Topic 5: On the Wild Side Flashcards
5.1) Ecosystem
All the organisms living in a particular area, known as the community, as well as all the non-living elements of the particular environment (e.g. climate, nutrients being cycles etc.)
5.1) Community
All of the populations of all the organisms living in a particular habitat at a particular time.
5.1) Population
All of the organisms of a particular species living in a particular habitat at a particular time.
Biotic Factors
Living factors such as: predators food availability, parasitism or disease, which control the numbers and distributions of organisms in a habitat.
Abiotic Factors
Non-living factors such as: light, oxygen or moisture levels, and temperature, which controll the numbers and distributions of organisms in a habitat.
5.3) The niche concept
Each species has a particular role in its habitat, called its ecological niche. This consists of its biotic and abiotic interactions with the environment. Species distribution and abundance within a habitat will depend on the number and type of ecological niches available within the habitat.
The niche concept states that only one ogranism can occupy each niche in a given habitat at a given time - if two or more species have a niche that overlaps, the best adapted will out-compete the others in surviving to reproduce.
CORE PRACTICAL 10) Ecology of a habitat
IV: Chosen abiotic factor (e.g. light intensity)
DV: Abundance of chosen species
CVs: Intervals on transect, size and type of quadrat used
Method:
1) Place transect down at a site with an obvious gradiant in an abiotic factor. Select a species that changes in abundance along the gradient.
2) Place quadrat at 1meter intervals along the transect.
3) Record the % cover for the chosen species. A square should only be counted if more that 1/2 of it is covered.
4) At each co-ordinate a measure of the IV should be taken. I.e use a photometer to measure light intensity at each coordinate.
5) Plot a graph of % cover against the chosen IV to investigate a correlation.
6) Carry out a statistical test on collected data
Risks assessment
Biohazard - allergies; soil; bacteria; contamination; wash hands after
Slippery surfaces; slip hazrad; wear appropriate footwear; don’t run
Succession
Succession is the process by which an ecosystem changes over time. The biotic conditions change as the abiotic conditions change.
Primary sucession
Occurs when an area previously devoid of life is first colonised by communities of organisms. This happens on land that’s been newly formed or exposed, e.g. by a volcanic eruption to form a new rock surface, or where sea level has dropped exposing a new area ofv land. There’s no soil or organic material to start with, e.g. just bare rock.
Secondary succession
This occurs with existing soil that is clear of vegetation. This may occur after an event such as a forest fire or where a forest has been cut down by humans.
Stages of succession
1) Seeds and spores are blown by the wind and begin to grow. The first species to colonise the area are called pioneer species.
2) Pioneer species, e.g. lichens and marram grass, are specially adapted to cope with the harsh conditions e.g. there’s no soil to retain water.
3) The pioneer species change the abiotic conditions - As pioneer species die, microorganisms decompose the dead organic material (humus). This forms a basic soil.
4) The basic soil retains water, making conditions less hostile for new organisms, like grass and small plants, with different adaptions to move in and grow.
5) When these organisms die and decompose more organic material is added to the soil making it deeper and richer in minerals.
6) Larger plants like shrubs can then start to grow.
7) Some species make change the environment so that it becomes less suitable for previous species and so they are outcompeted by new species.
8) As succession goes on biodiversity increases.
9) Climax community is reached - the ecosystem is supporting the largest and most complex community of organisms it can - it’s in a steady state.
Secondary succession happens in the same way but just begins at a later stage.
plagioclimax
When succession is stopped artificially, usually due to human activity e.g. lawnmowers prevent the growth of shrubs and trees in grassy fields.
Global warming
A term used to describe a gradual increase in the average temperature of the Earth’s atmosphere and surface over a significant period of time.
Climate Change
When the weather conditions in a region change significantly over a long period of time. Climate change can be caused by global warming.
Evidence for climate change
- Records of carbon dioxide levels
- Temperature records
- Pollen in peat bogs
-Dendrochronology
Records of carbon dioxide levels
- Atmospheric CO2 levels have fluctuated throughout earth’s history (due to events like volcanic erruptions), but recent increases have been faster + greater than ever. Together with the knowledge of CO2 as a greenhouse gas, there is strong evidence that CO2 released by human activities since the industrial rev. is contributing to increased global temps.
- CO2 levels can be measured by analysing the gas composition of bubbles in ancient ice cores. Ice is deposited as water freezes over time, so the deeper the ice, the older it is.
Temperature records
- Thermomenters can be used to measure air temperature, and therometer records from different places around the world over extended periods of time can be put together to show average global temperatures change over time.
- Av. global temp records since the mid-1800s show some temp fluctuations but an overall trend of increasing temp overtime. This time periods corresponds with the time during which humans have been burning fossil fuel thus increasing CO2 into the atmosphere.
Pollen in peat bogs
- under waterlogged and acidic conditions (which are poor for enzyme activity and therefore decomposition), partly decomposed dead plant metter accumulates, forming peat (the place where peat accumulates = a peat bog).
- Peat builds up in layers. Top layers = more recent, lower layers = older.
- Peat cores can be taken from a bog and the layer analysed to assess the pollen grains that have been perserved in the peat bogs.
- Because pollen grains are unique to each plant species, the plant species growing around the bog at dif. points in time can be indentified. Dif. plant species grow under dif. climactic conditions, thus we can use their presence to measure the climate of that time.
Dendrochronology
- The study of tree rings as the size of tree rings in affected by temperature.
- Most trees produce one ring in their trunks every year and the thickness of the ring depends on the climate when the ring was formed - when it’s warmer the rings are thicker ( because the conditions for growth are better).
- Scientists can take cores through tree trunks then date each ring by counting them back from when the core was taken. By looking at the thickness of the rings, they can see what the climate was like each year.
Sampling techniques
Frame Quadrats are normally 1m2 square frame divided into 100 squares. Each square represents 1% of the total area of the quadrat.
If an individual covers more than half of a square, it is counted as representing 1% of the quadrat.
Point quadrats is a horizontal bar on two legs with a series of holes at set intervals along its length. Pins are dropped through the wholes and every plant that each pin touches is recorded.
Quadrats are used to count the population size within a large area
Random sampling
Applied by dividing the area of interest into a grid and labelling the grid with coordinates. A random number generator provides a set of random coordinates. The quadrats can be placed using the coordinates.
Systematic sampling is a non-random sampling method where different areas within a habitat are sampled at regular intervals to avoid bias. It allows us to study of how species distributions change across different areas within a habitat.
Transects
A transect is a line across a habitat, usually placed using a tape measure. Transects are used when there is a change, or gradient, in abiotic conditions across the habitat and how this effects the abundance or distribution of a species across the environment (e.g. how abundance changes from open field to forest).
Line transect
A line transect records the species that makes contact with the tape measure at regular intervals along the transect.
Belt transect
A belt transect uses quadrats.
Quadrats are placed at regular intervals along the transect.
An abundance of different species in the quadrat can be measured by percentage cover or frequency.
5.13) What is meant by anthropogenic climate change and what causes it?
Anthropogenic climate change is the term forclimate change caused by human activities.
It is thought that increasing levels of greenhouse gases (CO2 and methane) are entering the atmosphere as a result of human activities, leading to the greenhouse effect and increased rates of atmospheric warming.
5.13) The greenhouse effect
- Short-wavelength UV radiation from the sun passes through the Earth’s atmosphere and is reflected from the Earth’s surface.
- The reflected rays are of a longer wavelength (infrared radiation (heat)). While some IR passes back through the atmosphere into space, some is absorbed by greenhouses gases, which re-emits heat in all directions so, trapping it in the Earth’s atmosphere.
- As a result the Earth’s atmosphere and the Earth’s surface become hotter.
5.13) Carbon dioxide
CO2 is released into the atmosphere by:
- fossil fuel combustion
- Damaging or destroying carbon sinks (trees (deforestation), soils(oil degredation), peatbogs (peat harvesting), the ocean (ocean warming)).
Atmospheric CO2 has fluctuated throughout history due to events like volcanic erruptions. But since the Industrail rev. in the 1700s (when fossil fuel combustion began) they have been on the rise. There’s a strong correlation between increasing CO2 level since the IR and increasing global temp, providing evidence for the role of human activities in gloabl warming.
5.13) Methane
Methane is produced naturally by some decomposing bacteria but levels have risen significantly in recent years due to human activties:
- released from the guts of ruminant mammals such as cattle. Intesive farming of animals has greatly increased their contribution to atmospheric methane.
- Landfill sites release methane when organic matter such as food waste decomposes.
- Extraction of fossil fuels from underground.
- Anearobic bacteria in waterlogged rice paddy fields
- Methane is trapped in ice, so as the Earth’s temp increases and Icy ground/glaciers begin to melt, natural stores of methane are released into the atmosphere.
5.14) How can existing data related to global warming be used?
- It is possible to use existing data relating to global warming tomake predictions about global temperaturesin the future
- Using data in this way is known asextrapolating from data. Extrapolated data can be used toproduce modelsthat show how the climate may change in the future
- Global warming predictions can be used to: planfor the future e.g. flood defences and Encourage people tochange their activitiese.g. burn less fossil fuels.
5.14 i) The Intergovernmental Panel on Climate Change (IPCC)
A group of climate scientists around the world that has used existing data toextrapolatehow global temperatures might change in the futureunderdifferent human activity scenarios producing projection graphs. e.g:
- If humans manage to immediately begin reducing fossil fuel use, global temperature change could be limited to around 1°C
- If humans do nothing to change their fossil fuel use, global temperature increase may exceed 4°C
The IPCC data can be added to other computer models on climate change to see how different parts of the world might be affected under the different scenarios
5.14 ii) limitations to models for climate change based on extrapolated data
- The IPCC has produced models based on several emissions scenarios, and wedo not know which of these scenarios is most likely or most accurate
- We do not know whetherfuture technologieswill be successful at removing greenhouse gases from the atmosphere.
- It is unknownexactly howatmospheric gas concentrations might affect global temperatures
- Globalclimate patterns are complex (they invlove a complex feedback system)and therefore predictions are difficult
- It is possible that a certaintipping pointin global temperatures could lead to a sudden acceleration in global warming e.g. permafrost melting may cause a sudden increase in atmospheric methane
- We don’t know exactly howfactors other than human activities (natural causes)may affect climate in the future e.g. a volcanic eruption could increase ash in the atmosphere, reflecting radiation back into space and cooling the earth
5.15) Effects of Climate change
Global warming can cause other types of climate change including:
1. Changing rainfall patterns This can affect the distribution of animals if they have to relocate due to flooding. The life cycles of organisms may be disturbed if their normal breeding sites are flooded or experiencing drought.
2. Changing seasonal cycles This can be problematic where organisms rely on each other for survival. (e.g. if caterpillars are hatching earlier in spring, hatching chicks miss the period when caterpillars are most abundant, and could starve.)
These changes will affect:
- The development of organisms (e.g. due to changes in food availability)
- The life-cycles of some animals (e.g. growth and reproduction is dependent on certain factors (i.e. temp and food availability), if these change so does the organisms ability to grow and reproduce).
- The distribution of species (If they aren’t adapted to changing conditions, they may have to relocate to areas with more suitable conditions, otherwise they may die out.) This increases interspecific competition.
Changing temps affect enzyme activities
5.16) What is the effect of temperature on enzyme activity and its impact on organisms?
An increase in temperature (due to global warming) will also affect enzyme activity. Initially, as temp increases the rate of reaction also increases. The rate of formation of enzyme-substrate complexes increase as the kinetic energy of molecules increases, leading to more frequent collisions. However, the rate of reaction decreases above the optimum temperature, as the enzyme molecules vibrate more, which breaks some of the bonds that hold the enzyme in shape. As a result, the shape of the active site changes, thus the enzymes become denatured.
Affects on organisms’ Life cycles, development, and distribution:
Enzymes controll organisms metabolic reactions.
- An increase in temp, means that metabolic reactions will speed up, so their rate of growth will increase. This also means they’ll develop and progress through their life-cycle faster.
- If the temp becomes too high for the organism, their metabolic reactions will slow down, so their rate of growth will decrease. This means they’ll progress through their life cycle slower.
- GW will also affect the distribution of species - all species exist where their ideal conditions for survival are (e.g temp). So when these conditions change, they will have to move to a new area where conditions are better. If they can’t move they may die out.
Measuring abiotic factors
Temp - thermometer
Rainfall - rain gauge
Humidity - hygrometer
O2 availably in aquatic habitats - oxygen sensor
Light intensity - Light meter
Ph of soil - A sample of soil is mixed with water and an indicator liquid that changes colour depending on the Ph (measured against a chart).
Moisture content - The mass of soil is measured before and after being dried out in an oven at 80-100dc (until it reaches a constant mass). The difference in mass as a % of the original mass of the soil in then calculated (this is the water content of the soil). Or use a moisture probe.
Topography
Relief (change in height of land) - take height readings using a GPS
Slope angle - clinometer
Aspect (direction of slope) - compass
5.20) Why is there controversy among scientific conclusions as to the degree to which humans are affecting climate change?
The scientific consensus reached on climate change may depend on who is reaching the conclusions.
For example:
- Sceintists working for an oil company may be more likely to say humans aren’t causing climate change because this would help keep their sales high
- Scientists working for a renewable energy company may be more likely to say that humans are cause climate change because this would increase their sales.
Ideas are validated and conclusions drawn via scientific conferences and publications in peer-review scientific journals, however conclusions scientists reach can be affected by the reliability of data, which is sometimes affected by bias.
5.20) There is contoversy over what actions should be taken to reduce climate change.
a) Suggest one group of people who might support increasing the use of biofuels to reduce global warming and one group who might oppose the increase of biofuel.
b) Suggest one group of people who might support increasing the use wind turbines to reduce global warming and one group who might oppose the increase of wind trubines.
Increasing the use of biofuels:
- Farmers might support this strategy as some governments fund the farming of crops for biofuels.
- Drivers might suppoert this strategy as biofuels are usually cheaper than oil-based fuels.
- Consumers might oppose this strategy as it requires farmland, which could cause food shortages.
- Conservationists might oppose this strategy as forests have been cleared to grow crops for biofuels.
Increasing the use of wind turbines:
- Companies that make wind turbine would support this strategy as their sales would increase.
- Environmentalists would suppoert this strategy as wt’s produce electricity without increasing atmopsheric co2 conc.
- Local comminities might oppose this strategy as some ppl think wt’s reun the landscape.
- Bird conservationists might oppose this strategy as many birds have been killed flying into wind turbines.
