Data from: Biodiversity change is uncoupled from species richness trends: consequences for conservation and monitoring

1. Global concern about human impact on biological diversity has triggered
an intense research agenda on drivers and consequences of biodiversity
change in parallel with international policy seeking to conserve
biodiversity and associated ecosystem functions. Quantifying the trends in
biodiversity is far from trivial, however, as recently documented by
meta-analyses which report little if any net change of local species
richness through time. 2. Here, we summarize several limitations of
species richness as a metric of biodiversity change and show that the
expectation of directional species richness trends under changing
conditions is invalid. Instead, we illustrate how a set of species
turnover indices provide more information content regarding temporal
trends in biodiversity, as they reflect how dominance and identity shift
in communities over time. 3. We apply these metrics to three monitoring
data sets representing different ecosystem types. In all data sets, nearly
complete species turnover occurred, but this was disconnected from any
species richness trends. Instead, turnover was strongly influenced by
changes in species presence (identities) and dominance (abundances). We
further show that these metrics can detect phases of strong compositional
shifts in monitoring data and thus identify a different aspect of
biodiversity change decoupled from species richness. 4. Synthesis and
application: Temporal trends in species richness are insufficient to
capture key changes in biodiversity in changing environments. In fact,
reductions in environmental quality can lead to transient increases in
species richness if immigration or extinction have different temporal
dynamics. Thus, biodiversity monitoring programs need to go beyond
analyses of trends in richness in favour of more meaningful assessments of
biodiversity change.01-Jun-2017