Mānuka-dominated ecosystems to improve water quality and provide economic return in the Lake Waikare catchment

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Once Lake Waikare was a source of sustenance for the whānau of Matahuru, however in recent years the health and wellbeing of the lake has been degraded by high inputs of nutrients, sediments and bacteria from the surrounding areas. This five year project funded by Waikato River Authority (commenced 2016) will look at the potential of mānuka-dominated ecosystems to increase water quality through increased infiltration, reduced sediment and nutrient run-off, and decreased nitrate and E. coli leaching. 

For this project the CIBR team is collaborating closely with Waikato Regional Council, Waikato District Council, Nga Muka Ltd, Te Riu o Waikato Ltd, Matahuru Marae/Nikau Estate Trust, and EcoQuest Ecological Foundation.  

Two experimental plots were set up covering 4 ha with 40,000 plants of 22 different species, with around 50% of those plants being mānuka. Run-off from the farm and soil indicators will be measured to compare the difference between run off from sections planted with only mānuka (monoculture), or mixed planting that is mānuka-dominated, to sections with no-planting (control). In the sections where the run off has passed through the planted areas, we would expect to see an improvement in the quality of water from farmland reaching the lake.

The first planting event was held in June 2017 beginning with a hui at Matahuru Marae, where the project team (CIBR, WRC, WDC, Nga Muka, Te Riu o Waikato, Matahuru Marae/Nikau Estate Trust, and Ecoquest) met with other members of the community to talk about what was hoped to be achieved from the various restoration projects taking place around the lake. Which links in with another project being carried out at the lake - Measuring the benefits of riparian vegetation restoration on the health and well-being of the lake and whānau of Matahuru, funded by the Vision Mātauranga capability fund. This project aims to learn about the community values and expectations regarding lake restoration and transform these into a system that can look at the ecological, social and cultural indicators top determine whether it has been successful. At this hui, community members talked about their perception of how the lake became degraded. Around 20,000 plants were planted at this first planting day, completed by 30-40 local community members, CIBR and ESR members, Nga Muka, Matahuru Marae, Te Riu o Waikato, Waikato Regional Council, EcoQuest members and students and students from the Te Wharekura o Manurewa and Te Kauwhata College.

The second planting day was held in October 2017, with members from ESR’s MASC site joining the planting along with CIBR members and members of the local community.

First planting 2017 v2

In 2018, run off collectors were installed to look at the differences in the run-off between the mānuka plots and pasture (control) plots, with 14 collectors installed across the different mānuka and pasture plots. In Autumn of 2018 soil samples were taken to give an initial indicator of the ecological functioning of the plots and of already established native sites surrounding the lake - there were four other sites visited that ranged from eight years old to over 50 years old. Vegetation analyses were also performed by EcoQuest to look at the diversity and abdundance of different invertebrate species at all the sites. During late 2018, more soil samples were taken and transects of the different plots to look at the different plants species present; recording survival, growth and weeds present. 

2018 activities for waikare

In 2019, the run off collectors have been monitored with samples collected for analysis when required. Additional transects of the different plots have been completed to monitor plant growth, survival and weed coverage. More soil sampling is planned for late 2019.


For more information, contact Maria Gutierrez Gines

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