Hawaii's Silverswords, Endangered Species Bulletin MayJune 2000 Vol by qfg42964


									by Robert Robichaux,
                                                            Reintroducing Hawaii’s
Steven Bergfeld, Marie
Bruegmann, Joan Canfield,
Patrice Moriyasu, Tanya
Rubenstein, Timothy
Tunison, and Frederick
                                                               O       f the many endangered plant
                                                            species in the Hawaiian Islands,
                                                                                                           lates, however, the Mauna Loa
                                                                                                           silversword suffered a severe decline.
                                                            silverswords have the highest profile          The surviving individuals, numbering
                                                            due to their radiant beauty and the            fewer than 1,000 plants, are confined to
                                                            severity of the threats confronting them.      three small natural populations widely
                                                            The large-scale reintroduction of              scattered across Mauna Loa.
                                                            greenhouse-grown seedlings is raising              In addition to direct threats from
                                                            hopes for the recovery of these spec-          alien ungulates, Mauna Kea and Mauna
                                                            tacular endemic species, although              Loa silverswords may face serious
                                                            serious challenges remain.                     indirect threats from alien insects,
                                                                The Mauna Kea silversword                  especially ants and wasps. These alien
A Mauna Loa silversword being
planted at Kulani Correctional                              (Argyroxiphium sandwicense ssp.                predators have the potential to decimate
Facility. Inmates from the facility                         sandwicense) had an historical range           populations of native bees and moths
have participated in an innovative                          that encircled Mauna Kea volcano at            that serve as pollinators, thereby greatly
volunteer program to help with                              8,500-12,500 feet (2,600-3,800 meters)         limiting seed set in silverswords.
silversword reintroduction.                                 elevation on the Island of Hawai‘i.
All photos by Joan Canfield
                                                            Based on the records of early natural-         Partnership for Recovery
                                                            ists, this silversword grew in abundance           Though the threats are daunting, the
                                                            and was a dominant plant of the                outlook for recovery of Mauna Kea and
                                                            subalpine and alpine ecosystems. In the        Mauna Loa silverswords has brightened
                                                            late 1700s, European voyagers intro-           considerably in recent years. Key to this
                                                            duced sheep and other alien (non-              reversal of fortune has been a public/
                                                            native) ungulates to the island. The           private partnership between the Volcano
(Opposite page, bottom) Members of                          alien animals spread rapidly, with the         Rare Plant Facility, Hawaii Division of
the sunflower family (Asteraceae),                          sheep population on Mauna Kea                  Forestry and Wildlife, Fish and Wildlife
silverswords have a rosette form,                           eventually exceeding 40,000. As alien          Service, National Park Service, Biologi-
with dagger-shaped leaves that are                          ungulate populations increased,                cal Resources Division of the U.S.
densely covered by silvery hairs.                           silverswords declined severely in              Geological Survey, and Hawaiian
Most silverswords flower only once,
                                                            distribution and abundance, presumably         Silversword Foundation. The Rare Plant
after growing for 30-50 years, with
the majestic flowering stalks of
                                                            due to heavy browsing. The small               Facility has grown the large number of
large rosettes often exceeding 1.5                          natural population of silverswords that        silversword seedlings destined for
meters in height.                                           persists on Mauna Kea now contains             reintroduction, closely tracking the
                                                            only 42 plants, all of them confined to        pedigree (or parentage) of each one.
                                                            cliffs and rock faces that are inacces-        Different agencies in the partnership
                                                            sible to ungulates.                            have then overseen the outplanting
                                                                The Mauna Loa silversword                  effort in different parts of the historical
                                                            (Argyroxiphium kauense) suffered a             ranges. The non-profit Silversword
                                                            similar fate. Historically, this species was   Foundation has worked closely with all
                                                            common in moist to wet ecosystems              of the partners to facilitate the collabo-
                                                            between 5,000 and 8,900 feet (1,500            rative initiative. By sharing expertise,
                                                            and 2,700 m) on Mauna Loa and                  resources, and enthusiasm, and by
                                                            Hualalai volcanoes. Following the              emphasizing on-the-ground actions, the
                                                            introduction and spread of pigs,               partnership has made major strides
                                                            mouflon sheep, and other alien ungu-           recently with silversword reintroduction.

    In 1999, we outplanted more than              The major threat to the recovery of
2,500 silverswords on Mauna Kea,              silverswords (and many other endan-
bringing the total reintroduced popula-       gered plant species in Hawaii) contin-
tion to about 4,000. (About 1,500             ues to be alien ungulates. Even at low
Mauna Kea silverswords were success-          numbers, these animals can have severe
fully outplanted by the Division of           impacts. On the upper slopes of Mauna
Forestry and Wildlife between 1973 and        Kea, for example, where alien ungulate
1998.) We planted the seedlings at            populations have been greatly reduced
multiple sites in the State Forest Reserve.   by a court-ordered removal program,
Survivorship has varied among the sites       browsing still caused significant seedling
and with the time of planting, but has        mortality, and serious damage to adult
been exceptionally high in some cases.        silverswords, at some of the outplanting
Of the 1,200 seedlings planted in late        sites in 1999. Because alien ungulates
fall on the east slopes of Mauna Kea,         are still abundant on Mauna Loa and
for example, more than 99 percent have        Hualalai, all of our outplanting sites for
survived their critical first 9 months on     Mauna Loa silverswords must be
the volcano.                                  protected by fencing, which ultimately
    We also outplanted more than 1,000        constrains the scope of the reintroduction
silversword seedlings on Mauna Loa            effort. Alien insects may also continue
and Hualalai in 1999. They went to            to pose a significant threat to the health
                                                                                              The Volcano Rare Plant Facility is part of the Center
protected sites in Hawaii Volcanoes           of native pollinator populations.               for Conservation Research and Training of the
National Park, Kulani Correctional                The large-scale reintroduction              University of Hawaii. In addition to growing
Facility, and State Forest Reserves.          strategy for silverswords, implemented          thousands of silversword seedlings for
Again, survivorship has varied among          through our public/private partnership,         reintroduction each year, the facility has
the sites, but has exceeded 90 percent at     highlights both the opportunities and           successfully propagated more than 70 other
                                                                                              endangered and threatened plant species from the
some locations.                               challenges for recovery of other
                                                                                              Island of Hawai‘i.
    To ensure high genetic diversity in       endangered plant species in Hawaii.
the reintroduced silversword popula-
tions, we have implemented a con-                Robert Robichaux is President of the
trolled crossing program in which we          Board of Trustees of the Hawaiian
hand-pollinate flowering silverswords in      Silversword Foundation. Steven Bergfeld
both the field and greenhouse to              is a Forester with the Hawaii Depart-
produce seeds (see Bulletin Vol. XXIII,       ment of Land and Natural Resources,
No. 2-3). Although hand-pollinating the       Division of Forestry and Wildlife. Marie
plants can be challenging at times,           Bruegmann is a Botanist with the Fish
especially on Mauna Kea, where we             and Wildlife Service’s Pacific Islands
must perch precariously on steep cliffs       Ecoregion Office. Joan Canfield is
and rock faces, the program has               Deputy Director of the Pacific Island
enabled us to significantly increase the      Ecosystems Research Center (USGS/BRD/
number of founders (or parents) for the       PIERC), U.S. Geological Survey, Biologi-
reintroduction effort, and to balance         cal Resources Division. Patrice Moriyasu
their genetic representation among the        is a Horticulturist with the University of
seedlings that are outplanted.                Hawaii, Center for Conservation
    Over the next year, we plan to            Research and Training, Volcano Rare
outplant another 2,000 silverswords on        Plant Facility. Tanya Rubenstein is
Mauna Kea and 8,000 silverswords on           Olaa-Kilauea Partnership Coordinator
Mauna Loa and Hualalai. Thus, we will         at Hawaii Volcanoes National Park
soon be about 40-60 percent of the way        (HAVO). Timothy Tunison is Chief of
towards achieving our long-term goal of       Resources Management at HAVO.
reintroducing more than 15,000 Mauna          Frederick Warshauer is a Botanist with
Kea and Mauna Loa silverswords                USGS/BRD/PIERC.
throughout their historical ranges.

                                                                               ENDANGERED SPECIES BULLETIN   MAY/JUNE 2000 VOLUME XXV NO. 3    23

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