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Xerarch Succession

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Xerarch Succession - An Introduction

Xerarch succession is a type of plant succession that begins on bare, extremely dry terrain or is constrained by the availability of water and eventually leads to a mature forest. These communities typically evolved in arid conditions, such as sand dunes and rock deserts. In actuality, “xero'' means “dry.” Additionally, xeroseres can also consist of lithoseres and psammoseres (sand) (rocks).

To put it another way, xerarch succession is a kind of plant succession that is seen in extremely arid environments. A desolate environment is colonised by plants, which then transform it into a forest (over a period of time). The peak of the succession process is formed by these woods. Deserts, sand dunes, and other arid ecosystems are where this ecological succession occurs.

Lichens produce rocks in the xerarch succession and exude acidic chemicals that aid weathering. Creating soil is aided by weathering. A mature forest finally results from xerarch succession, which begins in the bare ground that is extremely dry or is constrained by the availability of water.


Water availability is a constraint on plant succession known as xerosere. It comprises each phase of a xerarch succession. Ecological communities that are part of the Xerarch succession first appeared in arid environments like sand, salt, rock, and dune deserts. Lithoseres and psammoseres can both be found in a xerosere.

The term “xerosere” refers to the succession of environmental groups that first appeared in an extremely dry habitat, such as a rock desert, sand desert, dune desert, or on unweathered rock surfaces when the Xerosere first appears. Lichens are the first organisms to inhabit these basic types of the substratum. In a Xerosere, both plants and animals experience successive transformations.

Pioneer Species in a Xerarch Succession

Pioneer species are those that spread across a barren landscape. Lichens that can release acids to dissolve rock and aid in weathering and soil formation typically make up the primary succession in xerarch. Ecological succession is known as xerarch in arid places. Lichen is a symbiotic relationship in which a fungus and algae or cyanobacteria cooperate for the mutual benefit of both species. Acids secreted by lichens help weather and soil development during succession by dissolving rock.

In the xerarch succession species, mosses and lichens make up the pioneer community. The group of pioneer species is known as the pioneer. Over the base rocks, lichens create a crust that starts to decompose into the soil as a result of the chemical reactions that are sped up by the lichens and their organic waste.

Xerarch Succession Stages

  1. Crustose Lichen Stage: This is the first phase. Crustose lichen is the first living organism to appear on bare rock. They experience temperature extremes. Additionally, poor are organic substances and moisture. Rhizocorpon is its most prevalent species. Lecanora as well as Rhinodin.

Wind and water aid in the travel of these lichens through the soredia and spores they produce. Rain and dew drops can occasionally cause its surface to get damp. During the dry season, they absorb water. The rock weathers as a result of the carbonic acid they create. They set up the land for the following phase.

  1. Foliage Lichen Stage: The environment is now ideal for foliage lichens. The enormous leaves of foliage lichens resemble thalli. They are joined at a single location. They have the capacity to take up and hold more water as well as collect dust particles that aid in the continued formation of the substratum. They use Parmelia and Dermatocarpon as examples.

On the crusty lichens, they cast shade. As a result, crustose lichen growth is slowed or stopped. They raise the acidity of the soil. To it is put humus. It results in the creation of a fine, thin coating of soil and makes the rock abrasive. The habitat changes as a result.

  1. Moss Stage: This is the third stage. Mosses, like lichens, have evolved to withstand severe drought. Rhizoids are produced by xerophytic mosses, and they delve deeply into the rocky soil. Polytrichum, Tortula, and Grimmia species are moss types. They successfully compete with the prior lichens for water and mineral resources while covering them. A dense mat of older, decomposing moss pieces covers the rock’s surface. This mat boosts the soil’s ability to hold water as it gets thicker.

As a result, the habitat gets comparatively wetter. The soil layer has now increased, creating an environment which is suitable for herbaceous plants. Habitat changes lessen the xeric condition.

  1. Herbaceous (Plant) Stage: More dirt and minerals are deposited because of the vast moss growth. The soil has a lot of humus and litter. Wind-borne dust particles are also accumulated. Its ability to store water is thereby improved. There are currently established annual herbaceous plants there. Perennials and biennials eventually take their place. These plants speed up the weathering process. Transpiration or evaporation occurs. The temperature is lowered. Now, there are animals, fungi, and bacteria growth. There, a few xerophytes types of grass also grow.

  2. Shrub Stage: The habitat becomes ideal for shrubs as a result of the significant soil deposition, and they begin to migrate through the area. Phytocarpus and other shrubby plants are now beginning to grow. They get more compact. They overshadow the herbaceous vegetation. The establishment of thick shrubs enriches the soil even more. Shrubs’ roots delve deep into the ground. They cause large rock fissures to form. Soil formation is still going on.

  3. Forest or Climax Stage: These bushes’ roots, twigs, and decaying leaves all add humus to the soil. These significant reactions create habitat conditions that are more favourable for trees than for shrubs and plants. The development and establishment of woody plants are thus now permitted. The roots of these plants are deep. Most plants can’t thrive because of the shadow provided by these plants.

This stage is dominated by woody vegetation. If nothing alters in the environment to throw off balance, this stage essentially stays the same. It is a stable transitional stage. Thus, the wooded forest serves as this area’s apex. Sterculia, Terminalia, Woodfordia, Wrightia, Eugenia, and Ficus species are common tree species. Climate-controlled climax communities are also referred to as climatic climax communities. All these explain Xerarch succession in plants.

Interesting Facts

  • Extremely dry environments like sand deserts and rock deserts are where the Xerarch succession of ecological groups first appears.

  • The orange wall lichen, also known as xanthoria, is the first evidence of a xerarch succession.

  • Marble and granite can practically be eaten by Xanthoria. More than 100 different varieties of marble-eating lichen, for instance, can be found in St. Petersburg.

Important Questions

1. Are Lithosere and Xerosere the same?

Ans: In areas with high aridity, such as sand dunes, sand deserts, rock deserts, etc., a plant succession known as xerosere develops. On bare rocks, there is a plant succession known as lithosere.

2. What are the 4 stages of succession?

Ans: Nudation, Invasion, Competition and Reaction, and Stabilization or Climax are the sequential processes that make up the entire process of a primary autotrophic biological succession.

Key Features

  • Ecological communities that are part of the Xerarch succession first appeared in extremely dry environments like sand deserts, rock deserts, etc.

  • Pioneer species are those that move into a barren area. Lichens are the first species to appear in primary succession.

  • Succession in which the xeric habitat transforms into the mesic environment is called xerarch succession. The pioneer communities are lichen which seral crossing stages get transformed into mesic vegetation.

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FAQs on Xerarch Succession

1. What replaces the lichens in a xerarch succession?

The term “xerarch succession” refers to the successional stages that occur on bare rocks. In a xerosere, moses take the place of the pioneering species lichens. Mosses include, but are not limited to, Tortula, Grimmima, Polyerichum, etc.

2. In a xerarch succession, who secrete acids to dissolve rock?

Xerarch succession is the term used to describe the successional stages that occur on bare rocks. The pioneering species of lichens in a xerarch succession release acids that disintegrate rocks. This aids in the production of soil and weathering.

3. What is the process of succession?

According to Max Witynski, succession is the change of habitat and species over an ecological time scale.

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