In
ecology
Ecology () is the natural science of the relationships among living organisms and their Natural environment, environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosystem, and biosphere lev ...
, allogenic succession is
succession
Succession is the act or process of following in order or sequence.
Governance and politics
*Order of succession, in politics, the ascension to power by one ruler, official, or monarch after the death, resignation, or removal from office of ...
driven by the
abiotic component
In biology and ecology, abiotic components or abiotic factors are non-living chemical and physical parts of the environment that affect living organisms and the functioning of ecosystems. Abiotic factors and the phenomena associated with them und ...
s of an
ecosystem
An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...
.
In contrast,
autogenic succession
"Auto-" meaning self or same, and "-genic" meaning producing or causing. Autogenic succession refers to ecological succession driven by biotic factors within an ecosystem and although the mechanisms of autogenic succession have long been debated, ...
is driven by the
biotic component
An ecosystem (or ecological system) is a system formed by organisms in interaction with their environment. The biotic and abiotic components are linked together through nutrient cycles and energy flows.
Ecosystems are controlled by exter ...
s of the ecosystem.
An allogenic succession can be initiated in a number of ways which can include:
*
Volcanic eruptions
A volcanic eruption occurs when material is expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior h ...
*Meteor or comet strike
*Flooding
*Drought
*Earthquakes
*
Non-anthropogenic climate change
Allogenic succession can happen on a time scale that is proportionate with the disturbance. For example, allogenic succession that is the result of
non-anthropogenic climate change can happen over thousands of years.
Allogenic succession can also vary widely in spatial scale. Some disturbances, like landslides or localized floods, affect only small patches of land and initiate short-term successional processes. Others, such as glaciation or long-term tectonic shifts, can transform entire regions over millennia.
Human activities are also a major source of allogenic disturbance. Anthropogenic events, like deforestation, urbanization, mining, and agriculture, alter abiotic conditions like soil structure, water availability, and microclimates. These changes can trigger succession by creating new environments for colonization. For example, strip mining can expose bare substrate, initiating a succession that begins with pioneer species.
Example
The majority of
Salt Marsh
A salt marsh, saltmarsh or salting, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. I ...
development comes from allogenic succession. The constant exposure to water in the
intertidal zone
The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...
causes the soil of a salt marsh to change over time. This results in sedimentation and nutrient buildup that also slowly raises the level of the land. What started as a sandy soil with a slightly high
pH level, eventually becomes a loamy soil with a more neutral pH level. During this period, the soil-salinity will also change by starting low and eventually rising to higher levels from continued seawater exposure.
Glacier forelands are another example of ecosystems that form from
autogenic but also partly allogenic succession. The importance of this is estimated to be higher in earlier successional stages, regarding rock formations, slope angles and soil composition.
On a smaller scale, a treefall gap caused by wind or lightning can also trigger allogenic succession. The sudden change in light, moisture, and soil allows early successional species to establish, eventually leading to canopy regeneration.
See also
*
References
Ecological succession
{{Ecology-stub