Introduction to Ecology

Introduction to Ecology

• The term "ecology" was coined by German biologist Ernst Haeckel in 1869.
• The term is derived from Greek "Oikos" (house, habitat) and "Logos" (to study).
• Ecology is defined as the study of interrelationships between organisms and their environment, applying to both animals and plants.

Ecological Organization Levels

• Levels of ecological organization include Individual, Population, Community, Ecosystem, Biome, and Biosphere.

Ecosystem Overview

• An ecosystem is a defined area where plants and animals interact with each other and their non-living environment.
• Ecosystem nature depends on geographical features like hills, mountains, plains, rivers, lakes, and islands.
• Climatic conditions, such as sunlight, temperature, and rainfall, also influence ecosystem characteristics.

Ecosystem Characteristics

• Structure involves living (biotic) and nonliving (abiotic) components.
• Processes include energy flow and cycling of chemicals/matter.
• Change is dynamic through succession.

Ecosystem Services

• Supporting examples include soil formation, photosynthesis, and biodiversity.
• Provisioning examples include food, clean water, fish, and wood.
• Regulating examples include pollination, temperature control, flood control, water purification, and carbon storage.
• Cultural examples include aesthetic value, recreational opportunities, and education.

Components of Ecosystem

• Ecosystem components are categorized as abiotic and biotic.
• Abiotic components are non-living chemical and physical factors like water, air, nutrients, and solar energy.
• Physical and chemical factors influence organisms in terrestrial and aquatic ecosystems.
• Abiotic factors can act as limiting factors, influencing population size.
• Abiotic components include Climatic Factors (rain, temperature, humidity, light, wind, moisture) and Edaphic Factors (soil, pH, topography, minerals).
• Biotic factors include all living organisms that interact.
• Biotic factors can also be limiting, such as bacteria, animals, and plants.

Biotic Components

• Autotrophs (producers) make their own food through photosynthesis.
• Most terrestrial producers are green plants.
• Aquatic producers include algae and phytoplankton.
• Heterotrophs (consumers) obtain energy and nutrients by feeding on other organisms or their remains.
• Primary consumers (herbivores) eat producers (plants).
• Secondary consumers (carnivores) eat herbivores.
• Tertiary consumers are large carnivores that feed on secondary consumers.
• Quaternary consumers are the largest carnivores that feed on tertiary consumers and are not eaten by other animals.
• Omnivores have a mixed diet of both plants and animals.
• Decomposers (saprotrophs) break down dead organic matter into inorganic compounds via bacteria and fungi.
• Inorganic compounds return to producers (plants) as fertilizers
• Decomposers play a vital role in maintaining the nutrient cycle.

Classification of Ecology

• Autecology studies individual species and their populations, including behavior and adaptations. Also called Species or Population Ecology.
• Synecology studies communities, their composition, behavior, and environmental relations. Also called Community Ecology.

Classification of Ecosystems

• Aquatic ecosystems involve interactions of organisms in water. Marine ecosystems include oceans and deep seas. Freshwater ecosystems are classified as Lotic (running water such as rivers, streams, springs) and Lentic (standing water such as ponds and lakes).
• Terrestrial ecosystems involve interactions of organisms on land, including Grassland, Forest, and Desert ecosystems.
• Artificial ecosystems are maintained by humans, such as crop lands.

Terrestrial Ecosystems: Grassland

• Grasslands cover 32% of Earth's surface.
• They occur in regions too dry for forests but with more water than deserts.
• The classification is based on dominant vegetation, species, and climate.
• Temperate grasslands are in temperate latitude, have green vegetation, and fertile soil.
• Tropical grasslands are in tropical latitudes, have dry, brown vegetation, and soil is not fertile.
• Polar grasslands are in the northern hemisphere, have cold temperatures, and an average winter temperature of -34° Celsius.

Terrestrial Ecosystems: Forest

• Forests are dominated by trees.
• They include herbs, shrubs, climbers, lichens, and a wide variety of animals and birds.
• Types of forests include tropical rain forests, tropical deciduous forests, tropical scrub forests, temperate rain forests, temperate deciduous forests, and evergreen coniferous forests.

Food Chain

• Every organism needs energy to live.
• A food chain shows the sequence of who eats whom in a community to obtain nutrition.

Terrestrial Ecosystems: Deserts

• Deserts occur in areas where evaporation exceeds precipitation.
• Hot deserts have warm temperatures year-round and very hot summers.
• Cold deserts have short, warm summers and long, cold winters, found in north and south poles.

Artificial Ecosystems

• Artificial ecosystems are maintained by humans through energy input and manipulation, disrupting natural balance, such as crop lands.

Food Web

• A food web represents the feeding connections (what-eats-what) in an ecosystem.
• It is a simplified illustration of feeding methods linking an ecosystem.
• Food webs provide more than one food option and increase organism survival chances.

Energy Flow in Ecosystem

• The first law of thermodynamics: energy is neither created nor destroyed, only changed Ecosystem energy comes from the sun.
• The second law of thermodynamics: energy transformation results in heat loss. Heat loss occurs during energy transfer between trophic levels.

Ecological Pyramids

• Charles Elton proposed ecological pyramids in 1927.
• These pyramids are graphical representations of trophic structure and function.
• Pyramid of Numbers represents the number of individuals in each population in a food chain.
• Autotrophic level (base) is often larger, decreasing as you ascend.

Pyramid of Biomass

• Illustrates biomass amount in each trophic level.
• Biomass weight determined after dehydration.
• Shows the amount of matter lost between trophic levels.

Pyramid of Energy

• Shows energy available at each level.
• The block size represents the proportion of productivity.

Biogeochemical Cycles

• It is a pathway which a chemical substance moves through biotic (biosphere) and abiotic (lithosphere, atmosphere, hydrosphere) components of Earth. A cycle repeats itself.
• It involves carbon, oxygen, nitrogen, phosphorus, and water circulating through the biological and physical world .

Hydrological Cycle

• The water cycle involves evaporation, condensation, precipitation, and collection.
• Water is recycled between the atmosphere, land, ocean, and underground. Most water vapor enters the atmosphere through evaporation, turning liquid water to gas through the sun's energy. Water also evaporates from plants by transpiration, or through sublimation from snow and ice.
• Water vapor cools and forms droplets by condensation, creating clouds. If the droplets get too heavy, they fall as precipitation.
• The precipitation becomes part of bodies of water or stays in Earth's glaciers.

Carbon Cycle

• Carbon cycles between the atmosphere, plants, animals, and ground.
• Plants make food through photosynthesis from carbon dioxide from the air.

Nitrogen Cycle

• Bacteria called Rhizobia convert nitrogen to nitrogenous compounds in soil.
• Plants absorb soil nitrogen and animals eat plants.
• Nitrogen is returned to the environment after death, waste, or excretion.
• Nitrification and denitrification are also steps of the cycle.

Phosphorus Cycle

• Phosphorus cycles through the environment via phosphate rocks, organisms, erosion, and sedimentation.
• Rocks are mined for phosphorus.

Sulfur Cycle

• Sulfur cycles through the atmosphere, soil, water, and organisms.
• Hydrogen sulfide is released into the atmosphere during volcanic eruptions.