In a recent paper in Functional Ecology, Leonie Valentine, Richard Hobbs and collaborators investigated how bandicoot digging changed soil properties that subsequently altered seedling growth.
Many digging mammals, including the Australian marsupial quenda (Isoodon fusciventer) forage for food by digging small pits and creating spoil heaps with the discarded soil. This small-scale bioturbation could potentially alter soil nutrients and subsequently influence growth of plants.
Soil from the base of 20 recent quenda foraging pits (pit), the associated spoil heaps (spoil) and adjacent undisturbed soil (control) was collected and analysed for nutrients and microbial activity. Soil cores were collected from the same locations and seeds of the native canopy species, tuart (Eucalyptus gomphocephala), added to the soil under glasshouse conditions. Soil from the spoil heaps had the greatest levels of conductivity and potassium. Both the spoil and undisturbed soil had greater amounts of microbial activity and organic carbon.
In contrast, the pits had fewer nutrients and microbial activity. Seedlings grown in spoil soil were taller, heavier, with thicker stems and grew at a faster rate than seedlings in the pit or control soil. Bioturbation by ecosystem engineers, like quenda, can alter soil nutrients and microbial activity, facilitating seedling growth.
It is proposed that this may be caused by enhanced litter decomposition beneath the discarded spoil heaps. As the majority of Australian digging mammals are threatened, with many suffering substantial population and range contractions, the loss of these species will have long-term impacts on ecosystem processes.
Ref: Valentine LE, Ruthrof KX Fisher R, Hardy GEStJ, Hobbs RJ & Fleming PA. (2018) Bioturbation by bandicoots facilitates seedling growth by altering soil properties. Functional Ecology. https://doi.org/10.1111/1365-2435.13179.