Vlnovníci (Eriophyoidea) jsou téměř mikroskopičtí roztoči oválného až červovitého tvaru těla o délce pouhých 0,1 až 0,3 mm. Předpokládám, že je málokdo viděl, ale každý zájemce o přírodu si asi všiml znetvořenin – hálek (zoocecidií) na různých cévnatých rostlinách, v nichž bývají většinou skrytí. Hálky některých druhů dosahují značných rozměrů – tisícovky jedinců mohou vytvořit útvary délky 20–30 cm (např. druhu Stenacis triradiatus na vrbách nebo Aceria echii na hadinci). Nápadné jsou často i váčkovité
hálky milimetrových rozměrů, ukrývající jediného vlnovníka, protože se jich vyskytuje obvykle větší množství pohromadě a mívají i výrazné zbarvení (velmi běžný je třeba vlnovník lipový – Eriophyes tiliae na listech lípy). Až na několik druhů, které mohou škodit na kulturách pěstovaných rostlin, zůstávají znalosti o výskytu a druhovém spektru těchto roztočů na našem území neúplné.

Použitá a doporučená literatura: BAXTER, R.; HANSSON, L. Bark consumption by small rodents in the northern and southern hemispheres. Mammal Review, 2001, 31.1: 47-59. BERGERON, Jean-Marie. The use of seedling bark by voles sustained by high proteinic content of food. In: Annales Zoologici Fennici. Finnish Zoological and Botanical Publishing Board, 1996. p. 259-266. FLOWERDEW, J. R.; GURNELL, John; GIPPS, J. H. W. (ed.). The ecology of woodland rodents: bank voles and wood mice: the proceedings of a symposium held at the Zoological Society of London on 23rd and 24th of November 1984. GILBERT, Sonja, et al. Increasing vole numbers cause more lethal damage to saplings in tree monocultures than in mixed stands. Basic and applied ecology, 2013, 14.1: 12-19. HANSSON, Lennart. Vole densities and consumption of bark in relation to soil type and bark mineral content. Scandinavian Journal of Forest Research, 1992, 7.1-4: 229-235. HANSSON, L.; ZEJDA, J. Plant Damage by Bank Voles (Clethrionomys glareolus [Schreber]) and Related Species in Europe1. EPPO Bulletin, 1977, 7.2: 223-242. HEROLDOVÁ, Marta, et al. Rodent damage to natural and replanted mountain forest regeneration. The Scientific World Journal, 2012, 2012. HEROLDOVÁ, Marta, et al. Bark chemical analysis explains selective bark damage by rodents. Beskydy, 2009, 2.2: 137-140. HEROLDOVÁ, M., et al. Small forest rodents–an important factor in the regeneration of forest stands. Beskydy, 2007, 20: 217-220. HOMOLKA, M., et al. Plant biomass and prediction of debarking caused by rodents in artificial regeneration of forest stands. Julius-Kühn-Archiv, 2011, 432: 99-100. KORSLUND, Lars; STEEN, Harald. Small rodent winter survival: snow conditions limit access to food resources. Journal of Animal Ecology, 2006, 75.1: 156-166. SUCHOMEL, Josef, et al. Vole damage to planted tree regeneration conditioned by some environmental factors. AUSTRIAN JOURNAL OF FOREST SCIENCE, 2012, 129.1: 56-65. SUCHOMEL, Josef, et al. Factors influencing vole bark damage intensity in managed mountain-forest plantations of Central Europe. European Journal of Forest Research, 2016, 135.2: 331-342. VIRJAMO, Virpi, et al. Differences in vole preference, secondary chemistry and nutrient levels between naturally regenerated and planted Norway spruce seedlings. Journal of chemical ecology, 2013, 39.10: 1322-1334. VOOKOVA, B. CALORIC VALUES OF SOME WOODY PLANT-SPECIES OF FOREST ECOSYSTEMS OF THE MALE-KARPATY MOUNTAINS. EKOLOGIA CSFR, 1985, 4.1: 33-42.

We studied the impact of vole bark gnawing in forest plantations dominated by European Beech (Fagus sylvatica) in the Hrubý Jeseník Mts. and the Moravskoslezské Beskydy Mts. (Czech Republic) with diffe­rent habitat conditions. Considering the four present vole species, only the Field Vole (Microtus agrestis) caused significant damage, the impact of the Bank Vole (Clethriono­mys glareolus) being inconclusive. In both areas, occurrence of grasses was identified as the key factor determining the presence and abundance of voles (Microtus sp.). Saplings in the Hrubý Jeseník Mts. suffered significantly higher damage than those in the Moravskoslezské Beskydy Mts. (13,6 vs. 3,3 % damaged seedlings), with the degree of damage closely related to the abundance and spatial distribution of voles. We relate this finding to lower carrying capacity caused by the poor herb layer and the higher proportion of spruce monocultures surrounding the plantations in the Hrubý Jeseník Mts. Our results indicate that the artificial beech regeneration is more successful in mixed and spruce forests with rich undergrowth (Moravskoslezské Beskydy Mts.) than in large stands of the Norway Spruce (Pice abies) with reduced herb undergrowth (Hrubý Jeseník Mts.).