In the last decades, afforestation with no native species has been a common practice in Europe. In the particular case of Spain, the effects of plantations, using exotic tree species as larch or non-native pine in native oak and beech forests on the communities of oribatid mites, springtails, and nematodes have been studied, however little is known of their influence on Mesostigmata mites. In the current study we examined the mesostigmatid mite communities in two Japenese larch plantations (Larix kaempferi (Lamb.) Carr. and oak forest (Quercus pyrenaica Wild) to compare the mite assemblages and to determine if tree species replacements would affect soil Mesostigmata populations. A total of 2752 mites belonging to 56 species of 17 families were collected. There were differences in the diversity and species composition of the assemblages. A total of 13 species are new cites for the Iberian Peninsula: Gamasellodes bicolor, Geholaspis longispinosus, Geholaspis mandibularis, Pseudoparasitus dentatus, Pachyseius angustiventris, Holoparasitus obsoloni, Paragamasus disparinas, Paragamasus longisetosus, Amblyseius filixis, Veigaia bouvieri, Discourella baloghi, Trachytes eustructura, and Urodiaspis tecta.