Beheer landhabitat van boomkikkers: goed - beter - best

De landhabitat van een boomkikker is minder precies te duiden dan de waterhabitat. Ze is meestal groter en vaak samengesteld uit complexe vegetatiestructuren. Voor het functioneren van een gebied als leefgebied voor de boomkikker zijn de vegetatie en het landschap sterk bepalend. Daarom is het de moeite waard om de kenmerken van de landhabitat in detail te onderzoeken. In Zeeuws-Vlaanderen is 30 jaar geleden een ecologisch onderzoek aan boomkikkers uitgevoerd, waaruit interessante informatie over de landhabitat naar voren kwam. De verworven kennis kan worden gebruikt om bij het beheer, ook elders in Nederland, naar een optimale ontwikkeling van de landhabitat te streven. The presence of European Tree Frogs (Hyla arborea) is strongly determined by the quality of its terrestrial habitat, certain properties playing a key role. A detailed study of the species was made in Zealand Flanders in the 1980s, comprising more than 4500 observations of basking frogs in various locations in and around villages and at the edges of agricultural areas. Locations varied from gardens to small patches of uncultivated land between fields in the agricultural area in which the villages were situated. Apart from recording the gender, developmental stage and length of each individual, the plant species on which it was basking was noted together with the frog’s height above the ground. Not only the plant species but the structure of the vegetation was recorded and how long an individual stayed at a certain place. A long stay was interpreted as an expression of high habitat quality. Habitat quality was in turn related to the scale on which measures were taken and their intensity. The level of activity of man and livestock at that time proved to be of vital importance for the quality of the terrestrial habitat. Using manpower, measures were carried out on a small scale and at low frequency. The result was a vegetation with a fine-grained mosaic pattern. Moreover, groundwater levels were high enough to offer adequate humidity for a functional microclimate. The use of pesticides was negligible. Such conditions are hard to realize nowadays. The findings of this survey could serve as a reference for present-day nature management. If managers keep them in mind, their effort in trying to achieve high quality terrestrial habitat for the tree frog can be rewarded.