Watershed impacts — Maui Invasive Species Committee (MISC)

Measuring the impacts of invasive plants in Hawai’i’s watersheds

Posted on June 5, 2020 by MISC

University of Hawai’i professor and researcher Tom Giambelluca is looking to better understand how invasive plants, like strawberry guava on the right, disrupt the water collection function of a native rain forest like that on the left.

In Hawaiʻi, the supply of fresh plentiful water depends on the forest capturing moisture from fog drip and rain, and then move it to streams and aquifers. Scientists and resource managers know that invasive plants disrupt the capacity of a native ecosystem to collect water. In Hawaiʻi, invasive species are the greatest threat to the function of native ecosystems.

But there are many unanswered questions about how and to what degree invasive plants affect the water capture in Hawaiʻi. Water capture, depends on both rainfall and cloud or fog drip, water then moves through the forest and soil to streams and underground reservoirs (aquifers). Some water is lost through evaporation and transpiration – the movement of water from roots through the leaves and into the atmosphere.

Like straws, plants pull water out of the ground and release it into the air. Differences in both the physical structure and growth characteristics contribute to different rates of transpiration between native and invasive species. Tom Giambelluca is looking closely at those differences. Giambelluca is the director of the Water Resources Research Center and a Professor in the Department of Geography and Environment at the University of Hawaiʻi at Mānoa. He has spent much of his career looking at the impacts of invasive species on water resources in Hawaiʻi. His latest research attempts to tease out and quantify how invasive species increase the loss of water back into the atmosphere.

“One of the reasons invasive plants take over might be that they grow faster,” he says. “Faster growing plants tend to use more water” and over the long run, as invasive plants take over the native dominated forest, these differences in transpiration rates could have significant impacts on the cycle of water through the environment and the availability of water for human use.

To quantify these impacts, Giambelluca has relied on an experimental model of setting up monitoring equipment in paired sites where forest dominated by native species is growing immediately adjacent to stands of invasive plants. This site selection eliminates differences that may be caused by soil types and weather patterns in geographically separate locations. Weather can vary dramatically within small distance in Hawaiʻi. He then looks at the differences in transpiration by setting up tall towers filled with monitoring equipment and using measurements of water flow moving up the stems of sample trees.

But suitable study sites are hard to find – and funding additionally limits the number of sites he can potentially set up. With only a limited number of sites, he can’t accurately predict the impacts of invasive species may have on transpiration rates across the landscape.

So, Giambelluca is developing an experimental model wherein he can evaluate sites based on data that can be collected in a single day, therefore enabling his team to gain a better understanding of how individual differences in plant transpiration rates can impact water capture throughout Hawaiʻi. And he’s focusing primarily on leaves.

“Leaves are where the action is,” explains Giambelluca. “It’s where the plants control the uptake of carbon dioxide and release of water vapor.”

He takes a handful of measurements including the leaf area index (the surface area of all leaves over a given area), and leaf gas exchange rates of different plant species. The more leaves in an area, the higher the transpiration rates. Invasive – dominated forest tends to have a higher leaf area index (i.e,. more leaves). Plant species transpire at different rates. After he has enough data to be statistically significant, he can then combine that with distribution maps of plant species across Hawaiʻi, and better assess the impacts invasive species have on the amount of water lost through transpiration.

While still in the proposal stage with results a few years in the future, the potential outcomes from this research could help inform the decisions resource managers and funders face in setting priorities both for which species should be controlled as well as which areas are more sensitive to the impacts of invasion. In the meantime, enjoy a fresh glass of water brought to you by a native forest nearby.

For more information on Giambelluca’s research, check out his lab page at https://sites.google.com/a/hawaii.edu/ecohydrology_lab/

Lissa Strohecker is the public relations and education specialist for the Maui Invasive Species Committee. She holds a biological sciences degree from Montana State University. Kia’i Moku, “Guarding the Island,” is prepared by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that can threaten the island’s environment, economy and quality of life.

Originally published in the Maui News on November 9th, 2019.

Natural enemies could tame invasive Himalayan ginger

Posted on June 5, 2018 by Lissa Strohecker

Though not invasive in India where it is native, Himalayan ginger can completely transform a Hawaiian rainforest like it has in this section at 4,000-foot elevation above Haiku. Inset: Ginger fruits are spread long distance by birds and rats. FOREST and KIM STARR photo

The subtropical rainforests in the foothills of the Himalayan Mountains are amazingly diverse. In sections of India and Nepal, the forests are similar to Hawaiian rainforests in both temperature and rainfall-but the flora and fauna are radically different: this is the land of elephants and red pandas; 600 species of butterflies live here and over 400 species of orchids. But amongst the exotic plants there is one

The fruit of Himalayan ginger is a tasty treat for non-native birds, but this means the seeds are spread throughout the forest. Photo courtesy of Forest and Kim Starr.

that might be familiar to residents of Hawai’i-a yellow-flowered ginger that covers vast sections of Hawaiian rainforests.

Himalayan ginger, Hedychium gardnerianum, is native to the Himalayan foothills. There, it evolved over millennia supporting a diversity of species: the sweet nectar is a food for the long-tongued butterflies of the region and the plant lives in harmony with the species that surround it. Yellow flower stalks dot the landscape amongst hundreds of other orchids, gingers, ferns, and trees.

But in Hawai’i, Himalayan ginger dominates the landscape-growing fast and paving its way into the forest in an unrelenting march.

“Himalayan ginger displaces critical native vegetation layers, limits canopy tree recruitment, and hogs water resources in their massive rhizomes (roots). As it takes over and forms monotypic stands, it negatively impacts native flora and fauna, including Hawai’i’s unique arthropod complex and the Hawaiian honeycreepers,” says Alison Cohan, director of the Maui Nui Forest Program with The Nature Conservancy (TNC).

Introduced as an ornamental, Himalayan ginger escaped backyards and began invading rainforests of East Maui in the mid 1950’s. With seeds dispersed far and wide by birds and rats, the weedy plant spreads by leaps and bounds into the forest. Today, much of the mid-elevation rainforest of East Maui is a patchwork of native forest and alien ginger. But there is a lot left to protect: many ginger-free areas remain, including most of West Maui.

Ginger is a formidable foe and removing the plant is no simple task. Roots pave the forest floor like asphalt and every part of the rhizome must be removed. Bagged rhizomes take years to decay and if there is the slightest hole in the bag, hardy shoots emerge. If using herbicide, every portion of the root has to be treated. Plants on steep slopes and cliffs are inaccessible and impossible to remove until the weight of the water-logged roots causes entire sections to collapse in a landslide.

Why would ginger be a pest in one place but not another?

Djami Djeddour, weed biocontrol scientist with the Centre for Agriculture and Bioscience International, inspects a lone Himalayan ginger plant in India while searching for insects and fungi that live on the plant where it is native. These insects may be responsible for keeping the plant in check. DJAMI DJEDDOUR photo

The answer to that question is on the minds of resource managers in Hawai’i as well as New Zealand, Australia, and South Africa where the plant is invasive. With funding from organizations like TNC and the Hawai’i Invasive Species Council, research scientists traveled to India and collected insects and fungi that live on Himalayan ginger hoping to discover what keeps the fast-growing herb in balance there. An effective natural enemy could be a game changer for Hawai’i.

An effective natural enemy wouldn’t eliminate the plant, just bring it into harmony with the surrounding environment, much like it is in India and Nepal.

One of the most promising insects is a Cloropid fly that lives only on Himalayan ginger. The larvae live inside the stem stunting the growth and reducing flower production. Ginger natural enemies may be ready for release in New Zealand soon, promising progress for Hawai’i.

“The Nature Conservancy had been doing ginger work in Waikamoi for over 30 years, systematically conducting ginger control—containing the core population at the western edge of Waikamoi and eradicating outliers in native forest,” explains Cohan. Crews with Haleakala National Park work on the flowering pest in Kīpahulu Valley but the plant is widespread and thrives unchecked in wet places throughout the state.

There are ways you can help. Consider what you call the plant: though known for years as kāhili ginger, a pest destroying the rainforest does not deserve a moniker reminiscent of Hawaiian royalty much less one that might suggest that it belongs here. Perhaps call it toilet-brush ginger, as suggested by Pat Bily of TNC after years of removing it. Do not plant Himalayan ginger in your yard and remove it from your property before it spreads. Finally, participate in The Nature Conservancy’s quarterly volunteer trips removing ginger from Waikamoi Preserve. Contact hike_waikamoi@tnc.org if interested.

This article was originally published in the Maui News on April 8th, 2018 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

From the Forest to the Faucet – Every Drop Counts

Posted on October 6, 2015 by Lissa Strohecker

Big Bog, high above Hāna on the windward slopes of East Maui, and Puʻu Kukui, on West Maui are some of the wettest places on the earth with 360-400 inches of rainfall a year, so it’s hard to imagine water could ever run short. When overrun with water, it’s easy not to think about times of scarcity, much like the flow of money. Knowing now how much, when, where the dollars are coming from helps, as does prioritizing needs versus luxuries. If needs exceed income, we can earn more, spend less, or combine the two approaches.

ear the summit of Puʻu Kukui on West Maui clouds are the norm. The rain that falls here and on the slopes of Haleakalā supplies Maui residents year-round.

Near the summit of Puʻu Kukui on West Maui clouds are the norm. The rain that falls here and on the slopes of Haleakalā supplies Maui residents and visitors throughout the year.

The same is true for managing our limited water resources. Studies in Hawaiʻi are looking to see how what happens in our forests affects what comes out of our faucets.

Stream runoff is captured from East Maui to meet the needs of upcountry residents and agriculture.

Hydrologists develop water “budgets” to quantify how water moves through our environment and how much is captured for our use. They look at all the drops that go into and out of the watershed, whether in by rainfall and fog drip or out by runoff and evaporation. Sometimes water goes into the savings account – absorbed by the soil, then into the water table or aquifer through infiltration and recharge. On Maui, the water we use is either captured from surface runoff or pumped from the aquifer.

The Maui County Department of Water Supply tracks overall water use while striving to meet the needs of the community. Understanding hydrological cycles and water budgets, helps the Department plan for the future by looking at how to capture more water from the sky or spend less through runoff and evaporation to meet the needs of tomorrow. But how? Many factors influence water budgets. Research done on the mainland might not be relevant for Hawaiʻi, a comparatively tiny sprinkling of islands in the middle of a massive ocean. So the Department is working with the U.S. Geological Survey to study water systems on Maui to help prepare for the future.

The plants in a native Hawaiian forest effectively capture more water than many of the invasive plants that make up the lower elevation forests.

Differences in land cover and use affect hydrological processes, including whether native or non-native plants rule our forests. The drip-drip of water, condensing and falling from plants, is a critical source of moisture; it can easily make up 20% of the total water collected. On Lānaʻihale (the forested top of Lānaʻi), fog drip accounts for a whopping 60-80% of water input. Cook pines were planted on the island because of their impressive ability to capture fog drip, but native plants may do better. One study in forests on Hawaiʻi Island showed that 27% of the total precipitation was collected as fog drip in an ʻōhiʻa-dominated forest, but that number decreased to 16% where a forest had been invaded by strawberry guava.

Not all water that falls from the heavens makes it into the aquifer. Soil in a forest absorbs more water, and does so more quickly, than soil in nearby fields, pastures, or grassland. Forests transformed into monotypic stands of miconia plants typically have bare soil which likely captures less moisture. Water also evaporates into the atmosphere from the ground and off leaf surfaces, but the rate varies for different species. Research has shown that non-native plants release more water into the atmosphere than our native ʻōhiʻa.

One study on Hawaiʻi Island found that restoring a forest dominated by invasive trees to a native forest increased aquifer recharge. But results aren’t always consistent. A restoration project on Molokaʻi actually yielded a slight decrease in recharge. Given the complexities of our forest systems and the number of changes humans have caused over the years, it’s clear there are many mysteries yet to unravel about water systems in Hawaiʻi.

We do know that overall demand for water will only increase. Over time, so too will our understanding of how to preserve or restore healthy forests to help ensure we will have the amount of water we need, now and for future generations.

Find more information about how water cycles through forests in Hawaiʻi and on Maui including a water-budget model. You can also find tips on stretching your water budget at home on the County of Maui – Department of Water Supply’s website.

Originally published in the Maui News, July 14th, 2015 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Rapid ʻŌhiʻa Death – a new threat to our watersheds

Posted on May 19, 2015 by Lissa Strohecker

This ohia tree shows one of the characteristic symptoms of Rapid ʻŌhiʻa Death – the tree looks frozen or burnt, leaves still in place. Photo by J.B. Friday
This ʻōhiʻa tree shows one of the characteristic symptoms of Rapid Ohia Death – the tree looks frozen or burnt, leaves still in place. Photo by J.B. Friday

Five years ago, people living in the Puna district on Hawaiʻi Island started seeing native ʻōhiʻatrees in their yards dying. First, the leaves on a single limb or the whole tree would start to yellow and brown. Within days or weeks, the tree would be dead. “Trees look burnt or frozen,” explains Dr. Flint Hughes, a research ecologist with the USDA-Forest Service. He’s one of several scientists investigating the cause of Rapid ʻŌhiʻa Death, an apt description for a disease causing ʻōhiʻa to die so fast they don’t have time to drop their leaves.

Symptoms can appear in a single branch or the entire canopy of a tree. Pruning the affected brance will not save the tree since the Ceratocytis fungus is already established in throughout the tree. Photo by J. B. Friday

The disease spreads across landscapes nearly as fast. In 2012, it had killed ʻōhiʻa across about 1000 hectares (nearly 2500 acres). By last summer, it covered 6000 hectares. Healthy trees, young trees, old trees–it doesn’t matter—once symptoms appear, the tree will be dead within weeks.

A disease this virulent is potentially catastrophic for native species and watersheds. ʻōhiʻa are a keystone species for a Hawaiian rainforest. Like the uppermost stone in an arch, ʻōhiʻa is critical to the structure and function of the forest, both as refuge for native birds and other species, and as an effective way to transform what falls as rain into what comes out of the tap.

Last year, Hughes and his colleagues began to research what was happening. They knew it was a new phenomenon and not related to any previously known problems in ʻōhiʻa, such as ʻōhiʻa dieback or ʻōhiʻa rust. Within six months they had isolated the pathogen causing Rapid ʻŌhiʻa Death. The disease is caused by a fungus, Ceratocytis fimbriata. It gets into the sapwood of ʻōhiʻa, stopping the tree’s ability to transport water and sugars. “The fungus essentially strangles the tree,” says Hughes.

The ceratocytis fungus responsible for killing ohia accross 15,000 acres on Hawaii Island can be seen as a dark staining in the sapwood. Photo by J.B. Friday

Isolating the cause of Rapid ʻŌhiʻa Death, also called Ceratocytis wilt of ʻōhiʻa, is the first step. Ceratocytis has been present in Hawaiʻi for decades. In the Islands, it’s known only as a pathogen on sweet potato and taro, never before attacking ʻōhiʻa. In other parts of the world, Ceratocytis infects sycamore, eucalyptus, mango, coffee, cacao, citrus, poplar, fig, and rubber trees.

Researchers have yet to determine the origin of this recent outbreak—more than likely a new, more virulent strain of Ceratocytis was introduced but it is possible the existing strain jumped to ʻōhiʻa.

One of the researchers’ top priorities is determining how the disease is spreading. Other places

The Ceratocytis fungus spreads throughout the sapwood or vascular system of the ohia, eventually strangling the tree. The dark staining in this cross-section of an ohia is a symptom of infection by the Ceratocytis fungus. Photo by J.B. Friday

in the world, insects and contaminated equipment are vectors for spreading Ceratocytis, and that could be the case in Hawaiʻi. Until that’s determined, Hughes urges people not to move ʻōhiʻa—logs or seedlings. The fungus can survive in dead logs for a year or more. He suggests that it’s even possible that Ceratocytis spores may land on plants growing near ʻōhiʻa and movement of those plants may spread the disease

On Hawaiʻi Island some of the nicest stands of low-elevation ʻōhiʻa are gone, but researchers are not giving up. “One of the hopes is that we’ll see some genetic resistance in ʻōhiʻa, or there may be environmental constraints,” says Hughes. On Hawaiʻi Island, Ceratocytis has been found as high as about 1,400’ elevation in Mountain View, but that may reflect the relatively recent introduction rather than the full extent of its potential range.

Fungal spores of Ceratocytis on a dead log. The fungus can survive in dead logs for a year or more, and the disease can infect the plants for 2-3 months before symptoms appear. Help stop the spread by not moving ohia-logs or seedlings. Photo by J.B.Friday

They do know that the fungus can be present for months before any symptoms appear. During pathogenicity testing, ʻōhiʻa trees showed symptoms two or three months after inoculation. Pruning a symptomatic branch will not necessarily protect the tree as the fungus may have already spread throughout the tree and possibly to nearby trees.

Researchers have much to learn about Ceratocytis wilt on ʻōhiʻa. For now, they encourage people to clean boots and equipment after working on infested trees and caution against interisland movement of ʻōhiʻa logs and seedlings. Rapid ʻŌhiʻa Death is only known to occur on Hawaiʻi Island. If you are on Maui or elsewhere in the Islands and see symptoms: leaves quickly turning yellow or brown, dead trees looking burnt or frozen with leaves still in place, or tell-tale brown streaking on the dead wood, contact Hughes by phone, 808-854-2617, or e-mail fhughes@fs.fed.us Learn more online at http://www2.ctahr.hawaii.edu/forestry/disease/ohia_wilt.html

Originally published in the Maui News, May 10th, 2015 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Invasive plants=Less water

Posted on June 27, 2014 by Lissa Strohecker

This rainforest, in Puu Kukui on West Maui, is an example of an open canopy rainforest typical of native rainforest in Hawaii. This forest acts like a ‘sponge,’ absorbing water from rain and gently releasing to recharge streams and aquifers. MISC file photo

When rain falls from the sky by the bucket-load it can be tempting to take water for granted, but the trip from raincloud to tap relies on effective, functioning natural systems. In Hawai‘i, alien plants disrupt the forest’s ability to capture water.

Water follows a cycle through the environment. Water over the ocean evaporates becoming atmospheric moister, as it travels over land it condenses into clouds, falling to Earth as rain or fog drip. Once on the ground, water has three paths: 1) it’s taken up by plants that use it to move nutrients through their cells, then return it to the atmosphere via transpiration; 2) it fills streams, lakes and rivers, eventually returning to the ocean–minus what was used for irrigation or lost through evaporation; or 3) it seeps through the soil into underground pools called aquifers. These aquifers supply most of the water we use to drink, bathe, and grow our food.

Forests have evolved differently to take advantage of prevailing water cycles in their regions. In South America and Africa the greatest diversity of plants is found up in the canopy. In Hawai‘i most plant species are found in the lower third of the forest, closer to the forest floor. Hawaiian understory plants need sunlight filtering through an open canopy. Koa and ‘ōh‘ia, the dominant Hawaiian canopy trees, grow in such a way that light reaches the shrubs and groundcover below.

Koa and ‘ōh‘ia pull water from passing clouds as fog drip; the curved leaves of koa provide surface area to collect moisture from clouds and channel it down leaf tips to the forest floor. Spongy plants on ‘ōh‘ia branches and trunks absorb moisture from passing clouds. Alien species disrupt the system.

Strawberry guava, Psidium cattleanium, has invaded Hawaiian rainforests, growing so dense and so

Strawberry guava invaded forest in Makawao Forest Reserve

The invasive tree strawberry guava chokes out native plants. As it sheds bark, strawberry guava provides no habitat for the plants growing on the trunks of native species. Photo courtesy of Forest and Kim Starr.

fast that it chokes out other plants. A strawberry-guava-invaded forest captures water differently than our native forests. In Hawai‘i Volcanoes National Park researchers found that a forest dominated by strawberry guava delivered less water to the forest floor than an intact native rainforest. Researchers noticed several differences between the two forest types: more rain ran down the stems of strawberry guava than ‘ōh‘ia but less water was pulled from the passing clouds. This could result from structural differences. ‘Ōh‘ia have aerial roots and furrowed bark carpeted with mosses and small plants called epiphytes. The epiphytes and aerial roots soak up water from passing clouds. Strawberry guava bark is smooth and regularly shed; few plants grow on its trunk and branches.

Other invasive species disrupt the water cycle by sheer size—leaf size. Miconia trees with three-foot long leaves sweep into the forest, stealing light from the understory and transforming it into darkened forest, the soil bare but for miconia seedlings. As another researcher on Hawai‘i Island discovered, the huge leaves are more than just light-hogs. They collect water as if they were huge tarps, and, as anyone who has stood near the edge of a tarp in a rainstorm knows, it’s only a matter of time until the water

The forest floor under a miconia invasion is bare, often with exposed roots. Not a good sign for water collection. MISC file photo

dumps down. The drops running off of miconia turn out to be the largest drops ever measured. Larger drops hit the ground harder, and where miconia has smothered the understory, those drops fall on bare soil. Huge drops compact soil particles, preventing water from seeping down to aquifers, instead causing it to run off, carrying topsoil into streams and eventually the ocean where it can smother coral reefs.

These are only some of the ways invasive plants alter the forest’s ability to capture water. Water-hungry plants like Himalayan ginger pave the forest floor in tough roots. Huge trees like eucalyptus require more water to carry nutrients to their crowns than smaller trees. Unfortunately, the list goes on. Healthy forests mean reliable sources of water. Keeping invasive plants out of native forests is one way to help keep the water flowing from raincloud to tap

By Lissa Fox Strohecker. Originally published in the Maui News, March 11th, 2012 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee

And then the pollinator wasp arrived…

Posted on October 17, 2013 by Lissa Strohecker Leave a Comment

Bo tree, Ficus religiosa, is an attractive ornamental that was once safe to plant in Hawaii. Now the pollinator wasp for the bo tree is in Hawaii and this prolific seeder threatens watersheds. Photo by Forest and Kim Starr

Lori Buchanan, manager of Moloka‘i/Maui Invasive Species Committee (MoMISC), was in downtown Kaunakakai recently when she saw something strange sprouting out of the storm drain. It was a 3-foot tall seedling of a ficus—the very same tree she and her crew are working to remove from Moloka‘i.

Called the bo, peepul, or bodhi tree, Ficus religiosa is planted throughout Asia, Africa, and North America. According to legend, the Buddha sat beneath this species of tree when he meditated and attained enlightenment, hence it’s name. The Hindu deity Vishnu is reputed to have been born under a bo tree. These trees are often planted at Buddhist and Hindu temples. There is a bo tree at the Foster Botanical Garden on Oahu that is said to be a descendant of the tree under which Buddha sat.

Not that long ago, the bo tree couldn’t reproduce on its own in Hawai‘i; it only grew via cuttings. As a member of the Ficus family, it needs a specific wasp to pollinate its flowers in order to produce seeds. That wasp, Blastophaga quadraticeps, was not in Hawai‘i. The wasp crawls inside the minute flower to fertilize it. In 2007, when seedlings sprang up under the bo tree at Foster Garden, Hawai‘i entomologists knew the pollinator wasp had arrived.

Bo tree seedlings springing up out of a sidewalk crack on Molokai

Bo tree seedlings, like this one springing up out of a sidewalk crack on Molokai, indicate the pollinator wasp has arrived. Birds can easily spread seeds into the watershed. Photo by Forest and Kim Starr

The arrival of Blastophaga quadraticeps means that Hawai‘i has joined a relatively small list of places where Ficus religiosa can produce viable seed: India (where it’s native), Israel, and Florida. In Israel, the pollinator wasp fully invaded and Ficus religiosa now ranks alongside other Ficus as invasive and messy. Now that they produce fruit in Israel, purple figs stain the sidewalks, stick to shoes, and splatter cars left in the shade of a tree. Motorcyclists dodge slippery piles of fruit and beachgoers clean gummy residue off their gear.

On Moloka‘i, Buchanan isn’t worried about sidewalk saplings—she’s worried about the forests. “Birds spread the seeds and they [Ficus trees] can get into the forest and threaten the watershed,” she says. “They are prolific seeders and seedlings pop up wherever.” Bo tree could start to take over the native forest on Moloka‘i.

Ficus religiosa, like most Ficus, can grow almost epiphytically: a seedling doesn’t need soil initially but roots reach down until the find earth. Bo tree is technically more of a “splitter” than a strangler fig. Rather than smothering its host in roots, the seeds that sprout in the fork of a tree will send roots through the stem of the support tree, splitting it from the inside. It can find a home in sidewalks and drain sprouts, splitting those apart as well.

MoMISC is actively controlling this species on Moloka‘i, where less than a dozen trees

Bo tree can be recognized by the “tail” or drip-tip on the distinctive heart-shaped leaves. Photo by Forest & Kim Starr

were planted. Only one site with mature trees remains, and Buchanan and her crew are busy hunting down seedlings until the landowner agrees to have the plant removed. On other islands bo tree is planted widely enough that resources are too limited to remove it. But choosing to not plant this tree will slow its spread.

You can help MoMISC by keeping an eye out for bo tree seedlings in Central Moloka‘i, specifically in Kala‘e and Kaunakakai. The bo tree has distinctive heart shaped leaves that extend at the tip. According to Buchanan, the plant most closely resembles the Polynesian “canoe plant” milo, which also grows in the same areas on Moloka‘i. Bo tree has more dark green to grey glossy leaves. Any sightings of bo tree on Moloka‘i should be reported to MoMISC, 954-6585.

By Lissa Fox Strohecker. Originally published in the Maui News, October 13th, 2013 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Hawaiian land snails– a tale of evolution worthy of protection

Posted on July 22, 2013 by Lissa Strohecker Leave a Comment

The tale of Hawaiian land snails began millions of years ago as the first plants and animals began to colonize the islands. Researchers don’t know exactly how snails arrived – perhaps stuck to the feathers of a bird or on a floating tree trunk. But in a remarkable story of evolutionary radiation, some 21 or more of those first species that arrived over the millennia gave rise to more than 750 distinct species. Of those, 99% are endemic to Hawai‘i – found here and nowhere else.

This species of Newcomb’s tree snail used to be widespread on Maui but today is only known from a handful of places in the West Maui Mountains thanks to habitat loss and invasive predators-rats and the rosy wolf snail. Baby snails, like this one riding on mom, are rare. Photo courtesy of Hank Oppenheimer

Famously varied in color and shape, Hawaiians called them pūpū kuahiwi, or high-hill snails. Early Europeans collected these jewels of the forest, selling them as lei or to collectors. These snails are still highly valued. Current efforts focus on saving remaining species; high-elevation snail refuges are built to protect them.

Often native snails are found only on one island, or in a single valley or ridge, teetering on extinction because of habitat destruction, shell collection, and invasive species. Adding to the challenges, many Hawaiian land snails reproduce at what is truly a snail’s pace: some species are 3-7 years old at first reproduction and have only 4-7 young per year. They grow slowly—only 0.2 to 0.4 cm a year. Compare this to the invasive giant African snail (Achatina fulica) which reproduce at one year of age, lays up to 600 eggs annually, and grows about 2.5 cm per year.

One species of snail endemic to Maui, Newcomb’s tree snail or Newcombia cumingi, was once found from Lahaina to Makawao, but like most land snails, has become increasingly rare during the latter half of the 20^th century. It was last seen in 1938 by Bishop Museum researchers then rediscovered in 1994 by resource managers with the Maui Land and Pineapple Company’s Pu‘u Kukui Watershed Preserve (PKW).

“One hundred years ago they [native snails] were everywhere,” explains Dr. Kenneth Hayes, a University of Hawai‘i researcher who, along many others, has been working to find out how many West Maui snails remain. Today, 50 percent or more are gone, many turned into escargot for invasive predators—rats, Jackson’s chameleons, and the rosy wolf snail. According to Hayes, the remaining native snails have mostly been relegated to the few areas that still contain native forest, but even these refuges won’t last long if we don’t stem the tide of invasive species. Native snails dine primarily on the fungi that grow on native plants. Invasive plants change the way water moves through Hawaiian watersheds altering the ecosystem by changing what plants, animals, fungi or microbes can live there. The snails’ preferred fungi may not grow in altered habitats.

Pomaikai Kaniaupio-Crozier, conservation manager with PKW, is leading efforts to protect the Newcombia. With US Fish and Wildlife Service funding and partner help they are planning an exclosure in the native forest of West Maui to keep hungry predators from munching native snails.

The West Maui “snail refuge” will be modeled after similar exclosures on O‘ahu, where the O‘ahu Army Natural Resources Program has enclosed three areas to keep out rats, chameleons, and even the predatory rosy wolf snail. A 4-foot tall sheet metal fence topped by a curved lip deters rats and chameleons. Predatory snails face sheet metal at an impossible-to-scale 10 degree angle– if they do manage they hit an electric wire. One fence is equipped with an electronic sensing system that alerts managers via text message if debris falls on the fence.

The first step in protecting Newcombia is a population survey. “They are the size of a pinky fingernail and very cryptic,” says Kaniaupio-Crozier. “It’s like finding the needle in the haystack, looking for something that small in 8,600 acres. Up until a couple months ago we were getting pretty demoralized.”

Then they made a remarkable discovery. They found a new population, in totally unexpected habitat. The existing Newcombia population inhabited a wet area with lots of ‘ōhi‘a; the new population was found on ‘ākia, in much drier terrain. “There’s hope there may be another population somewhere else.”

From survey to construction, building the snail refuge will take several years. You can help. PKW is welcoming people interested in habitat restoration, monitoring, even joining in the brainstorming. Contact Kaniaupio-Crozier at pkaniaupio-crozier@mlpmaui.com or by phone, 870-4225. To learn more about the native and non-native land snails of Hawai‘i, contact Ken Hayes, khayes@hawaii.edu, Norine Yeung, nyeung@hawaii.edu, or visit the Hawaiian Land Snail Conservation Facebook Page.

As with many conservation projects, the snail exclosure at Pu‘u Kukui involves many agencies and partners: US Fish and Wildlife Service, National Science Foundation, University of Hawai‘i Mānoa, O‘ahu Army Natural Resources Program, Department of Land and Natural Resources, Plant Extinction Prevention Program, and more.

By Lissa Fox Strohecker. Originally published in the Maui News, July 14th, 2013 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Conservation: Helping the Economy and the Environment

Posted on March 26, 2013 by Lissa Strohecker Leave a Comment

Darryl “Kanamu” Tau‘a was an East Maui tour bus driver who lost his job during the decline in tourism post September 11, 2001. Imi Nelson, a recent Hāna High graduate, was looking for work that would keep him close to his family. That fall, in response to the economic downturn, the Hawai‘i state legislature appropriated $1.5 million to create an emergency environmental workforce that put 450 people back to work. Kanamu got a temporary job controlling miconia, a South American tree invading the East Maui watershed. Imi joined the dengue fever response crew, helping to eliminate the environmental conditions that foster disease-spreading mosquitoes. Later, when the Maui Invasive Species Committee (MISC) had openings on its Hāna miconia control crew, both Kanamu and Imi had the necessary field experience. They landed permanent jobs—hard to come by in rural Hāna.

Conservation means jobs and those jobs mean new skills. Kona Ball and Darrell Aquino of MISC prepare to rappel down a cliff while Robert Vincent of East Maui Watershed Partnership looks on.

Conservation means boots on the ground and fingers on the keyboard. In Hawai‘i, it means jobs for thousands of people throughout the state, from Hāna to Honolulu, Hilo to Hanalei. Local suppliers and contractors provide goods and services for conservation projects, further multiplying the benefits of dollars spent. Natural resource work in Hawai‘i brings an estimated $456.6 million to the economy as wages, goods, and services, according to a report on the Green Industry from the University of Hawai‘i Economic Research Organization. Funding comes from a variety of federal, state, county, and private sources, with the bulk spent employing an estimated 3,275 people working in the field or office. In addition to wages, these jobs as technicians, researchers, hunters, construction workers, data managers, grant writers and accountants, educators, and managers often provide extensive training and skill-set development opportunities.

University research highlights other economic benefits of conservation work, which protects our water supply, food, beaches and reefs, and makes Hawai‘i a great place to live and visit. Natural resource management safeguards more than just native birds, plants, and insects. Almost all of the water Maui County uses is captured from rainfall, and a healthy watershed is key to maintaining adequate and safe water supplies. Economists estimate that if the Ko‘olau watershed on O‘ahu was rendered unusable and no longer contributing to the aquifer, the loss would be between $4.57 and $8.52 million.

A conservation worker learning to attach an external load to a helicopter.

Conservation jobs have been somewhat insulated from the turmoil of employment in the tourism sector. Despite a decline in state job growth of 1 percent over the last five years, jobs in natural resources have increased 1.5 percent. People working in natural resources think that jobs will increase modestly, an opinion likely shaped by concerns about the current state of the economy. In Hawai‘i, where we rely on the environment for so many things, there is plenty of work to be done. Approximately 800,000 acres across the main Hawaiian Islands are in some kind of active conservation management, though there are an estimated 1,900,000 acres of healthy native ecosystem needing protection.

Nelson and Tau‘a continue to live in a rural community, in part because they have jobs in conservation and have learned skills during their employment. Investments spent protecting our environment translate into jobs today and healthy resources for future generations. To find out more about green industry in Hawai‘i check out the Green Growth Report by the University of Hawai‘i Economic Research Organization online at www.uhero.hawaii.edu.

By Lissa Fox Strohecker. Originally published in the Maui News, Feburary 10th, 2013 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.

Help Hawai‘i–harvest a Christmas tree

Posted on December 13, 2011 by Lissa Strohecker Leave a Comment

‘Tis the season, and tradition calls for pine trees to decorate Maui residents’ homes, although there are many palms decorated in Christmas lights as well. Most Christmas trees are shipped in, but there’s a history of growing pines in Hawai‘i. Ralph Hosmer, Hawai‘i’s first forester, came on the job in 1904. At the time, forests throughout Hawai‘i were in a sorry state. Since Polynesian times, people have greatly altered lowland forests, initially for settlement and taro cultivation, then for sugar cane and pastureland. Feral pigs, goats and cattle escaped into intact forests, trampling shallow-rooted plants and browsing slow-growing plants. Honolulu, prospering from the sugar boom, was exceeding existing water supplies by the 1870s. Recognizing the need to protect and restore vital watersheds, everyone from sugar cane barons to King Kalākaua began fencing out animals and planting trees, some of which were pines.

Mexican weeping pine (Pinus patula) creeps into the native forest of the Waikamoi preserve. Forrest and Kim Starr photo

Hosmer helped turn sentiments about forest protection into cohesive action. He established the first forest reserves in Hawai‘i, beginning in 1906 when Alexander & Baldwin ceded management of acreage on Maui to the territorial government. With newly acquired land, Hosmer accelerated efforts to fence out cattle and goats and planted fast-growing hardy trees. The goals were three-fold: to stop erosion, restore the watershed and provide for Hawai‘i’s timber needs. Hosmer’s experimental plantation high on the slopes of Haleakalā now bears his name, “Hosmer’s Grove.” He planted species familiar from his Mainland forestry background: redwood, ash and pines. For years to come, foresters continued planting non-native species. These trees did prevent erosion on overgrazed lands, but some escaped cultivation to invade nearby ecosystems and crowd out native species.

Three species – Monterey pine (Pinus radiata), Mexican weeping pine (Pinus patula) and maritime pine (Pinus pinaster) – are particularly invasive. They persistently threaten Haleakalā National Park and The Nature Conservancy’s Waikamoi Preserve, transforming native stands into pine forests. Pines grow fast, up to one foot per year and reach maturity quickly, producing seeds within six to eight years. A massive amount of tiny seeds spread easily on the wind, help these pines colonize new areas. Removing pines has proven essential to maintaining the shrub-land and alpine habitat of Haleakalā.

Over the years, crews at Haleakalā National Park have stopped a veritable woodland of pines. Bill Haus and the crew he works with have removed 87,920 pines from the park and surrounding areas since 1982. According to Natural Resource Program Manager Steve Anderson, “Without control, the slopes of the subalpine shrub land would be a pine forest.” Subalpine shrub land is critical habitat for a native plants and animals; conversion to a pine forest would turn this rare Hawaiian ecosystem into a biological desert – no native plants like māmane, pūkiawe, ‘ōhelo or ‘a‘ali‘i; no native birds like the ‘i‘iwi and ‘amakihi.

Monteray pine (Pinus radiata) growing inside Haleakalā crater alongside silverswords. There have been a flush of pine seedlings inside the crater in the last few years. Forrest and Kim Starr photo.

Pines threaten the crater as well. Haus and his crew have removed more than 1,500 pines from inside the crater, with a peak of 778 in 2010.

Anderson said: “I wouldn’t have thought it was possible (for the crater to become a pine forest) several years ago, but it’s clear that potential exists now.”

The recent flush of pine could be the result of the 2007 Polipoli fire. Pines, including those invading Haleakalā Crater, are serotinous, meaning certain pine cones are coated with a waxy substance. These cones stay closed until the heat of a fire melts the coating to release seeds. As an ecological adaptation, it helps pines take advantage of the ash-fertile conditions following a fire. But in Hawai‘i, this adaptation may offer a unique seed-scattering advantage. The Polipoli fire possibly spurred a huge seed release and associated winds carried the seeds into the crater. Pine seedlings are even growing alongside silverswords.

You can help protect the crater from pines, and take home a pine tree! Several organizations will be working with volunteers to remove pines in time for the holidays. Friends of Haleakalā National Park leads efforts to remove pine trees from the crater. Check out their website at fhnp.org for more information.

The Nature Conservancy will be working below Hosmer’s Grove on Dec. 17. Call or email Pat Bily at 856-7665 or pbily@tnc.org for details and to confirm attendance. Both trips are free and open to the public. Dress for wintery weather and bring rain gear, water, tools and rope to bring home your tree or wreath making supplies. Participants also may bring food. Eggnog is optional.

By Lissa Fox Strohecker
Originally published in the Maui News, December 11, 2011 as part of the Kia‘i Moku Column. Check out all of the MISC articles in the Kia`i Moku series at: www.hear.org/misc/mauinews/

Plans in the Pipeline to Protect ‘Ōhi‘a From ‘Rust’

Posted on December 1, 2011 by Lissa Strohecker Leave a Comment

Puccinia psidii or “ohia rust” is found on the leaves of an ohia tree. Rob Anderson photo

It starts with a spot, a tiny dot of orange on a leaf bound for Hawai‘i. It could be on cut foliage destined for a florist or on a tree fated for a Hawai‘i yard. The miniscule speck of orange grows, produces spores, and covers the plant. Hawai‘i’s moist climate creates the perfect habitat for the little orange organism, a type of fungus known as a rust that attacks plants—often fatally. The trade winds spread the rust spores to more hosts and within months trees across Hawai‘i have turned brown, lost their leaves, and begun to die.

If a new strain of this fungus rust arrives in Hawaii it could devastate ohia forests. Orange rust fungus covers the leaves of a rose apple tree. FOREST & KIM STARR photo

In 2005 the rust attacked an invasive tree in the myrtle family–rose apple, but the rust grows on many myrtaceae species, including ‘ōhi‘a. The Hawai‘i Department of Agriculture identified the rust as Puccinia psidii and named it “‘ōhi‘a rust” in recognition of its impact on ‘ōhi‘a. If a new strain of the rust arrives there is a very real chance that it will attack ‘ōhi‘a and cause the same level of damage as it did to rose apple. This could be devastating: ‘ōhi‘a makes up 80% of our native rainforest and is the keystone species in the watershed. In an effort to protect ‘ōhi‘a and our rainforest–the source of our water–the Hawai‘i Department of Agriculture is proposing a ban on the import of plants that could carry a new variety of the rust.

In 2008 HDOA implemented an interim rule, a temporary ban on the import of ‘ōhi‘a, but it was only active for one year. This new rule will protect ‘ōhi‘a as well as other, commercially important myrtle species, such as eucalyptus and ornamental trees.

‘Ōhi‘a covers nearly 1,000,000 acres in Hawai‘i, provides food for ‘i‘iwi, ‘apapane, ‘ākohekohe, and other rare birds; shelter for their nests; and habitat for native insects, snails, and other species.

Like a flu or a cold, there are different strains of rust. The strain of ‘ōhi‘a rust currently in Hawai‘i does kill ‘ōhi‘a seedlings, but very few. However, the impact could be much higher. To evaluate the rust’s threat, Hawaiian ‘ōhi‘a seedlings were grown in Brazil, the home range of the fungus. Researchers exposed the seedlings to various strains of the rust, some which proved deadly. These tests showed that a new rust strain is a potent threat to the Hawaiian forests and watersheds.

The ban will stop the import of plants and foliage of myrtle family that hitchhike into Hawai‘i from out-of-state or international sources. This material is commonly used in flower arrangements, but after the interim ban, many florists quit using eucalyptus as cut greens in flower arrangements. Local sources of eucalyptus can still be used, and in doing so, local jobs are protected along with ‘ōhi‘a. If growers want to import a myrtle species into Hawai‘i, they can do so after obtaining a permit and agreeing to quarantine the plant for one year.

Before the ban goes into effect HDOA will hold public hearings throughout the state. Buy local–support florists who use locally grown flowers and foliage, or use locally grown flowers and foliage yourself. By making this choice you are helping to protect ‘ōhi‘a and our forests. Visit www.hear.org/species/puccinia_psidii/ to learn more.

Article by Lissa Fox Strohecker

Originally published in the Maui News, October 9th, 2011 as part of the Kia‘i Moku Column.
You can find all the articles in the Kia‘i Moku series http://www.hear.org/misc/mauinews/