The Government is treating rural land management "like it's playing with Lego" by restricting the amount of trees that can be planted on farmland, the Forestry Owners Association says.
The government has announced sweeping changes to limit the amount of full farm to forestry conversions.
Federated Farmers welcomed the news saying it was good the government was taking steps to stop the "relentless march" of pine trees across productive farmland.
But Forest Owners Association chief executive Dr Elizabeth Heeg told Morning Report the move would cause problems for the country meeting its climate change targets and for the Emissions Trading Scheme.
She said the policy was a "blunt tool" which would mean not enough trees could be planed to tackle climate change.
"It's trying to fix a problem that's not there. Like we don't plant trees on highly productive farmland.
"They're treating rural land management like it's playing with Lego and that's just not the case."
While farmers might think they supported it, the move would prove to be problematic and confusing, Heeg said.
The amount of forestry land overall was still lower than 20 years ago and "people are over-reacting" as farmland recently switched back to forestry in a reversal of earlier conversions the other way, she said.
Agriculture and Forestry Minister Todd McClay told Morning Report the policy was "only part of the picture".
While it would mean fewer trees were planted on farmland, there was another announcement coming on planting on Crown-owned land of low farming or conservation value, he said.
And farmers could still plant trees, he said.
"We're building flexibility in and we're doing that to make sure there aren't any unintended consequences."
McClay said he believed New Zealand could still meet its 2030 climate targets.
He wouldn't be drawn on the specifics before the release of the Nationally Determined Contribution (NDC2) next year.
But he said the country would not be buying overseas credits to make up for missing the targets.
"No we don't have to go and buy credits overseas to meet our obligations and we're working very hard on that.
"We campaigned on meeting obligations... the idea of sending billions of dollars overseas is not palatable to anyone in New Zealand."
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