Data from: Functional extinction of a desert rodent: implications for seed fate and vegetation dynamics

Population declines of once-abundant species have often preceded
understanding of their roles within ecosystems. Consequently, important
drivers of environmental change may remain undiagnosed because we simply
do not know how species that are now rare or extinct shaped ecosystems in
the past. Australia's desert rodents are thought to have little
numerical impact on seed fate and vegetation recruitment when compared
with ants or with desert rodents on other continents. However most
research on granivory by Australian desert rodents has occurred in areas
where rodents were rare or functionally extinct. Here we ask if the
paradigm that rodents are relatively un-important granivores in Australian
deserts is an artefact of their historical decline. In the Strzelecki
Desert, the endangered rodent, Notomys fuscus is rare where introduced
mesopredators are abundant but common where dingoes (an apex predator)
suppress mesopredator populations. We used foraging trays to compare rates
of seed removal for a common shrub (Dodonaea viscosa angustissima hopbush)
between areas where N. fuscus, hopbush shrubs and their seedlings were
rare and common and found that seed removal was consistently higher where
rodents were common and hopbush rare. By excluding ants and rodents from
foraging trays we show that ants removed more seeds than rodents where
rodents were rare but rodents removed far more seeds than ants where
rodents were common. By manipulating rodents’ access to the soil seed-bank
we show that hopbush seeds persisted in greater numbers where rodents were
excluded than where they had access. Our results support the hypothesis
that granivory by rodents may once have been a far more important process
influencing the fate of seeds and shaping plant communities in arid
Australia and suggest that dingo extirpation has cascading effects on
shrub seeds. Our study highlights that functional extinction of rodents
may be an under-appreciated driver of vegetation change.