Dubautia herbstobatae
Encyclopedia
Dubautia herbstobatae is an endangered species
of shrub
which is endemic to Oahu
, Hawaii
.
This member of the silversword alliance
is a spreading shrub
that produces yellowish-orange flowers. Leaf size and arrangement vary from plant to plant. This shrub grows mainly in moist areas and is known to grow well on ridges and steep slopes. It is found in dry-mesic
to mesic habitat
s. It can often be found on open, north facing rocky slopes and cliff faces. The vegetation of habitats in these locations is usually sparse shrubland and scrubby forest grounds (U.S. Fish and Wildlife Service Pacific Islands Fish and Wildlife Office).
This species is known only from Ohikilolo Ridge and Keaau Valley in the Waianae Mountains on Oahu. The Hawaiian Islands
are the most isolated islands in the world in terms of distance from other land masses. The Hawaiian Islands also have a high diversity of habitat types. This isolation is part of the reasoning behind the Dubautia herbstobatae and other Hawaiian species being included on the Endangered Species List
. There is a limited amount of habitat appropriate for island species.
, especially by wildfire
, and introduced species
, particularly feral hogs
and goat
s.
Stochastic
events in the small populations that make up the species include environmental threats such as invasion of the habitat by tourists
and catastrophes such as fire and landslides.
has developed and implemented a plan to monitor this endangered species. It has designated critical habitat for Dubautia herbstobatae in two units totaling 198 acre (0.80127828 km²) on Oahu. The land consists of habitat on both state and private land. This land can be more easily monitored for threats to the species.
Recovery objectives include maintaining at least three naturally reproducing populations. When this objective is met, the species will be classified as stable. Actions include seed collection for genetic storage, fencing
select patches of plants within populations for short-term protection, surveying for populations in historical sites and suitable habitat, studying D. herbstobatae populations with regard to population size and structure, geographical distribution, flowering cycles, pollination
vectors, seed dispersal
agents, longevity, specific environmental requirements, limiting factors and threats, and reintroducing individuals into suitable habitat.
The U.S. Army is scheduled to manage the Makua Valley and the Makaha side of Kamaileunu Ridge in Hawaii. Currently, the U.S. Army is focusing on two largest populations at Ohikilolo. The goal of the U.S. Army monitoring these areas is to completely eradicate the goats in these areas. The Army has also put up a fence that runs along the southern perimeter of the Makua Valley to prevent goats from entering from adjacent valleys.
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
of shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
which is endemic to Oahu
Oahu
Oahu or Oahu , known as "The Gathering Place", is the third largest of the Hawaiian Islands and most populous of the islands in the U.S. state of Hawaii. The state capital Honolulu is located on the southeast coast...
, Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
.
This member of the silversword alliance
Silversword alliance
Silversword alliance refers to an adaptive radiation of over 50 species in the composite or sunflower family, Asteraceae. The group is endemic to Hawaii, and is derived from a single immigrant to the islands...
is a spreading shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
that produces yellowish-orange flowers. Leaf size and arrangement vary from plant to plant. This shrub grows mainly in moist areas and is known to grow well on ridges and steep slopes. It is found in dry-mesic
Dry-mesic prairie
Dry-mesic prairie has a high forb diversity and low percentage of grass cover. Dominant species are porcupine grass and Canada blue-joint grass....
to mesic habitat
Mesic habitat
In ecology, a mesic habitat is a type of habitat with a moderate or well-balanced supply of moisture, e.g., a mesic forest, a temperate hardwood forest, or dry-mesic prairie. Compared to a dry habitat, a mesic habitat is moister....
s. It can often be found on open, north facing rocky slopes and cliff faces. The vegetation of habitats in these locations is usually sparse shrubland and scrubby forest grounds (U.S. Fish and Wildlife Service Pacific Islands Fish and Wildlife Office).
This species is known only from Ohikilolo Ridge and Keaau Valley in the Waianae Mountains on Oahu. The Hawaiian Islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
are the most isolated islands in the world in terms of distance from other land masses. The Hawaiian Islands also have a high diversity of habitat types. This isolation is part of the reasoning behind the Dubautia herbstobatae and other Hawaiian species being included on the Endangered Species List
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
. There is a limited amount of habitat appropriate for island species.
Current status
Dubautia herbstobatae was listed as an endangered species by the US Government in 1991. At the time, fewer than 100 of the plants existed. With the implementation of a management plan, that number rose to roughly 500. The number has again grown, and current estimate of the population is around 1,200 individuals.Threats
The two main forces threatening D. herbstobatae are habitat destructionHabitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
, especially by wildfire
Wildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
, and introduced species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
, particularly feral hogs
Pig
A pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...
and goat
Goat
The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s.
Stochastic
Stochastic
Stochastic refers to systems whose behaviour is intrinsically non-deterministic. A stochastic process is one whose behavior is non-deterministic, in that a system's subsequent state is determined both by the process's predictable actions and by a random element. However, according to M. Kac and E...
events in the small populations that make up the species include environmental threats such as invasion of the habitat by tourists
Tourism
Tourism is travel for recreational, leisure or business purposes. The World Tourism Organization defines tourists as people "traveling to and staying in places outside their usual environment for not more than one consecutive year for leisure, business and other purposes".Tourism has become a...
and catastrophes such as fire and landslides.
Management
Current research areas involving D. herbstobatae include population estimates, estimates of destruction, success rate of plants reintroduced into the habitat, and the changing roles of the plant's threats. The Pacific Islands Fish and Wildlife Office of the United States Fish and Wildlife ServiceUnited States Fish and Wildlife Service
The United States Fish and Wildlife Service is a federal government agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats...
has developed and implemented a plan to monitor this endangered species. It has designated critical habitat for Dubautia herbstobatae in two units totaling 198 acre (0.80127828 km²) on Oahu. The land consists of habitat on both state and private land. This land can be more easily monitored for threats to the species.
Recovery objectives include maintaining at least three naturally reproducing populations. When this objective is met, the species will be classified as stable. Actions include seed collection for genetic storage, fencing
Fence
A fence is a freestanding structure designed to restrict or prevent movement across a boundary. It is generally distinguished from a wall by the lightness of its construction: a wall is usually restricted to such barriers made from solid brick or concrete, blocking vision as well as passage .Fences...
select patches of plants within populations for short-term protection, surveying for populations in historical sites and suitable habitat, studying D. herbstobatae populations with regard to population size and structure, geographical distribution, flowering cycles, pollination
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
vectors, seed dispersal
Seed dispersal
Seed dispersal is the movement or transport of seeds away from the parent plant. Plants have limited mobility and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from the parent plant...
agents, longevity, specific environmental requirements, limiting factors and threats, and reintroducing individuals into suitable habitat.
The U.S. Army is scheduled to manage the Makua Valley and the Makaha side of Kamaileunu Ridge in Hawaii. Currently, the U.S. Army is focusing on two largest populations at Ohikilolo. The goal of the U.S. Army monitoring these areas is to completely eradicate the goats in these areas. The Army has also put up a fence that runs along the southern perimeter of the Makua Valley to prevent goats from entering from adjacent valleys.
External links
- Dubautia spp. in Hawaiian Native Plant Propagation Database. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. (accessed March 10, 2011).
- The Hawaii Rare Plant Restoration Group