The freshwater environment

New Zealand has clean, abundant fresh water by world standards but with increasing demands and the effects of climate change, careful management is needed to protect our water resources.

Scion is exploring the role that forests play in providing freshwater resources and ecosystem services to New Zealand, such as water quality, water yield, recreation and biodiversity. This work supports the sustainable use of New Zealand’s fresh water resources to provide high quality fresh water for future generations.

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New Zealand forests’ freshwater environments and ecosystems

Forests generate high quality water. They moderate the local climate, influence the quantity, temperature and overall quality of stream water and aquatic ecosystems.

Planted forests almost always yield better water quality than other developed land uses. The cyclic nature of forestry means that, occasionally, forestry activities do affect water quality, for example during harvesting and for some years following replanting. After harvesting, especially on steeper land, the risks of erosion and debris finding its way into waterways is high.

Our work focuses on minimising these risks through:

  • Careful management of harvesting operations, particularly on steep land
  • Effective use of riparian management zones or logging slash to shelter stream channels
  • Optimising operational infrastructure
  • Advising communities, land owners and foresters on how best to protect and enhance their freshwater ecosystems.


Our research has also shown the potential of forestry as a remedial tool for degraded waterways. Planting forests can improve the water quality from land that was previously in pasture within 5-6 years by reducing water temperature, nutrient and sediment levels.

Forestry can improve water quality

Planting to control erosion is also helping to improve water quality in the Waiapu and Waikura catchments on New Zealand's East Coast.



Tim Payn, Scientist, Forest Ecology and Management
Tim Barnard, Associate Science Leader, Forest Ecology and Management

Managing riparian zones

Riparian margins enhance waterways and alleviate the environmental effects of forestry and other agricultural activities.

Harvesting can adversely affect the quality of nearby waterways by allowing a greater amount of sunlight in, and increasing the temperature of the water. Maintaining riparian zones during harvesting can help to maintain low light levels and temperatures, as well as reducing the amount of harvesting debris finding its way into the stream, and contributing to bank stability.

Riparian zones can also limit nutrients such as nitrogen leaching into waterways following harvesting, helping to maintain the aquatic community at similar levels to those found in mature pine and indigenous forest streams.

We provide practical advice to land managers on the establishment of riparian margins on both forested and pastoral land, including how wide the strips should be and the most appropriate vegetation to plant.

Indigenous species for riparian planting

Establishing native forest is expensive, mainly due to the cost of seedlings raised in containers. Our specialised mass propagation techniques make it possible to use some species of bare-root native shrubs as a cost-effective solution for riparian management zones.

See Diversifying commercial forestry/indigenous forestry


Tim Payn, Scientist, Forest Ecology and Management
Tim Barnard, Associate Science Leader, Forest Ecology and Management

Water testing services

Monitoring water quality through regular testing is key to maintaining a safe and reliable water source. Scion undertakes water, nutrient and contamination analyses for a wide range of industries, including forest managers, farmers, district councils and utility companies.

We offer routine and customised water quality and nutrient and elemental testing services that provide an indication of the state of health of the system or ecosystem being examined.

See Analytical laboratory services for further details.