Discussion
The
relationship between microbial biodiversity and functioning under land
use change
Our results provided direct experimental evidence that the association
between soil microbial diversity and ecosystem functioning was primarily
regulated by the keystone species under a subtropical land use change of
China. As excepted, many studies have documented changes in the
diversity of microbes and ecosystem functioning across land use types
(de Vries & Shade 2013; Allan et al. 2015; Zhou et al.2020). A few studies have explored the biodiversity-functioning
relationship varying in the
natural assembled communities,
which results may deviate from our familiar those in the experimental
communities (van der Plas 2019). In natural ecosystems, biodiversity
loss is random, and may be obscured by the abiotic factors (Turnbullet al. 2016; Veen et al. 2018). In this present study, our
results emphasized that microbial richness was the principal factor in
explaining the microbial respiration (mSR), and higher sensitivity of
the mSR induced by changes in the microbial richness was observed in the
afforested soils (Fig. 3; Fig. 4a). There were two possible explanations
for these patterns. First, in phase with the positive linear
diversity-ecosystem functioning relationship reported in experiments
(Delgado-Baquerizo et al. 2016a; Rivett & Bell 2018), which
indicated microbes contributed equally to the broad functioning (mSR).
Second, it could be related to the microbial unique characteristics
which might process much more rapid life cycle (e.g. hour to days) than
in macro-organisms (e.g. plants, month to years) (Schimel & Schaeffer
2012; Delgado-Baquerizo et al.2016a). This in fact estimated a
stable relationship when considering for relationship of microbial
biodiversity-functioning across land use change. More especially, we
found the negative relationship between the keystone species and mSR,
suggesting the identify effect did not have a perceptible effect on the
broad functioning, which occupied much resource than others to some
extent (Trivedi et al. 2017b; Chen et al. 2020).
In contrast, our results showed that the biodiversity-functioning
relationship of specialized functioning varied with land use types (Fig.
3d, e), possibly due to the heterogeneity across land use types. This
also revealed the existence of some degree of functional redundancy in
the amoA communities in afforested soils. It has been suggested
that cultivation applications may act as an environmental filter
selecting for those Nitrososphaera (affiliate to AOA), which are
sensitive to soil organic N supply (Zhou et al. 2015; Gaoet al. 2018).