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Drooping Brome

Drooping Brome

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Drooping brome or Cheat Grass, Bromus tectorum, is a grass
Poaceae
The Poaceae is a large and nearly ubiquitous family of flowering plants. Members of this family are commonly called grasses, although the term "grass" is also applied to plants that are not in the Poaceae lineage, including the rushes and sedges...

 native to Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, southwestern Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and northern Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

.

Description


Bromus tectorum is an annual
Annual plant
An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...

 bunchgrass, usually germinating in the autumn, overwintering as a seedling, then flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...

ing in the spring or early summer. If winter rainfall is limiting and spring moisture is adequate, the seeds will germinate in the spring, and the plants will flower that summer. It typically reaches 40–90 cm tall, though plants as small as 2.5 cm may produce seed. It is cleistogamous and self-fertile, with no evident out-crossing.

Below grade


Drooping Brome or Cheat Grass has an extensive root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...

 system. The wide-spreading lateral roots are one of the keys to the survival of this plant. A study showed that it had the capability to reduce soil moisture to the permanent wilting point to a depth of 70 cm, reducing competition from other species.

Seeds


The seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

s are dispersed by wind, small rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....

s, or attachment to animal fur, within a week of maturity. They are also moved as a contaminant in hay, grain, straw, and machinery. It is an abundant seed producer, with a potential in excess of 300 seeds per plant; seed production per plant is dependent on plant density. Under optimal conditions, it may produce 450 kg of seed per hectare with about 330,000 seeds/kg.

The seeds maintain high viability in dry storage, lasting over 11 years. In the field, under buried conditions, seeds will lose their viability in 2–5 years. The primary limit to germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...

 is inadequate moisture. Seeds can withstand high soil temperatures. Germination is best in the dark or in diffuse light. They germinate most quickly when covered with soil, but do not need to be in contact with bare soil; some leaf litter cover will generally improve germination and establishment of seedlings. Seedlings emerge rapidly from the top 2.5 cm of soil, and a few plants emerge from depths of 8 cm, but not from seeds 10 cm below the surface.

Habitat


Drooping Brome or Cheat Grass (Bromus tectorum) grows in many climatic areas. It is found primarily in the 150–560 mm precipitation zone. It will grow in almost any type of soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...

, including B and C horizons of eroded areas and areas low in nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

. It is most often found on coarse-textured soils and does not grow well on heavy, dry, and/or saline soils. It grows in a relatively narrow range of soil temperatures; growth starts at 2.0-3.5°C and slows when temperatures exceed 15°C.

Status as an exotic weed


Drooping Brome has been introduced to southern Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

, west central Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

, North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...

, South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...

, and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...

. It was first found in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 (where it is known as Downy brome or Cheatgrass) in 1861 in New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...

 and Pennsylvania
Pennsylvania
The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

, by 1928 reaching throughout the United States (including 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...

 and Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

), except for Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

 and portions of Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...

, Georgia
Georgia (U.S. state)
Georgia is a state located in the southeastern United States. It was established in 1732, the last of the original Thirteen Colonies. The state is named after King George II of Great Britain. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788...

, South Carolina
South Carolina
South Carolina is a state in the Deep South of the United States that borders Georgia to the south, North Carolina to the north, and the Atlantic Ocean to the east. Originally part of the Province of Carolina, the Province of South Carolina was one of the 13 colonies that declared independence...

; it is most abundant in the Great Basin
Great Basin
The Great Basin is the largest area of contiguous endorheic watersheds in North America and is noted for its arid conditions and Basin and Range topography that varies from the North American low point at Badwater Basin to the highest point of the contiguous United States, less than away at the...

, Columbia Basin
Columbia Basin
The Columbia Basin, the drainage basin of the Columbia River, occupies a large area–about —of the Pacific Northwest region of North America. In common usage, the term often refers to a smaller area, generally the portion of the drainage basin that lies within eastern Washington.Usage of the term...

, and part of the 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...

 that replaced California native plants
California native plants
California native plants are plants that existed in California prior to the arrival of European explorers and colonists in the late 18th century...

 in the Floristic Province's grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...

s and other habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

s.

Invasive species


Cheat Grass (Bromus tectorum) is an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

 in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

.

In the US, it grows on rangeland
Rangeland
Rangelands are vast natural landscapes in the form of grasslands, shrublands, woodlands, wetlands, and deserts. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, savannas, chaparrals, steppes, and tundras...

s, pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...

s, prairie
Prairie
Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...

s, fields, waste areas, eroded
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

 sites, and roadsides. It is much reviled by ranchers and land managers. Drooping Brome seeds are also a critical portion of the diet of the Chukar
Chukar
The Chukar Partridge or Chukar is a Eurasian upland gamebird in the pheasant family Phasianidae. It has been considered to form a superspecies complex along with the Rock Partridge, Philby's Partridge and Przevalski's Partridge and treated in the past as conspecific particularly with the first...

 and Grey Partridge
Grey Partridge
The Grey Partridge, Perdix perdix, also known as the English Partridge, Hungarian Partridge, or Hun, is a gamebird in the pheasant family Phasianidae of the order Galliformes, gallinaceous birds...

 which have been introduced to the US. Intensive sheep browsing of Cheatgrass in early spring has been used as a fire fuels reduction strategy in the hills adjacent to Carson City, Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...

.

Drooping broom has demonstrated a quantitative and qualitative response to recent and near-term changes in the concentration of atmospheric carbon dioxide. Laboratory experiments have shown that above-ground biomass increased 1.5-2.7 gram per plant for every 10 part per million (ppm) increase above the 270 ppm pre-industrial baseline. On the qualitative side, rising carbon dioxide decreased the digestibility and potential decomposition of drooping brome. In addition to stimulation of biomass, rising carbon dioxide may also increase the above ground retention of drooping broom biomass by decreasing removal by animals or bacteria. Ongoing increases in atmospheric carbon dioxide may contribute significantly to drooping broom productivity and fuel load with subsequent effects on 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...

 frequency and intensity.

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