Understanding the Environment

Environment Definition

• The term "environment" comes from the French word "Environner," meaning to encircle or surround
• The Environment (Protection) Act of 1986 defines the environment as the sum of water, air, and land, along with the inter-relationships among them, human beings, other living organisms, and materials
• In simpler terms, the environment encompasses all social, cultural, and physical conditions that surround, affect, and influence the survival, growth, and development of living organisms

Understanding Environmental Terminologies

• Environmental science studies the environment, specifically its biotic (living) and abiotic (non-living) components, and their relationships
• Environmental science is an interdisciplinary field integrating physics, biology, and geography to study the environment and solve environmental problems
• Environmental engineering applies engineering principles to protect and enhance environmental quality, public health, and welfare
• Environmental studies, or education, is the process of educating people to preserve environmental quality

Scope and Importance of Environmental Science

• Environmental science helps individuals to be aware of and sensitive to the environment and its problems, motivates active participation in environmental protection and improvement, develops skills to identify and solve problems and helps understand the need to protect natural resources
• The field evaluates environmental programs considering social, economic, ecological, and aesthetic factors, promotes cooperation in solving environmental problems locally, nationally, and internationally, and gives a clear picture of the current potential of resources and environmental status
• Environmental studies provides insight into the interdependent connection between nature and humans and relates directly to the quality of life, helps individuals understand development without environmental destruction, gives knowledge of different environments and hazards, and educates on protecting the environment.
• This field develops concern and respect for the environment

Earth's Life Support Systems

• The Earth itself is an integrated system divided into four subsystems: the geosphere, atmosphere, hydrosphere, and biosphere, all of which are interconnected
• Life is sustained by solar energy flowing through the biosphere, nutrient cycling within it, and gravity
• There are 4 main spheres of the environment:
  • Atmosphere: the air surrounding Earth
  • Hydrosphere: the bodies of water on Earth- oceans, rivers, lakes, and ponds
  • Lithosphere: the soil and rocks on Earth's surface
  • Biosphere: This contains all living organisms, their interactions in the environment and all that is capable of supporting life.

Atmosphere

• The atmosphere refers to the blanket of air up to 1500 km surrounding the Earth

Layers of the Atmosphere:

• The layers are based on the distribution of temperature with height, including the:
  • Troposphere
  • Stratosphere
  • Mesosphere
  • Thermosphere
  • Exosphere

Importance of the Atmosphere:

• Oxygen is essential for living organisms
• Carbon dioxide is essential for plants
• Dust particles aid precipitation
• Water vapor affects plants and living beings
• Ozone protects life from harmful UV rays

Hydrosphere

• The hydrosphere is the discontinuous layer of water at or near the Earth's surface, this includes liquid, frozen surface water and groundwater
• Its existence depends on the water cycle, also known as the hydrological cycle

Importance of the Hydrosphere:

• Essential for human needs
• Part of living cells
• Habitat for organisms
• Regulates temperature
• Supports atmosphere

Lithosphere

• The lithosphere is the solid rock covering the planet, including the crust and the upper part of the mantle
• Tectonic plates are the major contributor to the significance of the lithosphere

Biosphere

• The biosphere is the zone where the lithosphere, hydrosphere, and atmosphere interact
• This sphere supports life due to the presence of land, water, and air

Ecosystem Definition

• A.G. Tansley coined "Ecosystem" in 1935, combining "Eco" (environment) and "system" (complex coordinated unit)
• An ecosystem is a natural unit of biotic (living) and non-living components interacting to exchange materials and form a stable system

Ecosystem Structure and Composition

• An ecosystem is the basic functional unit of organisms and is the sum of:
  • Biotic components: living organisms, including producers, consumers, and decomposers
  • Abiotic components: non-living factors like climate (light, temperature, precipitation, wind, humidity), edaphic factors (soil pH, moisture, nutrients), and topographic factors (aspect, altitude)

Ecosystems: Fundamental Characteristics

• The structure includes living (biotic) and nonliving (abiotic) elements
• In processing, it consists of energy flow and cycling of matter/chemicals
• Change through dynamics and succession

Ecosystem Components:

• The ecosystem is made up of biotic and abiotic components
• Abiotic components include climatic, edaphic, and topographic factors that constitute light, temperature, precipitation, wind, humidity, soil pH, soil moisture, soil nutrients, aspect, and altitude
• Biotic components include producers (green plants, algae), consumers (herbivores, carnivores, omnivores), and decomposers (bacteria, fungi)

Biotic Structure

• Producers (autotrophs): Green plants synthesize their own food
• Autotrophs: Organisms that use sunlight to convert water and carbon dioxide into glucose, which includes photoautotrophs (photosynthesis) and chemoautotrophs (chemical energy)
• Consumers (heterotrophs): Organisms that obtain organic food by feeding on others
• Decomposers: Organisms deriving nutrition by breaking down complex organic molecules into simpler compounds like earthworms and ants

Ecosystem Functions

• Regulates biological energy flow rates
• Regulates nutrient flow rates by controlling production and consumption of minerals and materials
• Aids in biological regulation like nitrogen fixation

Types of Ecosystems

• A natural ecosystem functions as a unit with animals and plants and depends on solar energy
• There are two main categories of ecosystems: terrestrial and aquatic ecosystems
  • Terrestrial ecosystems are found on land, such as forests, grasslands, deserts, and tundra
  • Aquatic ecosystems contain plant and animal communities in water bodies, and are sub-classified into freshwater and marine ecosystems
• All ecosystems are either land-based (terrestrial) or water-based (aquatic)

Forest Ecosystem

• In the Indian continent, forests can be classified as coniferous and broadleaved forests
• Forest types depend on abiotic factors like soil, sunlight, and soil nature in a particular region
• Forest classification may be attempted depending on the tree species present like evergreen, deciduous, xerophytic and mangroves species

Forest Ecosystem Structure and Components:

• Biotic Components: The living components in a forest ecosystem consist of:
• Producers: Various trees, shrubs, and ground vegetation, classified by climate into tropical, subtropical, temperate, and alpine forests
• Consumers:
  • Primary: Herbivores, e.g., ants, flies, spiders, dogs, beetles, elephants, deer, mongooses
  • Secondary: Snakes, birds, foxes
  • Tertiary: Owl, peacock, lion, tiger
• Decomposers: Fungi and bacteria decompose dead organisms and reuse essential nutrients
• Abiotic Components: The nonliving components consist of: soil, air, sunlight, inorganic/organic components, and decaying organic matter

Grassland Ecosystem

• Grasslands are areas dominated by grasses on Earth's surface
• They occur in tropical and temperate regions with insufficient rainfall to support tree growth, but enough to sustain grass cover during the monsoon
• Grasslands exist in areas with hot/dry and warm/rainy seasons

Names of Grasslands:

• Known by different names across the world
  • Prairies of North America
  • Steppes of Eurasia
  • Savannas of Africa
  • Pampas of South America
  • Savanna of India
  • Downs of Australia
• Tropical grasslands are known as savannas which occur in eastern Africa, South America, Australia, and India

Grassland Ecosystem: Structures and Components

• Biotic component:
  • Producers: Grasses, herbs, and shrubs
  • Consumers:
    • Primary: Herbivores like grazing mammals and insects
    • Secondary: Carnivores that feed on herbivores
    • Tertiary: Carnivores that feed on secondary consumers
  • Decomposers: Bacteria, molds, and fungi which return minerals to the soil
• Abiotic components: Available nutrients in the soil with hydrogen, oxygen, nitrogen, phosphorus, and sulfur supplied by CO2, water, nitrates, phosphates, and sulfates

Grassland Ecosystem: Flora and Fauna

• Grasses dominate, with drought-resistant thorny trees in tropical grasslands
• Animals grazing on grasslands include badgers, foxes, zebras, and antelopes
• Supports rodents, reptiles, and insects

Grassland Ecosystem: Functions

• Energy flow via food chain
• Nutrient cycling (biogeochemical cycles)
• Ecological succession and development
• Homeostasis (cybernetic or feedback control mechanisms)
• Fertility of soil and regulate ecosystem productivity
• Reduction of mineral leaching due to low rainfall

Grassland Ecosystem: Economic Importance

• Grazing areas for rural communities
• Support farmers, shepherds and domestic animals
• Source of fodder which is collected and stored for cattle consumption
• Grass used for thatching houses and farm sheds
• Thorny bushes and branches used for fuelwood
• Overgrazing degrades grasslands
• Insects pollinate crops
• Predators include insectivores, like small mammals, reptiles, birds of prey, and amphibians

Grassland Classification:

• The world is divided into 2 zones:
  • Temperate (mid latitudinal zones and the interior part of the continents) zones
  • Tropical ( on either side of the equator and extend to the tropics)

Grasslands in India

• Grazing grounds and pastures in dry regions and Alpine Himalayas
• Perennial grasses dominant
• High altitude Himalayan pastures
• Tall elephant grass in Terai belt
• Semi-arid grasslands in Western/Central India, Deccan Plateau
• Diverse herbivores and mammals
• Threatened one-horned rhinoceros in Northeast India

Desert Ecosystems

• Found in low rainfall regions (250-500 mm/year) with high evaporation, occupies around 30% of land with organic-poor, mineral-rich soil
• Desert soils lacks organic matter but are rich in minerals. Desert plants have adapted to dry surroundings with minimized leaves

Desert Ecosystem, Structure and Components

• Biotic producers: Xerophytic plants
  • consumers
  • primary: Birds, camel, mouse.
  • secondary: Lizards, snakes, birds.
  • tertiary: Jungle cats, jackals, panthers
• Decomposers: Some fungi and bacteria

Desert Ecosystem: Functions

• Deserts facilitate the accumulation of these minerals, building potassium, gypsum, and borates

Aquatic Ecosystems

• Water-based habitats provide livelihood and life functions for organisms
• Aquatic ecosystems create the foundation for aquatic organisms
• Its features facilitate the transfer of water and significant chemical reactions
• The most prevalent organisms present are:
  • Nekton
  • Plankton
  • Benthos
• Freshwater aquatic ecosystems- lakes, oceans, ponds, rivers, swamps, coral reefs, wetlands
• Marine habitats, oceans, intertidal zones, reefs, and the seabed

Types of Aquatic Ecosystems

• Freshwater ecosystems covering 1% of Earth: lakes, ponds, rivers, streams, marshes, swamps, bogs, and ephemeral pools
• Sub divided into: lentic, lotic, wetlands and swamps

Lentic and Lotic Ecosystems

• Lentic areas consist of still water surfaces: lakes, ponds, reservoirs, and bogs
• Lotic areas consist of waterways: rivers and streams
• Insect/Fish species: Beetles, eels, trout, stone flies, and minnows
• Aquatic animals present: Beavers, otters, algae, frogs, salamanders

Marine Ecosystems

• Majority of the earth is covered in a marine ecosystem
• The earth consits of 5 oceans due to marine ecosystems Oceans, seas, intertidal zones, reefs, seabeds, estuaries, vents hydrothermal, pools rocks

Ocean Ecosystems

• The Pacific, Atlantic, Indian, and Arctic Oceans are the primary marine areas
• Sharks, whales, shellfish, seaguls all call the oceans home

Estuaries Ecosystems

• The estuaries connect fresh with salt water zones
• They are more saline, yet dilute to the ocean and seas, with economic importance for plant nutrients

Coral Reefs

• Corals or marine vertebrates support underwater structures
• An example is the hermatypes and hard reefs with function
  • Calcium carbonate
• Environmental needs- clear water access, sunlight, and the largest existing area sits at 1500 meters over
• These reef ecosystems are key to the environment and species present