Context-dependency of the impacts
The effect of the global changes did not vary across different habitat types or organism body size classes for most of our analyses. The lack of significance for body size was also highlighted when we analysed only the four most abundant taxonomic groups (Acari, Collembola, nematodes, and earthworms), which represent all three body size classes. The patterns for nutrient enrichment were the most surprising, where earthworms responded differently from the other three taxa. For the other GCs, there were limited differences. However, looking at community composition or functional and trophic groups instead of taxa or body size groupings may tease apart other context-dependencies . For example, previous work has shown various responses to environmental stressors and GCs depending on the different functional types of earthworms .
In other analyses, community composition of soil microbial communities were more affected than metrics of alpha- and beta-diversity to different GCs. Incorporating such metrics of soil fauna communities may be possible, especially in the case of nematodes and earthworms, as communities are often reported at the level of functional types. In addition, the biodiversity metrics used in this meta-analysis may not have captured all the changes that occur to soil communities in invaded ecosystems, resulting in the non-significant changes. For example, established that soil communities responded more similarly within trophic groups, and accounting for trophic group (and habitat type) within the meta-analytic framework was needed to see the impact of invasive species on soil fauna abundance.