Syllabus- Eco systems: Ecology and Eco-system; Food chains in Eco systems, Typology of eco system
Number of questions- Mains: 02, Prelims – 10
Mains Questions of the day-
1. Define the concept of carrying capacity of an ecosystem as relevant to an environment. Explain how understanding this concept is vital while planning for the sustainable development of a region.
Introduction-
Define the concept of carrying capacity.
Body-
Discuss the importance of the concept of carrying capacity.
Conclusion-
To face this future with confidence, humanity must endeavour to maintain the Earth’s carrying capacity at a productive yet sustainable level, through improved logistical foundations, a more cooperative political climate, and better scientific understanding.
Content-
Carrying Capacity (CC) can be defined as the population that can be supported indefinitely by its supporting systems.
In ecological terms, the carrying capacity of an ecosystem is the size of the population that can be supported indefinitely upon the available resources and services of that ecosystem.
In the broader sense, carrying capacity also means that all plants and animals which an area of the Earth can support at once. Change in carrying capacity for one species affects other populations in the area.
A simple example of carrying capacity is the number of people who could survive in a lifeboat after a shipwreck. Their survival depends on how much food and water they have, how much each person eats and drinks each day, and how many days they are afloat. If the lifeboat made it to an island, how long the people survived would depend upon the food and water supply on the island and how wisely they used it.
Sustainable development, which entails the maximum use of resources without damaging the system’s regenerative capacity, has a definite role to play in future policy planning. Sustainability requires managing all households — individual, community, national, and global — in ways that ensure that our economy and society can continue to exist without destroying the natural environment on which we all depend.
- Population Control: The notion that resource limitation must eventually constrain the growth of population is appealing, but appropriate estimation of regional carrying capacity would help to forge a definite course for planning.
- Women sensitization and education toward reproductive choices can play a dominant role in controlling pollution.
- Economic Planning: By carefully assessing the present and future availability of local resources, economic zones can be planned, which will help in mitigating the adverse effects of economic activities.
For Example: The establishment of Coca-Cola bottling plant in Plachimada, Kerala in 2000, resulted in the depletion of groundwater in the area and was shut down in 2004 due to widespread protest. Careful assessment of regional carrying capacity can help us prevent such incidents
- Agriculture Management: The concept of carrying capacity of an ecosystem can be very useful in proper crop management across the length and breadth of the country. It has been found that farmers are overutilizing the capacity of land without giving any due importance to its regeneration, which has led to the problem of desertification in Punjab and Harayana.
For Example: Farmers in water stress areas of Maharashtra are growing water intensive crops which have created drought like conditions in the region. Prior estimation of carrying capacity can help avert such chronic conditions.
- Under-used capacity of Food Production & Biodiversity: Using appropriate technological advancement, sustainability in food production methods and diversifying the use of biological resources can help attain harmony between natural resource and their utilization.
- Resource Management: Adaptive management is the most widely accepted solution for confronting the unpredictability of renewable resources. Natural resource management must consider the ever-changing interaction between physical and biological systems, and react according to acquired experience and historical knowledge in a continuous, iterative learning process.
The current ethos of ‘sustainable development’ is slanted towards preservation of the replacement capability of natural systems, rather than maximum use. However, the unceasing growth of world population may eventually bring inequilibrium between the two.
2. What is an ecosystem and mention its components? Mention the functions of an ecosystem?
Introduction:
Define ecosystem
Body:
Discuss the important components of the ecosystem
Mention the functions of an ecosystem.
Conclusion:
- Everything that lives in an ecosystem is dependent on the other species and elements that are also part of that ecological community.
- If one part of an ecosystem is damaged or disappears, it has an impact on everything else.
Content:
Ecosystem
An ecosystem is a geographic area where plants, animals, and other organisms, as well as weather and landscape, work together to form a life. Ecosystems contain
- Biotic or living parts include plants, animals, and other organisms and
- Abiotic factors or nonliving parts.
Ecosystem
- An ecosystem can be of any size but usually encompasses specific and limited species. E.g. Aquatic Ecosystem. (This is how ecosystem is different from Environment)
- Classification of Ecosystems:
- Forest, grassland and desert are some examples of terrestrial ecosystems
- pond, lake, wetland, river and estuary are some examples of aquatic ecosystems.
- Crop fields and an aquarium are human-made ecosystems.
Components of an Ecosystem
The components of the ecosystem are categorized into:
- Abiotic or non-living and
- Biotic or living components
Functions of Ecosystem:
- Ecological succession or ecosystem development
- Homeostasis (or cybernetic) or feedback control mechanisms
- Energy flow through the Food chain, Food web and Energy pyramid.
- Nutrient cycling (biogeochemical cycles)
- Ecological Succession: –
- The process by which communities of plant and animal species in an area are replaced or changed into another community of plants and animals over a period of time is known as ecological succession.
- The process involves a progressive series of changes with one community replacing another community until a stable, mature, climax community develops.
- The first plant to colonize an area is called the pioneer community.
- The final stage of succession is called the climax community.
- A climax community is stable, mature, more complex and long-lasting.
- Categories of Ecological succession:
- Primary Succession
- Secondary Succession
- Autogenic and Allogenic Succession
- Autotrophic and Heterotrophic succession
- Homeostasis in Ecosystem
- Homeostasis is the maintenance of stable equilibrium, especially through physiological (through bodily part functions. E.g. Cooling your body through sweating processes.
- Organisms try to maintain the constancy of its internal environment despite varying external environmental conditions that tend to upset their homeostasis.
- Ecosystems are capable of maintaining their state of equilibrium.
- This capacity of the ecosystem of self-regulation is known as homeostasis
- Energy Flow Through an Ecosystem – Trophic Levels
- A trophic level is the representation of energy flow in an ecosystem.
- Trophic levels:
- Autotrophs-Green plants (Producers)
- Heterotrophs-Herbivore (Primary consumers)
- Heterotrophs-Carnivores (Secondary consumers)
- Heterotrophs-Carnivore (Tertiary consumers)
- Heterotrophs-Top carnivores (Quaternary consumers)
- Energy flows through the trophic levels from producers to subsequent trophic levels is unidirectional.
- Energy level decreases from the first trophic level upwards due to loss of energy in the form of heat at each trophic level.
- This energy loss at each trophic level is quite significant. Hence there are usually not more than four-five trophic levels (beyond this the energy available is negligible to support an organism).
- The trophic level interaction involves three concepts namely
- Food Chain
- Food Web
- Ecological Pyramids
- Food Chain
- Transfer of food energy from green plants (producers) through a series of organisms with repeated eating and being eaten link is called a food chain.
- E.g. Grasses → Grasshopper → Frog → Snake → Hawk/Eagle.
- Each step in the food chain is called trophic level.
- A food chain starts with producers and ends with top carnivores.
- The trophic level of an organism is the position it occupies in a food chain.
- Food Web
- Multiple interlinked food chains make a food web.
- Food web represents all the possible paths of energy flow in an ecosystem.
- If any of the intermediate food chains is removed, the succeeding links of the chain will be affected largely.
- The food web provides more than one alternative for food to most of the organisms in an ecosystem and therefore increases their chance of survival.
- Ecological Pyramids:
- The pyramidal representation of trophic levels of different organisms based on their ecological position (producer to final consumer) is called as an ecological pyramid.
- The pyramid consists of a number of horizontal bars depicting specific trophic levels. The length of each bar represents the total number of individuals or biomass or energy at each trophic level in an ecosystem.
- The food producer forms the base of the pyramid and the top carnivore forms the tip. Other consumer trophic levels are in between.
- The ecological pyramids are of three categories:
- Pyramid of numbers,
- Pyramid of biomass, and
- Pyramid of energy or productivity.
- Nutrient cycling (biogeochemical cycles):
- Biogeo-Chemical Cycling or Nutrient Cycling
- Energy flow and nutrient circulation are the major functions of the ecosystem.
- Energy is lost as heat forever in terms of the usefulness of the system.
- Nutrients of food matter never get used up. They can be recycled again and again indefinitely.
- Based on the nature of the reservoir, a nutrient cycle is referred to as Gaseous or Sedimentary cycle
- Gaseous Cycle: the reservoir is the atmosphere or the hydrosphere such as water cycle, carbon cycle, nitrogen cycle, etc. and
- Sedimentary Cycle: the reservoir is the earth’s crust (soluble elements mostly found in earth’s crust) such as phosphorous cycle, Sulphur cycle, calcium cycle, magnesium cycle etc.
Prelims Question of the day:
1.Which of the following aquatic ecosystem contains salt concentration equal to or above 35ppt?
- Fresh water ecosystem
- Marine ecosystem
- Brackish water ecosystem
- Lake ecosystem
Answer: C
Explanation:
Aquatic Ecosystems
- Aquatic ecosystems refer to plant and animal communities occurring in water bodies.
- Aquatic ecosystems are classified into two subgroups:
1) Freshwater ecosystems, such as rivers, lakes and ponds;
2) Marine ecosystems, such as oceans, estuary and mangroves.
- Aquatic ecosystems are classified on the basis of salinity into the following types:
- Freshwater ecosystems: water on land which is continuously cycling and has low salt content (always less than 5 ppt) is known as fresh water.
There are two types of freshwater ecosystems:
1) Static or still water (Lentic) ecosystems, e.g. pond, lake, bogs and swamps.
2) Running water (Lotic) ecosystems, e.g. springs, mountain brooks, streams and rivers.
- Marine ecosystems: the water bodies containing salt concentration equal to or above that of seawater (i.e., 35 ppt or above). E.g. shallow seas and open ocean.
- Brackish water ecosystems: these water bodies have salt content in between 5 to 35 ppt. e.g. estuaries, salt marshes, mangrove swamps and forests.
2.Which of the following Aquatic organisms, live at the air-water interface (floating plant)?
- Neuston
- Periphytion
- Plankton
- Nekton
Answer: A
Explanation:
Aquatic Organisms:
The aquatic organisms are classified on the basis of their zone of occurrence.
- Neuston: These organisms live at the air-water interface, e.g. floating plants.
- Periphyton: These are organisms which remain attached to stems and leaves of rooted plants or substances emerging above the bottom mud such as sessile algae.
- Plankton:
- Microscopic floating organisms such as algae, diatoms, protozoans and larval forms are called plankton. This group includes both microscopic plants like algae (phytoplankton) and animals like crustaceans and protozoans (zooplankton).
- The locomotory power of the planktons is limited so that their distribution is controlled, largely, by currents in the aquatic ecosystems.
- Nekton: This group contains powerful swimmers that can overcome the water currents.
- Benthos: The benthic organisms are those found living at the bottom of the water mass.
3.Which of the following is the phenomenon related to shallow water bodies, when ice layer on the top of a water body can effectively cut off light, oxygen gets depleted and the fish die?
- Photic zone
- Aphotic zone
- Euryphytes
- winterkill.
Answer: D
Explanation:
Winterkill:
- An ice layer on the top of a water body can effectively cut off light. Photosynthesis stops but respiration continues in such water body.
- If the water body is shallow, the oxygen gets depleted, and the fish die. This condition is known as winterkill.
4.In which of the following Aquatic Ecosystem, we can find the estuaries, saltmarshes, mangrove swamps and forests?
- Freshwater Ecosystem
- Marine ecosystem
- Brackish water ecosystem
- Lake ecosystem
Answer: C
Explanation:
Aquatic Ecosystems:
- Aquatic ecosystems refer to plant and animal communities occurring in water bodies.
- Aquatic ecosystems are classified into two subgroups:
1) Freshwater ecosystems, such as rivers, lakes and ponds;
2) Marine ecosystems, such as oceans, estuary and mangroves.
- Aquatic ecosystems are classified on the basis of salinity into the following types:
- Freshwater ecosystems: water on land which is continuously cycling and has low salt content (always less than 5 ppt) is known as fresh water.
There are two types of freshwater ecosystems:
1) Static or still water (Lentic) ecosystems, e.g. pond, lake, bogs and swamps.
2) Running water (Lotic) ecosystems, e.g. springs, mountain brooks, streams and rivers.
- Marine ecosystems: the water bodies containing salt concentration equal to or above that of seawater (i.e., 35 ppt or above). E.g. shallow seas and open ocean.
- Brackish water ecosystems: these water bodies have salt content in between 5 to 35 ppt. e.g. estuaries, salt marshes, mangrove swamps and forests.
5.Which of the following represents the zone of transition between two biomes?
- Ecoline
- Photic zone
- Aphotic zone
- Ecotone
Answer: D
Explanation:
An ecotone is a zone of junction or a transition area between two biomes (diverse ecosystems).
Ecotone is the zone where two communities meet and integrate.
Example: Mangroves Ecosystem (between land and marine water ecosystems), Estuarine Ecosystem (between fresh water ecosystem and estuary ecosystem) and wetlands
6.Which of the following represents the shallow stretch of salt water separated from the sea by a low sand bank or coral reef?
- Lagoons
- Estuary
- Lakes
- Rivers
Answer: A
Explanation:
Lagoon:
- A lagoon is a stretch of salt water separated from the sea by a low sandbank or coral reef.
- Backwaters in Kerala are mostly lagoons where seawater flows inwards through a small inlet that is open towards the sea.
- In estuaries, the water flows fast and strong, while in lagoons the water is shallower and flows sluggishly.
- Estuaries are usually deeper than lagoons. Also, lagoons mostly don’t have any fresh water source while the estuaries have at least one. Lagoons are more saline than estuaries.
- Lagoons are formed due to falling in sea levels (coastline of emergence. E.g. Kerala Coast) whereas estuaries are mostly formed due to rise in sea levels (coastline of submergence. E.g. Konkan coast)
7.Which of the following term represents the salt water tolerant trees?
- Epiphytes
- Euryphytes
- Halophytes
- None
Answer: C
Explanation:
Halophytes:
- The phenomenon of salt tolerant trees is called halophytes.
- The Mangroves are salt tolerant trees, also called halophytes, and are adapted harsh coastal conditions.
- Mangrove vegetation facilitates more water loss. Leaves are thick and contain salt-secreting glands. Some block absorption of salt at their roots itself.
8. If a tropical rain forest is removed, it does not regenerate quickly as compared to a tropical deciduous forest. This is because of which of the following reason?
- The soil of rain forest is deficient in nutrients
- Propagules of the trees in a rain forest have poor viability
- The rain forest species are slow-growing
- Exotic species invade the fertile soil of rain forest.
Answer: A
Explanation:
- The soil of rain forest is deficient in nutrients because it rains almost every day
- The topsoil is continuously washed away
- Nutrients are also washed away (leaching of nutrients)
- Very little fertility remains in topsoil
- Most of the seeds don’t germinate for years
- Regeneration is very slow (it takes decades).
- But the layer below topsoil (sub-soil) is very fertile.
- Thus, plants grow very quickly once their roots reach the sub-soil and if they receive enough sunlight.
- Propagules of the trees in a rain forest have poor viability is also true
- Propagule: Detachable structure that can give rise to a new plant, e.g. a bud, sucker, or spore (sexual reproduction in plants).
- Seed-bearing plants are more significant than propagules in a rainforest.
- The plant species in rainforests compete for sunlight. Hence, they grow as rapidly as they can.
- The rainforest soil is heavily leached. Hence, they are not fertile. But exotic invasive species are a threat to the rainforests, especially when the forests are cleared.
9.Which of the following term associated to the study of interactions between organisms, organisms and the surroundings occurring?
- Ecosystem
- Ecology
- Environment
- Habitat
Answer: B
Explanation:
- Ecology is the study of interactions between organisms, organisms and the surroundings occurring within an ecosystem or environment.
- An ecosystem is a functional unit of the environment (mostly biosphere).
- An environment is a group of ecosystems.
- Environment Can be almost everything or a small region.
- Habitat Area where an organism lives.
- Biosphere: The region on earth that supports life.
- Ecosystem: Producers, Consumers, Decomposers and their relationships (tiny environment). It is the functional unit of the environment.
10.Which one of the following is the best description of the term “ecosystem”?
- A community of organisms interacting with one another
- That part of the Earth which is inhabited by living organisms
- A community of organisms together with the environment in which they live.
- The flora and fauna of a geographical area.
Answer: C
Explanation:
- That part of the Earth which is inhabited by living organisms is called biosphere.
- A community of organisms together with the environment in which they live is called as ecosystem.
- The flora and fauna of a geographical area are called as biodiversity.