Il ruolo delle precipitazioni occulte nella formazione e mantenimento della vegetazione forestale: il caso studio di Pantelleria

Le testimonianze storiche indicano per le isole circumsiciliane la presenza di floridi boschi che sono stati distrutti a seguito dei processi di deforestazione. In alcuni casi, dopo gli interventi di rimboschimento, la vegetazione riesce a ricostituirsi con difficoltà come a Lampedusa mentre in altri casi i processi di recupero sono molto rapidi. Un ruolo non indifferente viene svolto dalla presenza di piante in grado di diffondere propaguli ma anche dalle condizioni climatiche locali determinate sia dalla morfologia delle singole isole come, ad esempio, la presenza di rilievi montuosi, che dal particolare contesto oceanografico. I dati medi riportati dalle stazioni climatiche in termini di piovosità non giustificano in molti casi la presenza di una vegetazione forestale confermando il contributo, al ciclo idrologico, di componenti note come “precipitazioni occulte” (da condensa atmosferica o da nebbia) ed identificate correntemente come “Non-Rainfall-Water” (NRW). A dispetto dell’importanza data a questo fattore sono pochissime le informazioni quantitative, anche in ragione dello scarso grado di standardizzazione dei sistemi di misura dei processi di deposizione dell’acqua atmosferica. Nell’ambito delle indagini condotte su finanziamento del “Centre National de la Recherche Scientifique” francese (CNRS) - “Site d’Étude en Ecologie Globale, Pantelleria” e del programma CNRS-Mob-Île abbiamo avviato una indagine a Pantelleria collocando 8 microstazioni metereologiche lungo un transect ambientale dalla costa alla sommità del più importante rilievo dell’Isola (Montagna Grande, 830 m s.l.m.). La collocazione del sistema di rilevamento (umidità, temperatura, sensori di condensa e micro-lisimetri) ha reso necessaria una fase di messa a punto della strumentazione, che ha implicato anche l’individuazione e la caratterizzazione di sistemi e sensori per il rilievo ed il monitoraggio dei fenomeni di condensa atmosferica secondo approcci diversificati. Anche se ancora in modo non quantitativo, i risultati iniziali (in termini di frequenza e di durata dei fenomeni di deposizione registrati) suggeriscono come la componente NRW possa svolgere a Pantelleria un ruolo determinante nel ciclo idrologico generale, ma ulteriori osservazioni saranno necessarie per caratterizzare i fenomeni di deposizione sulle più importanti componenti del paesaggio dell’isola (vegetazione, muretti a secco, suolo

On the typology and the worship status of sacred trees with a special reference to the Middle East

This article contains the reasons for the establishment of sacred trees in Israel based on a field study. It includes 97 interviews with Muslim and Druze informants. While Muslims (Arabs and Bedouins) consider sacred trees especially as an abode of righteous figures' (Wellis') souls or as having a connection to their graves, the Druze relate sacred trees especially to the events or deeds in the lives of prophets and religious leaders. A literary review shows the existence of 24 known reasons for the establishment of sacred trees worldwide, 11 of which are known in Israel one of these is reported here for the first time. We found different trends in monotheistic and polytheistic religions concerning their current worship of sacred trees

The multiple dimensions of rural forests : lessons from a comparative analysis

Rural forests are characterized by different levels of formal and nonformal appropriation by rural communities who have generally managed, shaped, or rebuilt these forest formations over many generations with refined local knowledge and practices related to their use and perpetuation. Rural forests are therefore social-ecological systems that contribute to ecosystem and landscapes configuration, definition of rural territories, and sustainability of local livelihoods. Although some studies have attempted to explain their specificities, in specific geographical and social contexts, their characteristics are not well defined as they encompass highly diversified situations. This lack of comprehension of the identity of rural forests is at the heart of the lack of dialogue between forestry policies and rural forest development. Our major aim is to identify universal characteristics of rural forests as well as specificities that can differentiate them. Eleven situations of rural forests were analyzed by means of detailed, harmonized monographs, from developing and developed countries, and localized within contrasting ecological environments (humid tropics, dry forests, temperate forests) and socio-economic and public policies contexts. Qualitative data were obtained through a common analytical framework and were encoded with an approach based on the collective appreciation of the group of researchers who developed case studies. These were pooled within a common analysis chart and were processed by means of multivariate analyses. Results were further discussed taking into consideration four major characteristics that emerged from this analysis, and which form the identity of rural forests. These are: 1) specific forest structures and levels of integration in agricultural matrices which are linked historically to overall agroecosystem approaches and practices, 2) a multiscale approach to domestication practices from landscape to individual trees inscribed in continuities between "nature" and "culture", natural processes and human techniques of control and transformation, 3) multiple uses of plant species which vary in relation to the commercial or noncommercial status of their products and a reversible nature of these use patterns accordingly, 4) the imbricate nature of rules of access and control between state and customary levels, and between individual and collective levels, requiring specific formal and informal arrangements. Typologies of rural forests can be drawn along each of these major characteristics and provide a reliable system to analyze and understand the functioning of rural forests. Forestry approaches in rural contexts, hence, need to consider variations along these major lines that form the identity cards of rural forests

Homing abilities of dolphinfish (Coryphaena hippurus) displaced from fish aggregating devices (FADs) determined using ultrasonic telemetry

We conducted displacement experiments using acoustic tags to study the orientation abilities of dolphinfish (Coryphaena hippurus) around FADs. Eleven fish were passively monitored using coded transmitters and acoustic receivers attached to FADs, while seven others were actively tracked with a vessel using continuous acoustic tags equipped with pressure sensors. All these 18 dolphinfish were captured close to a FAD and released between 70 and 1720 m from it. Five fish out of the 14 that were displaced at more than 360 m from a FAD ( estimated detection range of our acoustic receivers, defining the target area during our experiment) returned to the target area. With one individual successfully returning to the target area after having been released at 1600 m from the FAD, the rate of return of fish released up to this distance was significantly higher than expected if they were moving at random, but many fish released at intermediate distances moved in other directions. Based on detailed statistical analysis of the return score, we estimated that dolphinfish are able to orientate towards a FAD area from at least 820 m. The connection between our definition of the target area and the association area of dolphinfish around a FAD is discussed, as well as the impact of stress and motivation in the rates of return observed. More experiments should be conducted to improve this first estimate. Specific experiments should also be designed to more accurately determine the association range of fish around FADs and their motivation to orientate towards FADs

Characterizing fish communities associated with drifting fish aggregating devices (FADs) in the Western Indian Ocean using underwater visual surveys [+ Erratum paru dans Aquat. Living Resour. 2017, 30, 26]

We adapted a visual census method, mainly used in demersal and reef fish studies, to characterize fish communities associated to drifting fish aggregating devices (FADs) in the Western Indian Ocean. Drifting FAD associated fishes from both equatorial (Seychelles) and tropical waters (Reunion Island) were examined by divers. A total of 32 species (belonging to 16 families) were observed associated with drifting FADs in equatorial waters, and 24 species (14 families) were found around FADs in tropical waters. Twenty species were found in both regions. The highest number of species observed at a single FAD was 18 (12 +/- 2, mean +/- SD) in equatorial and 13 (10 +/- 3) in tropical waters, not counting circumnatant species loosely associated with the FAD. Some species like Kyphosus vaigiensis, Canthidermis maculata, Elagatis bipinnulata, Acanthocybium solandri and Coryphaena hippurus were observed on all or most of the surveys. In this study, the contribution in biomass of the 18 common species associated with drifting FADs (but excluding circumnatant species), represents more than 98% of the biomass. The overall biomass values of closely associated species remains well below tuna biomass estimates for circumnatant tuna schools at FADs, estimated as high as 200 tons. The species that most significantly contribute to the by-catch in tuna purse-seines logically match those that showing the highest biomass values in our surveys (Carcharhinus spp., Elagatis bipinnulata, Coryphaena hippurus, Canthidermis maculata, and Acanthocybium solandri). One of the most abundant and ubiquitous species in our study was the spotted oceanic triggerfish Canthidermis maculata that sometimes formed massive schools of many thousands individuals around the drifting FADs. Future research is needed to explore the role of such non tuna species in the attraction and aggregation processes of tuna around drifting FADs

Satellite-linked acoustic receivers to observe behavior of fish in remote areas

Automated acoustic receivers are now widely used by biologists to study the behavior of fish. However, currently available acoustic receivers require physical recovery of the units to download stored data. Such operation is often difficult in remote study areas like in the open ocean. We present a new satellite-linked acoustic receiver (Vemco VR3-Argos) that allows downloading data through a satellite uplink (Argos). The VR3-Argos can last up to one year, sending GPS positions and tag data at regular time intervals. We illustrate the advantages of this new technology with tagging data from 121 fish of seven species (yellowfin tuna, bigeye tuna, skipjack tuna, wahoo, dolphinfish, silky shark and oceanic triggerfish) caught and released around drifting fish aggregating devices (FADs) in the Western Indian Ocean, far from any land. In opposition with the classic acoustic receivers (Vemco VR2), the use of VR3-Argos allowed to collect data for several weeks after leaving the drifting FADs. Maximum residence times of 3 days for bigeye tuna, 7 days for skipjack, 8 days for wahoo, 10 days for silky shark and 15 days for yellowfin tuna, dolphinfish and oceanic triggerfish could be recorded. VR2 and VR3-Argos are equivalent in terms of quality of residence times data, however depth data obtained through satellites are aggregated in 8 classes for compression purposes, which leads to a loss of precision available with raw data. Future directions of this technology are discussed