Gorse eradication, native forest regeneration
and carbon sequestration all in one
Over the past 32 years, the Maurice White Trust has transformed large swathes of its 1500 hectare (3700 acres) Hinewai Reserve from steep, gorse-infested ex-farmland back to its pre-settlement native forest ecosystems on Banks Peninsula south of Christchurch, New Zealand. The work began as an unlikely partnership between botanist and artist Hugh Wilson, who developed a passion for the plants and wildlife of his childhood home, and Maurice White, a local businessman with a passion for native birds. Together they established Hinewai as an experiment in botanical succession as a means to eliminate gorse and re-establish native forest ecosystems in catchments that run from the hilltops above Akaroa down to the sea. Their story is told in a wonderful video recently released: Fools and Dreamers.
The front gate
I first met Hugh in 2015 on a visit to New Zealand, a few months after I learned of his work and began to wonder if his ideas would work on my pesky gorse problems. After trying every online trick I knew to find his email address, I learned that the only ways to communicate with Hugh are: in person, by snail mail or by telephone. The latter is the least satisfactory. So I determined to visit him in person. I was entranced by Hinewai as a place in its own right as well as an inspiration about allowing nature to heal the damage we humans have inflicted on landscapes over the millennia.
The simple thesis underlying the transformation of Hinewai is that gorse can only grow in direct sunlight. It can’t even germinate in its own shade. Find a way to shade it, and it will die out. At the same time, gorse provides an ideal nursery for starting seedlings that can grow in shade, as the prickly, dense foliage of gorse deters browsers. The native trees of the Banks Peninsula are adapted to germinating in shade, but also love the sun when they get their heads above the understory. Voila! 32 years on, the few original remnant patches of native forest have now overtaken the bulk of the gorse infestation. This was not a matter of planting trees, but rather of allowing nature to do the work.
Hinewai Falls
Well, not all the work. Hugh and his band of merry men and women work quite hard at keeping introduced grazers (sheep, goats, deer, cattle, possums, rabbits, hares, etc) out the reserve. They also have worked hard to keep fire from gaining a foothold, as gorse seeds are activated by fire, and of course fire opens up or destroys the canopy, making the world safer for gorse. And, they’ve worked hard to build and maintain a network of hiking trails through the reserve, open to anyone to use. The resulting ecosystem is a joy to visit—full of native birds, with clear running streams, including a number of permanent waterfalls, and all the biodiversity you would expect of pristine native wilderness.
The only major fire on Hinewai occurred in the winter of 2011, due to a dry lighting strike. Interestingly, the native forest areas acted as natural fire suppression breaks, while the gorse areas burned merrily. The net result was nowhere near as devastating as Hugh and Co had feared.
Hinewai is also sequestering carbon at a high rate, contributing to global solutions for greenhouse gas emissions. As Hugh points out in the video, though, forest regeneration cannot possibly cancel the fossil fuel emissions from burning thousands of years of carbon sequestration in the past—more or less by definition. There is no choice but to change our profligate ways if we want to preserve life as we know it on earth.
Hugh on the track near his house.
So, how does this translate into Tasmanian conditions? Like New Zealand, much of our farmland has been taken over by gorse, introduced by early settlers as a forage crop for livestock (yes, really—it’s surprisingly nutritious and was made into chaff as winter feed for the cohort of working horses in England in the days when horsepower literally meant horses.).
Gorse providing a nursery for she-oaks, eucalypts and wattles on my farm.
As farmers, we are encouraged to control gorse with herbicides that have long-term residual effects, to bulldoze and to burn. All of these just make the world safer for gorse to germinate and regrow. The residual herbicides move through the soil and kill any native seedlings that escaped being sprayed directly. A few months before I read about Hugh’s work, I decided to just quit using herbicides, not knowing what I would do instead. What a wonderful discovery Hinewai was!
Unfortunately, our native trees for the most part don’t cast serious shade: think eucalyptus and silver wattle (Acacia dealbata). However, she-oaks (Allocasuarina verticillata) and blackwood (Acacia melanoxylon) do have dense canopies and gorse is unable to grow under either of them. The good news is that both she-oaks and blackwood trees can germinate under gorse. Since visiting Hugh, I have adopted his approach and now have a healthy nursery of she-oak and blackwood youngsters coming up through my dense gorse areas, which I like to think of as dead gorse walking. Give it another 30 years and it could look as good as Hinewai.
A grove of Tasmanian blackwood (on the left) in an area of sandstone outcrop, along the old highway which is my northwest boundary. Gorse on the right has not been able to penetrate the shade cast by the blackwoods.