California coastal prairie, also known as northern coastal grassland, is a grassland plant community of California and Oregon in the temperate grasslands, savannas, and shrublands biome. This ecosystem is found along the Pacific Coast, from as far south as Los Angeles in Southern California to southern Oregon. It typically stretches as far inland as 100 km, and occurs at altitudes of 350 m or lower.
California's coastal prairies are the most species-rich grassland types in North America, with up to 26 species present per square meter. [1] They have been described in literature as "previously unrecognized biodiversity hotspots," and are also known to provide an array of essential services—for instance, carbon storage, water filtration, agriculture, and livestock farming. [2] In spite of the numerous benefits associated with maintaining this ecosystem, it is considered to be one of the most threatened ecosystems in the state of California, [3] with less than one percent of undisturbed coastal prairie remaining today (mainly in or around Point Reyes National Seashore). It is also the single most urbanized major vegetation type in the US; 24% of coastal prairie habitat in California has been lost to urban sprawl. [4]
Among the most defining attributes of the California coastal prairie is its Mediterranean climate. This climate type entails hot and dry summers, cold and wet winters, and mild year-round temperatures as a result of close proximity with the Pacific Ocean.The growing season for these prairies takes place during the winter, and is followed by a dormant, low-rainfall period during the summer. [5] These seasonal changes to water availability have thus spurred a variety of adaptations favoring drought resistance across the many species endemic to these areas. Some perennial grasses utilize humid air as a source of up to 66% of their total water intake, making fog another indispensable abiotic factor in this ecosystem. [6] Other drought-resistant strategies include deep root systems, summer dormancy, and enhanced water storage (e.g. bulbs, tubers, taproots, etc.).
The California coastal prairie is commonly defined by its predominant grass species, of which there are two: Deschampsia coastal prairie (located in Point Reyes peninsula) and Danthonia coastal prairie (located in Bolinas Ridge). [7] This ecosystem can also be characterized by topographic features including sea bluffs, uplifted grassy bald hills, hillside slopes, lowland grasslands, and coastal marine terraces. [8] The centuries-long accumulation of organic matter within these coastal regions has culminated in the production of a rich and dark prairie soil that is commonly referred to as mollisol. As a result, the aforementioned coastal terraces are often used for agricultural purposes, [9] and can be seen in areas such as Santa Cruz and San Luis Obispo.
As a disturbance-dependent ecosystem, these coastal prairies are not only adapted to change, but cannot properly thrive without it. [10] Disruptive factors such as wind, fire, salt spray, digging, and grazing help to maintain more open (as well as healthy) grasslands; for example, they are crucial to facilitating the release of nutrients, stimulating microbial activity, and regulating competition between woody and herbaceous plants. [11] The profile of grazing species inhabiting these prairies has evolved over time in the following manner:
Conservation projects within the past couple of decades have involved the conversion of private pastures on coastal prairies into protected land. While these efforts are well-intended, the removal of grazers from this ecosystem rids it of the disturbance it requires, and is therefore thought to be responsible for such metrics as worsening soil quality and declining annual wildflower blooms in these areas. [13] In the absence of frequent fires—especially controlled burns—and many once-prominent grazing and burrowing species that evolved within this ecosystem, much of what is left of the California coastal prairie is being lost to shrub and tree encroachment. [14]
Before the Spaniards' arrival in California, Native American groups relied on grasslands' ecosystem for resources such as chia seeds, acorns, grass seeds, [15] and game like deer, quail and hares. [16] In order to expand their resource base, they managed the land through fire techniques, which flowered geophytes and boosted the growth of perennial grasses. Burning the existing chaparral and shrublands into grasslands was advantageous for such groups in generating the germination of chaparral annuals and therefore food supply for both humans and the mammals in the area. In general, it created open spaces which were favored by animals and opening up land for gathering fruits and seeds. [17]
In addition, indigenous groups effectively harvested the annual grasses through digging sticks, which dug for underground bulbs and seeds, and the seed basket, which collected seeds, like camas bulbs, and scattered those who weren't ripe in the process. [17]
When the Spanish arrived in the 1800s, cattle was introduced for grazing, effectively replacing the native populations of deer and elk. [16] In the process were introduced non-native species which, along with agriculture and the end of indigenous fire management practices, greatly decreasing the biodiversity of these ecosystems. [18]
Characteristic species of this community include: [19]
The entire coastal prairie biome can be completely restored, even after the plants seem to have disappeared for decades after grazing end, by unearthing their dormant native seeds in the soil, that are still viable underneath the weeds. Between 1992 and 2000, at 300 Byers Lane, La Selva Beach in Santa Cruz County, 70 acres of habitat went from 99% weed-covered to 95% native covered in only eight years, without sowing any seeds. [21]
Rare and endangered species found in the coastal prairie include:
The coastal prairies remains a unique ecosystem in that it is disturbance-dependent, meaning it relies on disturbances such as fires and grazing to survive. Years of overgrazing as well as the introduction of non-native species have had long-term impacts on Californian coastal prairies, with only 1% of native grassland remaining today. [18] These non-native species are either not suited as feed for the native mammals, or more woody plants have overrun the habitats of native herbs. [22]
Most recently, invasive perennial grasses are the greatest threat. These include velvet grass ( Holcus lanatus ), tall fescue ( Festuca arundinacea ), and Harding grass ( Phalaris aquatica ); [23] the impact of these species can be somewhat ameliorated by well-planned livestock grazing, which can reduce these species' cover and allow native species to persist. [24]
California's coastal prairies are protected by the California Coastal Act, which considers these habitat types to be Environmentally Sensitive Habitat Areas (ESHA). Akin to the endangered species act for habitat types on California's coast, ESHA protections disallow any harm to so designated habitats, except where such harm is necessary to otherwise restore the habitat as a whole (e.g., prescribed fire, grazing). [25]
Coastal Prairies of California are classified as critically endangered with the following stressors causing the most impacts: invasive species, low nutrient soils, urbanization, and unregulated recreational activities. [26] Debates remain on how to apply conservancy efforts to Californian coastal prairies, in balancing disturbances to allow for the flourishing of the native plants as well as quality pasture for grazers. [22] One such organisation focusing on this work is the California Native Grasslands Association, which has led diverse efforts to protect parks and areas with coastal prairies, such as in efforts to protect Point Molate and Tesla Park from construction projects. [27]
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type. Temperate grassland regions include the Pampas of Argentina, Brazil and Uruguay, and the steppe of Ukraine, Russia, and Kazakhstan. Lands typically referred to as "prairie" tend to be in North America. The term encompasses the lower and mid-latitude of the area referred to as the Interior Plains of Canada, the United States, and Mexico. It includes all of the Great Plains as well as the wetter, hillier land to the east. From west to east, generally the drier expanse of shortgrass prairie gives way to mixed grass prairie and ultimately the richer soils of the tallgrass prairie.
A grassland is an area where the vegetation is dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes, such as clover, and other herbs. Grasslands occur naturally on all continents except Antarctica and are found in most ecoregions of the Earth. Furthermore, grasslands are one of the largest biomes on Earth and dominate the landscape worldwide. There are different types of grasslands: natural grasslands, semi-natural grasslands, and agricultural grasslands. They cover 31–69% of the Earth's land area.
In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to free range and consume wild vegetations in order to convert the otherwise indigestible cellulose within grass and other forages into meat, milk, wool and other animal products, often on land that is unsuitable for arable farming.
Rangelands are grasslands, shrublands, woodlands, wetlands, and deserts that are grazed by domestic livestock or wild animals. Types of rangelands include tallgrass and shortgrass prairies, desert grasslands and shrublands, woodlands, savannas, chaparrals, steppes, and tundras. Rangelands do not include forests lacking grazable understory vegetation, barren desert, farmland, or land covered by solid rock, concrete, or glaciers.
The tallgrass prairie is an ecosystem native to central North America. Historically, natural and anthropogenic fire, as well as grazing by large mammals provided periodic disturbances to these ecosystems, limiting the encroachment of trees, recycling soil nutrients, and facilitating seed dispersal and germination. Prior to widespread use of the steel plow, which enabled large scale conversion to agricultural land use, tallgrass prairies extended throughout the American Midwest and smaller portions of southern central Canada, from the transitional ecotones out of eastern North American forests, west to a climatic threshold based on precipitation and soils, to the southern reaches of the Flint Hills in Oklahoma, to a transition into forest in Manitoba.
Fire ecology is a scientific discipline concerned with the effects of fire on natural ecosystems. Many ecosystems, particularly prairie, savanna, chaparral and coniferous forests, have evolved with fire as an essential contributor to habitat vitality and renewal. Many plant species in fire-affected environments use fire to germinate, establish, or to reproduce. Wildfire suppression not only endangers these species, but also the animals that depend upon them.
Holocarpha macradenia, commonly known as the Santa Cruz tarplant, is an endangered plant endemic to Northern California. Alternative common names for this plant are Santa Cruz tarweed or Santa Cruz sunflower.
Melilotus albus, known as honey clover, white melilot (UK), Bokhara clover (Australia), white sweetclover (US), and sweet clover, is a nitrogen-fixing legume in the family Fabaceae. Melilotus albus is considered a valuable honey plant and source of nectar and is often grown for forage. Its characteristic sweet odor, intensified by drying, is derived from coumarin.
Prairie restoration is a conservation effort to restore prairie lands that were destroyed due to industrial, agricultural, commercial, or residential development. The primary aim is to return areas and ecosystems to their previous state before their depletion.
Grasses are one of the most abundant floras on all continents, except Antarctica. Their divergence is estimated to have taken place 200 million years ago. Humans have intentionally and unintentionally introduced these species to North America through travel and trade. On the North American plains, prairies, grasslands, and meadows at least 11% of grasses are non-native. North America is considered a hotspot for many invasive species of grasses, which threatens all of the endangered native grass species and potentially threatens other grass species. Conservation tactics and management policies can help prevent invasive species from taking over and driving native North American plants to extinction.
Myrtle's silverspot is a medium-sized butterfly in the brush foot family (Nymphalidae), an endangered subspecies of the zerene fritillary. It is endemic to California, where it is known from only about four locations just north of the San Francisco Bay Area, including two at Point Reyes National Seashore. Its wingspan is approximately 2.2 inches (56 mm). The upper surfaces of the wings are golden brown with numerous black spots and lines. The undersides are brown, orange and tan with black lines and silver and black spots. Larvae are dark colored with many sharp branching spines on their backs. Myrtle's silverspot is larger and paler than the closely related Behrens' silverspot, which is now limited to the vicinity of Point Arena in Mendocino County. Myrtle's silverspot is also closely related to the Oregon silverspot.
The shortgrass prairie is an ecosystem located in the Great Plains of North America. The two most dominant grasses in the shortgrass prairie are blue grama and buffalograss, the two less dominant grasses in the prairie are greasegrass and sideoats grama. The prairie was formerly maintained by grazing pressure of American bison, which is the keystone species. Due to its semiarid climate, the shortgrass prairie receives on average less precipitation than that of the tall and mixed grass prairies to the east.
Conservation grazing or targeted grazing is the use of semi-feral or domesticated grazing livestock to maintain and increase the biodiversity of natural or semi-natural grasslands, heathlands, wood pasture, wetlands and many other habitats. Conservation grazing is generally less intensive than practices such as prescribed burning, but still needs to be managed to ensure that overgrazing does not occur. The practice has proven to be beneficial in moderation in restoring and maintaining grassland and heathland ecosystems. Conservation or monitored grazing has been implemented into regenerative agriculture programs to restore soil and overall ecosystem health of current working landscapes. The optimal level of grazing and grazing animal will depend on the goal of conservation. Different levels of grazing, alongside other conservation practices, can be used to induce desired results.
Festuca californica is a species of grass known by the common name California fescue.
Trifolium buckwestiorum is a rare species of clover known by the common name Santa Cruz clover.
Dalea purpurea is a species of flowering plant in the legume family known as purple prairie clover. Native to central North America, purple prairie clover is a relatively common member of the Great Plains and prairie ecosystems. It blooms in the summer with dense spikes of bright purple flowers that attract many species of insects.
Artemisia filifolia, known by common names including sand sagebrush, sand sage and sandhill sage, is a species of flowering plant in the aster family. It is native to North America, where it occurs from Nevada east to South Dakota and from there south to Arizona, Chihuahua, and Texas.
Festuca kingii is a species of grass in the family Poaceae known by the common names spike fescue and King's fescue. It is native to the western United States from Oregon and California east to Nebraska and Kansas.
Annual grasslands are a type of grassland ecosystem characterized by the dominance of annual grasses and forbs. They are most commonly found in regions with Mediterranean climates, such as California, and provide important habitats for a variety of wildlife species.