Ecological succession definition and stages
Succession is a directional, non-seasonal cumulative change in the types of plant species that occupy a given area through time. It involves the processes of colonization, establishment, and extinction which act on the participating plant species.
successions
Most successions contain a number of stages that can be recognized by the collection of species that dominate at that point in the succession. Succession begins when an area is made partially or completely devoid of vegetation because of disturbance.
Mechanisms of disturbance
Some common mechanisms of disturbance are fires, wind storms, volcanic eruptions, logging, climate change, severe flooding, disease, and pest infestation. Succession stops when species composition changes no longer occur with time, and this community is said to be a climax community.
climax community
The concept of a climax community assumes that the plants colonizing and establishing themselves is a given region can achieve stable equilibrium.
The idea that succession ends in the development of a climax community has had a long history in the fields of biogeography and ecology. One of the earliest proponents of this idea was Frederic Clements who studied succession at the beginning of the 20th century.
Ecological succession types and stages with diagram
On the basis of origin, ecological succession may be of following two types
· Primary succession – It is the establishment of plants on land that has not been previously vegetated. It begins with colonization and establishment of pioneer species.
· Secondary succession – It is the invasion of a habitat by plants on land that was previously vegetated. Removal of past vegetation may be caused by natural or human disturbances such as fire, logging, cultivation, or hurricanes.
Whereas on the basis of location, ecological succession may be xerarch or hydrarch:
Xerarch Succession
Plant succession
Plant succession starting on bare ground or rock and culminating in a mature climax forest is called xerarch succession. The pioneer species, such as lichens and mosses, result in the gradual accumulation of soil.
Lichen colonies
The lichen colonies on these boulders are the first step in xerarch succession. Along with mosses, they trap dust particles and form a layer of soil on the rock surface that allows other plants, such as grasses and herbs, to become established.
Hydrarch
Plant succession starting on relatively shallow water, such as ponds and lakes, and culminating in a mature forest is termed as hydrarch.
Xerosere
The term xerosere refers to changes in community structure during xerarch succession. It includes the different stages in a xerarch succession of ecological communities originated in extremely dry conditions such as sand deserts, sand dunes, salt deserts, rock deserts etc.
Comments
Post a Comment