; and third, the SOC stored in the finest soil fractions, physically protected, is not affected by fire.

Knowledge about vegetation and fire history of the mountains of Northern Sicily is scanty. We analysed five sites to fill this gap and used terrestrial plant macrofossils to establish robust radiocarbon chronologies. Palynological records from Gorgo Tondo, Gorgo Lungo, Marcato Cixé, Urgo Pietra Giordano and Gorgo Pollicino show that under natural or near natural conditions, deciduous forests (Quercus pubescens, Q. cerris, Fraxinus ornus, Ulmus), that included a substantial portion of evergreen broadleaved species (Q. suber, Q. ilex, Hedera helix), prevailed in the upper meso- mediterranean belt. Mesophilous deciduous and evergreen broadleaved trees (Fagus sylvatica, Ilex aquifolium) dominated in the natural or quasi-natural forests of the oro- mediterranean belt. Forests were repeatedly opened for agricultural purposes. Fire activity was closely associated with farming, providing evidence that burning was a primary land use tool since Neolithic times. Land use and fire activity intensified during the Early Neolithic at 5000 bc, at the onset of the Bronze Age at 2500 bc and at the onset of the Iron Age at 800 bc. Our data and previous studies suggest that the large majority of open land communities in Sicily, from the coastal lowlands to the mountain areas below the thorny-cushion Astragalus belt (ca. 1,800 m a.s.l.), would rapidly develop into forests if land use ceased. Mesophilous Fagus-Ilex forests developed under warm mid Holocene conditions and were resilient to the combined impacts of humans and climate. The past ecology suggests a resilience of these summer-drought adapted communities to climate warming of about 2 °C. Hence, they may be particularly suited to provide heat and drought-adapted Fagus sylvatica ecotypes for maintaining drought-sensitive Central European beech forests under global warming conditions.

One of the most outstanding issues of current environmental research is the need of reliable assessments of carbon stock (i.e. above-ground (a.g.) and below-ground biomass, deadwood, litter, and organic soil matter) within forest ecosystems. Although shrub vegetation plays an important role in accumulating carbon in many Mediterranean environments, there is still very little knowledge on the carbon they store. In this article, we analyze the a.g. carbon stock of several Mediterranean shrubby communities in Sicily (Italy), dominated by Pistacia lentiscus, Chamaerops humilis, Euphorbia dendroides and Spartium junceum. Plant samples for each species were selected, and morphometric attributes (height, crown diameter, diameter at breast height, etc.) were measured to establish models for estimating a.g. biomass. Dendrometric data were also used to support the assessment of shrub biomass at community level by coupling them with the coverage of the considered woody species estimated from several hundreds of phytosociological releve´s carried out on pre-forest Sicilian communities. Although the results of such an approach have to be considered as rough assessments, the trial proves interesting, given the lack of information on stand biomass of pre-forest vegetation within the Mediterraean region. L'articolo è disponibile sul sito dell'editore http://www.tandfonline.com

The role of insects in pollination and consequently in fruit set and quality was assessed in two commercial orchards of the cactus pear, Opuntia ficus-indica (L.) Mill., in Agrigento Province, Sicily. In 1997, insects visiting flowers were sampled during May–June (the first bloom) and July (the second bloom, induced by the “scozzolatura” practise). More than 50 insect species belonging to 10 orders were collected in May–June, while only five species of Hymenoptera Apoidea were collected in July. The quality of fruits arising from the second bloom showed that Hymenoptera alone were able to guarantee effective pollination. To verify the role of insects in pollination in 1996 (during only the second bloom), and in 1997 and 2009 (during both blooms), 60 single flowers were marked during each bloom; 30 of them covered with paper sleeves (which prevented natural pollination), while the others were not covered. After withering, fruits produced by marked flowers were analyzed in laboratory: in all years and blooms, the total number of seeds, the number of developed seeds, and the weight and the percentage of pulp were significantly lower for covered flowers than for non-covered flowers. The results are consistent with the hypothesis that native insects effectively carry out the pollination of cactus pear flowers.

The vegetation and fire history of few coastal sites has been investigated in the Mediterranean region so far. We present the first paleoecological reconstruction from coastal Sicily, the largest island in the Mediterranean Sea. We analysed pollen and charcoal in the sediments of Biviere di Gela, a lake (lagoon) on the south coast of Sicily. Our data suggest that the area became afforested after a marine transgression at ca. 7200 cal b.p. (5250 b.c.). Build-up of forest and shrublands took ca. 200–300 years, mainly with the deciduous trees Quercus, Ostrya and Fraxinus. Juniperus expanded ca. 6900 cal b.p. (4950 b.c.), but declined again 6600 cal b.p. (4650 b.c.). Afterwards, evergreen trees (Q. ilex-type and Olea) became dominant in the forest and Pistacia shrublands were established. Forest and shrubland reached a maximum ca. 7000–5000 cal b.p. (5050–3050 b.c.); subsequently forest declined in response to human impact, which was probably exacerbated by a general trend towards a more arid climate. During the Neolithic, fire was used to open the landscape, significantly reducing several arboreal taxa (Q. ilex, Fraxinus, Juniperus) and promoting herbs and shrubs (Achillea, Cichorioideae, Brassicaceae, Ephedra). Final forest disruption occurred around 2600 cal b.p. (650 b.c.) with the onset of the historically documented Greek colonization. We conclude that the open maquis and garrigue vegetation of today is primarily the consequence of intensive land-use over millennia. Under natural or near-natural conditions arboreal taxa such as Q. ilex, Olea and Pistacia would be far more important than they are today, even under the hot and rather dry coastal conditions of southern Sicily.

Ecological and evolutionary studies largely assume that island populations display low levels of neutral genetic variation. However, this notion has only been formally tested in a few cases involving plant taxa, and the confounding effect of selection on genetic diversity (GD) estimates based on putatively neutral markers has typically been overlooked. Here, we generated nuclear microsatellite and plastid DNA sequence data in Periploca laevigata, a plant taxon with an island–mainland distribution area, to (i) investigate whether selection affects GD estimates of populations across contrasting habitats; and (ii) test the long-standing idea that island populations have lower GD than their mainland counterparts. Plastid data showed that colonization of the Canary Islands promoted strong lineage divergence within P. laevigata, which was accompanied by selective sweeps at several nuclear microsatellite loci. Inclusion of loci affected by strong divergent selection produced a significant downward bias in the GD estimates of the mainland lineage, but such underestimates were substantial (>14%) only when more than one loci under selection were included in the computations. When loci affected by selection were removed, we did not find evidence that insular Periploca populations have less GD than their mainland counterparts. The analysis of data obtained from a comprehensive literature survey reinforced this result, as overall comparisons of GD estimates between island and mainland populations were not significant across plant taxa (N = 66), with the only exception of island endemics with narrow distributions. This study suggests that identification and removal of markers potentially affected by selection should be routinely implemented in estimates of GD, particularly if different lineages are compared. Furthermore, it provides compelling evidence that the expectation of low GD cannot be generalized to island plant popula- tions.

Tree of heaven (Ailanthus altissima) is regarded as invasive within urban and natural areas worldwide. Efficient methods to control it are significantly needed if we are to limit its well-known environmental and economic impacts. Up to now the use of herbicides has proven necessary since following mechanical damage, Ailanthus vigorously resprouts. However, the seasonal response of Ailanthus stems, treated with herbicides, has never been assessed. We compared the control efficacy recorded in autumn, winter and summer in an abandoned suburban citrus grove in Sicily, under Mediterranean-climate conditions. Glyphosate was injected within drill holes made in knee-high cut trees. Tree mortality and the resprouting ability of treated stems were significantly affected by the application timing and by diameter class of stems. Mortality was significantly lower in winter treatments within the smaller diameter class. Within the larger diameter class, only autumn treatments showed a notably higher mortality rate and a significantly lower growth of sprouts. Hence, autumn interventions are strongly recommended to effectively treat Ailanthus. Mortality was notably higher in the smaller diameter class. Our results confirm the importance of early intervention to control Ailanthus, also showing that the choice of the season is crucial to obtaining satisfactory control of its resprouting ability.

The essential oils (EOs) of green seeds from Daucus carota subsp. maximus growing wild in Pantelleria Island (Sicily, Italy) were characterized. EOs were extracted by steam distillation, examined for their inhibitory properties against food-borne Gram-positive and Gram-negative bacteria and analyzed for the chemical composition by gas chromatography (GC) and mass spectrometry (MS). Undiluted EOs showed a large inhibition spectrum against Gram-positive strains and also vs. Acinetobacter spp. and Stenotrophomonas maltophilia. The minimum inhibition concentration (MIC) was in the range 1.25 – 2.50 μl/ml for the most sensitive strains. The chemical analysis indicated that D. carota subsp. maximus EOs included 34 compounds (five monoterpene hydrocarbons, six oxygenated monoterpenes, 14 sesquiterpene hydrocarbons, four oxygenated sesquiterpenes, camphorene and four other compounds), accounting for 95.48% of the total oil, and that the major chemicals were carotol, β-bisabolene, and isoelemicin.

Abandonment of agricultural land and the subsequent recolonization by natural vegetation is known to cause increases in C contents, contributing to reduction in atmospheric CO2 concentrations. Assessment of the possible mitigation of CO2 excess requires understanding the SOC dynamics, the origin of C pools and the pathways of their transformation. The aims of this work were to assess, by using the δ13C signature, the changes of old and new organic C in total (soil organic carbon, SOC) and labile (microbial biomass C, MBC, dissolved organic C, DOC, CO2 efflux from soil) pools after vegetation change from vineyard (C3) to grassland (C4) under semiarid Mediterranean climate. Colonization of abandoned vineyard by the perennial C4-grass Hyparrhenia hirta after 15 or 35 years increased topsoil C stocks by 13% and 16%, respectively. Such an increase was attributed to new above- and below-ground biomass C input from H. hirta. The maximal incorporation of new C was observed in MBC, whereas the DOC derived mainly from old SOC. Based on d13C values of SOC, MBC, DOC and CO2 in C3 soil and in soils after 15 and 35 years of C4 grass colonization, 13C fractionation per se from changes in isotopic composition by preferential utilization of substrateswith different availability was separated. MBC in C3-C4 soil used more recent (13C-enriched) versus old C (relatively 13C-depleted) sources. The δ13C by decomposition of SOC to CO2 (δ13C of CO2 minus d13C of SOC) was higher than δ13C by microbial respiration (CO2 minus MBC), demonstrating that under semiarid climate, soil microorganisms do not always preferentially decompose themost available SOC pools. The use of δ13C signature of SOC after C3-C4 vegetation change combinedwith soil incubation is a powerful tool to assess the exchange between old and new C in pools of various availability. © 2014 Elsevier B.V.

Acacia cyclops is a widespread invader in Mediterranean-climate regions. However, although its naturalization in the Mediterranean Basin dates back only a few years ago, and the invasion process has not been studied hitherto. We investigated seedlings recruitment strategy adopted by A. cyclops in a small island (Lampedusa, Italy) where its natural regeneration was strictly confined under mother plants canopy. Healthy plants (DCP), plants at incipient senescence (SCP) and dead plants (DP) were distinguished according to vitality and canopy status. Living plants were also characterized in relation to leaf C and N isotope composition. Regeneration pattern (seedlings and saplings abundance) was related to the microclimatic differences (soil temperature, air temperature and humidity, soil nutrients, light) observed between canopies and adjacent open areas, and among canopy types. Living canopies ensure milder conditions, reducing extreme values as well as fluctuations between night and day. However, beneath canopies (DP, SCP and DCP) seedlings may benefit from significantly higher soil nutrients content than in the outside, while light availability was much higher under DP. Saplings to seedlings ratio was found to be around 12 under DP, while under SCP it was slightly higher than 1, and just less than 0.5 under DCP. Moreover, saplings growth was significantly higher under SCP and DP, suggesting a prominent role of light in driving seedlings recruitment. Stable isotope analyses of C and N provided ecophysiological information in relation to changes in canopies structure. Thus, while seedling stage appears to be more nutrient-limited, subsequent sapling stage is much more light-limited. Although the species is not yet displaying an invasive spreading on the island, our study provides clear evidence that senescent canopies are better facilitators than healthy in preserving the invasive potential of A. cyclops. This finding suggests some best practices in order to gradually reduce the presence of the alien species within its pristine nuclei of introduction.

Ailanthus altissima is a well-known invasive tree in many parts of the world showing an outstanding ability to establish within woodlands and other less-disturbed habitats. Previous studies have reported that control of this species is very difficult because of its strong resprouting. Indeed, effective control can be achieved only by mechanical treatment followed by the application of a systemic herbicide. Operating drills or saws and other mechanical equipment require electric power supply which is not readily available in many invaded sites, notably shrubslands and woodlands. In two study sites, we evaluated control obtained by glyphosate through a stem-injection technique and compared two sources of power for the electric drill used. More than 90% of the glyphosate-treated trees in this study appeared to be dead just 1 month after treatments, and a car battery plus inverter was the most practical electrical source for drilling stems in the field.

A new sedimentary sequence from Lago di Venere on Pantelleria Island, located in the Strait of Sicily between Tunisia and Sicily was recovered. The lake is located in the coastal infra-Mediterranean vegetation belt at 2 m a.s.l. Pollen, charcoal and sedimentological analyses are used to explore linkages among vegetation, fire and climate at a decadal scale over the past 1200 years. A dry period from ad 800 to 1000 that corresponds to the 'Medieval Warm Period' (WMP) is inferred from sedimentological analysis. The high content of carbonate recorded in this period suggests a dry phase, when the ratio of evaporation/precipitation was high. During this period the island was dominated by thermophilous and drought-tolerant taxa, such as Quercus ilex, Olea, Pistacia and Juniperus. A marked shift in the sediment properties is recorded at ad 1000, when carbonate content became very low suggesting wetter conditions until ad 1850-1900. Broadly, this period coincides with the 'Little Ice Age' (LIA), which was characterized by wetter and colder conditions in Europe. During this time rather mesic conifers (i.e. Pinus pinaster), shrubs and herbs (e.g. Erica arborea and Selaginella denticulata) expanded, whereas more drought-adapted species (e.g. Q. ilex) declined. Charcoal data suggest enhanced fire activity during the LIA probably as a consequence of anthropogenic burning and/or more flammable fuel (e.g. resinous Pinus biomass). The last century was characterized by a shift to high carbonate content, indicating a change towards drier conditions, and re-expansion of Q. ilex and Olea. The post-LIA warming is in agreement with historical documents and meteorological time series. Vegetation dynamics were co-determined by agricultural activities on the island. Anthropogenic indicators (e.g. Cerealia-type, Sporormiella) reveal the importance of crops and grazing on the island. Our pollen data suggest that extensive logging caused the local extinction of deciduous Quercus pubescens around ad1750. © The Author(s) 2013.

Secondary grasslands are one of the most common vegetation types worldwide. In Europe, and in the Mediterranean basin, human activities have transformed many woodlands into secondary grasslands. Despite their recognized role in the global carbon cycle, very few data are available for estimating the biomass of Mediterranean grasslands. We developed linear regression models in order to predict the biomass of two native Mediterranean grasses (Ampelodesmos mauritanicus and Hyparrhenia hirta) and an invasive alien grass (Pennisetum setaceum). Ampelodesmos mauritanicus is very common throughout the Mediterranean basin, mostly on north-facing slopes, H. hirta characterizes thermo-xeric grasslands, while P. setaceum is an alien species that is rapidly spreading along coastal areas. The measured morphometric attributes of individual plants as potential predictors were considered. The validation results corroborate the ability of the established models to predict above ground and total biomass of A. mauritanicus and P. setaceum. We also evaluated the total biomass per hectare for each species. The highest biomass per hectare was found for A. mauritanicus, whereas biomass was higher for H. hirta than for P. setaceum. The replacement of H. hirta by P. setaceum may reduce the total carbon storage in the ecosystem; however, P. setaceum allocates more resources to the roots, thus increasing the more stable and durable pool of carbon in grasslands.Los pastizales secundarios son uno de los tipos de vegetación más comunes en todo el mundo. En Europa y en la cuenca mediterránea, las actividades humanas han transformado muchos bosques en pastizales secundarios. A pesar de su reconocido papel en el ciclo global del carbono, hay muy pocos datos disponibles para la estimación de la biomasa de los pastizales mediterráneos. Hemos desarrollado modelos de regresión lineal con el fin de predecir la biomasa de dos gramíneas nativas del Mediterráneo (Ampelodesmos mauritanicus e Hyparrhenia hirta) y otra exótica e invasora (Pennisetum setaceum). Ampelodesmos mauritanicus es muy común en toda la cuenca mediterránea, sobre todo en pendientes orientadas al norte, Hyparrhenia hirta es característica de pastizales termo-xerófilos, mientras que Pennisetum setaceum es una especie exótica que se está extendiendo rápidamente a lo largo de las zonas costeras. Se consideraron los caracteres morfométricos de plantas individuales como factores de predicción potenciales. Los resultados han corroborado la capacidad de los modelos establecidos para predecir la biomasa aérea total de A. mauritanicus y P. setaceum. También se ha medido y evaluado la biomasa total por hectárea de cada especie: la mayor fue la que correspondía a A. mauritanicus, mientras que la H. hirta fue mayor que la de P. setaceum. Así pues, la substitución de H. hirta por P. setaceum puede reducir el carbono almacenado en el ecosistema, sin embargo, P. setaceum asigna más recursos a las raíces, lo que implica un almacenaje de carbono más estable y duradero.

Pictorial work of Antonello da Messina during the Sicilian period (1455-60) is considered less fruitful and less mature than during his stay in Venice (ca 1474-1476). While some art critics consider the painting “Saint Jerome in the study” a work of the first period, others believe that it was produced during the Venice period. The Authors analysed the plumage characters of the Rock Partridge, Alectoris graeca, depicted with symbolic significance in the painting, to try the identification of the population which the subject used as model could belong to. However, they conclude that the identification as a Sicilian as well as an Alpine Rock Partridge is doubtful and in this case the plumage of the bird depicted does not help to resolve the controversy of painting dating.

As occurred on many other little Mediterranean islands, agricultural activity at Lampedusa (Strait of Sicily) underwent a very strong decline in terms of surface area during the second half of the last century. In particular, cereal crops have ceased and horticulture is disappearing, while vineyards still occupy a reduced area but are quickly vanishing and currently survive thanks to a small number of old farmers. Here are presented the results of a research carried out by interviewing seven farmers in order to study not only the techniques and the germplasm used in local viticulture, but also the final use of grapes and an evaluation on the connection between traditional farming and agro-ecosystems plant species-richness. Vines were grown for wine, to produce fresh and sun-dried grapes, or to preserve them in alcohol. Several names of the local varieties suggest that they might have been introduced in Lampedusa from the neighbouring territories: being fishermen and farmers at the same time, local people had trade relationships with other Mediterranean areas such as Tunisia, Malta and Southern Italy. Furthermore, local farming plays a key role in plant conservation. In fact, the disappearance of agricultural systems is leading to the extinction of 43 plant species, some of them considered rare not only on the local level, but also on the regional and national one. Because of the small size of farmland and its fragmentation, local agriculture cannot be supported by the European Community. Therefore, in order to safeguard local viticulture, special systems of assistance and new managing policies - focused on rural development plans and showing which concrete actions are necessary and feasible to protect the agroecosystems - are needed.

The tree heath (Erica arborea L.), a small evergreen tree found in the Mediterranean region and parts of Eastern and Central Africa, produces lignotubers that are highly valued for making smoking pipes. The Peloritani Mountains of northeastern Sicily are historically one of the most important areas in Italy for the production of these high quality lignotubers, known as briar root wood. In the past, tree heath shrublands were also an important source of charcoal. Erica arborea utilisation has declined dramatically during the past century, mostly due to the decreasing demand for smoking pipes, as well as the increasing frequency of wildfires and large-scale afforestation activities in this region. Until recent decades, Erica arborea management (grub felling), which represented an important economic activity for some local communities, also contributed to wildfire prevention by maintaining low heath tree cover which helped to inhibit fire spread. The majority of Erica arborea maquis is currently found on State-owned lands where traditional harvesting practices (i.e., uprooting trees) is discouraged, leading to higher density stands more susceptible to fire. At present, the tree heath industry is in sharp decline, with irregular management of the resource and poor commercial value of heath root wood due in part to frequent fires. Recently social trends and the establishment of new protected areas in tree heath shrublands discourage the utilization of Erica arborea and the conservation of the material culture and landscape associated with its management. It is proposed that tree heath cultivation be continued only in those areas best suited in order to preserve its cultural and environmental roles, and that forest management practices be improved to increase the economic viability of tree heath grub felling activities.