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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.

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.

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.

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

Filed Under: Kia'i Moku Column, Watershed impacts Tagged With: 2015, invasive species water impacts, water budget maui, water cycle in Hawaii, watershed threats

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

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.

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/

Filed Under: Get Involved!, Invasive Plants, Watershed impacts Tagged With: haleakala national park, harvest pines, invasive pine trees, invasive species, Mexican weeping pine in hawaii, Monteray pine in Hawaii, the nature conservancy, volunteer opportunity, watershed threats

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