With a Helping Hand, Mother Nature Reclaims Kaupo
Haleakala has always held a special place in my heart. It’s one of the few places in Hawai`i where one can find true quiet and solitude and experience the joys of walking through predominantly native landscapes.
So when I heard that a major restoration project was under way along the Kaupo Gap trail, the southern exit from the crater, my curiosity was piqued. Had the botanists of Haleakala National Park actually managed to recreate a mesic forest in an area seriously degraded by goats, cattle and invasive grasses? I had to see for myself.
I wasn’t disappointed. As I stood in an eight-foot-high thicket of a`ali`i, where just five years ago only densely matted kikuyu grass had grown, I understood that it is possible to reverse much of the environmental damage wrought by alien species. It takes time, money, physical labor – often starting with fence-building and removal of troublesome animals – and, apparently, regular doses of herbicides, including some applied by helicopters. Other forms of human intervention, such as planting seedlings and seeds, also are helpful.
But it can be done, even in a place trampled under cattle drives, shorn by goats, smothered beneath matting grasses. The Haleakala “veg crew” – the botanists and dedicated field crew alike who spray herbicides, control Christmasberry and other weeds, haul water and plant native species – have shown at Kaupo that severely degraded lands can be returned to a good semblance of their original vegetative cover.
Still, ecosystem restoration in Hawai`i is more art than science, with serendipity playing a great role in the process. At Kaupo, the biggest surprise was the fecundity of the native seed bank. “Certainly I didn’t expect anything like this,” said park botanist Patti Welton as we walked through dense stands of koa, mamane, pilo and a`ali`i. Much of the vegetation, including the thicket of a`ali`i, had emerged on its own. “I was thinking our (nursery-raised) seedlings would be far more important than what came up naturally,” Welton said. “We’re really happy to have the seed bank working for us.”
We trod gently through the brush, careful not to step on tiny pilo and koa seedlings pushing up through the mulch-like mat of dead grass. How long can these species cling to life in the seed bank? How urgent is our task of restoration, of freeing these native landscapes from the alien cloak that has been thrown upon them?
It’s been many years since a mesic forest covered this particular swatch of land that is bordered on one side by lava flows and dry shrublands, and on the other by a lush wet forest. Historically this area was used as pasture for grazing cattle, which, along with feral goats, eventually denuded the land. In the mid-1980s the National Park Service completed its fence around Haleakala and eradicated the goats. Botanists immediately noticed a flush of native shrubs returning to the Kaupo corridor. But kikuyu, a dense, mat-forming grass introduced to nearby `Ulupalakua Ranch for forage, had found its way into the corridor, and without grazing pressure, it flourished. Before long, kikuyu had suppressed native seedling establishment and became potential fuel to feed brush fires that might start in the drier pastures down below.
By the time the Park Service considered restoring the lower Kaupo trail corridor, about all that remained of the native forest were a few large koa trees, four naio, and scattered shrubs. Restoration began in 1994 with four 20-by-20 meter plots. It was rough going in the remote conditions. Welton recalls frequently packing five gallons of water a half-mile up the steep trail from the parking area so crews could apply Round-Up to the kikuyu grass with backpack sprayers.
Meanwhile, a project using herbicide-spraying helicopters to control molasses grass in the western part of the Kaupo Gap was under way, made possible by Park Service funds to reduce the risk of grass fires. Botanists experimented with a similar approach in the trail restoration area. A task that took Welton’s crew days of hard labor could be accomplished in five minutes by helicopter. Not long afterword, koa was sprouting in the treated area.
Thus, a new project employing helicopter applications of herbicide was launched in 1996, which greatly accelerated the trail restoration project by controlling much larger areas of kikuyu grass than could be treated by hand. The “veg crew” needed to follow-up only with spot spraying or to treat areas under the existing tree canopy.
But using the helicopter added a new twist to the complexity of the project. Spraying often had to be rescheduled because of unpredictable winds or bad weather, yet timing was critical if native seeds and seedlings were to benefit from the life-giving properties of the winter rains. Meanwhile, Maui began to experience dry winters and summer droughts. Restoration is “really dependent on the right moment in the weather,” Welton explained. “You want to clear the grass at a time when the climate will be conducive to germination. The first few years there was a lot of rain, so we had a better survival rate from the natural flush than we have had lately. We want to help the system drive itself, rather than try to skew it.”
The story is told in the planting areas. Those that experienced the optimum combinations of herbicide treatment, outplanting support and rain are the most lush and dense. Other areas – where the soil is poorer, the rains less plentiful, or weeds still prevalent — tend to be more sparse; the vegetation is shorter and filling in more slowly. Still, the aliens are on the run everywhere in this corridor, and natives now dominate.
The “veg crew” experimented both with planting seeds and seedlings grown in the park’s tiny nursery. The seedlings did better than the seeds, but the native seed bank did best of all, especially the koa and a`ali`i. “The first year we planted 100 a`ali`i and more than a thousand came up a year later,” Welton says. “Now we’re seeing species requiring shade to regenerate, such as pilo and mamane, coming up naturally in the shade provided by the initial flush of koa and a`ali`i. Mamaki has also volunteered.”
Another unexpected change in the landscape is the emergence of large and interesting rock formations that had been hidden by the grass. The grass also concealed a lot of trash, which the “veg crew” has removed.
Welton said some weed species, such as castor bean, which has a seed bank several inches thick in places, also benefit from removal of the kikuyu grass, presenting the “veg crew” with a new challenge. And she’s keeping an eye on velvet, or Holcus, grass, although it’s not as big a concern as the kikuyu grass. “It’s competitive but doesn’t completely suppress regeneration of native species. You have to look at the aliens – will they be suppressive, promote fire, etc. – and then decide if you want to control them. Our goal is to get this forest so it can fend for itself, not necessarily to create a totally intact, pristine native ecosystem. You have to choose your enemy.”
A case in point is bull thistle. Once the kikuyu grass was controlled, thistle seeds blew in and emerged alongside the native seedlings. Some members of the “veg crew” thought it should be eliminated, but they couldn’t keep up with it all. As it turned out, Welton said, “once the native seedlings got established, the thistle wasn’t much of a problem.”
For Welton, who has come to know the corridor of land along the Kaupo trail as intimately as her own backyard, the six-year restoration effort has been a process of constant discovery and unfolding. “It’s so neat to look at this landscape now,” she said, pausing to point out “our first naio,” a healthy 12-foot specimen planted in November 1995. “Now, with this experience, we can see where and how to spray and control weeds, connect plots, plant. It’s one grand palette.”
Meanwhile, the work has eased a little. The crew has installed small catchment systems so water doesn’t have to be hauled in for herbicide touch-up treatments. And instead of focusing now on trees, the crew has moved into the understory phase, planting maile, kukae nene and native grasses. Most important, the project is far enough along that everyone is bolstered by the results.
Welton notes that the “veg crew” can get soggy and dispirited when faced day after day with the formidable task of fighting kahili ginger and clidemia in Kipahulu Valley. “This is our reward, a place to dry out, rejuvenate ourselves and remain inspired about our unrelenting battle with weeds.”
— Joan Conrow
Volume 11, Number 4 October 2000
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