Ecology Lecture Notes

Hydrosere (Hydrarch Succession) with PPT


Stages of Hydrosere

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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Zoology lecture notes and study materials

Parasitic Adaptations (Platyhelminthes, Nematodes, Insects and Plants)


parasitic adaptations

Parasitic Adaptations of Plants and Animals

What is meant by Adaptation?

Adaptation definition: ‘Any feature of an organism or its part which enables it to exist under conditions of its habitat is called adaptation.’ The adaptations are mainly to withstand the adverse conditions of the environment and to use the maximum benefit of the environment.

What are Parasites?

A parasite is an organism which lives in or on another organism (called host) and benefits by deriving shelter and nutrients from them. The parasitism is a type of negative ecological / biological interaction in nature where one organism gets benefited (the parasite) and the other is harmed (the host). The parasites may be microbes such as bacteria, virus and Mycoplasma, or animals such as liver fluke, worms, nematodes, some insects and plants such as Loranthus, Cuscuta etc. All types of parasites show peculiar adaptations to survive in or on the host system and to get maximum benefit from them.

Learn more: Positive and Negative Interactions in an Ecosystem

Parasites show three level adaptations, they are

(1).     Structural Adaptations (Morphological and Anatomical Adaptations)

(2).     Physiological Adaptations

(3).     Reproductive Adaptations

(1).  Structural Adaptations (Morphological and Anatomical) Adaptations of Parasites:

Ø  Feeding organs are usually absent in endoparasites.

Ø  Fluid feeding insects such as aphids have highly specialized mouth parts for the easy absorption of cell sap from the host.

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Ecology Lecture Notes

Xerophytes: Ecological Adaptations with PPT


ecological adaptations of xerophytes ppt

Xerophytic Adaptations of Plants
(Ecological Adaptations of Desert Plants)

What are xerophytes?

Ø  Xerophytes (xerophytic plants) are plants growing in dry habitats (xeric conditions) where the availability of water is very less.

Ø  Xeric habitat: places where water is NOT present in adequate quantity.

Ø  Xerophytes are the characteristic plants of deserts or semi-deserts areas.

Ø  Xerophytes can also grow in mesophytic conditions.

Ø  Xerophytes can tolerate:

$.  Extreme dry condition

$.  Low humidity

$.  High temperature

$.  High wind-flow

Ø  Three types of xeric habitats occurs on the earth:

(1). Physically dry habitat: the water retaining capacity of the soil very low and climate is dry (Example: a desert).

(2). Physiologically dry: water is present in excess, but not in the absorbable conditions or the plants cannot absorb it (Example: high salt water, high acidic water and high cold water, water as snow).

(3). Physically and physiologically dry: water present as mist, plants cannot absorb water from the atmosphere directly. (Example: mountain slopes)

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