Ecology and Ecosystems

• Various organisms populate the earth in diverse shapes and sizes.
• Biodiversity refers to the number of different species living in a region, adding to nature's charm, and represents its biological wealth.
• Organisms do not exist in isolation; they interact within an ecosystem (or ecological system).
• Ecosystems comprise all organisms and their physical environment, linked by nutrient cycles and energy flows.
• Covered topics include the food chain, trophic levels, ecological interactions, and the importance of biodiversity.

Biosphere & Ecology

• The biosphere is the part of Earth where life exists, extending to soil, atmosphere, and water.
• Ecology is the study of interactions between organisms and their surroundings, encompassing different ecosystems and environmental protection.
• The sun serves as the primary energy source for the living world.
• Biotic and abiotic factors are essential for the biosphere's existence.
• Abiotic factors include sunlight, air, soil, and water.
• Green plants convert light energy to chemical energy through photosynthesis.
• This energy is transferred to other organisms through the food chain.
• Plants performing photosynthesis are called producers.
• Organisms that depend directly or indirectly on plants are called consumers.
• Primary consumers are those that directly depend on plants.
• Secondary consumers feed on primary consumers.
• Tertiary consumers feed on secondary consumers.

Food Chains and Food Webs

• A food chain is a sequence of organisms linked by what they eat, from producers to consumers, and from prey to predators, scavengers, and decomposers.
• A food web is a complex network of interconnected food chains showing feeding relationships within a community.
• Natural interconnections between food chains form a food web.

Trophic Levels

• A trophic level indicates an organism's position in the food chain.
• Plants represent the first trophic level as the starting point of the food chain.
• Herbivores that get food directly from plants are in the second trophic level.
• Carnivores that depend on herbivores are in the third trophic level.
• Predators that prey on carnivores are in the fourth trophic level.
• An organism may occupy different trophic levels as the food web becomes more complex.
• There is a possibility of a fifth trophic level.

Ecological Interactions

• Predation benefits one organism but harms the other, as prey becomes the predator's food (e.g., deer and tiger).
• Parasitism benefits one organism and harms the other. The parasite depends on the host for nutrition (e.g., mango tree and Loranthus).
• Competition harms both organisms initially but benefits the one that wins (e.g., paddy and weeds).
• Mutualism benefits both organisms (e.g., flower and butterfly).
• Commensalism benefits one organism without benefiting or harming the other (e.g., mango tree and vanda).
• These interactions maintain the balance and stability of ecosystems; food relations are visible instances of organism interaction.

Diverse Ecosystems

• Examples of diverse ecosystems include forests, tundra, oceans, wetlands, and grasslands.
• Biodiversity includes all diverse organisms inhabiting Earth, along with their ecosystems, encompassing ecosystem, species, and genetic diversity.

Biodiversity Depletion

• Birds are found everywhere, but are vulnerable to changes in the ecosystem.
• Reasons for decline in bird diversity:*
• Large-scale destruction of ecosystems.
• Overexploitation of natural resources.
• Excessive use of chemicals in agricultural fields.
• Natural calamities and uncontrolled hunting of birds are the reasons for their extinction.
• Lack of natural habitat protection for birds.

Preserving Diversity

• Many national and international organizations and legal systems are dedicated to conserving biodiversity.
• There are two prevalent types of conservation methods: in-situ and ex-situ.
• In-situ conservation protects organisms in their natural habitats, such as in wildlife sanctuaries, national parks, and community reserves.
• Ex-situ conservation protects organisms outside their natural habitats.

Ex-Situ Conservation

• Protecting species from external threats by keeping them safe in specialized controlled environments.
• They can be conserved via botanical gardens, gene banks and zoological gardens.

Gene Banks

• Research facilities collect seeds and gametes to preserve them which can then be used to improve the genetic diversity of the plants.

Importance Of Biodiversity

• This is important for restoring and protecting nature against climate change.
• It sucks carbon out the air and can be used for medicines and fuels.
• It can be depleted by overuse of chemicals and natural disasters.