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Restoration Recipe for Midway Atoll

Midway has experienced various eras of landscape alteration over the past century, but the atoll is now entering a phase of restoration.

When one imagines the Hawaiian archipelago, images of gently swaying palms, verdant vegetation, cool breezes, and ocean waves come to mind. But, going up the chain of islands, this green scene begins to change. Palms give way to low-growing grasses and herbs; warm, humid weather changes to pronounced dry spells. When members of the 1891 Rothschild Expedition landed upon Midway, they were startled to find a (seemingly) desolate island.

“What I am now on is what is known as Sand Island. This island is almost bare and has hardly any birds… It is the most desolate place I ever was on. There is hardly any vegetation…”

Prior to permanent human settlement, early depictions of Sand Island described it as low, sandy, and with little vegetation. However, this was soon to change. Not long after the arrival of the Commercial Pacific Commercial Cable Company in 1903, Midway was designated as “unfit for human habitation” by the operations manager—this, in turn, initiated the long process of introducing hundreds of new species to Midway.

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USFWS Volunteer Emma Struivig de Groot outplants native Sea Purslane / ʻĀkulikuli (Sesuvium portulacastrum), along the South Shore to help develop quality habitat for native flora and fauna. Photo credit: Jon Plissner.

William Bryan was the first botanist to document Midways plant diversity in 1902; at that time, he only found 13 species. Although this number seems relatively low, the Northwestern Hawaiian Islands are considered to be relatively depauperate in terms of flora. Small and incredibly remote, immigration rates (or avenues by which plants could somehow make it to Midway, by means of wind, sea currents, or even animals) for plants are quite low. Yet, over 100 years later, nearly 200 species of plants can be found on the atoll (most of which are invasive, exotic species) and up to 389 have been observed at one time or another.

Midway underwent a transformation from “an uninhabited shimmering white pile of sand” to an “oasis of green in a blue desert.” Over time, the physical shape and extent of the atoll’s islands as well as the plant communities evolved (by mechanical means rather than natural processes), giving way to one novel environment after another—that collectively define this atoll’s layered landscape. From 1906 through 1930, nearly 9,000 tons of topsoil were imported from Honolulu and Guam—and in the process, introduced unknown amounts of soil organisms, insects, and (perhaps the most damaging) weeds. Open herblands and coastal scrub were replaced with coconut, banana, passion fruit, and various exotic fruits and ornamental plants. Ironwood trees (Casuarina equisetifolia) were also imported to provide residents with shade and wind cover. As Midway evolved from cable station to luxury travel destination and then naval base to surveillance place, so, too, did the atoll’s plant communities. Each era on Midway ushered in new occupants, who all brought with them new plants: soft, short grasses for golf courses; various palms for a tropical backdrop; and the tastes of home, like cantaloupe and cabbage.

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B-24s on Eastern Island, Midway Atoll in 1943; note the lack of vegetation surrounding runways and areas of use. Photo source: National Archives.

What’s the problem with this approximate Eden and Midway’s many exotic plants? Exotic plants might be valued by human inhabitants for aesthetic purposes or to provide certain crops; indeed, myriad plant species have been introduced all over the world for various reasons. But, they can also completely disrupt and degrade habitat needed for wildlife—especially so on seabird colony with 3 million birds packed into 2.4 square miles.

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Golden Crownbeard carpeting nearly all of Eastern Island in November 2011.

Many of the introduced plant species on Midway have become invasive over time; in other words, they thrive in Midway’s environment to the extreme, causing issues for native wildlife and plants. For example, Golden Beardtongue (Verbesina encelioides) is competitive and aggressive plant species that once covered 70% of Midway’s islands, growing so dense and so tall in certain patches that albatross chicks were unable able to fledge and died. Other species, such as Ironwood trees, have shallow root systems and are prone to falling over during intense storms and winds, injuring and killing birds below. Wild poinsettia (Euphorbia cyathophora) grows rapidly and outcompetes native plants for light, water, and nutrients and disrupts breeding habitat. And the list goes on.

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As does the work. To create and maintain quality habitat for the 2-3 million seabirds that breed here each year, vegetation-related work is a significant part of day-to-day work on this atoll system. Often times, habitat management involves removing invasive plant species, transplanting cuttings of native species like Sea Purslane / ʻĀkulikuli  (Sesuvium portulacastrum), or working in the greenhouse on cloning dune-stabilizing species such as Bunchgrass / Kāwelu (Eragrostis variabilis) and Naupaka (Scaevola taccada). 

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A Laysan Albatross (Phoebastria immutabilis) found this tray of native Button Sedge / Mauʻu ʻakiʻaki (Fimbristylis cymosa) the moment USFWS volunteers put the tray on the ground to prepare for outplanting. This is why habitat restoration is so critical to Midway Atoll’s wildlife! Photo credit: Kristina McOmber.

Restoration of the quality habitat of native plants is critical to the long-term success and sustainability of the myriad species that occur here—and invasive plant management is a key part of that. Although invasive plant management is a meticulous process, recovery is possible. For Midway Atoll NWR, though, restoration is not necessarily straightforward or simple. At first glance, Midway might evoke this idea of an isolated, pristine environment. However, after decades of dredging, building, digging, moving, and bulldozing, the atoll is far from it. As such, the traditional definition of ecological restoration doesn’t really describe current management to develop high-quality habitat for Midway’s diverse flora and fauna. Restoration is not simply going back to a time that once was. Instead, Midway is in a new era: the era of restoration—of what will be.

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Male Laysan Duck (Anas laysanensis) among native Nohu (Tribulus cistoides) on Eastern Island, Midway Atoll NWR. Photo credit: Wieteke Holthuijzen

We now face the challenge of managing this atoll system as the foundation of a robust and diverse seabird colony; to do so, we need to understand the past, be aware and adaptive to current needs of plants and wildlife alike, and think critically and creatively for the future. How do we restore an environment that is so drastically different than it was a century ago to a functioning ecosystem? What delineates a functioning ecosystem from one that is not quite so?

We have the honor to study and opportunity to restore this atoll system to a thriving, resilient refuge for native flora and fauna. And now, the need for safe, quality breeding habitat is all the more important as Midway’s wildlife face a new threat—invasive, predatory mice. Island Conservation and our partners are going to remove them in July 2020 and restore the balance on the Atoll, but we need your help. Learn more at http://www.noextinctions.org/.

Featured photo: Field of Albatross on Midway Atoll. Credit: Gregg Howald/Island Conservation

About Wieteke Holthuijzen

Wieteke Holthuijzen is a National Science Foundation graduate fellow at Northern Illinois University, where she studies the ecological impacts of introduced house mice on Midway through a collaborative research effort with Island Conservation and the U.S. Fish and Wildlife Service. Previously, Wieteke served as the Invasive Plant Control Specialist on Midway, helping to restore the atoll to a bustling seabird colony. She is intrigued by the nexus of nature and human presence and seeks to study and contribute to the conservation of imperiled species. In her spare time, she enjoys playing the cello, ukulele, banjo, and electric bass.

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