How can novel riparian ecosystems benefit catchment management?

By Dr Samantha Capon and Dr Gary Palmer

Weed control is often a major focus of riparian ecosystem management, especially in urban catchments. Our recent review, however, finds that novel riparian ecosystems can support many important ecological functions, particularly in highly modified catchments.

A novel riparian ecosystem in an urban setting in south-east Queensland, illustrating a combination of diverse exotic vegetation and human infrastructure (Photo: S. Capon)

We propose that catchment planning and management need to move beyond weed control to consider potential values of novel riparian ecosystems so these can be retained or enhanced for the benefit of both biodiversity and people.

Novel ecosystems comprise combinations of species, including exotic species, which have not historically occurred in a location and often exhibit new ecological interactions and functions. Riparian zones are particularly susceptible to exotic plant invasion because of their high levels of natural disturbance and connectivity.

Additionally, exotic plants often become ecosystem engineers in riparian habitats, further reshaping the structure and function of riparian ecosystems as well as the streams which they fringe.

In comparison to native riparian ecosystems, novel riparian ecosystems tend to be associated with a range of risks to streams and catchments including hydrological change, greater fire risk and biodiversity loss. Consequently, weed control has become a major focus of much riparian management.

In many cases, however, effective control or removal of riparian weeds is both expensive and challenging, if not impossible, and may produce unintended consequences (e.g. habitat loss).

Indeed, there is growing evidence to suggest that novel riparian ecosystems often support many important ecological functions including bank stabilisation, shading and provision of habitat. The role of novel riparian ecosystems is likely to be particularly important in highly modified catchments and under a changing climate.

In our new review, we synthesise evidence of the potential benefits of novel riparian ecosystems to biodiversity and ecological function. Our findings suggest that the management of riparian ecosystems must cut a balance between the benefits of weed control and the benefits of retaining or enhancing novel ecosystems .

This work appeared in Solutions

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