From a block of gorse-infected scrubland on Banks Peninsula, renowned botanist Hugh Wilson has spent half a lifetime growing Hinewai Reserve into a 1600-hectare paradise of regenerated native forest by leaving nature to it.

In addition to the birdsong of pīpipi as they fly through the bush, those visiting Hinewai Reserve in Banks Peninsula will soon also be able to hear the sounds of the sea, with the private reserve having recently expanded down to the coast.

Hugh Wilson, a renowned botanist and conservationist, had long held a dream of managing a bit of land where he could just "let nature re-assert herself". The 79-year-old has certainly found that in Hinewai, which he has called home for close to 40 years.

Wilson is affectionately referred to by neighbours as an "ecological imperialist", he says with a smile. Under his management as an on-site kaitiaki, the reserve has grown steadily from a 109-hectare block of bush in 1987 to over 1600-ha of regenerated native bush, largely in thanks to income gained through carbon sequestration.

"A lot of our land purchase fund comes from carbon credit income."

The recently purchased 80-ha block by the sea is one example, with work now underway developing a new track on the land.

However, Wilson and the Maurice White Native Forest Trust which manages the reserve are conscious of the tension that exists in allowing business to continue emitting behaviour through offsetting via carbon sequestration.

"We ethically vet every business our carbon credits are sold to. We only sell to businesses who are committed to carbon zero."

One-hectare of regenerated forest sequesters about 10 tonnes of carbon dioxide each year, he explains.

Carbon credits have paid between $15 per tonne at their lowest and up to $70 when prices are high.

"It is a significant income for sure," Wilson says.

Canterbury farmers, too, are increasingly willing to retire steep gulleys and fence them off to gain carbon credits and also increase biodiversity. Most were skeptical of Wilson's project when he started, he said.

Enemy of farmers, friend to few, gorse once infested the land which makes up Hinewai Reserve.

It's a scrub weed with vibrant yellow flowers and prickly leaves.

"The only effective way of getting rid of it was to let the native bush come through and shade it out and kill it," Wilson explains. Admittedly, he got a lot of flack over his plan to leave the gorse to give way to native forest…

Go to this episode on rnz.co.nz for more details