Ants, plants and river corridors

Ants, plants and river corridors: How do we protect the biodiversity of urban riparian zones?

Ku-ring-gai Council on Sydney’s north shore has partnered with Macquarie University to explore the biodiversity value of their creeks and streamside (riparian) environments and understand how environmental policies can be designed to protect these valuable ecosystems.

PhD student Christopher Ives has been investigating the relationship between riparian corridor width and biodiversity. Riparian corridors are important landscape features that help protect the health of creeks, provide critical habitat for a range of plants and animals and act as interconnected green networks that allow the movement of species throughout urban areas. Despite their environmental benefits, riparian corridors are under increasing threat from development and there is currently little scientific knowledge about how wide they need to be to protect the health of the bushland! This is where Christopher’s research steps in. To get a snapshot of riparian biodiversity, he assessed differences in communities of plants and ants across a range of widths.

Ants and other invertebrates are often overlooked in assessments of biodiversity because of their small size and the (relative) difficulties associated with identifying them. However, ants are particularly important to bushland health and biodiversity because there are many species of them and they act as ‘ecosystem engineers’ through interacting with other organisms, consuming huge amounts of food and even modifying the soil. Ants were sampled and identified along with plant species found alongside Ku-ring-gai’s urban streams. This data was used to compare the biodiversity from narrow strips of streamside bushland with larger reserves in good condition.

The results from this study recently published in Urban Ecosystems indicate that riparian corridors wider than ~50 m are needed to reduce the impacts of adjacent urbanised land on ant and plant biodiversity. Very narrow sites (those with less than 20 m of vegetation either side of the stream) were dominated by weeds and ‘opportunistic’ ant species that indicate high levels of disturbance compared with sites with wide corridors. This suggests that it’s very important to protect large areas of riparian vegetation and that narrow corridors may need rehabilitation to enhance their biodiversity value.

For more information about this research, contact Christopher Ives at christopher.ives@mq.edu.au. More information about Ku-ring-gai Council’s riparian protection policies and other biodiversity research can be found at http://www.kmc.nsw.gov.au/www/html/212-research-studies-papers-and-reports.asp

With research such as this providing greater understanding of the biodiversity on our doorstep, we can put in place policies that protect it now and ensure we will enjoy healthy bushland well into the future!

Article Reference:
Ives, C. D., Hose, G. C., Nipperess, D. A., Taylor, M. P., (in press). The influence of riparian corridor width on ant and plant assemblages in northern Sydney, Australia. Urban Ecosystems. Published Online 10 August 2010.

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