KMWP 2022 Biannual Impacts

KMWP support staff were busy in the first half of 2022. Activities accomplished are steps to protect and sustain the forests, waters, and people of the Ko‘olau Mountains.

High temperatures, dry air, and degraded soil are just some of the conditions that are present at the Ala Mahamoe Restoration Site, located in Moanalua Valley on O‘ahu. The Koʻolau Mountains Watershed Partnership (KMWP) and volunteers have been managing this restoration site since 2017 and it has come with many challenges. The amount of labor it takes to maintain the invasive weeds and ensure the native plants are getting water is a huge undertaking. However, KMWP has been working on solutions to decrease the mortality rate of native out plantings at Ala Mahamoe. In February 2021, KMWP support staff planned and planted native tree species incorporated with hydrogel granules and monitored its progress to date.

Hydrogel granules are non-toxic, water-storing polymers that can reduce plant watering by 50% and prevent soil compaction. Hydrogel granules absorb up to 300 times their own weight in water. When installed around new plantings, these granules slowly release moisture into the surrounding area, allowing the plant to potentially have a source of hydration and decreased temperatures in arid conditions.

Tree species hala (Pandanas heliotropus) and kou (Cordia subcordata) were planted in a 5-meter by 15-meter fenced clearing. KMWP does not use herbicide on invasive species at the Ala Mahamoe Restoration Site, so manual weed removal methods were used. Guinea grass (Megathyrsus maximus) clumps were uprooted and haole koa (Leucaena leucocephala) trees were cleared and stumps were scraped.

The clearing was split into three plots. Each plot was planted with 8 hala and 8 kou alternating. Plot A contained trees planted with hydrated granules. Plot B contained trees planted with dehydrated granules, and Plot C was the control with no granules installed. A total of 48 trees were planted and all were given 2 liters of water at their initial installation only.

To measure survivability, KMWP measured tree height and visual health biweekly for 1 year. During the winter season, ground cover seeds were distributed to assist with erosion from the rainy season. Additionally, KMWP continued invasive grass and tree seedling removal during visits.

Preliminary results showed hydrated granules were not as successful as dehydrated granules. All three plots showed high survivorship with regular maintenance. But, plot B (dehydrated granules) had the highest growth rate for kou and the highest survivorship for both kou and hala. Plot A (hydrated granules) had the slowest growth rate out of all plots. It is possible that Plot B was located in a drainage ditch, increasing the moisture levels compared to plots A and C. Plot C (no granules) hala growth was higher than either plot with granules.

Based on this snapshot of time that KMWP measured the trees, the general results showed that the survivorship of native tree plantings may increase with the implementation of these factors: installing a temporary fence, removing invasive plants regularly, and planting with dehydrated granules. The best use of hydrogels would be during the dry season when more water retention is needed. Hydrogel granules seem to provide the best results when installed in a dehydrated state. Plot B was the only plot where all trees survived over the year.

After discussions at the Hawaiʻi Conservation Conference and other partners using similar methods, KMWP continues to use dehydrated granules in drier restoration areas with the agreed amount of 1 teaspoon of dehydrated granules per plant installation. If considering using hydrogels in your plantings, KMWP advises discussing methods with other restoration partners using this application to learn and collaborate on future improved methods.

"It is a time to spend together in the community and learn together about this generous gift of 246 acres that we are blessed to steward." - First Presbyterian Church of Honolulu

KMWP staff supports the mission of its landowners. We are happy to highlight one of our newest landowning partners: First Presbyterian Church of Honolulu!

What activities does FPC do in the field for monitoring our watershed health?

Only 6 years ago, the company managing the golf course had completely clear-cut the trees between the fairways. All those trees and vegetation had been completely removed, and you could see from one hole to the next and on to the end of the course, unencumbered. In just a year and a half, all those areas blossomed again with life. One negative outcome of clearing all those areas was the explosion of invasive species populations. The seeds of albizia trees (Falcataria moluccana) took the most advantage of the flood of sunlight to the fertile, moist ground of those once cleared areas. Today, the property now has towering albizia trees. In the wet, mesic climate of the Koʻolau Mountains, these invasive trees show us the importance of our role in restoring the land and the healing that is needed. We want to be active participants in protecting the land.

KMWP has been an integral part of our restoration activities. We invite the community to join us on the last Saturday of each month for our Pilina Restoration Day where we connect to ʻāina and each other. On our inaugural Pilina Day, KMWP taught attendees how to hand girdle small-diameter albizia trees. In what would cost millions of dollars to cut down, we have girdled over 1,000 albizia trees with volunteer help and the knowledge imparted by KMWP.

We additionally have a native planting site, we affectionately call the “ʻEkaha planting” because of a beautiful big native ʻEkaha fern that was found near the surrounding plants. The site was originally cleared of non-native plants to protect large outdoor appliances that were being damaged by fallen debris. It now is a showcase of native plants including ma'o hau hele (Hibiscus brackenridgei), koa (Acacia koa), koki'o ke'oke'o (Hibiscus arnottianus), and lama (Diospyros sandwicensis). KMWP crew arrived and helped in the creation of the site with the initial plantings and laying down the weed mat. The ʻEkaha Planting site really serves as a showcase to those visiting the church.

What are FPC strategies to engage and educate residents and stakeholders to understand water resources?

We hope to engage the community through our Pilina Restoration Days. It is a time to spend together in the community and learn together about this generous gift of 246 acres that we are blessed to steward.

We have hosted a Citizen Forester Program with Smart Trees Pacific and Kaulunani Forestry Program. Through this program, we walked the entire cart path and recorded all large-diameter trees on the former course. We now know the types, sizes, and environmental and ecological benefits of all large-diameter trees on this ʻāina.

We also hosted a cultural study with Nohopapa, through the Windward Community College. Two interns completed their research of the stories, talked to kupuna (elders), and pulled archeological historic documents to create a sense of place. Currently, we are in a time of learning all that we can in order to be good stewards of this land.

What goals does FPC have for managing land?

Our current target invasive species is albizia. We will also be removing large African tulip trees (Spathodea campanulata) and are learning about other species to focus our attention on. We also use the kipuka management strategy to slow the spread of invasive species.

The sand traps throughout the old golf course have proven to be hard to maintain. So, we are planting koa (Acacia koa) and hala trees (Pandanus tectorius) inside the bunkers and sand traps to see if we can provide enough shade to create small native plant oases' throughout the course.

How can stakeholders get involved in preserving water and perpetuating watershed health?

We hope to engage the community through our Pilina Restoration Days.

These stories are just highlights of the first half of 2022. KMWP continues the mission to protect our Koʻolau Mountains and the watershed systems and we look forward to sharing more stories and impacts!

Keep up to date on all things KMWP at  koolauwatershed.org ,  Facebook ,  Instagram , and  Twitter .