Potravní preference hrabošů a biodiverzita drobných zemních savců na vlhkých orchidejových loukách (Rodentia: Arvicolinae) [Food preferences of voles and biodiversity of small terrestrial mammals in wet orchid meadows (Rodentia: Arvicolinae)]
Markéta Haisová, Fratišek Sedláček, Ondřej Cudlín, Hana Vejsadová
Food preference of small rodents to consume the roots of wild plants was studied on three wet meadows in southern Bohemia (Czech Republic) in 2002–2007. Small mammals were sampled for three nights in the autumnal periods in these meadows; 100 snap traps per a site, two 25-trap-rows in meadow parts with orchids and two without orchids. Roots of the carrot (as a control in year 2004) and roots of Selinum carvifolia (as a control in years 2005–2007) and roots of tested wild plant were put into one rectangle bait from a wire mesh. These baits were placed among traps on each line and their gnawing was classified. Simultanoesly, the food preference of Microtus arvalis under laboratory conditions was investigated with the roots of the same species as used in the field study (during years 2006–2007 bulbs of Dactylorhiza majalis were included). More individuals and more species of small mammals were trapped in the rows with orchids than in the rows without orchids. The highest number of individuals and of species of small mammals was sampled in 2004. In the food experiments in the field, the highest preference of carrot roots (control) was observed in 2004, while the rest of tested roots of wild plants (Selinum carvifolium, Sanguisorba officinalis, Lysimachia vulgaris) were less consumed. The preference of Selinum carvifolium roots and of parsley roots, used as a control plant in 2005–2007, was observed the highest, while the rest of roots of wild plants (Sanguisorba officinalis, Alchemila sp., Lythrum salicaria, Lysimachia vulgaris) were less consumed. Food preference evidenced in the laboratory experiments indicated that Microtus arvalis prefers the bulbs of Dactylorhiza majalis before the parsley roots. From other wild plant roots, the highest preference was observed on Selinum carvifolium. Any significant bulb destruction by small rodents of 20 selected Dactylorhiza majalis individuals on three studied meadows was not observed. The stomach content analysis of Microtus arvalis from these meadows showed only 3% of volume of the underground plant organs. To be summarised, destruction of orchid bulbs as well as the more preferred roots of wild plants by rodents could occur probably only when culmination of their population cycle runs.