Solution-Class 8-Science-Chapter-18-Ecosystems-Maharashtra Board

Air, water, minerals, soil are physical factors of an ecosystem. 

River, ponds, ocean are aquatic ecosystem.

Man is consumer in an ecosystem.

The interaction between the biotic and abiotic components present in a particular area is called an ecosystem.

• Living organisms are called biotic factors while the non-living components are called abiotic factors.
• The abiotic components include sunlight, water, soil, air, etc., and the biotic components include the different plants and animals found in an area, e.g., lake, forest, grassland, lions, deer, etc.
• The abiotic and biotic factors have a reciprocal relationship with each other.
• The ecosystem has plants as producers, animals as consumers and microbes as decomposers.
• The decomposers return the substances back to the nature by process of decomposition in which the organic complex molecules are reduced to their inorganic constituents.
• Thus the dead remains of plants and animals are once again recycled back to the nature in any healthy ecosystem

Biomes are a larger collection of small ecosystems which are similar in their structure.

• The identification of biomes is done on the basis of the vegetation cover constituting them. Biomes are of two main types, land biomes and aquatic biomes.
• The land biomes exist only on land. Land biomes are of following subtypes based on the abiotic factors. E.g. Steppe grasslands in Central Asia and Pampas in South America, Tundra ecosystem, ecosystems in Taiga, tropical rainforests, etc.
• Aquatic biomes include fresh water ecosystem, marine ecosystem and brackish water ecosystem found in the creeks.

Food web is the network of many food chains. The complex feeding relationships form a food web.

• In nature in any ecosystem, the food chains are not straight and linear. But these are quite complex.
• A prey is consumed by a predator but this predator can itself be a prey to some other predator.
• E.g. Frog is the predator for variety of insects but frog is preyed upon by snake and the snake can be eaten by a bird. The same bird can also feed on insects or frog.
• The interrelationships between different biotic components of any ecosystem thus form the complicated food web.

• Plants in an ecosystem are called producers because plants have the ability to produce food by performing photosynthesis.
• They are autotrophic and are able to utilize solar energy.
• By absorbing inorganic substances, they produce organic food.
• Therefore, they are called producers in an ecosystem.

• Large dams destroy the ecosystem because the construction of dams across river leads to mass deforestation, which results in the loss of biodiversity.

• It leads to the wide-scale loss of flora and fauna of that area.
• Construction of large dams creates undue pressure on the land surface caused due to stored water column. This may cause earthquakes.
• The human settlements are removed as their houses and farms are immersed under water.
• In all the above ways large dams destroy the ecosystems.

• Rhinos had become extinct long ago in last century due to unrelenting hunting in the Dudhwa forest.
• However, they were again restored by the various measures taken up by the government.
• In order to restore it back the breeding in captivity was attempted and the young ones were released in the natural habitat.
• Saving the precious wildlife is important and hence these efforts were done.

• Human population growth rate is very big as compared to other animals.
• Moreover, they are apex consumers in an ecosystem. Just like any other organisms, ecosystems provide all the basic needs to humans, too.
• However, man demands much more due to excessive population. The natural resources are utilized on the large scale only by man.
• Changing lifestyles, consumerism, degradation of nature and pollution are certain aspects which are created only by human beings.
• Increasing population has also lead to various devastating effects on our ecosystem as well.
• Increasing population has resulted in various problems like: Deforestation, Generation of waste, Land degradation, Loss of biodiversity, Industrialisation.
• All these cause increased stress on the ecosystems.

 Urbanisation is a term which refers to the general increase in population and the amount of industrialization of a settlement.

• When people do not get sufficient food and other amenities, they migrate to the cities. The cities provide employment for many people due to industries, factories and other facilities.
• Every day many people migrate to cities. This causes urbanization.
• Animal-human conflicts are very common in newly established urban areas which are near the natural forests.
• Due to increased population in cities, there is more need for housing. This results in loss of agricultural lands, marshlands, wetlands, forests and grasslands, etc.
• The natural ecosystems are lost in an attempt to have developmental work.
• Human interference causes changes in the ecosystems.
• When land usage is changed many naturally occurring species of plants and animals are exterminated.

• Wars can occur due to various reasons like differences and competition over land, water, mineral resources.
• It can also occur due to economic and political reasons.
• Many a times the religions and ethnicity are also causes for dispute.
• Due to international conflicts, the peace is disturbed and it results in War.

Ecosystem is made up of two types of components - biotic and abiotic components. 

• The abiotic factors such as air, water, soil, sunlight, temperature, humidity, etc. affect the biotic factors, i.e. the surviving plants, animals and microbes in the ecosystem.
• The type of abiotic factors in an ecosystem determine the survival of biotic factors. The population of these biotic factors is also dependent on the quality of abiotic factors.
• Both the biotic and abiotic factors in an ecosystem interact with each to maintain the balance of an ecosystem.
• The abiotic factors play an important role in the distribution and survival of biotic factors in an ecosystem.
• The proportion of abiotic factors is not constant and always keeps on changing as they are used or excreted by the biotic factors.

Both the images represent three different types of habitats.

The first image shows a desert and the kind of plants and animals which are found in this type of habitat. There is cactus and camel in this image which are adapted to such harsh environment.

• In desert ecosystem, the producers are green cactus and a palm tree. Since in desert there are scanty rains, the vegetation is very less.
• The soil is sandy soil. The consumers of the desert are also limited. In the above picture camel is shown which is a primary consumer in the desert ecosystem.
• Camel is very well adapted for the desert life. There is also scarcity of water in desert and hence cactus shows xerophytic (suitable to survive in desert) adaptations.

The second image shows a water body which is a type of aquatic ecosystem. It also shows grassland ecosystem which consists of long grasses and variety of plants and animals.

• In second picture, the forest ecosystem is shown. This forest must be tropical evergreen forest. The rainfall is heavy in such areas and hence different types of wetlands can be seen in forests.
• Wetlands support variety of life. A separate aquatic ecosystem does exist here which is closely interconnected with the terrestrial ecosystems through food chains and food web.
• The birds utilize the fish as their prey. The wild animals come to wetlands to quench their thirst.
• In this picture the Plants, grass, etc. are producers, small fishes in the lake are Primary consumers. They will be eaten by larger fishes which are secondary consumer in the aquatic ecosystem.
• The elephant is herbivorous animal and hence it is primary consumer. Snake is the secondary consumer while the birds of prey (eagle that is flying) and tiger are tertiary consumers.