Pioneer species

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Pioneer species of plant growing in cracks on a solidified recently erupted lava flow in Hawaii Plants Colonizing a Lava Flow on Hawaii.jpg
Pioneer species of plant growing in cracks on a solidified recently erupted lava flow in Hawaii
Pioneer plants growing on solidified lava on Pico, Azores, avoiding local laurisilva competition Ilha do Pico P6030599 (35239701531).jpg
Pioneer plants growing on solidified lava on Pico, Azores, avoiding local laurisilva competition

Pioneer species are hardy species which are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by fire. [1] Some lichens grow on rocks without soil, so may be among the first of life forms, and break down the rocks into soil for plants. [2] Since some uncolonized land may have thin, poor quality soils with few nutrients, pioneer species are often hardy plants with adaptations such as long roots, root nodes containing nitrogen-fixing bacteria, and leaves that employ transpiration. Note that they are often photosynthetic plants, as no other source of energy (such as other species) except light energy is often available in the early stages of succession, thus making it less likely for a pioneer species to be non-photosynthetic. The plants that are often pioneer species also tend to be wind-pollinated rather than insect-pollinated, as insects are unlikely to be present in the usually barren conditions in which pioneer species grow; however, pioneer species tend to reproduce asexually altogether, as the extreme or barren conditions present make it more favourable to reproduce asexually in order to no increase reproductive success rather than invest energy into sexual reproduction. Pioneer species will die creating plant litter, and break down as "leaf mold" after some time, making new soil for secondary succession (see below), and nutrients for small fish and aquatic plants in adjacent bodies of water. [3]

Contents

Examples of the plants and organisms that colonize such areas are pioneer species:

Pioneer fauna

The diagram above shows how pioneer species lead to soil formation and allow less rugged fauna to grow in the area. 1. Bare rock 2. Weathering allows hardy pioneer species to grow on the rocks. 3. Decomposition of pioneer species provides organic material to make soil. 4. Small annual plants are able to grow on the soil. 5. As the soil layer grows plants such as trees are able to colonize the area. Pioneer species colonization leading to primary sucession.svg
The diagram above shows how pioneer species lead to soil formation and allow less rugged fauna to grow in the area. 1. Bare rock 2. Weathering allows hardy pioneer species to grow on the rocks. 3. Decomposition of pioneer species provides organic material to make soil. 4. Small annual plants are able to grow on the soil. 5. As the soil layer grows plants such as trees are able to colonize the area.

The Pioneering fauna will colonize an area only after flora and fungi have inhabited the area. Soil fauna, ranging from microscopic protists to larger invertebrates, have a role in soil formation and nutrient cycling. Bacteria and fungi are the most important groups in the breakdown of organic detritus left by primary producing plants such as skeletal soil, moss and algae. Soil invertebrates enhance fungal activity by breaking down detritus. As soil develops, earthworms and ants alter soil characteristics. Worm burrows aerate soil and ant hills alter sediment particle size dispersal, altering soil character profoundly.

Though vertebrates in general would not be considered pioneer species, there are exceptions. Natterjack toads are specialists in open, sparsely vegetated habitats which may be at an early seral stage. [6] Wide-ranging generalists visit early succession stage habitats, but are not obligate species of those habitats because they use a mosaic of different habitats.

Vertebrates can effect early seral stages. Herbivores may alter plant growth. Fossorial mammals could alter soil and plant community development. In a profound example, a seabird colony transfers considerable nitrogen into infertile soils, thereby altering plant growth. A keystone species may facilitate the introduction of pioneer species by creating new niches. For example, beavers may flood an area, allowing new species to immigrate. [7]

Secondary succession and pioneer species

Centaurea maculosa, an example of pioneer species Centaurea maculosa.jpg
Centaurea maculosa , an example of pioneer species

Pioneer species can also be found in secondary succession, such as an established ecosystem being reduced by an event such as: a forest fire, deforestation, or clearing; quickly colonizing open spaces which previously supported vegetation. [8]

Common examples of the plants in such areas include:[ citation needed ]

See also

Related Research Articles

Ecosystem Community of living organisms together with the nonliving components of their environment

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the system through photosynthesis and is incorporated into plant tissue. By feeding on plants and on one another, animals play an important role in the movement of matter and energy through the system. They also influence the quantity of plant and microbial biomass present. By breaking down dead organic matter, decomposers release carbon back to the atmosphere and facilitate nutrient cycling by converting nutrients stored in dead biomass back to a form that can be readily used by plants and other microbes.

Epiphyte Non-parasitic surface organism that grows upon another plant but is not nourished by it

An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water or from debris accumulating around it. Epiphytes take part in nutrient cycles and add to both the diversity and biomass of the ecosystem in which they occur, like any other organism. They are an important source of food for many species. Typically, the older parts of a plant will have more epiphytes growing on them. Epiphytes differ from parasites in that they grow on other plants for physical support and do not necessarily affect the host negatively. An organism that grows on another organism that is not a plant may be called an epibiont. Epiphytes are usually found in the temperate zone or in the tropics. Epiphyte species make good houseplants due to their minimal water and soil requirements. Epiphytes provide a rich and diverse habitat for other organisms including animals, fungi, bacteria, and myxomycetes.

Ecological succession The process of change in the species structure of an ecological community over time

Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades, or even millions of years after a mass extinction.

Coarse woody debris

Coarse woody debris (CWD) or coarse woody habitat (CWH) refers to fallen dead trees and the remains of large branches on the ground in forests and in rivers or wetlands. A dead standing tree – known as a snag – provides many of the same functions as coarse woody debris. The minimum size required for woody debris to be defined as "coarse" varies by author, ranging from 2.5–20 cm (1–8 in) in diameter.

Secondary forest

A secondary forest is a forest or woodland area which has re-grown after a timber harvest, until a long enough period has passed so that the effects of the disturbance are no longer evident. It is distinguished from an old-growth forest, which has not recently undergone such disruption, and complex early seral forest, as well as third-growth forests that result from harvest in second growth forests. Secondary forest regrowing after timber harvest differs from forest regrowing after natural disturbances such as fire, insect infestation, or windthrow because the dead trees remain to provide nutrients, structure, and water retention after natural disturbances. However, often after natural disturbance the timber is harvested and removed from the system, in which case the system more closely resembles secondary forest rather than complex early seral forest.

Primary succession Gradual growth and change of an ecosystem on new substrate

Primary succession is one of two types of biological and ecological succession of plant life, occurring in an environment in which new substrate devoid of vegetation and other organisms usually lacking soil, such as a lava flow or area left from retreated glacier, is deposited. In other words, it is the gradual growth of an ecosystem over a longer period of time.

Fire ecology

Fire ecology is a scientific discipline concerned with natural processes involving fire in an ecosystem and the ecological effects, the interactions between fire and the abiotic and biotic components of an ecosystem, and the role as an ecosystem process. 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 require fire to germinate, establish, or to reproduce. Wildfire suppression not only eliminates these species, but also the animals that depend upon them.

Biological soil crust

Biological soil crusts are communities of living organisms on the soil surface in arid and semi-arid ecosystems. They are found throughout the world with varying species composition and cover depending on topography, soil characteristics, climate, plant community, microhabitats, and disturbance regimes. Biological soil crusts perform important ecological roles including carbon fixation, nitrogen fixation and soil stabilization; they alter soil albedo and water relations and affect germination and nutrient levels in vascular plants. They can be damaged by fire, recreational activity, grazing and other disturbances and can require long time periods to recover composition and function. Biological soil crusts are also known as biocrusts or as cryptogamic, microbiotic, microphytic, or cryptobiotic soils.

Grey dune

Grey dunes are fixed, stable sand dunes that are covered by a continuous layer of herbaceous vegetation. These dunes are typically located 50–100 meters from the ocean shore and are found on the landward side of foredunes. Grey dunes are named for their characteristic grey color which is a result of the ground cover of lichen combined with a top soil layer of humus.

A lithosere is a plant succession that begins life on a newly exposed rock surface, such as one left bare as a result of glacial retreat, tectonic uplift as in the formation of a raised beach, or volcanic eruptions. For example, the lava fields of Eldgjá in Iceland where Laki and Katla fissures erupted in the year 935 and the solidified lava has, over time, begun to form a lithosere.

Secondary succession

Secondary succession is one of the two types 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.

Ecological facilitation or probiosis describes species interactions that benefit at least one of the participants and cause harm to neither. Facilitations can be categorized as mutualisms, in which both species benefit, or commensalisms, in which one species benefits and the other is unaffected. Much of classic ecological theory has focused on negative interactions such as predation and competition, but positive interactions (facilitation) are receiving increasing focus in ecological research. This article addresses both the mechanisms of facilitation and the increasing information available concerning the impacts of facilitation on community ecology.

<i>Pittosporum undulatum</i> Australian tree

Pittosporum undulatum is a fast-growing tree in the family Pittosporaceae. It is sometimes also known as sweet pittosporum, native daphne, Australian cheesewood, Victorian box or mock orange.

Cross-boundary subsidy

Cross-boundary subsidies are caused by organisms or materials that cross or traverse habitat patch boundaries, subsidizing the resident populations. The transferred organisms and materials may provide additional predators, prey, or nutrients to resident species, which can affect community and food web structure. Cross-boundary subsidies of materials and organisms occur in landscapes composed of different habitat patch types, and so depend on characteristics of those patches and on the boundaries in between them. Human alteration of the landscape, primarily through fragmentation, has the potential to alter important cross-boundary subsidies to increasingly isolated habitat patches. Understanding how processes that occur outside of habitat patches can affect populations within them may be important to habitat management.

Crown sprouting is the ability of a plant to regenerate its shoot system after destruction by activating dormant vegetative structures to produce regrowth from the root crown. These dormant structures take the form of lignotubers or basal epicormic buds. Plant species that can accomplish crown sprouting are called crown resprouters and, like them, are characteristic of fire-prone habitats such as chaparral.

Barren vegetation Area of land where plant growth may be limited

Barren vegetation describes an area of land where plant growth may be sparse, stunted, and/or contain limited biodiversity. Environmental conditions such as toxic or infertile soil, high winds, coastal salt-spray, and climatic conditions are often key factors in poor plant growth and development. Barren vegetation can be categorized depending on the climate, geology, and geographic location of a specific area.

Cushion plant

A cushion plant is a compact, low-growing, mat-forming plant that is found in alpine, subalpine, arctic, or subarctic environments around the world. The term "cushion" is usually applied to woody plants that grow as spreading mats, are limited in height above the ground, have relatively large and deep tap roots, and have life histories adapted to slow growth in a nutrient-poor environment with delayed reproductivity and reproductive cycle adaptations. The plant form is an example of parallel or convergent evolution with species from many different plant families on different continents converging on the same evolutionary adaptations to endure the harsh environmental conditions.

Plant litter Dead plant material that has fallen to the ground

Litterfall, plant litter, leaf litter, tree litter, soil litter, or duff, is dead plant material that have fallen to the ground. This detritus or dead organic material and its constituent nutrients are added to the top layer of soil, commonly known as the litter layer or O horizon. Litter is an important factor in ecosystem dynamics, as it is indicative of ecological productivity and may be useful in predicting regional nutrient cycling and soil fertility.

Resprouter

Resprouters are plant species that are able to survive fire by the activation of dormant vegetative buds to produce regrowth.

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.

References

  1. Duram, Leslie A. (2010). Encyclopedia of Organic, Sustainable, and Local Food. ABC-CLIO. p. 48. ISBN   9780313359637.
  2. LICHEN BIOLOGY AND THE ENVIRONMENT, LICHENS OF and NORTH AMERICA, Sylvia and Stephen Sharnoff,
  3. Walker, Lawrence R.; Moral, Roger del (2003-02-13). Primary Succession and Ecosystem Rehabilitation. Cambridge University Press. ISBN   9780521529549.
  4. Amazing Lava Products and Forms, U.S. National Park Service. Retrieved 2015-06-16.
  5. "Surtsey - Colonization of the land". Archived from the original on 2017-11-17. Retrieved 2017-02-22.
  6. Faucher, Leslie; Hénocq, Laura; Vanappelghem, Cédric; Roundel, Stephanie; Tocqueville, Robin; Galina, Sophie; Godé, Cécile; Jaquiéry, Julie; Arnaud, Jean-Francois (2017-09-01). "When new human-modified habitats favor the expansion of an amphibian pioneer species: Evolutionary history of the natterjack toad (Bubo calamity) in a coal basin". Molecular Ecology. 26 (17): 4434–4451. doi:10.1111/mec.14229. ISSN   1365-294X. PMID   28667796. S2CID   25656968.[ permanent dead link ]
  7. Wall work, John Anthony (1970). Ecology of Soil Animals. McGowan-Hill. ISBN   978-0070941250.
  8. E., Ricklefs, Robert (2014-07-20). Ecology : the economy of nature. Relyea, Rick,, Richter, Christoph F.,, Revision of: Ricklefs, Robert E. (Seventh edition, Canadian ed.). New York, NY. ISBN   9781464154249. OCLC   961903099.
  9. Knox, Kirsten J. E.; Morrison, David A. (2005-06-01). "Effects of inter-fire intervals on the reproductive output of resprouters and obligate seeders in the Proteaceae". Austral Ecology. 30 (4): 407–413. doi:10.1111/j.1442-9993.2005.01482.x. ISSN   1442-9993.