An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native species that become harmful to their native environment after human alterations to its food web. Since the 20th century, invasive species have become serious economic, social, and environmental threats worldwide.
In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species, or of different species. These effects may be short-term, or long-term, both often strongly influence the adaptation and evolution of the species involved. Biological interactions range from mutualism, beneficial to both partners, to competition, harmful to both partners. Interactions can be direct when physical contact is established or indirect, through intermediaries such as shared resources, territories, ecological services, metabolic waste, toxins or growth inhibitors. This type of relationship can be shown by net effect based on individual effects on both organisms arising out of relationship.
Allelopathy is a biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms. These biochemicals are known as allelochemicals and can have beneficial or detrimental effects on the target organisms and the community. Allelopathy is often used narrowly to describe chemically-mediated competition between plants; however, it is sometimes defined more broadly as chemically-mediated competition between any type of organisms. The original concept developed by Hans Molisch in 1937 seemed focused only on interactions between plants, between microorganisms and between microorganisms and plants. Allelochemicals are a subset of secondary metabolites, which are not directly required for metabolism of the allelopathic organism.
Centaurea diffusa, also known as diffuse knapweed, white knapweed or tumble knapweed, is a member of the genus Centaurea in the family Asteraceae. This species is common throughout western North America but is not actually native to the North American continent, but to the eastern Mediterranean.
The rhizosphere is the narrow region of soil or substrate that is directly influenced by root secretions and associated soil microorganisms known as the root microbiome. Soil pores in the rhizosphere can contain many bacteria and other microorganisms that feed on sloughed-off plant cells, termed rhizodeposition, and the proteins and sugars released by roots, termed root exudates. This symbiosis leads to more complex interactions, influencing plant growth and competition for resources. Much of the nutrient cycling and disease suppression by antibiotics required by plants occurs immediately adjacent to roots due to root exudates and metabolic products of symbiotic and pathogenic communities of microorganisms. The rhizosphere also provides space to produce allelochemicals to control neighbours and relatives.
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. This article addresses both the mechanisms of facilitation and the increasing information available concerning the impacts of facilitation on community ecology.
Intertidal ecology is the study of intertidal ecosystems, where organisms live between the low and high tide lines. At low tide, the intertidal is exposed whereas at high tide, the intertidal is underwater. Intertidal ecologists therefore study the interactions between intertidal organisms and their environment, as well as between different species of intertidal organisms within a particular intertidal community. The most important environmental and species interactions may vary based on the type of intertidal community being studied, the broadest of classifications being based on substrates—rocky shore and soft bottom communities.
George David Tilman, ForMemRS, is an American ecologist. He is Regents Professor and McKnight Presidential Chair in Ecology at the University of Minnesota, as well as an instructor in Conservation Biology; Ecology, Evolution, and Behavior; and Microbial Ecology. He is director of the Cedar Creek Ecosystem Science Reserve long-term ecological research station. Tilman is also a professor at University of California, Santa Barbara's Bren School of Environmental Science & Management.
Plant ecology is a subdiscipline of ecology that studies the distribution and abundance of plants, the effects of environmental factors upon the abundance of plants, and the interactions among plants and between plants and other organisms. Examples of these are the distribution of temperate deciduous forests in North America, the effects of drought or flooding upon plant survival, and competition among desert plants for water, or effects of herds of grazing animals upon the composition of grasslands.
In ecology, a priority effect refers to the impact that a particular species can have on community development as a result of its prior arrival at a site. There are two basic types of priority effects: inhibitory and facilitative. An inhibitory priority effect occurs when a species that arrives first at a site negatively affects a species that arrives later by reducing the availability of space or resources. In contrast, a facilitative priority effect occurs when a species that arrives first at a site alters abiotic or biotic conditions in ways that positively affect a species that arrives later. Inhibitory priority effects have been documented more frequently than facilitative priority effects. Studies indicate that both abiotic and biotic factors can affect the strength of priority effects.. Priority effects are a central and pervasive element of ecological community development that have significant implications for natural systems and ecological restoration efforts.
Mark D. Bertness is an American ecologist, known for his work on the community assembly of marine shoreline communities.
A mycorrhizal network is an underground network found in forests and other plant communities, created by the hyphae of mycorrhizal fungi joining with plant roots. This network connects individual plants together. Mycorrhizal relationships are most commonly mutualistic, with both partners benefiting, but can be commensal or parasitic, and a single partnership may change between any of the three types of symbiosis at different times.
Alien species, or species that are not native, invade habitats and alter ecosystems around the world. Invasive species are only considered invasive if they are able to survive and sustain themselves in their new environment. A habitat and the environment around it has natural flaws that make them vulnerable to invasive species. The level of vulnerability of a habitat to invasions from outside species is defined as its invasibility. One must be careful not to get this confused with invasiveness, which relates to the species itself and its ability to invade an ecosystem.
Nurse plants are plants that serve the ecological role of helping seedlings establish themselves and protecting young plants from harsh conditions. This effect is particularly well studied among plant communities in xeric environments.
Nico Eisenhauer is a German biologist, soil ecologist and professor for experimental interaction ecology at Leipzig University.
The enemy release hypothesis is among the most widely proposed explanations for the dominance of exotic invasive species. In its native range, a species has co-evolved with pathogens, parasites and predators that limit its population. When it arrives in a new territory, it leaves these old enemies behind, while those in its introduced range are less effective at constraining the introduced species' population. The result is sometimes rampant growth that threatens native species and ecosystems.
Anna Traveset is a Spanish ecologist, particularly known for her work on ecological interactions between plants and animals, especially on islands.
Anna Amelia Sher is an American plant ecologist who is a professor at the University of Denver. She works on conservation and the restoration of areas invaded by Tamarix. She is the author of two textbooks, Ecology:Concepts and Applications and Introduction to conservation biology.
Joan Gardner Ehrenfeld was an American environmental scientist who was a professor at Rutgers University. Her research considered invasive species and ecology. She was elected Fellow of the American Association for the Advancement of Science in 2000.
The stress gradient hypothesis (SGH) is an evolutionary theory in microbial ecology and community ecology that provides a framework to predict when positive or negative interactions should be observed in an habitat. The SGH states that facilitation, cooperation or mutualism should be more common in stressful environments, compared with benign environments where competition or parasitism should be more common.
