Ensuring the sustainability of New Zealand's forests

8 April 2008

Ensuring the sustainability of forestry production in New Zealand is now possible thanks to productivity indicators identified by Crown Research Institute, Scion.

Forestry scientists at Scion have for the first time developed the key soil and environmental indicators that show the productive capacity of sites in every part of New Zealand where someone may want to plant a forest.

Senior soil scientist Dr Peter Clinton says these indicators will enable forest growers to monitor and maintain the productivity of their land over successive tree rotations.

“Measuring and recording data on these indicators is likely to become standard practice for forestry companies. By capturing this information, it will be possible to see whether the land’s productive capacity is being maintained by management options, or if it is declining.

“This will allow forest managers to develop site-specific silvicultural regimes that ensure the productivity of the soil is not depleted.”

The key soil indicators of productivity for radiata pine and cypress are: soil carbon to nitrogen ratio (CN ratio); total soil nitrogen and total soil phosphorous and; depth of top soil.

The key soil physical property is porosity. The key environmental variables are air temperature and root zone water storage.

“The more intensively a forest resource is managed, the more important these indicators will become,” Peter explains.

“Predicting the productivity of different sites will also be helpful for carbon modelling.”

The need for productivity indicators arose from New Zealand’s commitment to developing sustainable forest management practices, as evidenced through Government involvement in international forestry agreements such as the Montreal Process, and the forestry sector’s adoption of forest certification mechanisms.

Scion developed the indicators through extensive long term field trials.

“Now that we have defined these key indicators, our next task is to ensure that forest managers understand how they can be used to protect the productive capacity of New Zealand’s forestry land,” Peter says.

Scion will be running workshops starting in June 2008 to provide forest managers with information about how to monitor and apply these indicators.

If you are interested in attending a workshop, contact Peter Clinton at peter.clinton@scionresearch.com