Ecology Lecture Notes

Hydrosere (Hydrarch Succession) with PPT

Stages of Hydrosere

(Hydrarch Succession)

What is Hydrosere or Hydrarch Succession?

A succession originates in a water body (aquatic environment) is called Hydrosere or Hydrarch Succession. Such a succession does not necessarily lead to the development of a land community. If the water body is sufficiently large and with wave action, the succession usually results in the formation of a large aquatic climax community. If the hydrarch succession starts from a comparatively small water body such as a pond, there is always a high probability for the formation of a terrestrial climax community. The important characteristics of hydrosere are given below:

Ø  Hydrosere usually starts from a pond

Ø  Phytoplanktons will be the pioneer community

Ø  A forest or a grassland will be the climax community

Ø  Includes several seral stages of plant and animal communities

Ø  Seral communities of plants are more obvious than animals.

Just like other successions, the hydrosere is also completed through a sequence of several Seral Stages (Seral Communities). The seral stages of a typical Hydrosere succession are as follows:

Seral stages of Hydrosere

(1).  Phyto-planktons stage

(2).  Rooted submerged stage

(3).  Rooted floating stage

(4).  Reed-swamp stage

(5).  Sedge-meadow stage

(6).  Woodland stage

(7).  Forest stage

Process of Hydrosere

(1). Phytoplankton stage:

Ø  Phytoplanktons will be pioneer community in the hydrosere.

Ø  Algal spores are brought into the water in the initial stages of the succession.

Ø  These algal spores germinate and quickly colonize in the water body.

Ø  They multiply and grow for some time. They fix light energy (photosynthesis).

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Ecology Lecture Notes

Different Types of Ecological Succession

Classification of Succession

Types of Ecological Succession
(Classification of Ecological Succession)

In the previous post, we have discussed the Process of Ecological Succession. Here we will discuss the classification of different types of ecological successions. The ecological succession is classified into different types based on different criterions such as the origin of succession, cause, community composition and nature of substratum. An outline of the classification is given below:

(1).  Primary and Secondary Succession (based on the starting of succession)

(2).  Autogenic and Allogenic Succession (based on the cause of succession)

(3).  Autotrophic and Heterotrophic Succession (based on the community composition)

(4).  Hydrosere and Xerosere (based on the nature substratum)

(5).   Microsuccession (succession of microbes)

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Ecology Lecture Notes

Process of Ecological Succession (PPT)

Process of Succession

Stages of Ecological Succession
(Formation of an Ecosystem)

What is Ecological Succession?

Definition: Ecological succession is the gradual and sequential replacement of one community by the other in an area over a period of time. According to E.P. Odum (1971), the ecological succession is an orderly process of community change in a unit area. It is the process of change in species composition in an ecosystem over time. In simpler terms, it is the process of Ecosystem Development in nature.

Population Vs Community

Population: The group of individuals of a particular species occupying in a unit area. Example: population of Aedes aegypti (yellow fever mosquito) in an area.

Community: A community can be defined as a combination of different populations in an ecosystem. For example a pond ecosystem may consist of populations of Spirogyra (algae) Diatoms, Frogs, Fishes and Insects.

The community in an ecosystem is NOT stable. It passes through many developmental stages in definite sequence over a period of time. These developmental stages in most of the cases will be from simple to complex and it is collectively called as community dynamics.

Process of Ecosystem Succession

The ecological succession is a complex process and it may take thousands of years. Frederic Clements in 1916 for the first time proposed the sequential phases of an ecological succession. The process of succession is completed through a series of sequential steps as given below:

(1).      Nudation
(2).      Invasion
(3).      Competition and Co-action
(4).      Reaction
(5).      Stabilization (climax)

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Ecology Lecture Notes

Characteristics of Hydrophytes with PPT (Classification and Adaptations)

Water plants adaptations PPT

Hydrophytes: Classification and Adaptations
(Morphological, Anatomical and Physiological Adaptations of Aquatic Plants)

What is an adaptation?

Ø  “Any feature of an organism which enables it to exist under conditions of its habitat is called adaptation”.

Ø  Adaptations are for withstanding adverse conditions of environment and to utilize the maximum benefit of the environment (nutrition or conditions).

Ø  Adaptations in plants may be in:

1.   Morphological features

2.   Anatomical features

3.   Physiological characters

4.   Reproductive characters

Classification of plants based on water relation (Warming, 1990)

(1). Hydrophytes: plants growing in or near water.

(2). Xerophytes: plants adapted to survive under very poor availability of water.

(3). Mesophytes: plants growing in an environment which is neither very dry nor very wet.

What are hydrophytes?

Ø  Hydrophytes (aquatic plants, water plants) are plants growing in or near water.

Ø  These plants are adapted to survive in excess of water in their surroundings.

Ø  Greek: Hudor = water; Phyton = plant: water plant

Ø  Examples: Utricularia, Vallisneria, Hydrilla, Chara, Ceratophyllum, Trapa

Ø  Aquatic plants are the producers of the aquatic ecosystem.

Ø  They fix sunlight and ensures the survival of an aquatic ecosystem.

Ø  Even though plants originated in water, except algae, most of the aquatic plants are evolved from their mesophytic relatives.

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