Forest type shapes regional metacommunity structure
Community composition of soil microarthropods across Troodos was largely explained by forest type, irrespective of spatial and topoclimatic variation (Table 2; Table S6; Figure 4), suggesting a primary role of habitat filtering as a driver of regional metacommunity structure. The importance of habitat type in shaping the composition of soil microarthropod assemblages has been demonstrated by previous research comparing forest vs. grassland habitats (Arribas et al., 2021b; Caruso et al., 2012) or different grass and shrub species (Coulson, Hodkinson, & Webb, 2003; see also Doblas-Miranda, Sánchez-Piñero, & González-Megías, 2009), but to our knowledge, this is the first study to compare different forest types in a systematic way. Given the mosaic nature of Troodos (Figure 1), our sampling scheme revealed high turnover among nearby sampling sites of different woodland habitats (Figure 3), highlighting a major role of underlying forest-specific edaphic features for the community assembly of soil microarthropods (Eissfeller, Langenbruch, Jacob, Maraun, & Scheu, 2013). Leaf litter and vegetation type are documented to influence the soil environment through changes in microhabitat availability and physico-chemical edaphic properties (Berg & McClaugherty, 2008), and such local abiotic features might be driving a scenario of species sorting (Leibold et al., 2004) or even the existence of largely separate metacommunities inhabiting each forest type. In contrast to the general pattern, the communities of the two highland habitats of Black Pine (Pn ) and Stinking Juniper (Jn ) are more similar to each other (Figure 3; although still significantly different based on pairwise comparisons), suggesting that harsh climatic conditions at those high altitudes might be imposing a stronger environmental filter than forest-associated soil attributes. Alternatively, the spatial configuration of this highland woodland (composed of isolated small stands of Stinking Junipers embedded in a much larger Black Pine matrix) might facilitate dispersal among habitat patches and partly counteract the effects of habitat filtering (Leibold et al., 2004; Logue, Mouquet, Peter, & Hillebrand, 2011). These two hypotheses are not mutually exclusive and may jointly contribute to the higher similarity in community composition between these highland assemblages.