Authors: Szabó, Borbála; Korányi, Dávid;Gallé, Róbert;Lövei, Gábor;Bakonyi, Gábor;Batáry, Péter;

Soil invertebrates are important decomposers, but urbanization modifies soils heavily too. There are several contradicting results and theories in the literature on how urbanization affects soil invertebrates. Therefore, the main question of our research was to investigate how urbanization affects soil fauna, and how this is influenced by annual precipitation or mean annual temperature. We performed a systematic review using the Web of Science and Scopus databases (103 papers) and then performed a meta-analysis. Abundance showed an increasing trend, whereas species richness decreased significantly with urbanization, implying biotic homogenization. Abundance of Myriapoda and Isopoda increased significantly with urbanization. This is probably due to adaptation of some generalist species to urban conditions resulting in population increases. Species richness in general showed a negative trend, which was significant for Collembola, Annelida and Gastropoda. Most likely these animals are sensitive to soil compaction associated with urbanization. Mean temperature had no effect, but precipitation significantly modified the effects of urbanization on density. In drier regions, urbanization increases soil moisture because of irrigation, which can cause population increases. In humid regions, the urban environment is drier compared to surroundings leading to population decreases. Thus, as discussed above, climatic variations significantly affect the impact of urbanization.