The threats to the native forested watersheds often overlap or compound upon each other. Fire leads to exposed soil, which leads to erosion. Opened areas are prone to invasion by fire-tolerant invasive grasses. Climate change is expected to make all of these worse as rains shift and ecosystems bear the stress of long-term change in mere decades.
THE BAD GUYS
Our goal is to keep the ecosystems as healthy and native as possible so that they can adapt more readily to these threats.
In 2016, a fire burned over 6,000 acres and lasted over a month. The kikuyu grass kept smoldering and reigniting due to the high winds and deep meandering roots of Kikuyu.
It was a perfect storm - winds kept the fire burning for weeks, heavy rains created new water courses and washed tremendous amounts of sediment into nearshore waters
Shortly after, an additional fire burned over 600 acres, from the ocean to above 4,000 ft into our watershed protection area. Seeing the severity of this issue, LHWRP worked to bring together a coalition to put love for the land above all else. Residents of Department of Hawaiian Homelands (DHHL)-Kahikinui, DHHL reps, adjacent landowners, ranchers, fire fighters, invasive species managers, hunters, fire scientists, County and Maui Division of Forestry & Wildlife (DOFAW) officials, and ‘Aha Moku representatives came together to make a plan for protecting the natural and cultural resources of this area.
Afterward, the community received Firewise certification and have since received funding for firebreak work and continued public outreach regarding wildfire preparedness and prevention.
In our dryland areas, decades of escaped hooved animals and wild invasive ungulates, like deer, goats and feral cattle, demolished the land cover, leaving barren, hard-packed soil and rock.
A trial of various erosion control methods was funded by the Frost Family Foundation to help determine their efficacy: Check dames with logs harvested from invasive trees, rock dams where rocks are plentiful, gabions for inside of stream curtains where sediment impacts fence integrity, sediment control fabric placed in logs and flat with native seeds scattered.
Using seed gathered from the area, we are working to restore the degraded slopes with native plants that will hold the soil and rebuild the historical native biodiversity of the area. Using a‘ali‘i, koa and native grasses and sedges, this will also reestablish moisture captured from natural fog interception, create leaf litter, and physically block soil traveling down slope. We use US Geological Survey monitoring techniques to monitor levels of soil loss.
Currently the imminent threat to the protection of native watershed forests on leeward Haleakalā is feral ungulates. Ungulates that currently threaten watershed forests within the LHWRP are feral cows (Bos taurus), pigs (Sus scrofa), goats (Capra hircus), and Axis deer (Axis axis), all of which contribute to the degradation of watershed forests. The combined effect of these ungulates leads to accelerated levels of erosion, decimated vegetation and lack of canopy tree species recruitment has left many southern slopes completed denuded and potentially even void of critical soil components.
Feral goats are extremely damaging, especially because of their locally high population densities. Though preferential in diet, the high numbers of animals tend to devour nearly all plant materials, even extremely unpalatable species such as Styphelia, leaving only the green portions of Pteridium ferns unconsumed. Their omnipresent herbivory, especially of the keystone canopy species koa is extremely damaging to these forests. Goat herbivory of koa includes foliage, young branches, bark, seedlings, and even roots.
Feral cows are especially damaging and though in relatively low numbers, do a great deal of trampling and destruction of fern and shrub forest understories and are especially important in the destruction of rare plant species.
Feral pigs uproot and eat native plant species, are especially damaging to native fern understories and like feral cattle rare plant species of shady, ferny gulch situations. Feral pigs are also known to excavate the burrows and consume the young birds and tending adults of the Endangered ‘u’au (Hawaiian petrel, Pterodroma phaeopygia sandwichensis).
Axis deer are still in an exponential population growth phase on Maui. They are a unique ungulate because they are wild animals, having never been truly domesticated. As such they are extremely cryptic and thus proving a serious challenge for eradication.
Deer damage plants by browsing and grazing, chewing bark, and rubbing their antlers, sometimes killing shrubs and small trees. The trampling, browsing, and up-rooting of native plants also leads to the death of seedlings and subsequent forest decline.
Photo credit: Jacob Muise
Our ungulate strategy is a two step process: fence off the native watershed forest protection areas and then remove ungulates within those fences. Because Axis deer can jump a simple 4 foot fence, 8 foot high fencing is needed in most areas, especially the lower boundaries.
There are other areas within LHWRP set aside as Game Management Areas where hunting is accessible and encouraged. Currently most of the hunting on the south slope of Haleakalā is conducted by hunting clubs on private lands, due to the large tracts of private lands and landlocked state parcels with no hunting access. There is no public access for hunting within the State’s Kahikinui Forest Reserve.
Once ungulates are removed, replanting can begin and natural recruitment happens quickly.
In the top photo here, native plants have been replanted inside the fenced, protected area (left). Invasive grasses still dominate outside (right).
In the bottom photo here, a fenced area is seen from the air, where native plant natural regeneration is happening.
The Kahikinui Project is part of a reforestation effort led by a Hawaiian community on the island of Maui. The project aims to utilize over 500,000 pounds of wild, organic protein that need to be removed in order for restoration to be successful.
Unfortunately fences don't stop weeds from making it into our native forested watersheds. Wind, storms and birds can also carry seeds and drop them high into protected areas. The invasive Bocconia shown at right is actually growing under the fenceline!
Non-native, invasive, habitat-modifying plant species have the ability to out-compete native species that evolved here with few predators. Many of them have characteristics from their native ranges that allow them to do especially well in our fertile volcanic soil and humid climate.
Removing invasive plants is part of the two-tier ungulate removal process. Once areas are fenced and ungulates are removed, invasive plants can also be removed so that native, slow growing species have resources to regenerate.
Invasive weeds, especially gorse at Kahikinui and Bocconia at Nakula, would eventually proliferate to unmanageable levels if seed banks were not re-treated.
OTHER PRIORITY WEEDS
Our current focus for invasive weed efforts include mapping, monitoring, and control within the watershed partnership lands.
We are also working with the State of Hawai‘i, Division of Forestry and Wildlife (DOFAW) and the Hawai‘i Department of Agriculture (HDOA) to identify, research and release well-tested, proven biocontrol methods. In particular, biocontrol for banana poka, fireweed and strawberry guava are currently working to help weaken these species enough to give staff time to beat them.
Most biocontrol does not kill the plant entirely, it simply makes it harder for it to spread quickly throughout the area, giving watershed crews more time to control them manually.
The biocontrol shown here (at right) leaves galls on the leaves of strawberry guava, making it weaker and therefore less likely to fruit and spread.
One of the scariest threats to our native forest is Rapid ‘Ōhi‘a Death (ROD). ʻŌhiʻa (Metrosideros polymorpha), the most abundant native tree in the state of Hawaiʻi, are dying from a new fungal disease. On Hawaiʻi Island, hundreds of thousands of ʻōhiʻa have already died from this fungus, called Ceratocystis. Healthy trees appear to die within a few days to a few weeks, which is how the disease came to be called “Rapid ʻŌhiʻa Death.” This disease has killed trees in all districts of Hawaiʻi Island and has the potential to kill ʻōhiʻa trees statewide.
Hawai‘i receives new, serious pests every year, about half of them from foreign destinations and half from the U.S. mainland. In 2005 the Erythrina gall wasp (Quadrastichus erythrinae) decimated our native Wiliwili trees. In 2015 a 5-acre infestation of Little Fire Ant (LFA) was found in wet forests in East Maui, and crews from the Maui Invasive Species Committee and the Hawai‘i Ant Lab are still working to eradicate them.
Image: Molly Solomon/Hawaii Public Radio
Our focus is on supporting the HDOA in their inspections and providing access and resources for monitoring and surveys. The Hawai‘i Department of Agriculture’s new biosecurity strategy gives an unprecedented opportunity for positive change to help prevent new introductions of unwanted pests.
We can also educate our community by letting them know about current restrictions and laws that help prevent the spread of pests. For example there is an inter-island quarantine on the movement of ‘ōhi‘a and soil from areas infested with Rapid Ohia Death (ROD). ‘Ōhi‘a (including plants, flowers, leaves, seeds, twigs, cuttings, logs, mulch, frass) and soil on Hawai‘i Island may not be transported to other islands except by permit from the HDOA.
We can also spread the word on how individuals can reduce the spread of the disease using outreach tools like the brochure shown here.
There is also a need to investigate how to minimize threats to Hawaii’s other dominant forest species besides ‘ōhi‘a lehua and koa – hapu‘u, mamane, wiliwili, etc. – via regulation of importation of related taxa. Such efforts will not only serve to protect biodiversity but can also prevent lost future opportunities for Hawaii’s agroforestry industry and diversified agriculture.
OUR DISEASE & PEST STRATEGY
In a recent workshop led by Ecoadapt, a non‐profit dedicated to raising awareness of and meeting the challenges of climate change, land managers, government officials, planners, marine experts, water resource managers, and others were brought together to assess Maui Nui’s vulnerability to climate change.
Based on recent scientific studies, they highlighted some alarming trends in data:
On Maui, from 1998‐2013, dry season (May‐Oct) precipitation has declined by 3‐8% above the 1000 meter elevation, with the greatest reductions on windward slopes.
Maui is experiencing greater numbers of consecutive dry days, especially at higher elevations, increasing the risk of wildfire.
Maui’s groundwater base flow is decreasing.
We are experiencing more intense rain events due to a warmer atmosphere – however, in Hawai‘i overall rainfall has declined.
50‐75% of Maui’s reefs are already bleached.
Sea level is projected to rise by 1 foot by 2050.
With the severity of these projections and the low tolerance and narrow habitat range of many native species, protecting our intact watershed forests and adding to acreage of native forest would buffer some of these impacts, especially related to fire, runoff, erosion and invasive species impacts.
Climate monitoring stations have been established at two sites so far, with plans for at least two more. These will help document changes in climate and microclimate as restoration proceeds. We are also working with scientists from the U.S. Geological Survey to build upon studies conducted at Auwahi and elsewhere to document differences in hydrological function between native and non-native dominated forests.