Population asynchrony alone does not explain stability in species rich soil animal assemblages: the stabilising role of forest age on oribatid mite communities

1. The importance of microbial and plant communities in the control of the
diversity and structure of soil animal communities has been clarified over
the last decade. Previous research focused on abiotic factors, niche
separation and spatial patterns. Significant gaps still exist in our
knowledge of the factors that control the stability of these communities
over time. 2. We analysed a nine-year data set form the national Long-term
Ecological Research Network of Latvia. We focused on 117 oribatid species
from three Scots pine forests of different age (<40 yrs, 65 yrs,
and >150 yrs) and structure. For each forest type, 100 samples were
collected each year, providing very high replication and long of time
series for a soil community. We assessed different aspects of stability:
we used a dynamic null model, parametrised on observed growth rates, to
test the hypothesis that asynchrony in species populations stabilises
total community size; we also analysed alpha and beta diversity over time
to test the hypothesis that temporal variation in species composition and
relative abundances is controlled by forest attributes. 3. Real
communities can be more stable than their stochastic counterparts if
species are asynchronous, confirming for the first time the role of
asynchrony in stabilising soil communities. Yet, while some real
communities were more stable and had higher abundance and growth rates
than others, they were not necessarily more asynchronous than the less
stable communities. Species composition and relative abundances were also
less variable in the more stable communities. 4. Species asynchrony
generally stabilises species rich communities but is not sufficient to
explain different levels of stability between forests. Forest age is a key
factor explaining different levels of overyielding and so stability. Data
suggests that both asynchrony and high diversity of microhabitat structure
of Scots pine forests promote stability of soil animal communities.