Secondary Succession Definition
The secondary succession, a kind of ecological succession, is among the two major forms. This is the procedure of population growth or transformation after an environment has been altered or degraded.
Secondary succession happens on a medium that formerly sustained vegetation that has been disturbed by activities like fire, storms, floods, or man made disruptions. Primary succession takes place once pioneer species colonise a freshly produced medium devoid of soil and living creatures (including lava-formed rock or glacier-retreating regions).
Due to the fact that the soil and nutrients have previously been “normalised” by previous pioneer organisms, and that roots, seeds, and other biological creatures might be available in the substrate, the soil and nutrients are now suitable for the establishment of new pioneer species. Secondary succession is frequently quicker than primary succession.
Both abiotic and biotic elements of an ecosystem may be profoundly altered by the presence of fire. CO2, CO, and CH4 held in organic material are released into the environment by the burning process. Nevertheless, this preliminary depletion of nutrition is typically compensated and subsequently enhanced by the breakdown of remaining vegetable matter that denatures N, P, and K and returns into the soil. The soil’s moisture retention improves as a result of lower plant transpiration and more water reaching the top of the soil when leaf interception of precipitation is little or non-existent. Because acids burn, the pH of the soil frequently increases (becomes more alkaline) after a fire.
Species begin to recolonize a region after a fire, commencing the secondary succession process. Herbaceous plants with rapid growth, such as conifers and ferns, are frequently the first to invade since they demand a lot of light sources. These plants frequently already exist as seeds in the soil, or may quickly propagate from surrounding places. Slow-growing, shade-tolerant woody species gradually suffocate the earliest successional taxa that are ultimately supplanted or overshadowed by huge trees, resulting in the formation of forests and climax communities.
A mosaic of habitats is created within an area by the physical and biological properties of an ecosystem, in addition to the level of disruption (determined by fire severity and recurrence). This mosaic effect permits a wider diversity of species to colonise a region than would be possible in a region that has been biologically stable over an extended period of time. The kinds of animals and plants that may repopulate a place following a fire depend on the quality of the soil, the temperature, and the location’s topography.
Harvesting, Logging and Abandonment of Crop Land
Human-induced secondary succession is often caused by the abandonment of previously cultivated land. Land that has been extensively farmed is often deficient in nutrients, since nutrients have been removed repeatedly via harvest or logging. Agricultural practises often expose the land to significant rates of eroding soil. The absence of these kinds of land allows previously unable to colonise flora and animals to do so. Early plant succession following cessation of agriculture results in increases in soil biological matter, nutritional density, and permeability. Later in the succession, the establishment of shrubbery and root systems inside soils acts as a natural erosion barrier, permits for the regeneration of damaged ecosystems.
Because of the homogeneity of soil type and nutrients, secondary succession in human-altered landscapes varies from natural succession, particularly when chemical fertilisers have been used. This might result in the exclusive colonisation of a region by generalist species, slowing the succession process and limiting biodiversity.
Renewal After Disease
When an illness infects all members of a species in a certain location, the species is expected to go extinct rapidly. However, the advent of illness may be devastating to a species. The plant may recolonise when the seeds or roots persist in the soil after the live plant has perished, and the illness has been eradicated. Conversely, the disease might destroy numerous members of a species to permit the incursion of species that were previously unable to colonise the area, allowing a wider diversity of species to live in a given region.
Secondary succession may occur on a large scale and produce substantial effects on an environment or ecosystem, although it occurs more often on a local scale. Gap dynamics refers to the disruption and ensuing secondary succession that occurs when a space is created in a wild canopy due to the mortality and fall of only one tree or the loss of a major stem. The impact is most common in thick forests. The opening of a canopy gap enables light to reach the forest base, enabling herbaceous plants, shrubs, vines, and seedlings to use the fresh resources.
After a few years, faster-growing, taller plants emerge to occupy the lower canopy. This inhibits the development of shade-intolerant species while enabling shade-tolerant species to flourish. After 75–150 years, sun-loving (heliophilic) species begin to occupy the peak of the forest, while shade-tolerant plants create a steady population in the lower forests. A climax community is a stable condition that will stay in balance unless a fresh canopy gap appears.
Related Biology Terms
- The form of succession that develops on a fresh bedrock that is devoid of plants or other creatures.
- Climax Community: A relative state of stability or balance in species distribution that occurs when a population is not disturbed for an extended length of time.
- Hardy species are the first to inhabit a freshly damaged or constructed environment, kicking off the ecological succession process.
- Ecological Disturbance: A brief disturbance within a habitat that results in significant variations in the biotic and abiotic constituents of an ecosystem.
Question and Answer
1. Which types of plants are likely to colonize a disturbed habitat first?
- Tall, hardwood trees
- Herbaceous plants
- Shade tolerant plants
- None of the above
B is correct. Small herbaceous plants which require lots of sunlight are the first to colonize newly disturbed or damaged habitat. These are then suppressed by woody, shade-tolerant trees and shrubs.
2. Which of the following scenarios would not create a habitat suitable for secondary succession?
- Forest fire
- Volcanic eruption
C is correct. The lava flow from a volcanic eruption would create a new rock or substrate that would not allow for any of the previously living organisms to recolonize an area. The process by which pioneer species would inhabit this area would involve primary succession.
3. Secondary succession does not directly affect:
- Species diversity
- Soil nutrients
- Soil moisture content
A is correct. Secondary succession does not directly affect the amount of rain that falls in an area; however, it can affect the moisture retention properties of the soil.