Permanent forests planned as part of the government’s one billion tree programme need to be targeted at the country’s high-erosion areas, two leading environmental groups say.

Most plantation forestry isn’t allowed on land considered at very high risk of erosion – so-called red-zone land – without resource consent.

Exemptions are available when harvesting is done in small blocks, or when at least 75 percent of the canopy is maintained. But the Environmental Defence Society and Forest & Bird say it is unclear whether those continuous cover forestry practices would be viable in New Zealand.

Economic viability depends on a host of factors beyond the scope of the national environmental standards for plantation forestry – such as revenue streams, subsidies, and landowner aspirations – but they will need to be addressed if the country is to transition to more sustainable forestry methods, they say in a discussion paper on the country’s national forestry regulations.

“When it comes to establishing permanent forests, ensuring the one billion trees programme’s criteria are calibrated to favour red-zoned areas is critical,” according to the 42-page report.

“If these two things don’t happen, there is a real risk that red-zoned land will remain bare, or continue to rotate through a cycle of cover and stability to sediment loss, both of which are environmentally suboptimal.”

The one-year-old regulations were introduced to standardise forestry practices nationally, reduce costs and increase certainty for landowners and foresters.

But the Ministry of Primary Industries will start a formal review of them next month.

The one billion tree programme and the heightened role of forestry for regional development and carbon sequestration were cited as reasons when the review was announced in February. Other factors were severe flood damage below forestry areas at Marahau in Tasman and Tolaga Bay on the East Coast last year, and recommendations on biodiversity from other agencies.

Afforestation is a core part of the country’s strategy for meeting its climate change commitments and New Zealand already has about 1.7 million hectares of plantation forest.

But the Productivity Commission last year said a further 1.3 million to 2.8 million hectares would need to be planted to help get the economy to net-zero carbon by 2050. That would mean the extra 50,000 ha of annual planting implicit in the government’s goal to plant a billion trees by 2028 would have to continue at that same rate for a further 20 years.

The commission believed much of the planting would be on “marginal” sheep and beef land, although many groups doubt there is enough suitable land available.

Planting of slower-growing natives is favoured as a permanent carbon sink, but they are generally much more expensive than plantation species like pine and are slower to deliver a carbon benefit.

Forest & Bird, often calling for faster action on climate change, now finds itself seeking a more thoughtful – and inherently slower – approach to afforestation.

While plantation forestry presents a “significant opportunity” it also presents a significant risk if it is not carefully located and managed.

“How do we get the right tree, in the right place, for the right purpose,” the discussion paper asks.

While noting the regulations have operated for less than a year, the two groups argue their “desktop” analysis shows they are too permissive and that more needs to be done to mitigate the “significant” adverse environmental impacts from clear-felling.

The presumption that plantation forestry should generally be a permitted activity needs to be revisited, they say. They also want greater set-backs from waterways to better marry with government policy for fresh water protection.

While calling for greater use of continuous cover forestry, the paper suggests that should not be allowed in orange- and red-zoned areas – which the regulations class as posing a high or very-high erosion risk.

Planting and replanting of red-zone land is currently permitted if less than two hectares are harvested annually.

“The question needs to be asked: Should trees that are planted specifically for removal be put in these areas?

“They might provide some stabilisation benefits but those are short-term and the erosion and sediment discharge that will follow on harvesting will be significant, even from smaller areas.”

Radiata pine is typically harvested after about 28 years, according to NZ Wood.

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