Data from: Mesoclosures – increasing realism in mesocosm studies of ecosystem functioning

1. Experimental studies linking community composition to functioning are
typically confined to small and closed micro- or mesocosms. Such
restricted conditions may affect both species’ biology and their
environment. Yet, targeting simple features in the behaviour of species
may circumvent these constraints. Focusing on ecological functions
provided by dung beetles, we test whether large, open-top cages –
MESOCLOSURES – will intercept the flight trajectories of beetles, thereby
allowing manipulation of local community composition. 2. MESOCLOSURES were
built in both tropical forest (Brazil) and temperate grasslands (Finland),
thus testing their general efficiency. Within the respective environments,
we varied different aspects of MESOCLOSURE design: in the tropical forest,
we examined the impact of MESOCLOSURE dimensions on exclusion efficiency,
whereas in the temperate grassland, we assessed the potential for
selectively excluding and including community members by different mesh
sizes. In the temperate environment, we also went from method to
application, using MESOCLOSURES to relate community composition to
functioning under two simulated grazing regimes. 3. MESOCLOSURES allowed
efficient manipulation of dung beetle communities, maintaining dung beetle
densities at intended levels in both temperate and tropical systems. In
the tropics, the smallest cages (1 × 1 m) offered the highest contrast in
beetle densities inside vs. outside of the fence, whereas the largest
cages (9 × 9 m) offered the lowest. Nonetheless, densities inside cages
never exceed one-fifth of those outside. At the temperate site,
manipulations of community structure through mesh size yielded significant
differences in functioning and suggested an interaction between small
dung-dwelling species and large tunnelling species. Within cages, higher
grazing was reflected in augmented dung removal. 4. We conclude that
MESOCLOSURES can be effectively used to study dung beetle functions across
habitats and latitudes. As applied insights, the present study adds
resolution to the significance of different functional groups of dung
beetles and shows that grazing pressure may have an important impact on
the ecosystem functions that they provide. Overall, this study suggests
that targeted manipulation of dispersal may offer new solutions for
linking fauna to ecosystem functions with minimal impact on the processes
measured.