Loosely translated, liko nā pilina means "Budding (or growing) new partnerships (or relationships)" in the Hawaiian language. We chose this name for the project because our goal is to create hybrid communities to restore degraded Hawaiian lowland wet forest, using both native and non-invasive, non-native species (which we call exotic species). In other words, we are creating new forests using some plants which evolved in Hawai'i and others that have come here from around the world. For example, our plots include Hawaiian ōhi'a (Metrosideros polymorpha) and kōpiko (Psychotria hawaiiensis), as well as kukui (Aleurites moluccana, also known as candlenut in Australia) which arrived in Hawai'i with the Polynesians, and mango (Mangifera indica) which is a much more recent arrival (and is originally from India).Share this page!
The Hawaiian archipelago, like other oceanic islands, is very susceptible to biological invasions. Because of the archipelago's long isolation, it became home to unique flora and fauna which evolved on the islands. Although Hawaii's native biodiversity was relatively low (especially in comparison to other tropical biomes), the rates of endemism on the islands were very high. With the arrival of humans came a variety of new species and the extinction of some native species. In particular some species which have been introduced have become invasive- that is, they thrive in their new habitat to the extent that they are detrimental to native species and ecological functioning of native ecosystems. Lowland wet forests in Hawai'i have been hit especially hard by human activities and invasive species, to the point where there are very few of these forests left. The forest at our study site, the Keaukaha Military Reservation (KMR), is important because it still has native species in the canopy, particularly ‘ōhi'a, lama (Diospyros sandwicensis) and kōpiko. However, the presence of a multitude of invasive species means that even though the native species are present, there is very limited recruitment of seedlings happening. In other words, while the adults are surviving, few-if-any seedlings are surviving into adulthood. It's a case of 'dead men standing': when the existing adults die, this forest will become wholly made up of exotic and invasive species. Our project has two main goals; the first is to restore the forest in line with the land manager's (KMR) wishes. This means putting together a forest community that minimizes ongoing management costs and effort, enhances carbon storage, creates an open understory and benefits native biodiversity. The second goal is to test hypothesis about community assembly in a complex rainforest environment. To accomplish these goals, the first step was to remove the invasive species from our study plots. While 'weeding' sounds fairly simple and straightforward, things become a little more complicated when your weeds happen to be ~30 meters tall and have multiple trunks which are fairly entangled with other trees in the high canopy!!
The first step was to clear our plots of invasive species- this took us nearly a year to accomplish! The next, and very exciting, step was planting! But how did we choose what species to plant? We used a system based on plant species' functional traits, a series of measurements that can give you an idea of a species' functional role within a given environment. For example, data from leaf chemistry and wood density can tell you what sort of strategy (on the "live fast, die young" - "grow conservatively and slowly" spectrum) a species uses. We also collected data on seed mass (to get an idea of reproductive output/costs/dispersal), light use and water use, etc... In total we looked at 15 traits for nearly 40 species of native and exotic species.
Liko Na Pilina hybrid ecosystems project now collects data from 20 plots within the Kilauea Military Reserve degraded forest area. Of these 20 plots, 4 separate treatments and 1 control are tested in 4 separate locations. Each cycle, Liko Na Pilina staff and volunteers to collect data and analyze plot treatments and forest development. Some of these processes include:
Separating out leaf litter fall by species, litter is buried in mesh containers and left to decompose for 6 months, then retrieved and analyzed by observing the level of decomposition. Larger leaf pieces are picked out of each sample (measured roughly in quadrants and by existing species tag numbers) and finer samples are burned away to analyze leftover material. When organic material is burned off, remaining minerals can be weighed to help determine decomposition levels of specific species and treatments.
Nutrient absorbing beads (primarily measuring nitrogen and phosphorous) are placed inside of mesh pouches and buried in quadrants and by specifically selected out-plant species. These are left under heavy tropical rains for a set period of time where soil nutrient levels are collected and processed later in laboratories. Prior to deployment, bags are constructed and processing material are sanitized through acid washing. Levels of nutrients collected by each sample bag provide information about differing levels of soil nutrients in each quadrant and plot area, to compare plot treatments to controls.
Seed and Leaf Litter Collections
Liko Na Pilina crew and volunteers collect leaf and seed fall samples from each plot monthly, these are processed by weight and species. We measure differences in quantity of litter and seed fall from each species compared with plot treatments. Seeds from native and outplant species are measured over the long term. This contributes to long term plot treatment analysis.
Every cycle, native seedling growth is measured within meter by meter areas in each treatment and control plot. We count seedings of all known native and endemic plant species found within each plot, and compare these against different treatments.
Other experiments at KMR:
Pilina crew also assists with a guava thrip biocontrol study, light measurement studies, and phrenology among other collaborative projects.
Rebecca Ostertag (University of Hawai'i at Hilo), Susan Cordell (USDA Forest Service at the Institute of Pacific Island Forestry) and Peter Vitousek (Stanford University) are the principal investigators. Other UH Hilo team members include Nicole DiManno, and formerly Jodie Schulten. Other Forest Service staff include Amanda Uowolo and formerly Taite Winthers-Barcelona and Laura Warman. Other Stanford people include Bill Buckley- our chainsaw-meister and artist extraordinaire, and Donnie Rayome, our new postdoc.
We’ve had many interns work on the project. Funding was provided by the Strategic Environmental Research and Development Program (SERDP), which is administered by the Department of Defense (Grant # RC-2117) Importantly, we've had an amazing group of volunteers, visitors and interns without whose help we would not have gotten as far as we have!
Thank you all!
We are using a mix of native and exotic species because native species alone (at least in KMR) are unable to maintain their recruitment levels and keep the invasive species out. Previous work at KMR has shown that invasive species quickly recolonize plots after removal. Although maintaining plots relatively weed-free becomes a lot easier after the invasive seed bank is exhausted, this still involves hundreds of intensive people-hours in the field. This is not feasible for KMR either from an ecological or economic perspective. It's not that we don't think native species should be used... we just think restoring this site to a functional forest (which includes native species, and their seedling recruitment) is more feasible if we mix native and exotic species.
Based on species traits, our hypothesis is that using a mixture of species will create a more diverse and complementary "trait space", than if we just used native species. In other words, it will be harder for the invasive species to get a foothold and outcompete the rest of the plants in a "hybrid" community than in a solely native one. This means that our hybrid communities should be able to sustain themselves with a lot less management (after the initial push) than a community made up only of native species. An important thing to mention is that we are not even thinking of introducing new species to the Big Island! All of the species considered have been here for quite some time, have shown not to be invasive here, and, in many cases, are already found in East Hawai’I Island.
Plants found in plot treatments include:
Mangifera indica, Mango
Calophyllum inophyllum, Kamani
Aleurites moluccana, Kukui
Thespesia populnea, Milo
Pandanus tectorius, Hala
Pritchardia beccariana, Loulu
Pipturus albidus, Māmaki
Rhus sandwicensis, Neneleau
Morinda citrifolia, Noni
Tetraplasandra hawaiensis, ‘Ohe
Syzygium malaccense, Mountain Apple/’Ohi’a ‘Ai
Cocos nucifera, Coconut/Niu
Antidesma platyphyllum, Hame
Cibotium glaucum, Hapu´u Pulu (G)
Cibotium menziesii, Hapu´u I´i (M)
Psydrax odorata, Alaheʻe
Samanea saman, Monkeypod
Artocarpus altilis, Ulu/Breadfruit
Myrsine lessertiana, Kōlea lau nui
Download plant species flashcards!
For more photos of the project, visit the gallery
October 2015- Seedling studies, established plant measurements on growth, seed input and litterfall, and maintenance have been part of regular Pilina objectives this past year, we have also continued phenology studies, soil decomposition experiment and are now wrapping up the two year count of Ohi'a seeds. The site and crew has managed through several natural disaster warnings and plots remain intact and resilient.
September 2014- We were fortunate that our plots did not receive any damage from Hurricane/Tropical Storm Iselle, and we are a long way from the current lava flow coming from Kilauea volcano. Our first seedling monitoring effort was a great success! The results are in, and we have more than two orders of magnitude of native seedlings per m2 in our treatment plots than in our reference plots. In other words- while in the reference plots there is less than one seedling per square meter, some of our treatment plots have more than 10 seedlings in the same area!
January 2015- Official start of the experiment. All seedlings planted!
Cordell S, et. al. 2016. Quandaries of a decade-long restoration experiment trying to reduce invasive species: beat them, join them, give up, or start over? Restoration Ecology 24(2): 1-6.
Cordell S, et al. 2009. Evaluating barriers to native seedling establishment in an invaded Hawaiian lowland wet forest. Biological Conservation (142): 2997-3004.
Ostertag R, et. al. 2015. Using plant functional traits to restore Hawaiian rainforest. Journal of Applied Ecology 52(5): 805-809.
Ostertag R, et al. 2009. Ecosystem and restoration consequences of invasive woody species removal in Hawaiian lowland wet forest. Ecosystems (12): 503-515.
Applied Ecologists blog
Environment Hawaii (pg. 9-10)
University of Hawai'i News
UH Hilo Chancellors Blog
Susan Cordell's After Dark In the Park presentation
SERDP newsletter 22 Sep 2014
USDA Climate Hub
Computer science students Hybrid Ecosystems Inspired REST Program
Restoring Ecosystems Services Tool, or REST for short, is an analytical software designed for use by Biology researchers and land resource managers to assist in restoring or developing local ecosystem functions.
REST uses functional trait analysis to process plant species data that can help users to develop plot treatments similar to those found at Liko Na Pilina experimental site, using climate appropriate and complimentary native and exotic plant species.
download REST here!
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