''Arctostaphylos confertiflora'' is a rare species of

manzanita Manzanita is a common name for many species of the genus ''Arctostaphylos''. They are evergreen shrubs or small trees present in the chaparral biome of western North America, where they occur from Southern British Columbia and Washington to Or ...

known by the common name Santa Rosa Island manzanita. This

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

, where it grows on the

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

bluffs of Santa Rosa Island in the

Channel Islands The Channel Islands ( nrf, Îles d'la Manche; french: îles Anglo-Normandes or ''îles de la Manche'') are an archipelago in the English Channel, off the French coast of Normandy. They include two Crown Dependencies: the Bailiwick of Jersey, ...

. This manzanita is listed as an

endangered species An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inv ...

by the United States Government.

Description

This is a small, twisting manzanita with blood red to gray bark and glandular bristles on its branches. The leaves are light, dull green, and hairy or bristly. The small flowers are rounded and milky white, less often pale pink, and bunched densely in

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...

s. The fruits are fuzzy

drupe In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...

s around 1 centimeter (0.4 in.) in diameter. The plant can grow to about 1.8 meters (6 ft.).

Ecology

Pollinators

European Honeybees,

bumblebee A bumblebee (or bumble bee, bumble-bee, or humble-bee) is any of over 250 species in the genus ''Bombus'', part of Apidae, one of the bee families. This genus is the only extant group in the tribe Bombini, though a few extinct related gener ...

s, and

hummingbird Hummingbirds are birds native to the Americas and comprise the biological family Trochilidae. With about 361 species and 113 genera, they occur from Alaska to Tierra del Fuego, but the vast majority of the species are found in the tropics aro ...

s all

pollinate Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, a ...

the Santa Rosa Manzanita.2007, Sants Rosa Island Manzanita (Arctostaphylos confertiflora) 5-Year Review: Summary and Evaluation, US Fish and Wildlife Service

Habitat

The Santa Rosa Manzanita inhabits

chaparral Chaparral ( ) is a shrubland plant community and geographical feature found primarily in the U.S. state of California, in southern Oregon, and in the northern portion of the Baja California Peninsula in Mexico. It is shaped by a Mediterranean c ...

and

conifer Conifers are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single ...

forest habitats on Santa Rosa Island. These areas have a usual

climate Climate is the long-term weather pattern in an area, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteorologic ...

of wet winters and dry summers. The habitat also experiences cyclic fire disturbance.

Range

The manzanita is found exclusively on Santa Rosa Island in the Channel Islands in California. The plants are found mainly on the eastern side of the island, where there are two sizable populations - one on Black Mountain and one on South Point. The Black Mountain population is the most significant. There are no accurate population estimates.2021, Sants Rosa Island Manzanita (Arctostaphylos confertiflora) 5-Year Review: Summary and Evaluation, US Fish and Wildlife Service

Life History

The life history and reproductive processes of this species are unknown. However, due to the isolated nature of the island's endemic locations, the Santa Rosa Island Manzanita does not have the ability to have a widespread habitat. This leaves the species at risk to natural disasters,

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...

, other forms of habitat loss, and predators. This caused a significant drop in the population until 2014, when the predators were removed from the island. Santa Rosa Manzanita seed

germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...

is likely stimulated by fire. Seeds are then protected in the soil. The seeds can grow after fire or until another disturbance clears the undergrowth. Individual plants can live for many years and bloom from January to April. They are

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

and die back during the rest of the year. The manzanita has a low reproductive success rate, resulting in very few young plants. Individual plants can live for 50 years or more.

Conservation

The most recent population count comes from 2006, when it was estimated that 6,000-8,600 individual plants were on Santa Rosa Island. Monitoring data has suggested that population numbers have increased from 1990-2012, but this is not confirmed.

Historical and Current Distributions

The Santa Rosa Manzanita has only ever been found on Santa Rosa Island. Currently, the largest population is on Black Mountain, in the middle of the island. South Point, on the south coast of the island, also has a large part of the population. Because the plants live for so long, there is not enough long-term data to determine past population numbers.

Major Threats

Historically, the Santa Rosa Island Manzanita was most threatened by

ranching A ranch (from es, rancho/Mexican Spanish) is an area of land, including various structures, given primarily to ranching, the practice of raising grazing livestock such as cattle and sheep. It is a subtype of a farm. These terms are most often ...

on Santa Rosa Island. Animals grazed the plants and caused soil erosion. Between 1960-2014 all imported animals such as

sheep Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...

pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus ...

cattle Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...

deer Deer or true deer are hoofed ruminant mammals forming the family Cervidae. The two main groups of deer are the Cervinae, including the muntjac, the elk (wapiti), the red deer, and the fallow deer; and the Capreolinae, including the reindeer ...

, and

elk The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...

were removed from the island. Ranching no longer exists as a threat. Soil loss from non-animal erosion, such as rainfall, decrease the

soil seed bank The soil seed bank is the natural storage of seeds, often dormant, within the soil of most ecosystems. The study of soil seed banks started in 1859 when Charles Darwin observed the emergence of seedlings using soil samples from the bottom of a lak ...

. Fire suppression efforts, which limit fire disturbance on the island, decreases potential germination. Due to the small population size, plants are vulnerable to random extinction. The Santa Rosa Island Manzanita is threatened by intense storms and longer, dryer droughts because of

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...

. The plants are at risk from insect

predation Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...

, but the extent of damage from this threat is unknown.

ESA Listing

The Santa Rosa Island Manzanita was ruled as “warranted but precluded” under the

Endangered Species Act The Endangered Species Act of 1973 (ESA or "The Act"; 16 U.S.C. § 1531 et seq.) is the primary law in the United States for protecting imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of ec ...

(ESA) in 1993. The ruling was reviewed in 1996. The Santa Rosa Manzanita was determined to be endangered under the ESA in 1997. The species is listed as endangered by the

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

, and it does not appear that that status will change within the next five years.

5-Year Review

The

U.S. Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with othe ...

still considers the Manzanita an endangered species as of 2021. Threats regarding climate change, soil loss, and insect predation are still being eliminated. In order to remedy the threat of soil loss, studies of the Santa Rosa Island’s seed bank and germination rates have been planned. With the removal of the imported

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s in 2014, the Fish and Wildlife Service removed the invasion of non-native mammal species as a threat.

Species Status Assessment

There is no official Species Status Assessment on the Santa Rosa Island Manzanita that has been conducted by the U.S. Fish and Wildlife Service.

Recovery Plan

There are plans to store Santa Rosa Island Manzanita seeds in the

Center for Plant Conservation The Center for Plant Conservation (CPC) is a not-for-profit organization consisting of a network with more than 50 institutions. The mission is to conserve and restore the rare native plants of the United States and Canada. CPC represents a netwo ...

(CPC) seed bank. This is a storage facility for seeds that will ensure there are seeds to draw from if repopulation is necessary. The U.S. Fish and Wildlife service has plans to research how the plant germinates and propagates. Because little is known about how the plant reproduces, it is challenging to artificially produce new plants. The Fish and Wildlife Service wants to implement a fire management plan that will ensure there is enough disturbance to clear competing ground cover. Then seeds can grow while preserving seed banks. Erosion control is important in maintaining soil seed banks but is awaiting to be established. Generally, the population is in need of regular monitoring as it is unclear if the population is increasing, decreasing, or stable.

References

External links

Jepson Manual Treatment

USDA Plants Profile

Photo gallery
{{Taxonbar, from=Q4787655 confertiflora Endemic flora of California Natural history of the California chaparral and woodlands Natural history of the Channel Islands of California