Q.Define ecological succession. Explain Hydrarch succession and Xerarch succession in brief.

Secondary succession starts on land that already had life and still has soil (e.g. degraded forests); bare rock, sand and new ponds are primary succession sites.

Succession is of two kinds:

• Primary succession starts on lifeless, soil-free surfaces — bare rocks, newly cooled lava, sand dunes, or newly formed ponds — and is very slow because soil must first form. …

A climax community is the stable, self-perpetuating end-stage of ecological succession and does not evolve further under existing conditions.

Ecological succession proceeds through a pioneer community, a series of changing seral (transitional) communities, and finally reaches a climax community that is in equilibrium with the prevailing climate and environment. Because the climax community is stable and self-maintaining, it does not undergo further directional change unless the environment itself is …

Pioneer species are the hardy first colonisers of an empty habitat, initiating the process of ecological succession.

When ecological succession begins on an entirely new or disturbed substrate (such as bare rock in xerarch succession, or a newly formed pond in hydrarch succession), the very first organisms to establish themselves there are called pioneer species. They are typically hardy, fast-dispersing, stress-tolerant organisms (e.g. lichens and mosses on bare rock, or phytoplankton in a new pond) capable of surviving harsh initial conditions with little soil or nutrients. Through their growth and death, pioneer species gradually modify the environment (e.g. by adding organic …

Xerarch succession begins on dry, bare substrates like rock, starting with crustose lichens and progressing through mosses before herbs, shrubs, and trees establish.

Ecological succession that begins in a dry area (e.g., bare rock) is called xerarch succession, and it proceeds through a well-defined sequence of seres:

1. Crustose lichens (pioneer community) colonise bare rock, secreting acids that weather the rock surface and begin soil formation.
2. Mosses replace lichens once a thin layer of soil has formed, further building organic matter. …

Succession is the sequential, directional replacement of communities in an area, culminating in a stable climax community.

Ecological succession is the natural process by which the community structure of an area changes progressively over time. It starts with pioneer species that are able to colonise a bare (primary succession) or disturbed but previously vegetated (secondary succession) area. These pioneers gradually alter the local environment (e.g. by contributing to soil formation), making conditions suitable for other, often more complex, species to establish. This replacement continues through a series of intermediate seral stages until a relatively stable, self-sustaining climax community is reached, w …

Succession is the sequential, directional change of communities in an area, ending in a stable climax community.

Ecological succession refers to the natural, sequential process by which the species composition of a community in a particular area changes over time. It begins when pioneer species colonise a bare or disturbed area (primary succession, e.g. bare rock) or a previously vegetated but disturbed area (secondary succession, e.g. after a fire or flood). These pioneers gradually modify the environment (soil formation, microclimate), making it suitable for other species to invade and eventually replace them. This sequence of communities (the sere) continues through several intermediate stages until a relatively stable, self-perpetuatin …