Which Statement Best Describes Ecological Succession

Which Statement Best Describes Ecological Succession

Learn more about breakthroughs pioneered at the Academy of Chicago

Ecological succession, explained


Ecological succession is the process past which the mix of species and habitat in an area changes over fourth dimension. Gradually, these communities replace ane another until a “climax community”—like a mature forest—is reached, or until a disturbance, similar a fire, occurs.

Ecological succession is a fundamental concept in ecology. The written report of succession was pioneered at the Academy of Chicago by Henry Chandler Cowles, who was likewise ane of the founders of ecology as a discipline, every bit he studied the plants of the Indiana Dunes.

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What is ecological succession?

Ecological succession is the process past which natural communities supercede (or “succeed”) one some other over time. For example, when an old subcontract field in the midwestern U.Southward. is abandoned and left alone for many years, information technology gradually becomes a meadow, then a few bushes grow, and eventually, trees completely make full in the field, producing a wood.

Each plant community creates conditions that subsequently allow different plant communities to thrive. For example, early colonizers like grasses might add together nutrients to the soil, whereas later on ones like shrubs and trees might create cover and shade. Succession stops temporarily when a “climax” community forms; such communities remain in relative equilibrium until a disturbance restarts the succession process.

In this video from the National Park Service, Tim Watkins and Robert Boyd explore the Indiana Dunes, learning about its history as an important case written report for the development of ecological succession theory.

Understanding how succession happens in a variety of ecosystems—and what kinds of disturbances and time spans lead to the formation of different establish and animal communities—is of import for scientists who want to empathise ecosystem dynamics and finer protect or restore natural communities.

For case, many natural communities in North America have adapted to periodic disturbances from wildfires: This tin help maintain prairie or savanna communities that depend on open habitat and nutrient cycling that might occur as a effect of burn.

What are primary and secondary ecological succession?

There are ii major types of ecological succession: chief succession and secondary succession.

Primary succession
happens when a new patch of land is created or exposed for the first time. This tin can happen, for example, when lava cools and creates new rocks, or when a glacier retreats and exposes rocks without any soil. During principal succession, organisms must start from scratch. First, lichens might adhere themselves to rocks, and a few small plants able to alive without much soil might appear. These are known as “pioneer species.”

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Gradually, the decomposition of those plants contributes to soil formation, and more and larger plants begin to colonize the expanse. Eventually, enough soil forms and enough nutrients go bachelor such that a climax community, like a woods, is formed. If the site is disturbed later this point, secondary succession occurs.

Secondary succession
happens when a climax community or intermediate community is impacted by a disturbance. This restarts the bicycle of succession, but non dorsum to the get-go—soil and nutrients are still present.

For example, after a woods fire that kills all the mature trees on a particular landscape, grasses might abound, followed by shrubs and a variety of tree species, until eventually the community that existed earlier the fire is present again.


A climax customs is the “endpoint” of succession inside the context of a detail climate and geography. In the midwestern U.Due south., for instance, such a customs might exist a hardwood wood with oaks and hickories as the ascendant tree species.

A climax community will persist in a given location until a disturbance occurs. However, in many ecosystems, disturbance occurs oft enough that a matrix of customs types may be consistently nowadays on the landscape.

For instance, in an surface area decumbent to wildfires like the western U.S., mature forests may exist nigh grassy meadows with fewer, scattered trees. Consistent disturbance and variation in factors similar h2o and nutrient availability over the grade of decades thus allows many plant and animal communities to thrive within a particular climatic and geographic niche—non just those adapted to the absenteeism of disturbance seen in climax communities.


What is an example of ecological succession?

Ecological succession can occur in many contexts and over many time spans.

In Hawaii and Republic of iceland, primary succession occurs on lava flows where new land has formed; in Canada’s Athabasca Dunes, information technology happens when new sand is deposited along a lakeshore; in the Andes, it occurs when glaciers retreat.

In many regions, secondary succession occurs where wildfires have destroyed conifer forests, or where old agricultural land is reverting to meadow or scrubland.

What these examples have in mutual is that the climax community is not the start one present on the landscape after succession begins: Offset, intermediate communities occupy the space, sometimes for many years, creating ideal conditions for the communities that follow.

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Plant succession at the Indiana Dunes

The Indiana Dunes, xl miles southeast of Chicago and today the site of both a state and a national park, served as the original field site for research on ecological succession in plant communities, and continue to serve as an ideal case study. (If you visit the dunes, you can walk along the Dune Succession Trail, which highlights the different stages of succession in a real-earth context.)

In the 1890s, University of Chicago botanist Henry Chandler Cowles noticed that dunes which were further from Lake Michigan had different plants growing on them than dunes closer to the lake. The lakeside dunes had just beach grass, whereas those further from the shore had other plants like cottonwoods that could grow in sandy soil. Dunes even so further back had pines, and finally behind them were mature oak forests that did not resemble the grassy dunes near the lake at all.

Through conscientious ascertainment and comparisons, Cowles determined that the linear succession of these communities in infinite too represented a linear progression in time. The dunes uttermost from the lake were the oldest and had been stable for longest, since sand shifts oft in the wind without plants to hold it in place.

From this, he inferred that plant communities trended toward oak forests in northern Indiana over decades and centuries, and that each community created the soil and microclimate weather condition required for its successor customs to thrive: as grasses and cottonwoods stabilized dunes and added nutrients, they were replaced by afterward successional communities.


How do we understand ecological succession today?

Ecological succession is a foundational concept in ecology, which equally a field examines the construction and dynamics of biological communities. Today, the concept of ecological succession continues to be studied from new angles equally humans change the global environs more than than e’er before. As new nuances have been added to the original theory, insights take emerged that are valuable to humans interested in managing natural resources.

For example, contempo studies show that even in “climax” communities, changes in what resources are available may shift the residuum of the species composition over fourth dimension, fifty-fifty without a formal disturbance. Other work has examined the impact of biodiversity loss, invasive species, climate alter and other anthropogenic factors in altering the way ecosystems respond to change.

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Equally native species get extinct or become rare, new species enter ecosystems, and climate baselines shift, the communities that once dominated an ecosystem may be less likely to eventually return afterwards a disturbance. Nonetheless, studying succession tin also provide valuable insights for ecologists and wildlife managers interested in restoring those natural systems: through careful management such as controlled called-for or invasive species control, people can help ecological communities stay strong.

Henry Chandler Cowles, ecological succession and the Academy of Chicago



The University of Chicago played a key part in pioneering the scientific study of ecological succession and ecology as a bailiwick more than broadly. Following his pivotal dissertation piece of work in the Indiana Dunes as a UChicago doctoral student, Henry Chandler Cowles went on to become a professor, remaining at UChicago for more than three decades, until the early 1930s. He taught generations of students most the ecology of North America through grade field trips beyond the continent from Maine to Alaska, California and Texas.

The trips—and Cowles’ fieldwork—are documented in the University’s special collection of American Ecology Photographs, which show Cowles, students, and American landscapes from a century agone in great variety and detail. Cowles’ papers are as well housed in the Hanna Holborn Gray Special Collections Research Eye, and can be found here. Additionally, Cowles’ student Victor Ernest Shelford became an influential ecologist in his ain right and a leader in the founding of the Nature Conservancy, a major conservation nonprofit.

In the early 20th century, the Academy of Chicago was also home to other noted ecologists and marine biologists, including George Damon Fuller and Warder Clyde Allee, an early expert on social relationships in animals and an important figure in the development of ecology.

Today, the University of Chicago remains a leader in research on ecology and evolutionary biological science. The Academy’southward Warren Woods Ecological Field Station in Berrien County, Michigan offers students, kinesthesia and staff the opportunity to study and find ecosystem dynamics in a landscape that includes both remnant (undisturbed) woods, restored prairie and old fields.


Which Statement Best Describes Ecological Succession

Source: https://news.uchicago.edu/explainer/what-is-ecological-succession