aice environmental: topic 2

Define the terms bias and prediction.

Bias: When a scientist knowingly or unknowingly incorporates, systematic errors into sampling or testing by selecting or encouraging one outcome over another

Prediction: A statement of the expected results of an experiment if the hypothesis is true.

Compare the meaning of independent and dependent variables

Independent: What is being manipulated, the Cause of a behavior or effect

Dependent: what occurs due to the manipulation of the IV

Describe the main considerations when testing a hypothesis.

• should be a statement, not a question

• must include a cause and effect relationship, a short explanation for an observation that can be tested through an experiment

Explain what is required for a hypothesis to become a scientific theory

The hypothesis must be heavily supported by scientific evidence

ex: carbon emissions into the atmosphere result in the increased ability of the atmosphere to retain heat. This is no longer a hypothesis; it is a theory.

Define the term climate change.

a significant and lasting change in the distribution of global weather patterns over time scales that range from decades to millions of years.

Outline the difficulties associated with the usage of historical climate chage data.

The collection began as early as 1880, which is useful, however:

• Considerations of what equipment was used, when exactly it was collected, and even the historical context of the collection time.

• The data must be analysed, reassessed, and even collected again to gain accurate information

• There’s a limited amount of historical data available

How is climate change measured and data collected?

Ice Cores:

• The weight of the snow compresses the previous layers of snow, eventually forming deep ice sheets, which trap air bubbles in the ice. Those bubbles preserve information about the atmosphere at the time they formed, depositing climate information from that time onto the ice sheet, such as the air's gaseous composition and other atmospheric pollutants.

Technology:

• Analyzing information in sediments and tree rings has also made it easier to determine changes to the climate in the past.

• More recently, weather stations and precise weather equipment have resulted in reliable global data, while satellites can also track many different types of weather data, for example: temperature, precipitation, ocean temperatures, greenhouse gas levels

Why is bias so important when analyzing scientific data?

Bias reports or analyzation of data creates false reporting of climate change statistics; this can result in doubts about the reality of climate change and its effects

Briefly describe the benefits and limitations of climate models.

Benefits:

• Can be used to understand the possible changes in future cimate trends, and analyze past trends

Limitations:

• Uncertain because some processes in the climate system occur on such a small scale, or are so complex that data is not available to reproduce them in the models.

Outline the differences between primary and secondary data.

Primary data is collected by oneself suring field work, or during an experiment/observation

• Think primary = first person, personal data

Secondary data is data that was once primary, but once it has been used by another researcher, it becomes secondary.

• Think Secondary = second person usage

Define random sampling.

Sample points are selected using random numbers. These can be generated using a computer system or by creating a grid pattern of the study area.

Every point has an equal chance of being chosen

Define systematic sampling.

When a regular pattern is used to identify sample points,

• Ex. asking every third house on the left-hand side of the street to answer a questionnaire, or sampling every fifth square metre on a field grid pattern

List the necessary inclusions when collecting data from any sample.

• The minimum size that will give meaningful results is 100

• while the maximum sample size is 10% of the population, as long as this number does not exceed 1000.

  • ex. If the population is 20,000, 10% = 2000, so the data included must only be for 1000 individuals

Outline the main sampling techniques. (State and give brief description.)

Point sampling: selecting a number of points within an area (either randomly or systematically) and determining how many of those points hit a specific plant species.

Line sampling: data is collected along a straight line, and, for example, every plant that is touching the line is noted down

Area or quadrant: Data is collected within a 4-sided quadrat of a pre-determined size. Data can then be used to determine the frequency of each species throughout the whole sample area

Define ‘Pitfall trap’ and outline its benefits and limitations.

Def: used to sample populations of insects that are active on the ground.

• This trap usually consists of a cup or beaker that is buried so that the lip of the container is level with the surface of the ground. The insects fall into the trap and can be identified when the trap is checked

Limitations:

• Predatory insects may eat other insects in the trap, so often alcohol or another substance is put into the trap to kill the insects.

• Identifying the insects requires training and skill.

• It takes time to visit the sites, the amount of sites included in a sample site must be limited.

• If left for too long, the trap can fill with water, so insects are killed or washed away.

• The traps can only catch small insects, and flying insects could escape.

• Urban areas do not lend themselves to this type of sampling, as their surfaces tend to be hard, and containers need to be sunk into the ground.

Benefits:

• Traps are easy and inexpensive to set up.

• Traps can be left for long periods of time to increase the chance of catching samples

Define ‘Sweep nets’ and outline its benefits and limitations.

Def: Sweep nets are nets that are mounted on a pole. They are used to collect insects and other invertebrates from long grass. The net can either be raised above the plants and moved in a figure of eight motion, or kept in the vegetation and swung in a pendulum motion

Benefits:

• Heavy vegetation does not lend itself to this type of sampling.

• Not all insects are equally ‘catchable’, so the sample may not represent all

species present.

• Time-consuming and could damage plants.

Limitations:

• This method is inexpensive and easy to use, and does not require a lot of time or skill to complete. Volunteers can assist in the collection of samples

Define ‘Beating tray’ and outline its benefits and limitations.

Def: A beating tray consists of a light-coloured cloth (Figure 2.25) that is stretched across a square or rectangular frame. The frame is then held underneath a tree branch or a shrub, and the foliage is shaken. The insects that fall from the branches land on the cloth and can be examined and identified.

Benefits:

• The method is relatively easy to use.

• A representative sample can be obtained in a short period of time.

Limitations:

• Flying insects may fly off as soon as they fall onto the tray.

• Plants can be damaged.

• Time of day can influence the number and type of species captured.

Define ‘Kick Sampling’ and outline its benefits and limitations.

Def: used to sample invertebrates living on the bed of a river or stream. The sweep net is placed downstream of the point of sampling, with the water flowing into it. The researcher kicks the substrate of the riverbed for a measured period of time in each sample, and the dislodged organisms are collected in the net for identification later

Benefits:

• Quick to carry out and inexpensive

Limitations:

• Small species may be missed if the net size is too large.

• Species that are stuck to rocks will be missed.

• This method is also difficult to carry out in very silty or shallow waters.

Define ‘Light trap’ and outline its benefits and limitations.

Def: Light traps attract certain insects. The source of light can include fluorescent lamps and UV lights. These traps are widely used to collect data on nocturnal moths

Benefits:

• Light traps make the sampling of nocturnal insects easier.

• Light traps can also be used in marine environments to complement sampling for plankton using tow nets or for collecting organisms that may avoid tow. This method of sampling is helpful for ease of identification and collection.

Limitations:

• Night-time temperatures and humidity may limit the abundance and types of species caught.

• Some insects are attracted by light at long range but repelled at short range, so their species and numbers may not be caught in the sample. To solve this problem, some light traps have a large base to catch insects.

Define ‘Capture-mark-recapture’ and outline its benefits and limitations.

Def: used to estimate the size of a population where it is not practical to catch all the individuals within it. This is a live trap technique, where the individuals are trapped and then marked harmlessly. The investigator then records information about them before releasing them back into the population where they were trapped. When the area is resampled, those individuals that have previously been caught are easy to identify, and their recapture is recorded along with all the individuals captured for the first time. For larger animals and even insects, marking using tags may be used to identify the sampled organisms later

Benefits:

• Harm to the individuals can be kept to a minimum.

• This type of sampling can be carried out in remote locations and the exactnsample point can be revisited at later dates.

Limitations:

• It is possible that the trapping or marking of an individual lowers its chance of survival.

• The marks may not be easy to see the next time the individual is trapped.

• An individual trapped once may have a lower chance of being trapped again through learned behaviour.

• Live trapping is used, so traps need to be checked regularly to ensure individuals come to no harm.

Define ‘Turbidity’ and outline its benefits and limitations.

Def: the cloudiness or haziness of water due to sediments. Higher levels of turbidity have many negative impacts on aquatic life (pollution blocks sunlight from aquatic plants, limiting photosynthesis). Turbidity is measured by the amount of light scattered by the material in the water when light is shone onto the sample.

Benefits:

• It is easy to make quick visual comparisons between sites.

• It is easy to make comparisons at a site over time.

Limitations:

• Turbidity is measured using a simple visual assessment. However, this is susceptible to researcher bias. Equipment is available to give precise readings to avoid this problem.

Define big data.

extremely large sets of data that are collected using technology. This data is analysed using computers to reveal patterns, trends, and associations.

What are the limitations of big data?

• The volume of data is often so large that it can be difficult to determine what the data indicates

• The need for large, complex computer systems, with storage banks and speeds that can cope with the volume of information; these are very complex mechanisms that are hard to install and expensive.

What are geospatial systems, and what are they used for?

Geographic information systems (GIS) are designed to capture, store, analyse, and manage geographic data. This tool allows users to create interactive searches, analyse geographic information, edit data, and present results.

What are satellite sensors used for?

uses satellite information to track changes on Earth’s surface or in the atmosphere; many applications focus on long term changes like;

• changes to vegetation/forest cover

• sea-level rises

• carbon dioxide and temperature changes in the atmosphere, oceans, and on land

• land and sea ice monitoring.

What is radio tracking, and what is it used for?

A technology used to collect information about an animal through radio signals transmitted from a device attached to the animal. Radio tracking systems use radio frequencies to ensure that individual animals can be identified and tracked.

What is computer modeling used for?

uses computer programs to analyse data and predict outcomes through mathematical analysis. Modelling allows for an integrated environmental assessment, which is the assessment of an environmental question using a wide range of studies across disciplines that have a common environmental link

What is crowd sourcing, and what is it used for?

The practice of engaging a group of people, or ‘crowd’, to collect data.

Crowdsourcing collects information from scientists and the population in a region about their observations, changes they are experiencing, and how they have managed to cope with the changes. This data can identify changes occurring in the environment, and can be used to solve the problem.