Moderation is best: Effects of grazing intensity on plant-flower visitor networks in Mediterranean communities

The structure of pollination networks is an important indicator of ecosystem stability and functioning. Livestock grazing is a frequent land use practice that directly affects the abundance and diversity of flowers and pollinators and, therefore, may indirectly affect the structure of pollination networks. We studied how grazing intensity affected the structure of plant-flower visitor networks along a wide range of grazing intensities by sheep and goats, using data from 11 Mediterranean plant-flower visitor communities from Lesvos Island, Greece. We hypothesized that intermediate grazing might result in higher diversity as predicted by the Intermediate Disturbance Hypothesis, which could in turn confer more stability to the networks. Indeed, we found that networks at intermediate grazing intensities were larger, more generalized, more modular, and contained more diverse and even interactions. Despite general responses at the network level, the number of interactions and selectiveness of particular flower visitor and plant taxa in the networks responded differently to grazing intensity, presumably as a consequence of variation in the abundance of different taxa with grazing. Our results highlight the benefit of maintaining moderate levels of livestock grazing by sheep and goats to preserve the complexity and biodiversity of the rich Mediterranean communities, which have a long history of grazing by these domestic animals.The research has been co-financed by the European Union (European Social Fund—ESF) and Greek National funds through the Operational Program “Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF)—Research Funding Program: THALES: Investing in knowledge society through the European Social FundPeer Reviewe

SECONDARY METABOLITES IN THE FLORA OF VIKOS-AOOS NATIONAL PARK: A CHEMOTAXONOMIC STUDY

THE PRESENT THESIS IS DEALING WITH THE PRESENCE OF CERTAIN CATEGORIES OF SECONDARY METABOLITES IN NATIVE PLANT TAXA OF VIKOS-AOOS NATIONAL PARK. A GREAT VARIETY OF HABITATS IS FOUND WITHIN THE PARK. NINE VEGETATION ZONES WERE DISTINGUISHED, ON THE BASIS OF THE DOMINANT TAXA. FROM THE 114 TAXA SCREENED, SAPONINS WERE DETECTED IN 53 TAXA, ALKALOIDS IN 46 TAXA, AND FLAVONOIDS (FLAVANONES OR/AND DIHYDROFLAVONOLS) IN 66 TAXA. THE ESSENTIAL OIL CONTENT OF 29 TAXABELONGING TO THE FAMILIES LAMIACEAE AND ASTERACEAE WAS ESTIMATED AND THE MAIN VOLATILE CONSTITUENTS OF 13 TAXA WERE IDENTIFIED. THE RELATION BETWEEN THE PRODUCTION OF THESE SECONDARY METABOLITES AND THE TOTAL RANGE OF THE TAXA, THEIR LOCAL DISTRIBUTION IN THE DIFFERENT HABITATS OF THE NATIONAL PARK AND TH EIR DURATION AND LIFE FORM IS DISCUSSED.ΑΝΤΙΚΕΙΜΕΝΟ ΤΗΣ ΔΙΑΤΡΙΒΗΣ ΕΙΝΑΙ Η ΔΙΕΡΕΥΝΗΣΗ ΤΗΣ ΠΑΡΟΥΣΙΑΣ ΟΡΙΣΜΕΝΩΝ ΔΕΥΤΕΡΟΓΕΝΩΝ ΜΕΤΑΒΟΛΙΤΩΝ ΣΕ ΑΥΤΟΦΥΗ ΦΥΤΑ ΤΟΥ ΕΘΝΙΚΟΥ ΔΡΥΜΟΥ ΒΙΚΟΥ-ΑΩΟΥ. Ο ΔΡΥΜΟΣ ΧΑΡΑΚΤΗΡΙΖΕΤΑΙ ΑΠΟ ΤΗΝ ΥΠΑΡΞΗ ΜΕΓΑΛΗΣ ΠΟΙΚΙΛΙΑΣ ΒΙΟΤΟΠΩΝ. ΜΕ ΒΑΣΗ ΤΑ ΚΥΡΙΑΡΧΑ ΦΥΤΙΚΑ ΕΙΔΗ ΔΙΑΚΡΙΘΗΚΑΝ 9 ΖΩ ΝΕΣ ΒΛΑΣΤΗΣΗΣ. ΑΠΟ 114 TAXA, ΤΑ ΟΠΟΙΑ ΕΛΕΓΧΘΗΚΑΝ, ΑΝΙΧΝΕΥΘΗΚΕ Η ΠΑΡΟΥΣΙΑ ΣΑΠΩΝΙΝΩΝ ΣΕ 53 TAXA, ΑΛΚΑΛΟΕΙΔΩΝ ΣΕ 46 TAXA ΚΑΙ ΦΛΑΒΟΝΟΕΙΔΩΝ (ΦΛΑΒΟΝΟΝΩΝ Η/ΚΑΙ ΔΙΥΔΡΟΦΛΑΒΟΝΟΛΩΝ) ΣΕ 66 TAXA. ΕΚΤΙΜΗΘΗΚΕ Η ΠΕΡΙΕΚΤΙΚΟΤΗΤΑ ΣΕ ΑΙΘΕΡΙΟ ΕΛΑΙΟ ΣΕ 29 TAXA ΤΩΝ ΟΙΚΟΓΕΝΕΙΩΝ LAMIACEAE ΚΑΙ ASTERACEAE ΚΑΙ ΠΡΟΣΔΙΟΡΙΣΤΗΚΑΝ ΤΑ ΚΥΡΙΑ ΠΤΗΤΙΚΑ ΣΥΣΤΑΤΙΚΑ 13 TAXA. ΔΙΕΡΕΥΝΗΘΗΚΕ Η ΣΧΕΣΗ ΤΗΣ ΠΑΡΑΓΩΓΗΣ ΤΩΝ ΠΑΡΑΠΑΝΩ ΔΕΥΤΕΡΟΓΕΝΩΝ ΜΕΤΑΒΟΛΙΤΩΝ ΑΠΟ ΤΑ ΦΥΤΑ ΜΕ ΤΗΝ ΕΞΑΠΛΩΣΗΚΑΙ ΤΗΝ ΚΑΤΑΝΟΜΗ ΤΟΥΣ ΣΤΑ ΕΠΙΜΕΡΟΥΣ ΕΝΔΙΑΙΤΗΜΑΤΑ ΤΟΥ ΔΡΥΜΟΥ, ΤΗ ΣΥΝΟΛΙΚΗ Ε ΞΑΠΛΩΣΗ ΚΑΙ ΤΗΝ ΚΑΤΑΝΟΜΗ ΤΟΥΣ ΣΤΑ ΕΠΙΜΕΡΟΥΣ ΕΝΔΙΑΙΤΗΜΑΤΑ ΤΟΥ ΔΡΥΜΟΥ, ΤΗ ΣΥΝΟΛΙΚΗ ΕΞΑΠΛΩΣΗ, ΤΗ ΔΙΑΡΚΕΙΑ ΖΩΗΣ ΚΑΙ ΤΗ ΒΙΟΤΙΚΗ ΜΟΡΦΗ ΤΟΥΣ

FamiliPlantsDryad

Degree and d' for the plant species in the study network

SummaryNetLevelDryad

Network-level characteristics for the 33 study network

GuildDryad

Degree and d' for each insect species in the study network

StandardNetwDryad

Network-level characteristics for the standardized network