Cutting back on climate change - Terralink helps with government monitoring

2 July 2002

One of the most pressing environmental issues of our time is worldwide climate change, with its potential to wreak havoc in agricultural and other areas. As part of New Zealand’s commitment to international efforts to slow greenhouse gas emissions into the Earth’s atmosphere, our government is planning to ratify the Kyoto Protocol in August this year.

When the Protocol comes into force, its signatories will be required to cut emissions of greenhouse gases to 1990 levels in the period 2008-2012.

An important part of any effort to reduce greenhouse gas emissions is accurate information on the current status of emissions and accumulations. The Ministry for the Environment (MfE) is responsible for monitoring carbon in New Zealand - keeping an eye on carbon emissions and ‘sinks’. Carbon sinks are areas such as growing forests, scrub, and soil, all of which absorb carbon dioxide from the air and store it as carbon.

MfE’s Carbon Monitoring System - currently being implemented by Landcare Research and Forest Research, and sub-contractors Wildland consultants - relies on accurate, up-to-date, detailed information about New Zealand’s forest cover and other carbon reservoirs.

And this is where Terralink International came in.

Having worked previously with the Ministry to develop a complete Land Cover Database (LCDB) for the country, Terralink is now working on a pilot to create an updated version. The original LCDB was derived from satellite imagery from the summer of 1996-97. Crown LCDB stakeholders are committed to five-yearly updates of the database, so that meant developing an updated version from satellite imagery captured last summer.

This new, improved version of the LCDB won’t just be current - it’ll also portray New Zealand land cover with greatly improved accuracy and detail.

“The Landsat satellite imagery we’re using for this latest version of the database includes a number of new colour bands,” says Phil Wall of Terralink. “These allow us to differentiate classes of vegetation with greater accuracy and detail than was previously possible.”

As a result, the updated LCDB will contain twice as many land cover classes as the original. “In the existing database,” says Phil, “ ‘scrub’ was a single category covering both gorse and areas of manuka and kanuka. Now we’re able to separate those types of vegetation into different classes. Similarly, we can now differentiate between areas of young planted forest and mature trees - and between indigenous and planted vegetation.”

Used alongside the first LCDB, too, the new database will provide a five-year snapshot of how land use is changing over time. Changes in land use affect the quantities of carbon released into or absorbed from the atmosphere - damage to forests by pests, for example, may reduce stored carbon, whereas regenerating scrub on former farmland accumulates it.

And the more detail available on New Zealand’s land cover and patterns of land use, the better our contribution will be in the management of responses to climate change.