Driving forces of soil fauna community construction
Recent global syntheses of soil communities have identified contrasting
environmental controls on the distribution and abundance of soil animal
groups (Alice et al., 2020). Our research shows that soil texture and
temperature, especially the lowest temperature in the region, were
important factors in shaping the distribution pattern of soil animals in
East Asia. Similar conclusions were drawn from other studies. For
example, global earthworm communities were observed to be strongly
impacted by climatic variables (Phillips et al. 2019), and nematode
abundances were observed to be increased with an increase in SOC content
(Van Den Hoogen et al., 2019). However, these soil animal communities
were also found to be influenced by other additional factors. For
instance, soil acidity was found to influence global earthworm
communities across natural and managed ecosystems, with higher species
richness at intermediate soil pH levels (Johnston & Sibly, 2018).
Nematode abundances were found to be decreased with increasing soil pH
on a global scale (Van Den Hoogen et al., 2019). And interestingly
termites were influenced by climatic factors on a regional scale, with
termite diversity being highest in moist lowland tropical rainforest
ecosystems (Jones & Eggleton, 2010).
Relationships of soil animal groups on a global scale broadly follow
those identified for soil fungi and bacteria (Johnston & Sibly, 2020).
On the global scale, climatic factors were found as the main factors
affecting the diversity of soil fungi in global natural ecosystems
(Tedersoo et al., 2014), and soil organic carbon level was found as the
main factor affecting fungal diversity (Liu et al., 2015) on regional
scales (Northeast China). The changes of temperature and SOC were
further expected to cause microbial community composition shifts between
fungal and bacterial dominance, leading to various trophic transfer
efficiency to their soil animal consumers (Carrillo et al., 2016). The
research results showed that SOC, temperature, especially the extreme
minimum temperature are environmental factors that affected the overall
distribution of soil animals in East Asia. Our study generalized these
results to entire soil animal communities, and showed a dominance of
small soil animals (e.g., Nematoda, Acari, Collembola) in high-latitude
with low temperature and higher SOC contents, and greater abundances of
larger soil animals (e.g., Chilopoda, Coleoptera) at mid- to low
latitudes in more neutral temperature with lower SOC
contents.
Nevertheless, our research was inconsistent with the global research
results of species distribution dominated by pH (Johnston & Sibly,
2020). The reason for this inconsistency may be because numerous taxa
showed hemispheric asymmetries in latitudinal diversity gradients: trees
(Burns, 2007), mammals (Gaston et
al., 1995), termites (Eggleton et al., 1994), birds (Blackburn &
Gaston, 1996), spiders (Platnick & Norman, 1991), ants (Dunn et al.,
2009) and triatomids (Rodriguero & Gorla, 2004). Simultaneously,
predacity soil animals are more susceptible to environmental impacts
than phytophage animals (Roslin et al., 2017), which may lead to
different distribution pattern of different functional soil animals in
East Asia. This may be attributed to the relatively
broad ecological niches of species
with higher trophic levels, leading to multiple environmental
requirements and adaptations (Chen et al., 2014; Turney & Buddle,
2016).