Carbon sequestration – how does NZ redwood stack?

In Issue59 by FIEA

New Zealand has committed to a net-zero emissions target by 2050. Carbon uptake by rapid planting of new forests is the only way New Zealand has to remove CO2 from the atmosphere at the speed required to meet our net-zero target. The centrepiece of New Zealand’s afforestation response to climate change is radiata pine as the species has high growth rates over the short term. However, the growth rate of radiata pine declines after 30 years, which may limit the country’s ability to build enduring carbon stocks if we establish large areas of this species as permanent carbon forests.

The establishment of native forests has been widely advocated and these species provide important ecosystem services and cultural value. However, as native trees grow a lot slower than exotic species, particularly over the short term, it will be difficult to reach net-zero emissions by 2050 using a high proportion of planted native species.

Although the current public debate around reaching net-zero emissions is polarised around the establishment of radiata pine or natives, there are other options that could rapidly sequester carbon over both the short and long term. Coast redwood (redwood) is one of the most promising of these options.

Redwood is a fast-growing exotic tree species native to the western US that can maintain high growth rates over hundreds of years and has been found to store more carbon than forests dominated by any other species. Individuals within this species include some of the oldest and tallest living trees on earth that have reached ages exceeding 2,200 years and heights of 115 m.

Although redwood has considerable potential the species currently occupies only 1% of the NZ plantation area which is considerably lower than the 90% covered by radiata pine. A new study by Michael Watt and Mark Kimberley, published in the latest (May) issue of NZ Journal of Forestry, predicts and spatially compares the amount of carbon sequestered by redwood with that of radiata pine throughout New Zealand.

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Source: Scion

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