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A psammosere is the sequence of plant succession that has been initiated on sand. [1]
A psammosere is an intermediate stage in ecological succession, known as a seral community, that began life on newly exposed coastal sand. Most common psammoseres are sand dune systems. Psammosere is a form of xerosere succession, meaning it begins in an environment with limited to no freshwater availability. [2]
Psammosere's literal meaning is “originating on sand". It was named by Frederic E. Clements who described the sequence in Plant Succession 1916, [3] although it had also been observed by Henry Chandler Cowles after he conducted several studies on the sand dunes surrounding Lake Michigan, which was influenced by the work of Eugenius Warming. [4]
In a psammosere, the organisms closest to the sea will be pioneer species: [5] halophytes (salt-tolerant species) such as littoral algae and glasswort, with marram grass stabilising the dunes. Progressing inland, many characteristics of the ground change which helps determine the natural succession of the dunes.
For instance, the drainage slows down as the land becomes more compact and the soils improve in quality, and the pH drops as the proportion of seashell fragments reduces and the amount of humus increases. Sea purslane, sea lavender, meadow grass and heather eventually grade into a typical non-maritime ecosystem. The first trees (or pioneer trees) that appear are typically fast-growing trees such as pine, birch, willow or rowan. In turn these will be replaced by slow-growing, larger trees such as ash and oak. This is the climax community, defined as the point where a plant succession does not develop any further because it has reached equilibrium with the environment, in particular the climate.
The later stages of a psammosere appear when the sand stops moving due to lower wind speeds. These lower wind speeds can be because of distance from the shoreline or the formation of higher dunes, acting as windbreaks, or a combination of both of these factors. [6] The process by which different stages succeed each other is known as "plant colonisation". [5]
In an idealised model of a coastal psammosere at the seaward edge of the sand dune, the pH of the soil is typically alkaline/neutral with a pH of 7.0/8.0 particularly where shell fragments provide a significant component of the sand. Further inland, the soil's pH decreases as the soil gets more acidic. [7] Tracking inland across the dunes, a podsol develops with a pH of 5.0 – 4.0, followed by mature podsols at the climax with a pH of 3.5 – 4.5.
Psammosere succession is also extremely vulnerable to human activities. At beaches, footpaths over dunes will trample grass, creating exposed sand. This exposed sand can be blown away very easily, leading to the roots becoming exposed and neighbouring plants dying. This creates blowouts, which can set back psammosere succession. [8]
Efforts have also been made to improve the psammosere in some regards. In some areas, pine trees are an invasive species and can take over heathland. [9] The National Trust in the UK encourages people to pull up small Pine trees [10] as they can leave needles on the ground, which can prevent further psammosere succession through the dropping of needles.
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes, with little or no vegetation, are called ergs or sand seas. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (upflow) side, where the sand is pushed up the dune, and have a shorter slip face in the lee side. The valley or trough between dunes is called a dune slack.
In scientific ecology, climax community or climatic climax community is a historic term for a community of plants, animals, and fungi which, through the process of ecological succession in the development of vegetation in an area over time, have reached a steady state. This equilibrium was thought to occur because the climax community is composed of species best adapted to average conditions in that area. The term is sometimes also applied in soil development. Nevertheless, it has been found that a "steady state" is more apparent than real, particularly across long timescales. Notwithstanding, it remains a useful concept.
Ecological succession is the process of change in the species that make up an ecological community over time.
Indiana Dunes National Park is a national park of the United States located in northwestern Indiana managed by the National Park Service. It was authorized by Congress in 1966 as the Indiana Dunes National Lakeshore and was redesignated as the nation's 61st national park on February 15, 2019. The park runs for about 20 miles (32 km) along the southern shore of Lake Michigan and covers 15,349 acres (6,212 ha). Along the lakefront, the eastern area is roughly the lake shore south to U.S. 12 or U.S. 20 between Michigan City, Indiana, on the east and the Cleveland-Cliffs steel plant on the west. This area's conservation scheme is enhanced by the older Indiana Dunes State Park. To the west of the steel plant lies West Beach and a small extension south of the steel mill continues west along Salt Creek to Indiana 249. The western area is roughly the shoreline south to U.S. 12 between the Burns Ditch west to Broadway in downtown Gary, Indiana. In addition, there are several outlying areas, including Pinhook Bog, in LaPorte County to the east; the Heron Rookery in Porter County, the center of the park; and the Hoosier Prairie State Nature Preserve and the Hobart Prairie Grove, both in Lake County, the western end of the park.
Henry Chandler Cowles was an American botanist and ecological pioneer. A professor at the University of Chicago, he studied ecological succession in the Indiana Dunes of Northwest Indiana. This led to efforts to preserve the Indiana Dunes. One of Cowles' students, O. D. Frank continued his research.
A sandhill is a type of ecological community or xeric wildfire-maintained ecosystem. It is not the same as a sand dune. It features very short fire return intervals, one to five years. Without fire, sandhills undergo ecological succession and become more oak dominated.
The Sandhills or Carolina Sandhills is a 10-35 mi wide physiographic region within the U.S. Atlantic Coastal Plain province, along the updip (inland) margin of this province in the states of North Carolina, South Carolina, and Georgia. The extent of the Carolina Sandhills is shown in maps of the ecoregions of North Carolina, South Carolina, and Georgia.
Primary succession is the beginning step of ecological succession where species known as pioneer species colonize an uninhabited site, which usually occurs in an environment devoid of vegetation and other organisms.
Blowouts are sandy depressions in a sand dune ecosystem (psammosere) caused by the removal of sediments by wind.
Xerosere is a plant succession that is limited by water availability. It includes the different stages in a xerarch succession. Xerarch succession of ecological communities originated in extremely dry situation such as sand deserts, sand dunes, salt deserts, rock deserts etc. A xerosere may include lithoseres and psammoseres.
Secondary succession is the secondary ecological succession of a plant's life. As opposed to the first, primary succession, secondary succession is a process started by an event that reduces an already established ecosystem to a smaller population of species, and as such secondary succession occurs on preexisting soil whereas primary succession usually occurs in a place lacking soil. Many factors can affect secondary succession, such as trophic interaction, initial composition, and competition-colonization trade-offs. The factors that control the increase in abundance of a species during succession may be determined mainly by seed production and dispersal, micro climate; landscape structure ; bulk density, pH, and soil texture.
Henry Allan Gleason (1882–1975) was an American ecologist, botanist, and taxonomist. He was known for his endorsement of the individualistic or open community concept of ecological succession, and his opposition to Frederic Clements's concept of the climax state of an ecosystem. His ideas were largely dismissed during his working life, leading him to move into plant taxonomy, but found favour late in the twentieth century.
Ammophila arenaria is a species of grass in the family Poaceae. It is known by the common names marram grass and European beachgrass. It is one of two species of the genus Ammophila. It is native to the coastlines of Europe and North Africa where it grows in the sands of beach dunes. It is a perennial grass forming stiff, hardy clumps of erect stems up to 1.2 metres (3.9 ft) in height. It grows from a network of thick rhizomes which give it a sturdy anchor in its sand substrate and allow it to spread upward as sand accumulates. These rhizomes can grow laterally by 2 metres in six months. One clump can produce 100 new shoots annually.
Sand dune ecology describes the biological and physico-chemical interactions that are a characteristic of sand dunes.
Cowles Bog is a 4,000-year-old wetland complex in Indiana Dunes National Park, near Chesterton, Indiana. It is named for Henry Chandler Cowles who did his pioneering work in ecology and ecological succession here. His work brought international attention to the area which led to efforts to preserve the Indiana Dunes. It was designated a National Natural Landmark in 1965. It contains bog, fen, marsh, wet meadow, swamp, and pond habitats.
Ammophila breviligulata is a species of grass native to eastern North America, where it grows on sand dunes along the Atlantic Ocean and Great Lakes coasts. Beachgrass thrives under conditions of shifting sand, sand burial, and high winds; it is a dune-building grass that builds the first line of sand dunes along the coast. Beachgrass is less vigorous in stabilized sand, and is only infrequently found further inland than the coastal foredunes. On the Atlantic coastline of North America, Ammophila breviligulata has been observed as far south as North Carolina, and is often planted in dune restoration projects. Ammophila breviligulata was introduced to the Pacific coast of North America in the 1930s. It is proving to be invasive, and is increasingly important to coastal ecology and development in Oregon, Washington, and British Columbia.
Florida scrub is a forest ecoregion found throughout Florida in the United States. It is found on coastal and inland sand ridges and is characterized by an evergreen xeromorphic plant community dominated by shrubs and dwarf oaks. Because the low-nutrient sandy soils do not retain moisture, the ecosystem is effectively an arid one. Wildfires infrequently occur in the Florida scrub. Most of the annual rainfall falls in summer.
Leymus arenarius is a psammophilic (sand-loving) species of grass in the family Poaceae, native to the coasts of Atlantic and Northern Europe. Leymus arenarius is commonly known as sand ryegrass, sea lyme grass, or simply lyme grass.
The Indiana Dunes comprise ten different habitats. Each provides for a unique combination of plants and animals. The range of the Indiana Dunes varies depending your source. The Indiana Lake Michigan Coastal Program uses the river drainage systems along the shoreline. This expands the area from the areas of lakeshore southward to the edges of the Valparaiso Moraine. This entire region has been dune landscapes since over 114,000 years before present (YBP). Traditionally, the Indiana Dunes area thought of as a narrow area along the shores of Lake Michigan, including the areas of Marquette Park in Gary, Indiana (1920), Indiana Dunes State Park (1926) and Indiana Dunes National Park,. The identified ten habitats can be found in these parks, where they have been preserved, but are also visible throughout the three counties of Northwest Indiana.
Ecological succession can be understood as a process of changing species composition within a community due to an ecological disturbance, and varies largely according to the initial disturbance prompting the succession. Joseph Connell and Ralph Slatyer further developed the understanding of successional mechanisms in their 1977 paper and proposed that there were 3 main modes of successional development. These sequences could be understood in the context of the specific life-history theories of the individual species within an ecological community.