Ábrahám Levente: Biomonitoring a Dráva folyó magyarországi szakasza mentén 2000-2004 - Natura Somogyiensis 7. (Kaposvár, 2005)

Tóth, Sándor: Monitoring dragonflies on the section of the Drava between Őrtilos and Vízvár (Insecta: Odonata) - Szitakötők monitorozása a Dráva mente Őrtilos és Vízvár közötti szakaszán (Insecta: Odonata)

36 NATURA SOMOGYIENSIS more effective than locating larvae. From the point of view of monitoring, however, only the survey of all three stages of the life cycle can result in a roughly realistic picture of the fauna of the sampling sites. A well-appraisable result in the monitoring by the Dráva can be expected from the examination of the whole dragonfly assemblage of the sampling sites. The protected and - within that group - the very rare taxons mainly listed in the Bern Convention are given priority treatment in the course of the monitoring. Already the first few years' experiences in monitoring referred to the fact that especially the shallower wetlands of the area are extremely vulnerable, primarily due to the partial or occasionally full drying out owing to the draughty weather. In 2001 two new sampling points had to be marked out partly as a result of this problem. Material and method In the monitoring of dragonflies, personal collecting and observation - aided by useful information through bringing up larvae - is fundamental. Both population- and community-level monitoring play a role in sampling. Both methods are based on the principles laid down in volume V. of NBmR (Hungarian Biodiversity monitoring System) (FEKETE et al. 1997, FORRÓ 1997). The population-level sampling of dragonflies by the Dráva also happens on the basis of the principles of NBmR concerning dragonflies (AMBRUS et al. 1997). This work is aimed at the research of the following five local species listed in the Bern Convention: Besides population-level monitoring, successful work requires - also based on the principles laid down in NBmR (DÉVAI 1997a) - the community-level monitoring of dragonflies as well. The two methods organically complement each other. In communitylevel monitoring it is worth following the proposal concerning the quantitative survey of dragonfly imagoes (DÉVAI 1997b). In monitoring, besides the species listed in the Bern Convention, it is practical to treat the other protected taxons separately as well. Owing to its interesting flatland occurrence - out of the non-protected taxons - it is worth dealing with Pyrrhosoma nymphula interposita VARGA, 1968, frequent in our hilly and mountainous areas but rare in plains. The work took place on the three sampling sites (environs of Zákány-Őrtilos, Lankóciforest, region of Bélavár-Vízvár) proposed for monitoring by Directorate of the DunaDráva National Park. The sampling frequency occurs in harmony with the phenological features of the whole dragonfly assemblage, taking the differing swarming characteristics of the individual populations into account (DÉVAI 1976a). Maximum 3-4 sampling sites per day Date of the samples (monthly) Total samples Maximum 3-4 sampling sites per day IV. V. VI. VII. VIII. IX. X. Total samples Maximum 3-4 sampling sites per day 10-15. 5-10. 18-23. 5-10. 17-25. 1-10. 17-22. 4-9. 22-27. 15-21. 10-15. Total samples Number of samples 9 9 9 9 9 9 9 9 9 9 9 99