Ecotone

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Reed beds are a common form of lakeside ecotone. The beds tend to accumulate organic matter which is then colonised by trees, forcing the reeds further into the lake. Blick vom Lons Turm HemmelsdorferSee Ausfluss aalbek.jpg
Reed beds are a common form of lakeside ecotone. The beds tend to accumulate organic matter which is then colonised by trees, forcing the reeds further into the lake.

An ecotone is a transition area between two biological communities, [1] where two communities meet and integrate. [2] It may be narrow or wide, and it may be local (the zone between a field and forest) or regional (the transition between forest and grassland ecosystems). [3] An ecotone may appear on the ground as a gradual blending of the two communities across a broad area, or it may manifest itself as a sharp boundary line.

Contents

Etymology

The word ecotone was coined by Alfred Russel Wallace, who first observed the abrupt boundary between two biomes in 1859.[ citation needed ] It is formed as a combination of ecology plus -tone, from the Greek tonos or tension – in other words, a place where ecologies are in tension.

Features

Fig.1 & 2 show simple ecotones with equal and homogeneous surfaces in both cases. Fig.3 shows an inclusion of each medium in the other, creating multiple ecotones, which are shown in a more complex form in figure 4. Fig. 5 & 6 show the edges of forests or banks treated in such a way as to lengthen the ecotone considerably without excessively modifying the environment. Fig.7 shows a common interpenetration of media (such as that found at the edge of a forest). Fig.8 shows an ecotone that could have been formed by an animal modifying its environment. EcotoneLamiotCommons4.jpg
Fig.1 & 2 show simple ecotones with equal and homogeneous surfaces in both cases. Fig.3 shows an inclusion of each medium in the other, creating multiple ecotones, which are shown in a more complex form in figure 4. Fig. 5 & 6 show the edges of forests or banks treated in such a way as to lengthen the ecotone considerably without excessively modifying the environment. Fig.7 shows a common interpenetration of media (such as that found at the edge of a forest). Fig.8 shows an ecotone that could have been formed by an animal modifying its environment.

There are several distinguishing features of an ecotone. First, an ecotone can have a sharp vegetation transition, with a distinct line between two communities. [4] For example, a change in colors of grasses or plant life can indicate an ecotone. Second, a change in physiognomy (physical appearance of a plant species) can be a key indicator. Water bodies, such as estuaries, can also have a region of transition, and the boundary is characterized by the differences in heights of the macrophytes or plant species present in the areas because this distinguishes the two areas' accessibility to light. [5] Scientists look at color variations and changes in plant height. Third, a change of species can signal an ecotone. There will be specific organisms on one side of an ecotone or the other.

Other factors can illustrate or obscure an ecotone, for example, migration and the establishment of new plants. These are known as spatial mass effects, which are noticeable because some organisms will not be able to form self-sustaining populations if they cross the ecotone. If different species can survive in both communities of the two biomes, then the ecotone is considered to have species richness; ecologists measure this when studying the food chain and success of organisms. Lastly, the abundance of introduced species in an ecotone can reveal the type of biome or efficiency of the two communities sharing space. [6] Because an ecotone is the zone in which two communities integrate, many different forms of life have to live together and compete for space. Therefore, an ecotone can create a diverse ecosystem.

Formation

Changes in the physical environment may produce a sharp boundary, as in the example of the interface between areas of forest and cleared land. Elsewhere, a more gradually blended interface area will be found, where species from each community will be found together as well as unique local species. Mountain ranges often create such ecotones, due to the wide variety of climatic conditions experienced on their slopes. They may also provide a boundary between species due to the obstructive nature of their terrain. Mont Ventoux in France is a good example, marking the boundary between the flora and fauna of northern and southern France. [7] Most wetlands are ecotones. The spatial variation of ecotones often form due to disturbances, creating patches that separate patches of vegetation. Different intensity of disturbances can cause landslides, land shifts, or movement of sediment that can create these vegetation patches and ecotones. [8]

Plants in competition extend themselves on one side of the ecotone as far as their ability to maintain themselves allows. Beyond this competitors of the adjacent community take over. As a result, the ecotone represents a shift in dominance. Ecotones are particularly significant for mobile animals, as they can exploit more than one set of habitats within a short distance. The ecotone contains not only species common to the communities on both sides; it may also include a number of highly adaptable species that tend to colonize such transitional areas. [3] The phenomenon of increased variety of plants as well as animals at the community junction is called the edge effect and is essentially due to a locally broader range of suitable environmental conditions or ecological niches.

Ecotones and ecoclines

An ecotone is often associated with an ecocline: a "physical transition zone" between two systems. The ecotone and ecocline concepts are sometimes confused: an ecocline can signal an ecotone chemically (ex: pH or salinity gradient), or microclimatically (hydrothermal gradient) between two ecosystems.

In contrast:

Examples

See also

Related Research Articles

<span class="mw-page-title-main">Biome</span> Biogeographical unit with a particular biological community

A biome is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. Biomes may span more than one continent. A biome encompasses multiple ecosystems within its boundaries. It can also comprise a variety of habitats.

<span class="mw-page-title-main">Ecoregion</span> Ecologically and geographically defined area that is smaller than a bioregion

An ecoregion is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation . Ecoregions are also known as "ecozones", although that term may also refer to biogeographic realms.

<span class="mw-page-title-main">Edge effects</span> Ecological concept

In ecology, edge effects are changes in population or community structures that occur at the boundary of two or more habitats. Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range. As the edge effects increase, the boundary habitat allows for greater biodiversity.

<span class="mw-page-title-main">Grassland</span> Area with vegetation dominated by grasses

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, like 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.

<span class="mw-page-title-main">Savanna</span> Mixed woodland-grassland ecosystem

A savanna or savannah is a mixed woodland-grassland ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses. According to Britannica, there exists four savanna forms; savanna woodland where trees and shrubs form a light canopy, tree savanna with scattered trees and shrubs, shrub savanna with distributed shrubs, and grass savanna where trees and shrubs are mostly nonexistent.

<span class="mw-page-title-main">Alpine tundra</span> Biome found at high altitudes

Alpine tundra is a type of natural region or biome that does not contain trees because it is at high elevation, with an associated harsh climate. As the latitude of a location approaches the poles, the threshold elevation for alpine tundra gets lower until it reaches sea level, and alpine tundra merges with polar tundra.

<span class="mw-page-title-main">Wallace Line</span> Line separating Asian and Australian fauna

The Wallace line or Wallace's line is a faunal boundary line drawn in 1859 by the British naturalist Alfred Russel Wallace and named by the English biologist T.H. Huxley that separates the biogeographical realms of Asia and 'Wallacea', a transitional zone between Asia and Australia also called the Malay Archipelago and the Indo-Australian Archipelago. To the west of the line are found organisms related to Asiatic species; to the east, a mixture of species of Asian and Australian origins is present. Wallace noticed this clear division in both land mammals and birds during his travels through the East Indies in the 19th century.

<span class="mw-page-title-main">Landscape ecology</span> Science of relationships between ecological processes in the environment and particular ecosystems

Landscape ecology is the science of studying and improving relationships between ecological processes in the environment and particular ecosystems. This is done within a variety of landscape scales, development spatial patterns, and organizational levels of research and policy. Concisely, landscape ecology can be described as the science of "landscape diversity" as the synergetic result of biodiversity and geodiversity.

This glossary of ecology is a list of definitions of terms and concepts in ecology and related fields. For more specific definitions from other glossaries related to ecology, see Glossary of biology, Glossary of evolutionary biology, and Glossary of environmental science.

<span class="mw-page-title-main">Wallacea</span> Biogeographical region

Wallacea is a biogeographical designation for a group of mainly Indonesian islands separated by deep-water straits from the Asian and Australian continental shelves. Wallacea includes Sulawesi, the largest island in the group, as well as Lombok, Sumbawa, Flores, Sumba, Timor, Halmahera, Buru, Seram, and many smaller islands. The islands of Wallacea lie between the Sunda Shelf to the west, and the Sahul Shelf including Australia and New Guinea to the south and east. The total land area of Wallacea is 347,000 km2 (134,000 sq mi).

<span class="mw-page-title-main">Environmental gradient</span>

An environmental gradient, or climate gradient, is a change in abiotic (non-living) factors through space. Environmental gradients can be related to factors such as altitude, depth, temperature, soil humidity and precipitation. Often times, a multitude of biotic (living) factors are closely related to these gradients; as a result of a change in an environmental gradient, factors such as species abundance, population density, morphology, primary productivity, predation, and local adaptation may be impacted.

<span class="mw-page-title-main">Foundation species</span> Species that structures an ecology

In ecology, the foundation species are species that have a strong role in structuring a community. A foundation species can occupy any trophic level in a food web. The term was coined by Paul K. Dayton in 1972, who applied it to certain members of marine invertebrate and algae communities. It was clear from studies in several locations that there were a small handful of species whose activities had a disproportionate effect on the rest of the marine community and they were therefore key to the resilience of the community. Dayton’s view was that focusing on foundation species would allow for a simplified approach to more rapidly understand how a community as a whole would react to disturbances, such as pollution, instead of attempting the extremely difficult task of tracking the responses of all community members simultaneously. The term has since been applied to a range of organisms in ecosystems around the world, in both aquatic and terrestrial environments. Aaron Ellison et al. introduced the term to terrestrial ecology by applying the term foundation species to tree species that define and structure certain forest ecosystems through their influences on associated organisms and modulation of ecosystem processes.

<span class="mw-page-title-main">Guinean forest–savanna mosaic</span> Tropical forest, savanna, and grassland ecoregion in West Africa

The Guinean forest-savanna mosaic, also known as the Guinean forest-savanna transition, is a distinctive ecological region located in West Africa. It stretches across several countries including Guinea, Sierra Leone, Liberia, Ivory Coast, Ghana, Togo, Benin, Nigeria, and Cameroon. This region is characterized by a unique blend of forested areas and savannas, creating a diverse and dynamic landscape.

The following outline is provided as an overview of and topical guide to ecology:

Altitudinal zonation in mountainous regions describes the natural layering of ecosystems that occurs at distinct elevations due to varying environmental conditions. Temperature, humidity, soil composition, and solar radiation are important factors in determining altitudinal zones, which consequently support different vegetation and animal species. Altitudinal zonation was first hypothesized by geographer Alexander von Humboldt who noticed that temperature drops with increasing elevation. Zonation also occurs in intertidal and marine environments, as well as on shorelines and in wetlands. Scientist C. Hart Merriam observed that changes in vegetation and animals in altitudinal zones map onto changes expected with increased latitude in his concept of life zones. Today, altitudinal zonation represents a core concept in mountain research.

Tropical ecology is the study of the relationships between the biotic and abiotic components of the tropics, or the area of the Earth that lies between the Tropic of Cancer and the Tropic of Capricorn. The tropical climate experiences hot, humid weather and rainfall year-round. While many might associate the region solely with the rainforests, the tropics are home to a wide variety of ecosystems that boast a great wealth of biodiversity, from exotic animal species to seldom-found flora. Tropical ecology began with the work of early English naturalists and eventually saw the establishment of research stations throughout the tropics devoted to exploring and documenting these exotic landscapes. The burgeoning ecological study of the tropics has led to increased conservation education and programs devoted to the climate.

<span class="mw-page-title-main">Montane ecosystems</span> Ecosystems found in mountains

Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures fall as elevation increases, causing the ecosystem to stratify. This stratification is a crucial factor in shaping plant community, biodiversity, metabolic processes and ecosystem dynamics for montane ecosystems. Dense montane forests are common at moderate elevations, due to moderate temperatures and high rainfall. At higher elevations, the climate is harsher, with lower temperatures and higher winds, preventing the growth of trees and causing the plant community to transition to montane grasslands and shrublands or alpine tundra. Due to the unique climate conditions of montane ecosystems, they contain increased numbers of endemic species. Montane ecosystems also exhibit variation in ecosystem services, which include carbon storage and water supply.

<span class="mw-page-title-main">Biogeographic classification of India</span>

Biogeographic classification of India is the division of India according to biogeographic characteristics. Biogeography is the study of the distribution of species (biology), organisms, and ecosystems in geographic space and through geological time. India has a rich heritage of natural diversity. India ranks fourth in Asia and tenth in the world amongst the top 17 mega-diverse countries in the world. India harbours nearly 11% of the world's floral diversity comprising over 17500 documented flowering plants, 6200 endemic species, 7500 medicinal plants and 246 globally threatened species in only 2.4% of world's land area. India is also home to four biodiversity hotspots—Andaman & Nicobar Islands, Eastern Himalaya, Indo-Burma region, and the Western Ghats. Hence the importance of biogeographical study of India's natural heritage.

The Southern Siberian rainforest is an area of temperate rainforest in South Central Siberia that occurs primarily along the Altai and Sayan mountain ranges in Khakassia and Tuva as well as a small area in the Khamar-Daban Mountains near Lake Baikal in Buryatia. The forest encompasses a total area of approximately 6,000 square kilometres (2,300 sq mi). The larger portion of the forest in the Altai and Sayan Mountains runs across a latitude range that encompasses between 51.5 degrees to 56 degrees north latitude, and a longitude range running between 86 degrees to 95 degrees east longitude. The region overlaps with the Golden Mountains of Altai World Heritage Site. Ecological zones range from hemiboreal forest to a forest-steppe ecotone and include a wider variety of plant species than surrounding areas.

<span class="mw-page-title-main">Amazon biome</span> Ecological region of South America

The Amazon biome contains the Amazon rainforest, an area of tropical rainforest, and other ecoregions that cover most of the Amazon basin and some adjacent areas to the north and east. The biome contains blackwater and whitewater flooded forest, lowland and montane terra firma forest, bamboo and palm forest, savanna, sandy heath and alpine tundra. Some areas of the biome are threatened by deforestation for timber and to make way for pasture or soybean plantations.

References

  1. ↑ Senft, Amanda (2009). Species Diversity Patterns at Ecotones (PDF). University of North Carolina. Archived from the original (Master's thesis) on 2011-09-30. Retrieved 2011-01-07.
  2. ↑ Pearl, Solomon Eldra; Berg, Linda R.; Martin, Diana W. (2011). Biology. Belmont, California: Brooks/Cole.[ page needed ]
  3. 1 2 Smith, Robert Leo (1974). Ecology and Field Biology (2nd ed.). Harper & Row. p.  251. ISBN   978-0-06-500976-7.
  4. ↑ The Editors of Encyclopædia Britannica. “Ecotone.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 23 Jan. 2012, www.britannica.com/science/ecotone.
  5. ↑ Janauer, G.A (1997). "Macrophytes, hydrology, and aquatic ecotones: A GIS-supported ecological survey". Aquatic Botany. 58 (3–4): 379–91. doi:10.1016/S0304-3770(97)00047-8.
  6. ↑ Walker, Susan; Wilson, J. Bastow; Steel, John B; Rapson, G.L; Smith, Benjamin; King, Warren McG; Cottam, Yvette H (2003). "Properties of ecotones: Evidence from five ecotones objectively determined from a coastal vegetation gradient". Journal of Vegetation Science. 14 (4): 579–90. doi: 10.1111/j.1654-1103.2003.tb02185.x .
  7. ↑ Kubisch, P; Leuschner, C; Coners, H; Gruber, A; Hertel, D (2017). "Fine Root Abundance and Dynamics of Stone Pine (Pinus cembra) at the Alpine Treeline Is Not Impaired by Self-shading". Front Plant Sci. 8: 602. doi: 10.3389/fpls.2017.00602 . PMC   5395556 . PMID   28469633.
  8. ↑ Swanson, F. J.; Wondzell, S. M.; Grant, G. E. (1992). "Landforms, Disturbance, and Ecotones" (PDF). Landscape Boundaries. Ecological Studies. 92: 304–323. doi:10.1007/978-1-4612-2804-2_15. ISBN   978-1-4612-7677-7 . Retrieved 11 November 2022.
  9. ↑ Maarel, Eddy (1990). "Ecotones and ecoclines are different". Journal of Vegetation Science. 1 (1): 135–8. doi:10.2307/3236065. JSTOR   3236065.
  10. 1 2 Backeus, Ingvar (1993). "Ecotone Versus Ecocline: Vegetation Zonation and Dynamics Around a Small Reservoir in Tanzania". Journal of Biogeography. 20 (2): 209–18. doi:10.2307/2845672. JSTOR   2845672.
  11. ↑ Brownstein, G; Johns, C; Fletcher, A; Pritchard, D; Erskine, P. D (2015). "Ecotones as indicators: Boundary properties in wetland-woodland transition zones". Community Ecology. 16 (2): 235–43. doi: 10.1556/168.2015.16.2.11 .
  12. 1 2 Smith, Deborah R (2011). "Asian Honeybees and Mitochondrial DNA". Honeybees of Asia. pp. 69–93. doi:10.1007/978-3-642-16422-4_4. ISBN   978-3-642-16421-7.
  13. 1 2 Hughes, Jennifer B; Round, Philip D; Woodruff, David S (2003). "The Indochinese-Sundaic faunal transition at the Isthmus of Kra: An analysis of resident forest bird species distributions". Journal of Biogeography. 30 (4): 569–80. doi:10.1046/j.1365-2699.2003.00847.x. S2CID   55953315.
  14. ↑ Theeraapisakkun, M; Klinbunga, S; Sittipraneed, S (2010). "Development of a species-diagnostic marker and its application for population genetics studies of the stingless bee Trigona collina in Thailand". Genetics and Molecular Research. 9 (2): 919–30. doi: 10.4238/vol9-2gmr775 . PMID   20486087.
  15. ↑ Alfano, Niccolò; Michaux, Johan; Morand, Serge; Aplin, Ken; Tsangaras, Kyriakos; Löber, Ulrike; Fabre, Pierre-Henri; Fitriana, Yuli; Semiadi, Gono; Ishida, Yasuko; Helgen, Kristofer M; Roca, Alfred L; Eiden, Maribeth V; Greenwood, Alex D (2016). "Endogenous Gibbon Ape Leukemia Virus Identified in a Rodent (Melomys burtoni subsp.) from Wallacea (Indonesia)". Journal of Virology. 90 (18): 8169–80. doi:10.1128/JVI.00723-16. PMC   5008096 . PMID   27384662.
  16. ↑ Tanzler, R; Toussaint, E. F. A; Suhardjono, Y. R; Balke, M; Riedel, A (2014). "Multiple transgressions of Wallace's Line explain diversity of flightless Trigonopterus weevils on Bali". Proceedings of the Royal Society B: Biological Sciences. 281 (1782): 20132528. doi:10.1098/rspb.2013.2528. PMC   3973253 . PMID   24648218.
  17. ↑ Steve Nadis (11 June 2016). "Life on the edge". New Scientist.
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