IB BIO Y2 Unit 1 : Stability and change/Climate Change/Biodiversity

Ecosystem

Are biological communities of interacting organisms and their physical environments

Components of An ecosystem

• Biotic (All of the living things)

  • Producers/Autotrophs

  • Consumers/Heterotrophs

  • Decomposers

• Abiotic (All of the non-living things)

  • Sun

  • Water

  • Temperature

Examples of stable ecosystems

• Are stable without human activity

Ex) Tropical rain forests, deserts are stable because people don’t live there.

Specific: The Kalahari desert is estimated to be 60 million years old.

Requirements for stability in ecosystems (4)

• A supply of energy (from the sun)

• Genetic diversity (so the population can overcome challenges)

• Recycling of nutrients (carbon, phosphorus cycle)

• Climatic variables within tolerance levels

Tipping point

Is a critical threshold that, when crossed, leads to large and irreversible changes in the climate

Ex)

• The amazon rainforest (Deforestation can lead to it being a carbon source)

• Ice caps in the Atlantic (It could raise the ocean levels)

Deforestation of the Amazon rainforest (IB Specific)

• Up to 20% of the Amazon Rainforest has been deforested since the 1970s

Before deforestation (what they initially do) :

• Generate atmospheric water vapour by transpiration which cools the atmosphere and modifies wind patters (air flow)

• Are carbon sinks (removing CO2 from the atmosphere)

After deforestation (what they are doing now):

• The loss of rainforest will impact wind and rainfall patterns, which will have an impact on climate change.

• Ongoing deforestation brings concern for climate change!

• It is at its tipping point!

Transpiration

the process where plants release water vapor into the atmosphere, primarily through tiny pores on their leaves called stomata

Calculating Percent change

Percent change= Final-Initial / Initial x 100

Mesocosm

Is any indoor experimental system that examines the natural environment under controlled conditions

• Allow scientists to control and manipulate variables while investigating ecosystems

• No Animals should be harmed!

• The mesocosms need the four requirements in order to be a stable environment.

Harvesting of crops and fish

• Can be sustainable If the rate of harvesting is lower than the rate of replacement.

• Monitoring the population size and age of plants/fish

• Sufficient adult organisms harvested

• Can remove parts of a plant without damaging the health of the plant

Sustainable fishing

is harvesting fish at a sustainable rate

• The fish population does not decline over time because of fishing.

• Uses selective methods to maximize fish capture without causing fish populations to decrease

• The rate of harvesting has to be lower than the rate of replacement!

Maximum Yield

is the largest catch of fish that can be sustained over time without causing the fish stocks to decrease

*Can’t go over the maximum yield!

Example of Sustainable fishing (Pacific Cod)

• They are caught under strict annual catch limits to prevent over-fishing

• Stock assessments show populations are healthy in most regions

• Catch-share program helps reduce by catch (too much catch) (share the catch with individuals)

• Fishing gear rules and closed areas protect habitats of the fish

• Scientists collect data using the Capture Mark Release Recapture method

Example of Sustainable harvest (Silver Top Palms)

• Silver top Palm is used to produce a range of traditional products in the Bahamas

• The leaves of the plants are removed from the plant, without killing the plant so leaves can be harvested in the future!

*Harvest only the leaves

Negative Factors that affect sustainable agriculture (5) *

• Soil erosion: Many agriculture human practices breakdown the soil which reduces the fertility of the soil for future generations

• Leaching of nutrients: The excess use of fertilizers (overuse) can result into nearby ecosystems (Rivers, lakes) → can lead to Eutrophication

• Supply of fertilizers and other inputs: The manufacture of fertilizers and other chemicals has an impact on environment!

  • Ex) Mining of Phosphates for fertilizers

• Pollution: Agrochemicals (pesticides and fertilizers) can affect the long-term health of the soil.

• Carbon Footprint: Many agricultural practices releases a significant amount of CO2, which contributes to climate change

Plastic

Are a range of organic synthetic materials that persist in the environment because they do not biodegrade

Micro/Macro plastic

• Micro: Produced by the physical breakdown of Macroplastics (less than 1 mm)

• Macro: large debris (more than 1 mm)

  • Ex) Plastic bag

Effects of Plastics on Laysan Albatrosses

The consumption of plastic is the cause of death for many of the Laysan albatrosses
(They will eat the plastics and die)

Effects of Plastics on Sea turtles

• Sea turtles will mistake plastic bags for jellyfish or will consume plastic when there is a shortage of food

• Ingestion of the plastics can be fatal to the sea turtles (and to future generations)

• Plastics debris can become wrapped around the turtle, restricting movement and growth.

Nature of Science

• Scientists can influence the actions of citizens if they provide clear information and data-driven evidence

• The media can affect society by changing the public perception globally which has driven measures to address plastic pollution.

Rewilding

Aims to restore degraded ecosystems back to their natural state

3 things rewilding can include

1. Reintroduction of a keystone species including apex predators such as wolves in the yellowstone national park

2. Re-establishing the connectivity of habitats over large areas through wildlife corridors

3. Management of ecosystems to reduce human impact

Wildlife corridor (4)

Are areas of habitat which connect wildlife separated by human activities or structures.

• Usually a bridge

• as simple as a deer yield sign

Wildlife corridors…..

• Increasing biodiversity: Movement of animals across habitats tends to increase biodiversity.

• Migration: many animals need to migrate between seasonal habitats

• Expanding habitat range: allows plants and animals to recolonize their natural habitat

• Greater genetic variety: the corridors increase the size of the gene pools which increases genetic variation

How does human activity affect ecosystems

• Humans reduce the biodiversity of ecosystems

• Deforestation

Specific case study Hinewai Reserve

• The Hinewai Reserve in New Zealand was set up in 1987 on farmland

• The goal of the reserve is to regenerate native vegetation and is an example of a managed natural ecosystem.

• The reserve has been left to regenerate without human interference.

• Gorse species (a type of plant) are not native to the Hinewai reserve but have been left there to act as a nurse canpoy for growing tree saplings, as natural succession occurs.

Climate change

Climate change

Refers to the significant, long-term shifts (decade or longer) in global or regional climate patterns

Ex)

• Temperature

• Precipitation

• Other measures of climate

Anthropogenic climate change

Climate change caused by human activity
Anthropogenic: Human activity

4 major Anthropogenic cause to climate change

1. Burning of fossil fuels (combustion of fossil fuels) and wood releases carbon dioxide into the atmosphere

2. Agricultural practices, farming cows, sheep and rice releases methane

3. Deforestation and land-use changes

4. Waste management

Greenhouse gases

gases in the atmosphere that trap heat and warm the planet

• Water vapor is the most prominent greenhouse gas that contributes to the greenhouse effect

• The most prominent human caused greenhouse gas is CO2

Ex) CO2, methane, Water Vapor

Positive correlation

Both variabales move in the same direction!

• As one variable increases, the other variables increase as well

Negative correlation

Variables move in opposite directions

• As one variable increases, the other variable decreases

Linear correlation

No correlation
(Horizontal Straight line across)

The relationships between carbon dioxide and temperature in Antarctica ice cores

There is a positive correlation between the relationship between carbon dioxide concentration and temperature in Antarctica ice cores

Positive feedback loop

Increases the risk of global warming

Ex)

• Loss of snow and ice

• Decrease in permafrost

Loss of snow and ice

• White snow reflects most solar radiation

• Darker lands and water absorbs more solar radiation in the form of heat!

• Which contributes to global warming

Decrease in permafrost

• Permafrost is soil that remains below freezing for at least 2 years. (Lots of carbon are stored in permafrost)

• Increased temperatures thaws the permafrost away

• Due to increasing temperatures, peat is decomposed by bacteria, releasing CO2 and methane into the atmosphere.

  → which further melts permafrost because it contributes to global warming

Carbon sinks in the Boreal Forest

• CO2 is trapped in the Boreal forest in the ground, as low temperature reduces the rate of decomposition.

• However, Warmer temperatures and decreased snowfall leads to more droughts as water is evaporated.

• The Lack of water reduces primary productivity (the rate at which produces store organic compounds in the their biomass) of plants, reducing photosynthesis.

• So, Carbon cannot be stored in the ground anymore, which decreases the amount of CO2 taken OUT of the atmosphere in the ground.

What actions have led the Boreal forrest to be at a tipping point?

• Forest browning occurs due to the prolonged periods of drought, which increases the frequency and intensity wildfires.

• Forest fires release carbon stored in the biomass of plants as well as carbon stored in the soil as peat. (As plants burn, the carbon stored in those plants gets released)

*They now release more carbon than they absorb! = Tipping point which could accelerate climate change

Loss of polar Habitats: What is the trend?

Decreasing trend for the area of Arctic sea ice over time

Land Ice VS Sea Ice

Land ice: Ice forming on land from fresh water and snow

Sea ice: Ice forming from salt water

Global warming and its impact on emperor penguins

• Climate change = loss of sea ice

• Emperor penguins depend on sea ice(land-fast ice) to form breeding colonies

• The loss of snow ice reduces the number of penguin colonies

• Sea ice is melting earlier, often before penguin chicks are capable of swimming in the icy waters

• Which leads to fewer penguins surviving to the next year

*As a result, they have a risk of becoming extinct

Global warming and its impact on walrus populations

• Climate change = loss of sea ice

• Walruses depend on ice floes (large masses of free-floating ice) for resting between feeding and hunting

• The loss of ice floes affects walruses’ ability to hunt and feed their young

• Walruses are now resting in beaches (farther away from food source)

• Stampedes of walruses are crushing their young to death

• They also have to travel further to hunt for food and feed their young

• Due to this the population of walruses are going down

Nutrient upwelling

Is a process in which cold nutrient-rich water rises from the bottom of oceans towards the surface of oceans

• It is dependent on patterns of ocean and wind currents

Normal nutrient upwelling:

1. Winds blow across surface waters

2. Allows water below to rise up, bringing nitrate and phosphate to the phytoplankton on the surface

3. Phytoplankton growth is stimulated by the nutrient-rich waters

4. The high primary productivity(rate at which producers accumulate organic materials into their biomass) of phytoplankton supports a biodiverse community of organisms in marine ecosystems

Climate change: Its impact on nutrient upwelling

• Climate change = changes wind patterns

• Nutrient upwelling is highly dependent on strong winds moving the warm waters away, which lets cold water to rise

• Changes in wind patterns change the frequency and extent of nutrient upwelling

• Alternation of ocean circulation patterns: changing wind patterns also impact ocean circulation patterns altering the frequency and extent of nutrient upwelling

• No nutrient upwelling = less phytoplankton

• decrese in phytoplankton will have a cascade effect on marine ecosystems (decreasing fish, marine animal population)

Poleward shift and upward slope

Poleward shift: Refer to the movement of species’ movement toward the poles (Northern hemisphere, Southern hemisphere) in response to climate change

Upward slope: As the climate changes, the range of species is changing as they move to higher elevations on mountains.

Upward slope range shifts on montane bird species in New Guinea

• Climate change= Temperature increases

• As temperature increases, many bird species are shifting to cooler and higher altitudes

• As the range of birds moves upslope, their habitat becomes compressed due to limited areas on the mountains

• The bird population is decreasing at lower altitudes with higher temperatures

• Which results in less birds

Poleward shift on North American sugar maple trees

• As temperature increases, the range of North American trees is moving northward (to cooler regions)

• The upward movement of trees Northward is contracting the overall range of many North American tree species.

Coral reefs

• Increased CO2 concentrations cause ocean acidification and suppression of calcification in corals.

• Increases in water temperatures are a cause of coral bleaching

• Loss of corals causes the collapse of ecosystems

Why is the pH of the ocean is decreasing?

-pH has decreased over the past centuries (8.179 to 8.069)

• pH decreases because of the increasing concentrations of dissolved CO2 in the ocean → the ocean becomes more acidic → which lowers the pH

decreasing pH of oceans and the affect on corals *

• As atmospheric Co2 increases, more Co2 diffuses into the oceans

• Co2 reacts with water to form Carbonic acid (H2CO3), which reduce the pH of the oceans

• Carbonic acid dissociates, releasing hydrogen ions (H+)

• The hydrogen ions react with carbonate ions to form hydrogen carbonate ions (HCO3-), which reduces the available carbonate ions available for corals

• Corals use dissolved carbonate ions to build calcium carbonate exoskeletons

• Increasing concentrations of (Hydrogen ions) H+ in the ocean reduce the availability of carbonate ions, as hydrogen ions react with carbonate ions to produce hydrogen carbonate ions

• As atmospheric CO2 concentrations increase, more carbon dioxide diffuses into the oceans

• The reduced availiabity of carbonate ions makes it more difficult for many coral speices to produce their exoskeletons.

Ocean acidification will slow the growth of many coral species, as they produce weaker exoskeletons

Coral bleaching

• Zooxanthellae algae and corals have a mutualistic relationship

• zooxanthellae is responsible for the color of coral reefs

• increasing ocean temperatures stress corals and they expel zooxanthellae, losing their color (bleached)

• Bleached corals are not dead but they have a danger of starvation as they have lost their food source

• which causes them to die!

Death of Coral and the impact on the ecosystem (coral reefs)

• Coral reefs are a biodiverse ecosystem, which depends on the presence of corals!

• Ocean acidification and coral bleaching kill the corals, which leads to the collapse of the coral reef ecosystems

• Corals provide shelter for many marine organisms (protection from predators)

• Therefore, death of corals = collapse of ecosystem = extinction of many ocean species

Carbon sequestration

Is the process of capturing and storing atmospheric carbon dioxide.

• Plants absorb CO2 during photosynthesis

• Carbon is stored in plant biomass as carbon compounds

• When plants die, some carbon is stored in the soil (wetlands)

• Forests and peatlands act as long term carbon sinks

Ex)

• Afforestation

• Forest regeneration

• Restoration of peat-forming wetlands (Reforestation)

Afforestation

The establishment of forests in location where there was no recent tree cover

Forest regeneration

occurs when a forest grows back after a disturbance such as harvesting of trees.

Restoration of Peat-forming wetlands

Many wetlands have been drained but can be restored in wetlands

Peat formation

• Peat forms when organic matter is not fully decomposed because of acidic and/or anaerobic conditions in waterlogged soils.

• Peat forms in waterlogged soils in temperate and boreal zones and also very rapidly in some tropical ecosystems.

Is it best to have native or nonnative species for afforestation?

Native because non-native species has a risk of becoming invasive species and overtaking/harming the native species

Phenology

The study of cyclic and seasonal natural phenomena, especially in relation to climate, plant and animal life.

Ex) Circadian rhythm

Photoperiod and temperature relationships affect by climate change

Variables such as photoperiods and temperature patterns are examples of variables that influence the timing of many biological events, such as:

• Flowering- Plants producing flowers

• Budburst- the emergence of new leaves at the beginning of a growing season

• Migration- Many bird species migrate between breeding and wintering grounds

• Nesting- birds build nests to lay eggs and raise offspring

Photoperiod

Is a length of time in a day that an organism receives light

Interaction between species are being disrupted by climate change

Ex)

• Reindeer and Arctic Mouse-ear Chickweed

• Great tit and Caterpillar biomass

Reindeer and Arctic Mouse-ear Chickweed

• The northward migration of reindeer is synchronized with the growth of Arctic mouse-eared chickweed

• The growth of arctic mouse-eared chickweed is primarily determined by an early increase in temperature.

• The migration of reindeer is primarily determined by photoperiod. They begin to move North as the days begin to lengthen in early Spring.

• The arctic mouse-eared chickweed is a plant that completes its life cycle very quickly during the summer months

• The growth of arctic mouse-eared chickweed is starting earlier due to increased temperatures

• This reduces the availability of arctic mouse-eared chickweed as a food source for the migrating reindeer when they arrive. (Because they will be close to dead by then)

Great tit and caterpillar biomass

• The hatching of the great tit offspring is synchronized with the abundance of caterpillars in Spring.

• Caterpillars are an important food source for the birds and their offspring

• Photoperiods are the primary trigger for egg laying of great tits

• Increasing temperatures is the trigger for the growth and development of caterpillars

• the peak biomass of caterpillars is occurring earlier in the year, due to global warming

• The offspring of great tits are hatching after the peak caterpillar biomass, so there is a shortage of food for the offspring.

• The number and mass of offspring produced by great tits has decreased as a consequence of the earlier peak biomass of caterpillars.

Spruce Bark Beetle

Spruce Bark Beetle feed on Spruce trees

• The normal life cycle of Spruce Bark Beetles takes two years

• However, due to warmer summer temperatures, Spruce Bark Beetles are completing their life cycle in a year

• This contributes to an increase in spruce bark beetle populations due to reproducing more frequently, and the death of many spruce trees.

Evolution of Tawny owls

• Tawny owls can have grey plumage or brown plumage.

Climate change is acting as a selective pressure on the colour of tawny owls.

• Selection pressures: Decreasing snow cover due to increasing temperatures as a result of climate change.

• Genetic variation: There is genetic variation within the tawny owl population. Tawny owls can have brown plumage or grey plumage. Sources of genetic variation include mutations, crossing over during meiosis and random mating.

• Intraspecific competition: Tawny owls produce more offspring than the environment can support. The owls compete for resources and avoid predators.

• Favourable adaptations: Brown tawny owls are more likely to survive milder winters, as they are better camouflaged when there is no snow on the ground.

• Survive and reproduce: The brown tawny owls are more likely to survive and reproduce than the grey owls.

• Genetic inheritance: The allele for the favourable trait of brown is more likely to be passed to the next generation of owls.

• Natural selection: The frequency of the allele for brown plumage increases in the tawny owl population over time. This is an example of evolution by natural selection.

The frequency of brown tawny owls is increasing over time.

Biodiversity

Biodiversity

Is the variety of life in all of its forms

The 3 strands to Biodiversity

• Ecosystem diversity: is the variety of ecosystems found in an area or on earth

• Species diversity: is the number and relative abundance of species found within an ecosystem

• Genetic diversity: is variety of genes and alleles present in a species (Species with high genetic diversity are more likely to survive changes to the environment through the process of natural selection.)

Estimation of the number of species found on earth

• Around 1.2 million species have been discovered

• However, scientists estimate that there are around 8.7 million species in total

• Scientists predict that there were more species but they likely became extinct

Mass extinction

• There have been at least five mass extinctions

• Mass extinction = loss of biodiversity

• The disappearance of a large number of species (about 75% of earth’s species) over a relatively short period of geological time

Anthropogenic species extinction

is the loss of species due to human activities.

• Many scientists believe that humans are causing the 6th mass extinction event

Ex)

• habitat destruction

• climate change

• pollution

• over-exploitation (over-hunting)

• invasive species

Taxonomy

Is the study of names

Lumpers Vs Splitters

Lumpers: scientists who tend to have fewer distinct groupings.

• Focus on similarities between groups of organisms

Splitters: scientists who recognize more different species in a taxonomic group than scientists who are ‘lumpers’

• Focus on differences between groups of organisms

The Giant Moa

• Lived on the North island of New Zealand until 500 years ago

• They had few predators before the arrival of humans

• The Maori people hunted the bird for food, clothing and Jewelry.

• They were over-exploited, as hunting killed far more birds than were replaced through reproduction

Caribbean Seal monk

• They became extinct in 2008

• They were overhunted by humans for clothing, meat and Blubber (fat=oil=use oil for light)

• They couldn’t replenish themselves.

Ecosystem loss

• one of the biggest causes of biodiversity loss is the destruction of habitats and ecosystems due to human activity

Mixed Dipterocarp Forests of Southeast Asia

• Are tropical rain forests with many species of dipterocarp trees.

• They are some of the most biodiverse ecosystems on our planet

Ecosystem loss of mixed Dipterocarp forests

Human activities are the cause of loss of rain forests of Borneo.

Human activities include:

• Deforestation for wood

• Agriculture

• Mining

• Climate change

• Hunting/poaching

Ecosystem loss of mixed Dipterocarp forests: Deforestation for wood

The hardwood timbers of the rain forests are valued and are sold for profit

Ecosystem loss of mixed Dipterocarp forests: Algriculture

Deforestation is caused by the development of palm oil plantations

Ecosystem loss of mixed Dipterocarp forests: Mining

The rainforests are rich in coal, metals and diamonds. Excavation for mining can directly destroy the rainforests. 

Ecosystem loss of mixed Dipterocarp forests: Climate change

Human activities are contributing to climate change. Climate change can result in change in rainfall patterns, floods and droughts which impact the biodiversity of organisms.

Ecosystem loss of mixed Dipterocarp forests: Hunting/poaching

Animals are hunted for meat, skin and medical practices and to be sold as exotic pets

Loss of ecosystem: Mangroves

Human activities are the cause of loss of mangroves in Florida.

• Coastal infrastructure and Tourism: Mangrove forests have been cleared for resorts and cities= loss of mangroves

• Agriculture: Farms from the mangroves release fertilizers and pesticides which harms plant and animal life.

• Fishing and Aquaculture: Over fishing of vulnerable species removes links in food chains within the ecosystem. Fish farming releases excessive nutrients into the mangroves which could lead to eutrophication and algae blooms.

• Climate change:sea levels rise as a result of climate change which is a threat to the mangroves, as many tree species are unable to tolerate more salt water from higher tides

Evidence for biodiversity crisis

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) is an independent intergovernmental body established in 2012, which provides policy makers with assessments of data collected on the biodiversity of our planet.

• It is important that the data collected is reliable

• The surveys need to be repeated to determine if there is a change in the biodiversity of ecosystem over time

• IPBES said “Human actions threaten more species with global extinction now than ever before.”

Biodiversity (Richness and eveness)

Biodiverse ecosystems have a richness and evenness of organisms.

• Richness: number of different species

• Eveness: relative population of each species (how close the populations numbers are to each other)

Biodiverse ecosystems should have a wide variety of different species, all of which have relatively large populations.

Simpson’s biodiversity index

D= N(N-1)/ E n(n-1)

D= Diversity

N= Total number of organisms

n= number of organisms in a species

Measures: The biodiversity

High Simpson’s index = greater biodiversity, suggests a stable site with many different niches (high richness and eveness) → Usually a climax community

High Simpson’s index Vs Low Simpson’s index

• High index value: greater biodiversity, suggests a stable site with many different niches (high richness and eveness) → Usually a climax community

• A low index value suggests a site with few potential niches where only a few species dominate (low richness and evenness)

Citizen scientists

Professional scientists studying biodiversity require as much data as possible

• Citizens collect and share data with professional scientists

Pros and cons of citizen scientists

Pro:

• Increases the quantity of data collected

• Cost effective, as citizen scientists are volunteers

• Increased public engagement in conservation (and science)

Con:

• Data quality: the data collected by volunteers may be of varying quality

• Bias of volunteers: volunteers may have personal biases on where they collect data

Causes of biodiversity crisis: Human population growth (6)

The growing human population is the reason for biodiversity loss around the world

• Overexploitation of resources

• Urbanization

• Deforestation

• Algriculture

• Pollution:

• Invasive species

Causes of biodiversity crisis: Overexploitation of resources

Over-exploitation is the unsustainable use of resources, when resources are harvested faster than they can be replenished.

• It disrupts food webs which decreases biodiversity

Causes of biodiversity crisis: Urbanization

Is the movement of people to cities and towns which leads to the loss of ecosystem and biodiversity

Causes of biodiversity crisis: Deforestation

Happens due to the demand for wood, agriculture and land

• Clearing the Earth’s forests destroys ecosystems which reduces biodiversity.

Causes of biodiversity crisis: Algriculture

• It displaces natural ecosystems, decreasing biodiversity

• Farm wastes fertilizers and pesticides enter natural ecosystems, distrupting food webs and biodiversity.

Causes of biodiversity crisis: Pollution

Is the introduction of harmful substances into the environment.

• Many human pollution harms the organisms that live there, causing a decrease in biodiversity

Causes of biodiversity crisis: Invasive speices

Introduced species become invasive when they harm the native ecosystem

• Invasive species disrupt food webs resulting in the loss of biodiversity.

• Global transport has increased the risks of invasive species, pests and diseases entering ecosystems for the first time.

• Invasive species, pests and diseases can interfere with food webs in ecosystems, resulting in a decrease in biodiversity.

Conservation of biodiversity

focuses on protecting natural ecosystems from harm, including preventing the extinction of species.