Introduction to Ecosystems

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Ecosystems

• Ecosystems feature living organisms interacting with each other and their environments.
• They consist of biotic (living) and abiotic (non-living) components.
• A.G. Tansley introduced the term "Ecosystem" in 1935.

Types of Ecosystems

• Terrestrial are land-based ecosystems
  • Forest ecosystems maintain temperature and serve as carbon sinks.
  • Grassland ecosystems are dominated by grasses.
  • Tundra ecosystems have cold climates, little rainfall, and are mostly snow-covered.
  • Desert ecosystems have hot days, cold nights, and minimal rainfall.
• Aquatic ecosystems are water-based
  • Freshwater ecosystems include lakes, rivers, and wetlands with no salt content.
  • Marine ecosystems include seas and oceans with high salt content and greater biodiversity.

Components of an Ecosystem

• Abiotic components are non-living elements like climate, soil, water, sunlight, and air.
• Biotic components are living organisms
  • Producers (autotrophs) are green plants that produce food via photosynthesis.
  • Consumers (heterotrophs) depend on producers for food.
    • Primary consumers are herbivores.
    • Secondary consumers are primary carnivores like snakes and foxes.
    • Tertiary consumers are large carnivores like wolves.
    • Quaternary consumers are apex predators like lions and tigers.
  • Decomposers (saprotrophs) are bacteria and fungi that break down dead matter.

Ecosystem Functions

• Ecosystems regulate ecological processes and support life
• They cycle nutrients between biotic and abiotic components and maintain balance among trophic levels.
• They cycle minerals through the biosphere and help in the synthesis of organic compounds.

Ecological Concepts

• The food chain is the flow of energy from producers to consumers to decomposers.
• The food web is a network of interconnected food chains in an ecosystem.
• The ecological pyramid is a graphical representation of energy, biomass, and population across trophic levels.

Energy Flow in Ecosystems

• Solar energy is the primary energy source
• Photosynthesis converts solar energy into chemical energy.
• Energy flow is unidirectional (Sun → Plants → Herbivores → Carnivores → Decomposers).
• The First Law of Thermodynamics states that energy is conserved but can change forms.
• The Second Law of Thermodynamics states energy transformation leads to some loss as heat.

Ecological Interactions

• Positive interactions are beneficial for one or both species
  • Commensalism is where one benefits, and the other is unaffected.
  • Proto-cooperation is where both species benefit but are not dependent.
  • Mutualism is where both benefit and depend on each other.
• Negative Interactions are harmful for one species
  • Competition involves a struggle for limited resources.
  • Predation involves one species (predator) killing and eating another (prey).
  • Parasitism involves one species living off another.
  • Antibiosis is where one species produces substances harmful to another.

Ecological Succession

• Primary succession starts from bare land.
• Secondary succession occurs in areas where life existed but was disturbed.
• Autogenic succession is driven by changes caused by organisms in the community.
• Allogenic succession is driven by external environmental factors.
• The climax community is the stable, mature ecosystem after succession.

Productivity in an Ecosystem

• Primary productivity is the rate at which plants convert solar energy into chemical energy
  • Gross Primary Productivity (GPP) measures the total energy captured by plants.
  • Net Primary Productivity (NPP) measures the energy left after plants use some for metabolism.
• Secondary productivity is the rate of energy storage at consumer levels.

Biogeochemical Cycles

• The water cycle involves evaporation, condensation, precipitation, and runoff.
• The carbon cycle involves photosynthesis absorbing CO2, and respiration releasing it.
• The nitrogen cycle involves fixation by bacteria, uptake by plants, consumption, and decomposition.
• The phosphorus cycle involves phosphates in rocks, weathering, absorption by plants, animal consumption, and decomposition.

The Ecosystem

• Ecosystems include living organisms interacting with each other and their non-living environmental factors and support life through energy transfer and nutrient cycles.

Energy Flow in the Ecosystem

• Energy flow supports life by providing organisms with the energy needed for survival.
• The sun powers most ecosystems
• Less than half of solar radiation reaches earth
• Plants use sunlight to convert carbon dioxide and water into glucose and release oxygen.

Photosynthesis Steps

• Sunlight is absorbed by chlorophyll during light absorption.
• Water molecules break into hydrogen and oxygen during water splitting.
• Glucose formation occurs via hydrogen combining with carbon to form glucose.
• Oxygen is released into the atmosphere during oxygen release.

Thermodynamics Laws

• The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed
  • Solar energy is converted into chemical energy by plants.
• The Second Law of Thermodynamics states that energy transfer is not 100% efficient, and some energy is always lost as heat
  • At each trophic level, organisms lose energy in metabolic processes.

Ecological Pyramid

• An ecological pyramid represents the energy, biomass, or population at each trophic level
  • The Pyramid of Energy shows energy loss at each level (only 10% is passed on).
  • The Pyramid of Biomass represents the total mass of organisms at each level.
  • The Pyramid of Numbers displays the population of organisms at each level.

Productivity in the Ecosystem

• Primary productivity is how plants convert sunlight into energy
  • Gross Primary Productivity (GPP) is total energy from photosynthesis.
  • Net Primary Productivity (NPP) is the energy available after plants use some for respiration.
  • High NPP Ecosystems include rain forests and coral reefs.
  • Low NPP Ecosystems are deserts and deep Oceans.
• Secondary productivity is the rate of energy transfer to animals.
  • Herbivores, carnivores, and decomposers convert plant energy into their own biomass.
• Energy decreases as it moves up the food chain

Ecological Succession

• Ecological succession is the natural process of change in an ecosystem over time.
• Primary Succession happens when a new land area is formed.
• Secondary Succession occurs after a disturbance.

Succession example:

• Bare land is colonized by moss and lichens, succeeded by grasses and shrubs, then young trees, leading to a mature forest.
• Deforestation reduces photosynthesis and has various effects
• Pollution affects solar energy absorption and nutrient cycles.
• Climate change shifts energy flow, impacting ecosystems.
• Agriculture and Urbanization disrupt natural succession processes.
• Utilizing renewable energy, reducing waste and conserving forests help safeguard the ecosystems

Definition of Forest Ecosystem

• A forest ecosystem is a self-sustaining biological community composed of plants, animals, and microorganisms that interact with their physical environment.

Features of Forest Ecosystem

• Forests are essential renewable natural resources because they regenerate over time and play a crucial role in maintaining global climate, create oxygen, and absorb CO2.
• The feature includes diverse biotic and abiotic components
• They acts as self-sustaining units that cycle energy and nutrients and offer oxygen production, carbon sequestration, and climate regulation.
• They uphold wildlife and plant biodiversity and regulate temperature, humidity, and the water cycle.

Forest Ecosystem Types

• They are classified based on climate, rainfall, and temperature.
  • The tropical evergreen forest in equatorial regions with high rainfall, supports high biodiversity.
  • Tropical deciduous forests receive moderate rainfall and tree leaves in the dry season to conserve water.
  • Temperate evergreen forests in coastal areas with moderate to high rainfall, supporting organic floor.
  • Temperate deciduous forests experience four distinct seasons with moderate rainfall dominated by trees.
  • The taiga/boreal forest in northern regions experiences long winters with low precipitation, dominated by evergreens.

Forest Ecosystem Structural Characteristics

• Layers exist
  • The emergent layer consists of tall trees
  • The canopy features a thick roof of leaves
  • The understory is made up of small trees and shrubs
  • Forest floors are dark and humid.
• Biotic components include autotrophs like trees and mosses.
• Organisms like deer consume additional entities.
• Abiotic components include soil, air, and sunlight.

Functions of Forest Ecosystem

• Plants convert sunlight into food during energy flow.
• Nutrients are recycled
• Decomposing leaves enrich the soil and they influence rainfall and groundwater retention.
• Trees prevent erosion

Forest Ecological and Economic Importance

• Forests provide habitat for millions of species and help maintain global climate stability by absorbing CO2.
• They prevent soil erosion, are sources of timber and non-timber products, and contain medicinal plants and are Ecotourism destinations.

Grassland Ecosystems

• Grassland Ecosystems are transitional ecological communities in regions where the soil and climate do not support significant tree growth and are characterized by grasses and seasonal rainfall.

Grassland Types

• Desert grasslands are found in semi-arid regions, support sparse vegetation, and experience hot summers.
• Flooded grasslands feature high moisture, support aquatic plants, and are found in wetlands.
• Montane Grasslands locate above the treeline, experience cold temperatures.
• Tropical Grasslands are located near the equator and experience warm temperatures year-round with seasonal rainfall.
• Temperate Grasslands are found in mid-latitude regions.

Grassland Ecosystem Characteristics

• Grasslands dominate vegetation with few trees.
• Grasslands experience wide temperatures variations with rainfall variation.
• Grasslands host a huge number of herbivores.
• The soil has a great quantity of nutrients.

Grassland Ecosystem Adaptations

• Some have the Fire that removes dead plant and some species have resistant roots
• Grassland adapt drought with deep roots
• Grassland animals migrate Seasonally

Structure & Components of Grassland Ecosystem

• Abiotic Components: Include soil nutrients, Climate, Sunlight, Water
• Biotic Components: Include Producers and Herbaceous plants, Consumers and Herbivores.

Food Chain & Energy Flow

• Grass → Grasshopper → Mouse → Snake → Eagle → Fungi
• Energy flows from producers to consumers.
• Energy reduces at each trophic level.

Functions: Key Points

• Grasslands exist in climate conditions.
• Grasslands characterized by Soil, rain, grasses and animals.
• Grass land is threatened by human activities.

Desert Ecosystem Definition

• Deserts are unique environments characterized by low rainfall.

Desert Ecosystem Key facts

• They cover 33% of Earth's land surface and receive less than 250mm of year rainfall.
• They experience fluctuation in temperature.

Desert Types

• Hot deserts experience a minimal rainfall.
• Cold deserts experience low temperatures and snowfall.
• Semi-arid deserts experience in rain and temperature.
• Coastal deserts receive low rainfall.

Desert Ecosystem Features

• Deserts have low moisture and less than 250mm of annual rainfall.
• They adapt to withstand weather.
• The plants include Cacti and herbs, while the populations are minimal.

Desert Ecosystem components

• The desert's plants contain shrubs, trees and there are mosses in there.
• There are insects, hares, lions contained in there too and has a minimal role.
• Desert soils are poor in organic.

Functions of Desert Ecosystem

• They are unique for life- adapted flora and fauna.

Definitions

• Succulents- survive with minimum water.
• Salt production happens through evaporation.
• Deserts are rich with minerals.

Aquatic Ecosystems

• In aquatic ecosystems, organisms interact in water for ecological balance.
  • These exhibit high of bio diversity and they act dynamically that create efficient system.
• Temperature, Sunlight and Oxygen.
  • They are salty with pH and high flow depths
• The ecosystem are home to algae, plants zooplankton and marine- worms with support .
  • The ecosystems maintain productivity and they maintain underground levels creating transition zones.

Aquatic Ecosystem Threats

• Pollution in urban areas
• Overuse of deforestation
• Overuse of climate change.

Biodiversity review

• Biodiversity refers to the interactions in various organisms.
• Genetic diversity is within a species and in a relative.
• A geographic and area exhibits ecosystem diversity.
  • Species richness- Number of species in the given area with richness.
  • It increases when high, has low example like Everest and Rainforest. Native species has indicator

Types of biodiversity based ecological niche

• Can survive in environments that eat generalist and specialist species.
• Those not native are introduced and they have a key for stability.

Importance of species Diversity

• Key points are stability and survival.
• The biodiversity offers pollination to ensure diverse areas and to sustain.

Ecosystem diversity

• Includes terrestrial and forest that contribute to change and support life.
• These are at risk because of pollutions

Threats to biodiversity

• All living things are destroyed affecting survivals like deforestation. - Solutions include less pollution over illegal activity in order to conserve.

Definition: water quality

• They determine quality for sustainability.

The factors that affect water include

• events causing sediment and nutrients.
• Water has natural contamination but some help clean it by filtration where contamination affects.

Water Pollution

• Key point summary
• Contributer : Pollution - Prevention include. - Sewage - The sewage are bacteria that release illness and harm.