Bracken (Pteridium) is a genus of large, coarse ferns in the family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produce sex cells. Brackens are noted for their large, highly divided leaves. They are found on all continents except Antarctica and in all environments except deserts, though their typical habitat is moorland. The genus probably has the widest distribution of any fern in the world.
Vegetation is an assemblage of plant species and the ground cover they provide. It is a general term, without specific reference to particular taxa, life forms, structure, spatial extent, or any other specific botanical or geographic characteristics. It is broader than the term flora which refers to species composition. Perhaps the closest synonym is plant community, but vegetation can, and often does, refer to a wider range of spatial scales than that term does, including scales as large as the global. Primeval redwood forests, coastal mangrove stands, sphagnum bogs, desert soil crusts, roadside weed patches, wheat fields, cultivated gardens and lawns; all are encompassed by the term vegetation.
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.
An ecotone is a transition area between two biological communities, where two communities meet and integrate. It may be narrow or wide, and it may be local or regional. 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.
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.
Forest dynamics describes the underlying physical and biological forces that shape and change a forest ecosystem. The continuous state of change in forests can be summarized with two basic elements: disturbance and succession.
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 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.
The intermediate disturbance hypothesis (IDH) suggests that local species diversity is maximized when ecological disturbance is neither too rare nor too frequent. At low levels of disturbance, more competitive organisms will push subordinate species to extinction and dominate the ecosystem. At high levels of disturbance, due to frequent forest fires or human impacts like deforestation, all species are at risk of going extinct. According to IDH theory, at intermediate levels of disturbance, diversity is thus maximized because species that thrive at both early and late successional stages can coexist. IDH is a nonequilibrium model used to describe the relationship between disturbance and species diversity. IDH is based on the following premises: First, ecological disturbances have major effects on species richness within the area of disturbance. Second, interspecific competition results from one species driving a competitor to extinction and becoming dominant in the ecosystem. Third, moderate ecological scale disturbances prevent interspecific competition.
Frederic Edward Clements was an American plant ecologist and pioneer in the study of vegetation 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.
In ecology, a disturbance is a temporary change in environmental conditions that causes a pronounced change in an ecosystem. Disturbances often act quickly and with great effect, to alter the physical structure or arrangement of biotic and abiotic elements. A disturbance can also occur over a long period of time and can impact the biodiversity within an ecosystem.
Patterned vegetation is a vegetation community that exhibits distinctive and repetitive patterns. Examples of patterned vegetation include fir waves, tiger bush, and string bog. The patterns typically arise from an interplay of phenomena that differentially encourage plant growth or mortality. A coherent pattern arises because there is a strong directional component to these phenomena, such as wind in the case of fir waves, or surface runoff in the case of tiger bush. The regular patterning of some types of vegetation is a striking feature of some landscapes. Patterns can include relatively evenly spaced patches, parallel bands or some intermediate between those two. These patterns in the vegetation can appear without any underlying pattern in soil types, and are thus said to “self-organize” rather than be determined by the environment. Several of the mechanisms underlying patterning of vegetation have been known and studied since at least the middle of the 20th century, however, mathematical models replicating them have only been produced much more recently. Self-organization in spatial patterns is often a result of spatially uniform states becoming unstable through the monotonic growth and amplification of nonuniform perturbations. A well known instability of this kind leads to so-called Turing patterns. These patterns occur at many scales of life, from cellular development to pattern formation on animal pelts to sand dunes and patterned landscapes. In their simplest form models that capture Turing instabilities require two interactions at differing scales: local facilitation and more distant competition. For example, when Sato and Iwasa produced a simple model of fir waves in the Japanese Alps, they assumed that trees exposed to cold winds would suffer mortality from frost damage, but upwind trees would protect nearby downwind trees from wind. Banding appears because the protective boundary layer created by the wind-most trees is eventually disrupted by turbulence, exposing more distant downwind trees to freezing damage once again.
Patch dynamics is an ecological perspective that the structure, function, and dynamics of ecological systems can be understood through studying their interactive patches. Patch dynamics, as a term, may also refer to the spatiotemporal changes within and among patches that make up a landscape. Patch dynamics is ubiquitous in terrestrial and aquatic systems across organizational levels and spatial scales. From a patch dynamics perspective, populations, communities, ecosystems, and landscapes may all be studied effectively as mosaics of patches that differ in size, shape, composition, history, and boundary characteristics.
Alexander Stuart Watt FRS(21 June 1892 – 2 March 1985) was a Scottish botanist and plant ecologist.
Climax species, also called late seral, late-successional, K-selected or equilibrium species, are plant species that can germinate and grow with limited resources, like low-sun exposure or low water availability. They are the species within forest succession that are more adapted to stable and predictable environments, and will remain essentially unchanged in terms of species composition for as long as a site remains undisturbed.
In ecology, a priority effect is the impact that a particular species can have on community development due to prior arrival at a site.
Ptaquiloside is a norsesquiterpene glucoside produced by bracken ferns during metabolism. It is identified to be the main carcinogen of the ferns and to be responsible for their biological effects, such as haemorrhagic disease and bright blindness in livestock and oesophageal, gastric cancer in humans. Ptaquiloside has unstable chemical structure and acts as a DNA alkylating agent under physiological conditions. It was first isolated and characterized by Yamada and co-workers in 1983.
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.
Gap dynamics refers to the pattern of plant growth that occurs following the creation of a forest gap, a local area of natural disturbance that results in an opening in the canopy of a forest. Gap dynamics are a typical characteristic of both temperate and tropical forests and have a wide variety of causes and effects on forest life.
The Chimanimani Mountains are a mountain range on the border of Zimbabwe and Mozambique. The mountains are in the southern portion of the Eastern Highlands, or Manica Highlands, a belt of highlands that extend north and south along the international border, between the Zambezi and Save rivers.
