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

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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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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Ecology Lecture Notes

Difference between Oligotrophic and Eutrophic Lakes


characteristics of lake ecosystem

Oligotrophic vs Eutrophic Lakes
Similarities and Difference between Oligotrophic vs Eutrophic Lakes / Ponds

Lake Ecosystem is an example for a lentic ecosystem. An aquatic ecosystem with stationary or relatively still water is called lentic ecosystem. Based on the trophic state* and productivity, the lake ecosystem is divided into three categories.

(1). Oligotrophic lakes

(2). Eutrophic lakes

(3). Mesotrophic lakes

(1). Oligotrophic lake: a lake with low productivity, low nutrients and clear water with drinking water quality.

(2). Eutrophic lake: a lake with high productivity, high nutrients and with dark water. The water is usually not good for drinking purpose.

(3). Mesotrophic lake: a lake with intermediate nutrient level and productivity.

This post describes the similarities and differences between an Oligotrophic Lake Ecosystem and a Eutrophic Lake Ecosystem as a comparison table.

Similarities between Oligotrophic and Eutrophic Lakes / Ponds

Ø  Both are aquatic ecosystems.

Ø  Both are natural ecosystems.

Ø  Both contain biological and abiological components.

Ø  Water in both ecosystems is rich in oxygen.

Ø  Both are lentic ecosystems.

Ø  Both ecosystems show thermal stratification.

Difference between Oligotrophic and Eutrophic Lakes/Ponds

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Ecology Lecture Notes

Major Threats to Biodiversity by Human Activities (Simple, Easy Ecology Lecture Notes)


Causes of biodiversity loss degradation

‘It is that range of biodiversity that we must care for – the whole thing –
rather than just one or two stars’

David Attenborough


What are major threats to biodiversity?

Major threats to biodiversity are:

1.  Habitat destruction/Deforestation

2.  Introduced and invasive species

3.  Genetic pollution

4.   Over exploitation

5.   Hybridization

6.   Climate change

7.   Diseases

8.   Human over-population

(1). Habitat destruction/Deforestation:

Ø  Habitat destruction and deforestation has played a key role in extinction

Ø  Habitat loss occurs when natural habitats are modified for human needs

Ø  Factors causing habitat destruction are: Over-population, Deforestation, Pollution and Global warming

Ø  Habitat size and number of species are systematically related

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