Ecology-Environment, Ecosystem, Ecotone, Biome

Table of Contents

Definition of Ecology:

• The term “Ecology” is derived from the Greek words:
  • ‘Oikos’: Meaning home or place to live.
  • ‘Logos’: Meaning study.
• Literally, ecology is the study of the home of nature.
• Ecology is defined as “a scientific study of the relationship of living organisms with each other and with their environment.”
• It examines how organisms are molded by their environment and how they make use of environmental resources, including energy flow and mineral cycling.

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1.1 Historical Context of Ecology

• The roots of ecology lie in Natural History, which dates back to human civilization.
• Since early history, humans have engaged in ecological practices, knowingly or unknowingly, for survival.
• In primitive societies, every individual needed an intimate understanding of their environment to survive. This knowledge included understanding the forces of nature and the behaviors of surrounding plants and animals.
• Ancient Indian texts contain numerous references to ecological principles:
  • The classical texts from the Vedic period, such as the Vedas, Samhitas, Brahmanas, and Aranyakas-Upanishads, mention several ecological concepts.
  • The Indian medical texts, Charaka-Samhita and Sushruta-Samhita, indicate a deep understanding of plant and animal ecology.
• Details from these texts include:
  • Classification of animals based on habit and habitat.
  • Classification of land in terms of soil nature, climate, and vegetation.
  • Descriptions of plants typical to various localities.
  • Insights from Charaka-Samhita: Air, land, water, and seasons are essential for life, and polluted air and water are harmful to health.

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1.2 Environment and Its Components

• The environment refers to everything that surrounds or affects an organism during its lifetime.
• It is defined as “the sum total of living and non-living components, influences, and events surrounding an organism.”
• All organisms, from viruses to humans, depend on the environment for food, energy, water, oxygen, shelter, and other needs.
• The relationship and interaction between organisms and their environment are highly complex.
• The environment includes both living (biotic) and non-living (abiotic) components.
• The environment is not static. Both biotic and abiotic factors are continuously changing.

Components of the Environment:

• Abiotic Components: Include non-living factors such as energy, radiation, temperature, water, atmospheric gases, wind, fire, gravity, topography, soil, and geological substratum.
• Biotic Components: Include living organisms such as green plants, non-green plants, decomposers, parasites, symbionts, animals, and humans.

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1.3 Levels of Organization in Ecology

• There are six main levels of organization in ecology:

1.3.1 Individual

• An organism is an individual living being capable of functioning independently.
• It may be a plant, animal, bacterium, fungus, or other living entity.
• An organism is composed of organs, organelles, or other parts that work together to carry out life processes.

1.3.2 Population

• A population is a group of organisms, usually of the same species, occupying a defined area during a specific time.
• Population growth rate refers to the percentage change between the number of individuals in a population at two different times.
• Population growth can be positive or negative.
• Factors that increase population size: Birth and immigration.
• Factors that decrease population size: Death and emigration.
• Limiting factors for population growth include both abiotic and biotic components.

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1.3.3 Community

• Populations of plants and animals seldom occur in isolation. Instead, they form communities where individuals of different species interact and depend on one another.
• Example: Animals require plants for food and trees for shelter. Plants require animals for pollination, seed dispersal, and soil microorganisms to facilitate nutrient supply.
• Communities are often named after the dominant plant species.
  • Example: A grassland community is dominated by grasses but may also contain herbs, shrubs, trees, and associated animals.
• Communities are not fixed or rigid and can vary in size.

Structure of a Community

• The number of species and the size of their populations vary greatly.
• A community may consist of one or several species.
• Environmental factors determine the community’s characteristics and the organization pattern of its members.
• The characteristic pattern of a community is termed its structure. This includes:
  • Roles played by different populations.
  • The range of habitats they occupy.
  • The diversity of species in the community.
  • The spectrum of interactions among species.

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1.3.4 Ecosystem

• An ecosystem is a structural and functional unit of the biosphere, consisting of a community of living beings and their physical environment.
• It involves interactions and the exchange of materials between living organisms and their surroundings.
• An ecosystem includes elements like plants, trees, animals, fish, birds, microorganisms, water, soil, and people.
• Ecosystems can vary greatly in size, from a small tree to an entire forest.
• Every living thing in an ecosystem depends on other species and elements within that ecosystem.
• If one part of an ecosystem is damaged or disappears, it can impact everything else.
• A healthy, sustainable ecosystem is one in which all elements live in balance and are capable of reproducing themselves.

Difference Between Ecology, Environment, and Ecosystem

• Ecology: The scientific study of relationships between organisms and their environment.
• Environment: The external conditions and factors surrounding an organism.
• Ecosystem: A community of organisms interacting with each other and their environment, functioning as a unit.

Example of this relationship:

• Ecology: The study of employees’ relationships with their workplace.
• Environment: The workplace itself, where employees perform their duties.
• Ecosystem: The complete set of circumstances, including colleagues, managers, projects, and office culture, interacting as a unit.

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Components of an Ecosystem

• The components of an ecosystem are the same as those of the environment.

1. Abiotic Components

• These are the inorganic, non-living parts of the world.
• Include soil, water, air, light energy, and chemicals like oxygen and nitrogen.
• Also involve physical processes like volcanoes, earthquakes, floods, forest fires, climate, and weather conditions.
• Abiotic factors determine where and how well an organism exists in its environment. They may interact, but a single factor can limit an organism’s range.

Specific Abiotic Factors:

• Energy: Essential for life, provided directly by the sun to plants. Animals obtain energy indirectly by consuming plants or other animals.
• Rainfall: Critical for life. Many biochemical reactions occur in water, and it helps regulate body temperature. Water bodies provide habitats for aquatic organisms.
• Temperature: Influences survival, as organisms can only tolerate certain temperature ranges.
• Atmosphere: Responsible for creating conditions suitable for life on Earth.
• Substratum: Land covered by soil where various organisms thrive. Aquatic organisms live in water bodies, while some microbes live in extreme conditions like hot water vents.
• Materials:
  • Organic Compounds: Proteins, carbohydrates, and lipids formed from inorganic compounds upon decomposition.
  • Inorganic Compounds: CO2, water, sulfur, nitrates, phosphates, and metal ions essential for life.
• Latitude and Altitude: Influence temperature and climate, affecting biomes and wildlife distribution.

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2. Biotic Components

• Include all living organisms: Plants, animals, and microbes.
• Classified into producers and consumers based on their functional attributes.

Primary Producers (Autotrophs)

• Green plants, certain bacteria, and algae.
• Synthesize carbohydrates from carbon dioxide and water using sunlight through photosynthesis.
• In terrestrial ecosystems, producers are typically herbaceous and woody plants. In aquatic ecosystems, producers are various species of microscopic algae.

Consumers (Heterotrophs/Phagotrophs)

• Cannot produce their own food and depend on plants or animals.
• Divided into:
  • Macro Consumers: Feed on plants, animals, or both.
    • Herbivores: Primary consumers (e.g., cow, rabbit).
    • Secondary Consumers: Feed on primary consumers (e.g., wolves).
    • Tertiary Consumers: Feed on secondary consumers (e.g., lions).
    • Omnivores: Eat both plants and animals (e.g., humans, monkeys).
  • Micro Consumers (Saprotrophs/Decomposers):
    • Bacteria and fungi decompose dead organic substances, releasing nutrients back into the ecosystem.
    • Earthworms and certain soil organisms, like nematodes and arthropods, help in decomposition and are known as detrivores.

Classification of Ecosystems

• Ecosystems are categorized into:
  • Natural Ecosystems:
    • Terrestrial: Examples include forests, grasslands, and deserts.
    • Aquatic: Further divided into freshwater and marine ecosystems.
      • Freshwater: Includes lakes, ponds, rivers, and streams.
      • Marine: Includes oceans, seas, and estuaries.
  • Human-Made Ecosystems: Examples include crop fields and aquariums.

Homeostasis in Ecosystems

• Ecosystems have the ability to maintain a state of equilibrium and regulate their own structure and functional processes.
• This capacity for self-regulation is known as homeostasis.

Goods and Services Provided by Ecosystems Ecosystems provide a wide range of goods and services that are essential for human survival and environmental health, including:

• Provision of food, fuel, and fiber.
• Supply of shelter and building materials.
• Purification of air and water.
• Detoxification and decomposition of wastes.
• Stabilization and moderation of the Earth’s climate.
• Moderation of floods, droughts, and temperature extremes.
• Generation and renewal of soil fertility, including nutrient cycling.
• Pollination of plants, including many crops.
• Control of pests and diseases.
• Maintenance of genetic resources that are crucial for crop varieties, livestock breeds, medicines, and other products.
• Cultural and aesthetic benefits that enhance human well-being.

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Ecotone

• An ecotone is a transition zone between two or more diverse ecosystems.
  • Example: Mangrove forests act as an ecotone between marine and terrestrial ecosystems.
  • Other examples include grasslands, estuaries, and riverbanks.

Characteristics of Ecotones

• Ecotones can be narrow or wide.
• They have conditions intermediate to the adjacent ecosystems, creating a zone of tension.
• Ecotones are linear and show a progressive increase in species from one community while simultaneously showing a decrease in species from the adjacent community.
• They often contain unique species not found in the neighboring ecosystems.
• The number of species and population density may be higher in ecotones, a phenomenon known as the edge effect.
• Edge species are organisms that are more abundant in these zones. The edge effect is particularly significant for birds in terrestrial ecosystems. For instance, bird density is often higher in the ecotone between a forest and a desert.

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Ecological Niche

• A niche refers to the unique role or place of a species in an ecosystem.
• It encompasses all biological, physical, and chemical factors that a species needs to survive, stay healthy, and reproduce.
• Each species has a unique niche, meaning no two species have identical niches.
• Understanding a species’ niche is crucial for conservation efforts. When conserving a species, it is essential to ensure that all its niche requirements are met.

Types of Ecological Niches

1. Habitat Niche: The physical space where a species lives.
2. Food Niche: What a species eats, decomposes, or competes with for food.
3. Reproductive Niche: How and when a species reproduces.
4. Physical and Chemical Niche: Factors like temperature, land shape, land slope, humidity, and other requirements.

Do You Know?

• Two schemes, Nagar Vana Udyan Yojana and School Nursery Yojana, have been launched:
  • Nagar Vana Udyan Yojana: Aims to create at least one city forest in each city, covering a minimum area of 25 hectares. The goal is to establish 200 city forests across the country.
  • School Nursery Yojana: Encourages students to develop a lasting bond with nature by involving them in nursery activities.

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1.3.5 Biome

• Biomes are large regions of the terrestrial biosphere characterized by distinct climate, vegetation, animal life, and general soil type.
• Each biome is unique and determined by climatic factors, especially temperature and precipitation.
• No two biomes are exactly alike.

Biome Distribution Based on Temperature and Precipitation

1. Tundra:
   • Location: Northern and southernmost regions of the world near the poles.
   • Flora: Stunted shrubs, lichens, mosses, and sedges in the southern parts; trees are absent.
   • Fauna: Reindeer, arctic foxes, polar bears, snowy owls, lemmings, and arctic hares. Reptiles and amphibians are almost absent.
2. Taiga (Boreal Forest):
   • Location: Northern Europe, Asia, and North America.
   • Climate: Moderate temperature compared to the tundra.
   • Flora: Coniferous evergreen trees like spruce, pine, and fir.
   • Fauna: Birds, hawks, fur-bearing animals like mink, elk, puma, Siberian tigers, wolverines, and wolves.
3. Temperate Deciduous Forest:
   • Location: Central and southern Europe, eastern North America, western China, Japan, New Zealand.
   • Climate: Moderate temperature and abundant rainfall.
   • Flora: Trees like beech, oak, maple, and cherry.
   • Fauna: Various vertebrates and invertebrates. These forests are also productive agricultural areas.
4. Tropical Rainforest:
   • Location: Equatorial regions, abundant with diverse life.
   • Climate: High temperature and rainfall.
   • Flora: Multiple layers of broad-leafed evergreen trees. Home to 40% of the world’s plant and animal species.
   • Fauna: Animals and epiphytic plants concentrated in the canopy zone.
5. Savannah:
   • Location: Predominantly in Africa.
   • Flora: Grasses with scattered fire-resistant trees and thorny shrubs.
   • Fauna: Grazers like antelopes, buffaloes, zebras, elephants, and rhinos; predators like lions, cheetahs, and hyenas; small animals like mongooses and various rodents.
6. Grassland:
   • Location: North America, Ukraine, and other temperate regions.
   • Climate: Temperate with low rainfall.
   • Flora: Dominated by grasses.
   • Fauna: Herbivores like bison and antelopes, rodents like prairie dogs, wolves, and a variety of ground-nesting birds.
7. Desert:
   • Location: Continental interiors with low and sporadic rainfall.
   • Climate: Low humidity, hot days, and cold nights.
   • Flora: Drought-resistant plants like cacti and sagebrush.
   • Fauna: Reptiles, small mammals, and various bird species.

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Aquatic Systems

• Aquatic systems are not termed biomes but are divided into distinct life zones based on salinity, nutrient levels, water temperature, and sunlight penetration.
• Major aquatic ecosystems include:
  1. Freshwater Ecosystem:
     • Types: Lotic (moving water, e.g., streams, rivers) and Lentic (still water, e.g., lakes, ponds).
     • Characteristics: Vary in physical, chemical, and biological properties.
  2. Marine Ecosystem:
     • Coverage: About 75% of the Earth’s surface, with an average depth of 3,750 meters.
     • Salinity: Approximately 35 parts per thousand, mostly sodium chloride.
  3. Estuaries:
     • Formed where freshwater from rivers meets seawater.
     • Highly productive compared to adjacent river or sea ecosystems.
  4. Coral Reefs and Mangroves:
     • Serve as crucial habitats for diverse marine species.

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1.3.6 Biosphere

• The biosphere is the part of Earth where life exists, integrating the atmosphere (air), hydrosphere (water), and lithosphere (land).
• It is a thin layer around Earth, comparable to the skin of an apple if the Earth were that size.
• Life is abundant between 200 meters below the ocean surface and 6,000 meters above sea level.
• The biosphere does not extend to extreme regions like the highest mountains, deepest oceans, or the poles, where conditions are too harsh to support life.
• Dormant life forms, like fungal spores and bacteria, may exist at extreme altitudes but are not metabolically active.
• Energy: The sun provides the necessary energy for life.
• Nutrient Recycling: Essential nutrients come from air, water, and soil and are recycled repeatedly.

Distribution of Organisms in the Biosphere

• Living organisms are not uniformly distributed throughout the biosphere.
• Some regions, like the polar areas, host only a few species due to harsh climatic conditions.
• In contrast, tropical rainforests are rich in biodiversity, containing over 50% of the world’s plant and animal species. These forests are teeming with life, both in the canopy and on the forest floor.

Factors Affecting Life in the Biosphere

1. Sunlight
   • The primary energy source for life on Earth.
   • Photosynthesis: Sunlight drives photosynthesis in plants, which forms the base of the food chain. This energy is transferred to herbivores and then to carnivores.
   • Sunlight influences the Earth’s temperature and climate, affecting where different organisms can live. For example, deserts receive high solar energy but lack water, while polar areas receive limited sunlight.
   • Seasonal variations in sunlight determine migration patterns and reproductive cycles of many species.
2. Air
   • The atmosphere consists of 78% nitrogen, 21% oxygen, and trace amounts of gases like carbon dioxide, argon, and others.
   • Oxygen: Vital for the respiration of most organisms. It is absorbed by plants and animals to release energy from food.
   • Carbon Dioxide: Critical for photosynthesis in plants. Plants absorb carbon dioxide to synthesize glucose and release oxygen as a byproduct.
   • The composition of air influences the health of organisms and ecosystems. For instance, high levels of pollution can harm living beings.
3. Water
   • An essential component for all forms of life. It facilitates biochemical reactions in cells and helps transport nutrients and waste products.
   • Water covers about 70% of the Earth’s surface and provides habitats for countless aquatic organisms.
   • In terrestrial environments, water availability influences plant distribution. Deserts have specialized plants like cacti that store water, whereas rainforests have vegetation that thrives in moisture-rich conditions.
   • Water regulates body temperature in living beings and acts as a solvent for nutrients and minerals.
4. Soil
   • The foundation of terrestrial ecosystems, soil provides essential nutrients and minerals for plant growth.
   • Soil quality and composition vary across regions, influencing the type of vegetation that can grow. For instance, sandy soils support desert plants, while rich loamy soils are ideal for agriculture.
   • Contains a diverse community of microorganisms, such as bacteria and fungi, which play a crucial role in decomposing organic matter and recycling nutrients.
   • Soil Structure: Affects water retention, root penetration, and the distribution of plant species. Healthy soil promotes biodiversity and supports complex food webs.

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