We investigate how native vegetation and ecosystems can improve water quality and benefit from biowaste. Our research has shown that native species can mitigate water pollution and native plantings can thrive with the application of both biosolids and treated wastewater. We are committed to developing a sustainable approach that can transform both community biowaste and marginal or unproductive land through the planting of native vegetation. We carry out this research in the field and in collaboration with local communities, councils, the University of Canterbury, and Manaaki Whenua/Landcare Research.
Using New Zealand native vegetation to improve water quality
Working with colleagues at Lincoln University New Zealand, we have demonstrated that the antimicrobial properties of mānuka and kānuka (usually recorded in honey and essential oils) are also present in root systems. This means that microbial contaminants (measured by E. coli as an indicator) die-off is much faster under mānuka and kānuka than under pasture. Further, mānuka and kānuka have deep root systems which reduces nitrate leaching in comparison to pasture or radiata pine.
With these results in mind, restoring native vegetation where mānuka and kānuka are included in the margins of waterways, could reduce the amount of nutrients, sediments and pathogens that arrive from farming lands. In the same way, plantations of mānuka and kānuka could be used to safely land-treat biowastes such as municipal wastewater or biosolids.
ESR is leading projects around Lake Waikare and Lake Wairarapa to demonstrate and quantify the potential of mānuka and kānuka dominated native vegetation, to increase the water quality affected by farming activities. These projects are funded by the Waikato River Authority, Waikato Regional Council, Greater Wellington Regional Council, and ESR Strategic Science Investment Funding, and count on numerous collaborators: Ngā Muka Ltd, Te Riu o Waikato Ltd, Matahuru Marae / Nikau Farm Trust, Ecoquest, Rangitane, Kahungunu ki Wairarapa and Manuka Farms.
Current projects are seeking to find other native plants with similar properties as mānuka and kānuka. As a first step, we are screening a list of potential native plants for their antimicrobial properties. For this, plant extracts of 15 native species from North Island and South Island are being tested against important pathogens such as Staphylococcus aureus, and Campylobacter jejuni. We expect to increase the knowledge about potential native plants for reducing pathogen and nitrogen loads into waterways, as well as to provide incentives for increasing the biodiversity in riparian plantations.