| Titre : | The Impact of Winter Cutting on Arthropods and Passerines in Reedbeds / encadrement B Poulin, G Lefebvre |
| Titre original: | Der Eingfluss der Mahd auf Arthropoden und Singvögel in Schilfbeständen |
| Auteurs : | Martin Schmidt, Auteur |
| Type de document : | Thèse |
| Editeur : | Göttingen (Germany) : Göttingen Universität, 2000 |
| Format : | 24 |
| Langues: | Anglais |
| Index. décimale : | P3 (Conservation - Etudes Regionales.(Aménagement. Développement. Pollution. Protection)) |
| Résumé : |
Arthropods and passerines were sampled in four replicates of cut and uncut reedbeds in Camargue (Southern France) in order to study the impact of winter cutting on the fauna. The focus is on beetles (Coleoptera) and spiders (Araneida), and on their interactions with passerines. The composition of the birds'diet was analysed by forced regurgitations. The The impact of passerines on their prey populations was tested with u bird exclosure experiment.
1. Cut reedbeds had more green stems, less dry stems and a thinner Inter layer than the uncut sites. Eight limes more individuals of Auchenorrhyncha and Aphidina were found in cut reedbeds. They profit from the higher food availability, less masking of their host plants by dry reed stems and possibly from a lower predation pressure. The saprophagoux orders - mainly Isopoda - had 1 R times lower densities in cut reed. They were obviously missing the litter and the dry stems which normally provide them with food and shelter 2. Culling had a significant impact on the species composition of vegetation- and ground dwelling spiders and beetles In each of these four cases, species with higher and lower densities in cut reed were found There was no general trend of diversity among these four groups. 3. Five spider and beetle species from the vegetation had lower densities in cut reed. They were probably missing the dry stems and panicules which provide hides and overwintering opportunity. The diversity of beetles on the vegetation in cut reedbeds was lower than in uncut reedbeds. 4. Nine cpigaeic spider and beetle species were more numerous in cut reedbeds. Because these species were mainly hygrophilous. they may have bcncfitted from the summer irrigation of the cut sites. 5. Ciubiona juvenis. Ciubiona phragmitis and Marpusa canettrinii represent the major part of the bird food. Since these species were rarer in cut than in uncut reedbeds, the food availability index for birds was also lower there. 6. The number of species or individuals of birds was not related to cutting. They were both positively correlated with stem length. 7. In the bird exclosure experiment, no change in arthropod abundances was detected in the predator-free cages. One possible reason is that the prey species were too mobile to build up higher population densities within the cages. Hence (his experiment cannot be conclusive as whether birds have a depredation impact on their prey populations. The results of this study show that large scale reed cutting in the Camargue has some negative consequences for the fauna. These consequences could probably be reduced if a mosaic of cut and uncut areas was implemented. |
Exemplaires (1)
| Code-barres | Cote | Support | Localisation | Section | Disponibilité |
|---|---|---|---|---|---|
| 11522 | P3/46 | Thèse | Bibliothèque | Conservation - études régionales | Disponible |
