Approccio alla caratterizzazione di un lembo di bosco vetusto: il caso di Monte Egitto

An integrated approach to characterize an old growth forest patch; the Monte Egitto case study Old growth forests, i.e. forests which have achieved a remarkable age without or with a very limited disturbance, are nowadays subject of detailed studies in order to understand their characters and capacity of ecosystems services providing. In Sicily only few wooded areas are classified as old growth forest, following the heavy land use change toward agriculture during the centuries. This paper reports the results of a study carried out to characterize the vegetation of a little crater on the Mount Etna, where a residual open wood of Quercus congesta (an endemic oak of Southern Italy) survived the year 1651 lava flows surrounding the crater. About 35 years ago inside the crater some areas were planted with Calabrian Black Pine. As a consequence today there is a remarkable competition between trees of the two species. An integrated approach monitoring was adopted, taking into account both trees and understory (herbs, shrubs and tree regeneration) characters as well as bird fauna, in order to describe the current situation and monitor the effect of pine plantation thinning aimed at favouring oak regeneration and reducing pine-oak competition

Le zone ornitologiche della Sicilia: un metodo per l'individuazione oggettiva di ecoregioni.

Gli autori presentano una zonizzazione ecologica della Sicilia costruita in maniera oggettiva su base ornitologica con i dati sulla distribuzione delle specie nidificanti raccolti nei periodi 1979-1984, 1985-1992 e 1993-2006. Le maglie quadrate 10x10 km in cui erano riportati i dati originali sono state raggruppate con una cluster analysis sulla base della somiglianza della comunità ornitica nidifican- te, utilizzando le specie indicatrici per individuare il livello ottimale di raggruppamento che caratte- rizza ciascun gruppo e, insieme alle categorie di uso del suolo, fitoclimatiche e geologiche prevalen- ti al loro interno, i caratteri ecologici principali di ciascun gruppo. Sono state individuate nel complesso sette zone ornitologiche: (1) isole circumsiciliane, (2) pianure costiere mediterranee, (3) sistemi agricoli mediterranei della vite, (4) sistemi agricoli mediterranei steppici, (5) sistemi agricoli mesomediterranei (6), montagne mesomediterranee e (7) montagne temperate. La zona (1) risulta ben caratterizzata da uccelli marini (Calonectris diomedea, Puffinus yelkouan, Hydrobates pelagicus melitensis) e specie legate a scogliere ed ambienti rocciosi (Falco eleonorae, Falco peregrinus, Monti- cola solitarius). La zona (2) è caratterizzata da specie legate ai litorali (Charadrius alexandrinus) o agli ambienti umidi (es.: Himantopus himantopus, Ixobrychus minutus, Anas platyrhynchos) e compren- de, in sostanza, ambienti prevalentemente costieri, pianeggianti e non aridi, anche coltivati (Cistico- la juncidis). Carattere decisamente agricolo hanno le zone (3), (4) e (5), con la zona (3) priva di spe- cie indicatrici e che comprende i sistemi più poveri dal punto di vista ornitologico e la zona (4) invece, che include le aree con carattere più steppico (specie indicatrici: Sturnus unicolor, Falco biar- micus, Burhinus oedicnemus). La zona (6) è quella più eterogenea, caratterizzata da moltissime spe- cie indicatrici, legate alle rupi (Neophron percnopterus, Aquila chrysaetos, Pyrrhocorax pyrrhocorax), alle aree aperte (Alauda arvensis, Lullula arborea, Anthus campestris) con alberi sparsi (Lanius sena- tor), ai boschi (Turdus viscivorus, Certhia brachydactyla); molte di queste specie sono di elevato inte- resse (es.: Milvus milvus, Milvus migrans), indicando la grande importanza conservazionistica di que- sta zona ornitologica. La zona (7) è ben caratterizzata da specie legate al bosco e a climi freschi (Phylloscopus collybita, Periparus ater, Poecile palustris siculus, Sitta europaea). In generale le zone ornitologiche mostrano una corrispondenza molto limitata con zonizzazioni su base fitoclimatica e una maggiore corrispondenza invece con le classificazioni dei sistemi di paesaggio che includono anche gli aspetti dell’azione storica dell’uomo sul territorio

Close-to-Nature Silviculture to Maintain a Relict Population of White Oak on Etna Volcano (Sicily, Italy): Preliminary Results of a Peculiar Case Study

Habitat loss is a potential long-term effect of projected climate change for Mediterranean forest ecosystems. Here, we investigated the effectiveness of a close-to-nature silvicultural practice to conserve an old-growth white oak forest patch in Sicily (Italy) and promote regeneration dynamics. The study area, although small, is distinctive for its isolation, position and environmental characteristics. We conducted a Before-After Control-Impact (BACI) study to analyse the responses of different taxonomic groups (vascular plants and birds) to silvicultural treatments (selection thinning, no thinning), and to determine whether close-to-nature silviculture practices may cause significant shifts in the investigated communities. Specifically, we assessed the responses of (1) vascular plants by means of species diversity and taxonomic distinctness indices and (2) birds in terms of diversity, abundance and forest specialisation. Preliminary results suggest that cautious close-to-nature silviculture practice could-by mimicking natural gap dynamics-contribute to maintaining old-growth forest patches and promote oak seedling emergence without short-term detrimental impacts on biodiversity. Although the monitoring has to be repeated over the long-term, the multi-taxon approach and indices incorporating information on taxonomic relationships into diversity measures were demonstrated to be valuable tools for interpreting biotic community structure and dynamics

PROGETTO LIFE11 ENV IT 215 RESILFORMED - RESILIENZA AL CAMBIAMENTO CLIMATICO NELLE FORESTE MEDITERRANEE

Le condizioni climatiche delle regioni mediterranee, caratterizzate da frequenti annate siccitose, contribuiscono all’indebolimento degli ecosistemi forestali. Come risultato le foreste riducono le loro capacità produttive e sono più soggette a fenomeni di degrado secondario. Inoltre i contesti economico-sociali possono acuire il degrado con la diffusione di uno scorretto uso della risorsa (tagli boschivi, pascolamento) e con la diffusione degli incendi boschivi. L’obiettivo generale del progetto è preservare i sistemi forestali in ambiente mediterraneo dai rischi derivanti dai cambiamenti climatici, tramite processi di naturalizzazione, aumento di biodiversità e migliorata reattività, nei processi di recupero, in seguito ad eventi destabilizzanti. Obiettivo specifico è implementare una politica forestale regionale in grado di aumentare la capacità di resilienza delle foreste siciliane, migliorandone l’efficienza ecosistemica e favorendo la salvaguardia della biodiversità. Tra le azioni principali previste dal progetto, che si concluderà alla fine del 2015, si possono citare la classificazione delle categorie forestali siciliane in funzione della sensibilità alla desertificazione, l’indagine diacronica sull’uso e copertura del suolo dei principali paesaggi forestali siciliani, la definizione di prassi selvicolturali specifiche; la realizzazione di 120 ettari di interventi dimostrativi in 6 aree della Sicilia; la realizzazione di 6 piani di indirizzo forestali attraverso processi partecipativi con le popolazioni locali. Nella fase finale del progetto è prevista l’implementazione delle linee strategiche sperimentate con ResilForMed nel Piano Forestale Regionale della Sicilia

Reducing Non-Radiative Voltage Losses by Methylation of Push–Pull Molecular Donors in Organic Solar Cells

Organic solar cells are approaching power conversion efficiencies of other thin-film technologies. However, in order to become truly market competitive, the still substantial voltage losses need to be reduced. Here, the synthesis and characterization of four novel arylamine-based push-pull molecular donors was described, two of them exhibiting a methyl group at the para-position of the external phenyl ring of the arylamine block. Assessing the charge-transfer state properties and the effects of methylation on the open-circuit voltage of the device showed that devices based on methylated versions of the molecular donors exhibited reduced voltage losses due to decreased non-radiative recombination. Modelling suggested that methylation resulted in a tighter interaction between donor and acceptor molecules, turning into a larger oscillator strength to the charge-transfer states, thereby ensuing reduced non-radiative decay rates

Orientation dependent molecular electrostatics drives efficient charge generation in homojunction organic solar cells

Organic solar cells usually utilise a heterojunction between electron-donating (D) and electron-accepting (A) materials to split excitons into charges. However, the use of D-A blends intrinsically limits the photovoltage and introduces morphological instability. Here, we demonstrate that polycrystalline films of chemically identical molecules offer a promising alternative and show that photoexcitation of α-sexithiophene (α-6T) films results in efficient charge generation. This leads to α-6T based homojunction organic solar cells with an external quantum efficiency reaching up to 44% and an open-circuit voltage of 1.61 V. Morphological, photoemission, and modelling studies show that boundaries between α-6T crystalline domains with different orientations generate an electrostatic landscape with an interfacial energy offset of 0.4 eV, which promotes the formation of hybridised exciton/charge-transfer states at the interface, dissociating efficiently into free charges. Our findings open new avenues for organic solar cell design where material energetics are tuned through molecular electrostatic engineering and mesoscale structural control

Bird diversity in Turkey oak (Quercus cerris) coppices and transitory stands in the northern Apennines

In the last decades, socio-economical changes occurred in Italy have deeply affected woodland, particularly coppices. Although most of them, above all in public land, are being converted to high forests, in the last years coppices have been experiencing an increase in their use. The claimed need to reconcile silviculture and biodiversity conservation calls for a better understanding of the effects of coppice management practices on the different components of biodiversity. Using birds as environmental indicators, we studied differences in species composition and diversity of bird communities in coppices and “transitory stands” (ex-coppices recently converted in high stands) in the Alpe della Luna forest (Arezzo), in Tuscan Apennines. Relative frequency of each species and the mean abundance and richness at point level were compared among forest typologies. To test the effects of different management types on bird communities, descriptive models (GLM) have been applied using stand age and the amount of non-forest habitats as predictors. Our results show that 34.4% of the species (57.1% considering only forest species) are affected by the forest management type: 9 species (7 considering only forest species) were more common in transitory stands, while only two (of which one considered forest species) in coppices. Overall, richness is higher in transitory stands, where species of mature forests have been found; on the contrary, coppices did not host any open habitat species, as stated in other studies. Richness in forest species is positively related to stand age for both coppice and transitory stands; the amount of open habitats is positively correlated with number of open-habitat species, but it did not negatively affect richness in forest species that apparently did not suffer for any boundary effect

Molecular quadrupole moments promote ground-state charge generation in doped organic semiconductors

The role of local environmental interactions on the generation of free charge carriers in doped organic layers is investigated. Via a classical micro‐electrostatic model, a dual effect of molecular quadrupole moments of host and dopant molecules on doping is demonstrated. Namely, electrostatic interactions ease ionization of the dopant by altering the energy level alignment between the host and the dopant and reduce the barrier for charge dissociation by flattening the energy landscape around the ionized dopants. These results indicate that tailoring molecular quadrupole moments of the host and/or dopant are an attractive strategy toward improved doping efficiency in organic semiconductors