4.1 Ecosystems

Biomes: a form of ecosystems that are smaller than the biosphere

• Hot deserts (Middle of continents + western coasts; 14% of Earth’s surface):

  • High daytime & low nighttime temperature; generally light winds

  • >250mm of rainfall annually; high evaporation rates

  • Light colored soil that’s dry & sandy; top layer may be absent/very thin due to lack of vegetation

  • Cacti have drought tolerant seeds with waxy cuticles to prevent water from escaping

  • Human impact: mining, removal of rare species, & use of groundwater + drying out surface water

• Tropical Rainforest (Equatorial zones of Asia + Central America & Asia):

  • Temperatures range from 22-31°C; low diurnal temperature (difference b/t high and low temperature in the same day)

  • 2000mm of rainfall per year w/ high humidity levels; daily convectional rainfall

  • Red/yellow soil; high rainfall = nutrients + clays being leached out & replaced with aluminium oxide (high rate of decomposition)

  • Tall + thin trees allow for light, thin bark eliminates the need to conserve water, & leaves have a waxy surface with drip tips to allow excess water to runoff + prevent algae

    • Helps support high biodiversity

  • Human impact: deforestation, mining, urbanization, agriculture, & desertification

• Grassland (Middle of continents - away from coasts):

  • Temperatures range from 20-35°C

  • Up to 750mm of rainfall annually w/ wet summer; unpredictable rainfall

    • Distinct dry & wet seasons

  • Red soil (high iron), highly weathered + porous allows for rapid drainage & thin layer on surface decays rapidly due to high temperatures

    • Soils aren’t very fertile; limited vegetation

  • Vegetation: grasses & umbrella shaped trees

    • Trees are spread apart & root systems are either widespread (to absorb water) or deep (reach groundwater during dry season)

  • Human impact: grazing, urbanization, & less biodiversity due to loss of habitat + hunting

• Tundra (North Asia + S. America & S. coast of Greenland):

  • Temperatures range from -34-12°C; strong polar winds

  • Less than 250mm of rain annually & short summers

  • Dark brown soil, permafrost (permanently frozen) sub layer, organic material at surface

  • Vegetation: small plants that grow close together & are low to the ground

    • Waxy hair to coat them from cold & wind, shallow root systems due to permafrost

  • Human impact: melting of permafrost (methane) & drilling for resources

• Major abiotic factors of a biome: temperature & precipitation

Primary and secondary Succession

• Ecological succession: process of an ecosystem changing & developing

• Primary succession: uncolonized areas → soil isn’t capable of sustaining life

  • Pioneer species (lichens & mosses) will establish themselves on bare rock

    • Start formation of soils by breaking down the rock → grasses + shrubs can grow

  • e.g) new lava flow, newly formed sand dunes, & newly quarried rock face

  • takes longer than secondary

• Secondary succession: colonized area that was disturbed or damaged (hasn’t eliminated all life/removed all nutrients)

  • Soil is present; pioneer species = small plants

  • e.g) where a mudslide occurred or trees have fallen

• Intermediate community: change from the initial community, but the final stage hasn’t been reached

• Climax community: final stage of succession; depends on climate

  • Can take a few days to hundreds of years

• Species involved in succession are controlled by abiotic factors like geology & climate

Primary productivity: the rate in which energy is converted into organic material by autotrophs

• Gross primary productivity: total amount of biological productivity within ecosystem/biome

  • Energy production per unit area / units of time

• Net primary productivity: amount of energy captured minus energy used for respiration

  • GPP - Respiration

  • Decreases as distance from the equator increases

• Abiotic factors that affect productivity: CO2, water, sunlight

• Ecosystem productivity: rate at which biomass is produced within an ecosystem

Ecological (trophic) pyramids

• Compare communities within/between ecosystems by analyzing their trophic levels

  • Represents energy, number of individuals/biomass in each trophic level

• Pyramid of energy shows feeding relationships of an ecosystem

  • Greatest amount of energy at the bottom → ~10% transfer of energy b/t levels

    • Energy loss as heat due to respiration & excretion

• Normal pyramid of numbers: largest # of organism at the bottom

  • Producers at bottom & tertiary consumers at the top

  • Along with a pyramid of biomass can have an unusual/inverted shape

    • Number below can support upper trophic levels

4.2 Managing the conservation of biodiversity

Native and invasive species

• Native species: originated & developed in a specific region/ecosystem and adapted to living there

  • Indigenous: occurring naturally in a specific area; native to an ecosystem

• Invasive species: outcompete other species in the area it has invaded → changes balance in the ecosystem it invades

  • Can be native (outcompete other organisms in the ecosystem) or non-native

  • Primarily spread through human activity & often spread rapidly

  • Degrade native ecosystems → harmful to human health + local economies

• Loss of indigenous flora = reduced biodiversity

  • Invasive species of flora have different characteristics → decrease organisms dependent on native flora

• Potential impacts of invasive species: grazing, competition, predation, & disease transmission

Benefits of conserving biodiversity

• Food security: protects plants, animals, & genetic resources that support soil fertility, disease regulation, & pollination of crops

• Economic growth + poverty reduction: many poor populations depend on natural areas for their livelihoods; forests provide timber, food, & water

• Combating climate change: forested areas can reduce CO2 levels & coastal ecosystems can lessen the impact of storm surges

• Medical resources: medicinal qualities in plants to treat illness

• High genetic diversity: greater stability → species are able to adapt to various conditions (e.g. disease & climate change)

• Cultural and recreational value: biodiversity reflects social values + local beliefs

  • e.g) a culture may use rivers for baptism

Methods of conserving biodiversity

• Protection of species + biodiversity

• Sustainable harvest: use of a resource that ensures its constant supply without harming future yields/causing irreversible damage to an ecosystem

  • Requires educational + legislative solutions

  • Optimal harvest (set % of resource is harvested) & systematic random sampling (set % of material harvested from a defined part of an ecosystem) are sustainable

• CITES (int’l trade in endangered species): aims to ensure sustainable trade & protect endangered animals + species

  • Limitation: hasn’t stopped illegal trade of protected species & voluntary participation

• IWC (Int’l Whaling Committee): manage & conserve whale species globally

  • Catch limits are still too high & lacks punishment for those who don’t comply

• EU CFP (Euro. Union Common Fisheries Policy): set rules for fishing fleets in EU waters

  • Limited applicability; West Africa is being overfished

• ITTO (Int’l Tropical Timber Org.): encourage sustainable forest management + tropical timber harvest & trade

  • Large forest areas = hard to catch illegal harvesting

• IUCN Red List: scientific info + tools to guide int’l actions in conservation

  • There may be species on the list that aren’t

• EDGE: aims to protect species on the verge of extinction & have unique evolutionary history

  • EDGE Score: combined endangered conservation status + distinctiveness of species

• Captive Breeding: breeding endangered species in captivity with the goal of releasing them back into protected wild areas in the future

  • Aims to develop a self-sustaining population of a species

  • Can lead to inbreeding w/ weak genetic traits → lower survival rates

Habitat conservation and creation

• Rewilding: restoring an area of land to its natural uncultivated state

  • Reintroduced species + communities can thrive → biodiversity increases & ecosystem health improves

• Extractive reserves: land where access & resource use rights are allocated to local groups or communities (e.g. managed sustainable extraction of natural resources)

  • Giving local communities rights → more inclined to protect resources

• Protection of habitats: protects the whole habitat + each species benefits

  • Encourages species protection & biodiversity conservation

• Nature reserves: legally protected area that is of importance for organisms or geology

  • Conservation, protecting natural resources, & scientific research

• National parks: protects landscapes, wildlife, & natural features of large areas that are of conservational, education, or scientific interest

  • Protected by national laws

• Marine conservation zones: nat’l/int’l importance with rare or threatened species + habitats that require protection

  • Typically don’t have a fishing ban, but have “no-take” zones (prohibits destroy natural resources)

  • MCZs form a greater network of protected zones

4.3 Impacts of human activity on ecosystems

Human impacts on tropical rainforests

• Deforestation: causes fragmentation + lost of tropical forests

  • Plants + animals in the fragmentation ecosystem remain vulnerable (those that do survive cause a rapid decline in biodiversity)

  • Loss of genetic material + biodiversity

• Exploration for + mining of minerals → forests being made into roads + infrastructure

  • Mining can lead to water, air, soil, noise, & light pollution

• Agriculture: depletes the soil of nutrients due to soil erosion

• Soils are thin + lack nutrients → due to leaching & heavy rainfall

  • Nutrients = stored in biomass

  • Completely deforested areas → soils collapse + high soil erosion

• Contributes to climate change → forests store a lot of carbon (e.g. in photosynthesis)

Sustainable management of tropical rainforests

• Preserve rainforests to: maintain biodiversity, protect the production of resources, manage climate change, & manage local water quality

• Debt reduction: many tropical rainforests are found in LICs that have high levels of debt

  • Instead of remove rainforests to generate income → some HICs agreed to write off debt

    • In return, HIC asks for the protection of an area of the rainforest

• Int’l agreements: manage species + forested areas through sustainable harvesting(e.g. CITES)

  • Need to include: educating those exploiting resources & providing consequences to negative action(s)

• Legislation + protected areas: establishment of anti-deforestation public policies + private measures can significantly protect forested areas, biodiversity, + forest’s ability to absorb CO2

  • Needs to be rolled out across countries w/ large areas of tropical rainforests

Human impact on Antarctica

• Climate change: warming oceans → loss of ice

  • Ocean acidification (from excess CO2) has caused a loss of biodiversity

• Fishing: overfishing leads to the loss of krill, which can lead to the collapse of food chains

• Tourism: increases potential of oil + sewage spillage (overall pollution)

  • Can disturb colonies of Antarctic animals

  • No individual gov’t has the power to set regulations

• Ozone depletion: CFCs → hole in the ozone layer in the stratosphere above Antarctica

  • Strong and frequent winds + storms

• Scientific research: helps understanding the continent + environment processes there

  • Can raise global awareness + used in formation of int’l laws

  • Research stations have a negative environmental impact

Strategies for managing the impacts of humans on Antarctica

• Legislation & int’l agreement (e.g. The Antarctic Treaty):

  • Features like: banning the mining of minerals, cooperation b/t countries in scientific investigation, & no nuclear testing/disposal of nuclear waste

  • Prohibits the import of non-native flora & fauna species w/o a permit

• Protected areas are continually set up

• Tourism control through agreements like the IAATO

  • Stricter agreements are being put into place (e.g. requiring a tour operator to have a permit)

  • Educate tourists, reduce noise & light pollution, waste management policies