Unit A Lesson A7 Ecosystem Research
Completion requirements
Lesson A7: Ecosystem Research
Video Lesson
Making effective decisions about how to manage ecosystems requires that appropriate data must be collected. Watch this video to learn about ecosystem sampling and study.
Lesson A7: Ecosystem Research
Alberta’s Disappearing Caribou
A healthy ecosystem is a balanced system. Relationships between organisms have important roles in maintaining balance. Human activities can alter the balance of an ecosystem in unexpected ways, and the resulting effects on ecosystems can be difficult to predict. Ecologists use several methods to monitor ecosystems and species at risk. An example of unintended consequences is the decline of Alberta’s woodland caribou.
Industrial development is changing the landscape of northern Alberta. This forested region is home to many species of wildlife. Among them is the woodland caribou. Is industrial development affecting this species? How do we know? To understand changes in the caribou population, the group must be monitored.
A healthy ecosystem is a balanced system. Relationships between organisms have important roles in maintaining balance. Human activities can alter the balance of an ecosystem in unexpected ways, and the resulting effects on ecosystems can be difficult to predict. Ecologists use several methods to monitor ecosystems and species at risk. An example of unintended consequences is the decline of Alberta’s woodland caribou.
Industrial development is changing the landscape of northern Alberta. This forested region is home to many species of wildlife. Among them is the woodland caribou. Is industrial development affecting this species? How do we know? To understand changes in the caribou population, the group must be monitored.
Reading and Materials for This Lesson
Science in Action 7
Materials:
Science in Action 7
Reading: Page 51
Materials:
medium-sized bowl, dried beans, paper cup, a marker pen, paper and pencil, ruler
Figure A.3.7.1 – A caribou stag stands majestically in a snowstorm.
Figure A.3.7.2 – Caribou are difficult prey for wolves.
Figure A.3.7.3 – A smaller white-tailed deer is an easier catch.
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Sampling Techniques for Ecosystems
Northern Alberta is vast. How can we monitor caribou over such a large area? We cannot count and follow every individual. The first step in monitoring this species is to take samples. Watch this video to see how various sampling methods can used for different populations. Plants, fish, and wild animal populations can be estimated using sampling techniques.
Northern Alberta is vast. How can we monitor caribou over such a large area? We cannot count and follow every individual. The first step in monitoring this species is to take samples. Watch this video to see how various sampling methods can used for different populations. Plants, fish, and wild animal populations can be estimated using sampling techniques.
Sampling Allows for Accurate Estimates
You saw in the video that you can use a square hoop to estimate the number of plants in an area. You count every plant inside the hoop, and then you throw the hoop down again and count. This way, you can count a few plants to get an estimate of the total plants in an area. Caribou, on the other hand, are large animals that cover vast territories. They are always on the move. To sample caribou and other mobile animals, scientists often do aerial surveys. By flying back and forth over sample areas, they can estimate how many individuals live in a large area. By repeating these surveys over time, they obtain a reasonably accurate summary of how the caribou population is changing.
You saw in the video that you can use a square hoop to estimate the number of plants in an area. You count every plant inside the hoop, and then you throw the hoop down again and count. This way, you can count a few plants to get an estimate of the total plants in an area. Caribou, on the other hand, are large animals that cover vast territories. They are always on the move. To sample caribou and other mobile animals, scientists often do aerial surveys. By flying back and forth over sample areas, they can estimate how many individuals live in a large area. By repeating these surveys over time, they obtain a reasonably accurate summary of how the caribou population is changing.
Scientists surveyed caribou, wolves, and white-tailed deer over several years. They were surprised to find how interconnected caribou, wolves, and white-tailed deer are. What affects one species affects the others.
The story of Alberta’s caribou decline is a story of complex species interrelationships. It begins with human activity. The scientists found that deer populations increased around areas of recent industrial activity. Here, large areas of forest were cleared recently. Those areas now supported grass., which are plants that white-tailed deer prefer. Easier access to food meant the deer population increased over time. The wolf population increased, too, because they had more prey to eat.
Caribou tend to live in the northernmost reaches of Alberta. Normally, wolves find them difficult prey because caribou are larger than deer, and they can walk through very deep snow that wolves find difficult. These factors maintained a sustainable balance between caribou and wolf populations. Industrial development changed this balanced picture.
The story of Alberta’s caribou decline is a story of complex species interrelationships. It begins with human activity. The scientists found that deer populations increased around areas of recent industrial activity. Here, large areas of forest were cleared recently. Those areas now supported grass., which are plants that white-tailed deer prefer. Easier access to food meant the deer population increased over time. The wolf population increased, too, because they had more prey to eat.
Caribou tend to live in the northernmost reaches of Alberta. Normally, wolves find them difficult prey because caribou are larger than deer, and they can walk through very deep snow that wolves find difficult. These factors maintained a sustainable balance between caribou and wolf populations. Industrial development changed this balanced picture.
Figure A.3.7.4 – This quadrat is a 1-m square hoop.
Scientists were surprised to discover how sensitive caribou are to industrial development. Caribou require large areas of undisturbed forest. Small herds migrate seasonally and return to the same location every year to give birth. Roads, seismic lines,
pipelines, well sites, and cutblocks fragment their habitat. These structures interrupt their migratory routes. This put stress on the population.
Figure A.3.7.5 – Roads interfere with caribou migration routes.
The situation worsened for the caribou when wolves discovered industrial access roads. They now had easier routes to caribou. A greater wolf population, easier access to caribou, and habitat fragmentation mean that caribou now face a dire situation. The
caribou population is declining every year in Alberta to the extent that caribou is now considered a threatened species. At their current rate of decline, they will be extinct by 2100.
Caribou are very closely monitored now. Individuals are captured and collared with GPS collars. Every movement is tracked by satellite. Scientists want to learn all they can about the animals’ behaviour so they can help the species. Human activity has brought the woodland caribou to the brink of extinction. What can we do to reverse its fate? Monitoring is the first step.
Caribou are very closely monitored now. Individuals are captured and collared with GPS collars. Every movement is tracked by satellite. Scientists want to learn all they can about the animals’ behaviour so they can help the species. Human activity has brought the woodland caribou to the brink of extinction. What can we do to reverse its fate? Monitoring is the first step.
Lesson Activity
Wildlife Sampling
How do scientists gather data so they can make decisions regarding wildlife management? How do they know how big a population is when they cannot count every individual? In this activity, you will learn how to sample wildlife using the Capture-Recapture technique.
How do scientists gather data so they can make decisions regarding wildlife management? How do they know how big a population is when they cannot count every individual? In this activity, you will learn how to sample wildlife using the Capture-Recapture technique.
Capture-recapture, or mark and recapture, is a technique commonly used by ecologists to estimate the size of a population.
Materials:
Materials:
- medium-sized bowl
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dried white beans (about one or two cupfuls)
DO NOT COUNT THE BEANS! - small paper or plastic cup
- a marker pen
- paper and pencil
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calculator
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ruler
Download:
DOWNLOAD this document. It provides a space for you to write answers to questions later in this activity. It also provides a chart for you to record your observations.
Instructions:
DOWNLOAD this document. It provides a space for you to write answers to questions later in this activity. It also provides a chart for you to record your observations.
Instructions:
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Place all the beans in the bowl. Estimate how many beans are in the bowl. Do this by simply looking at the beans in the bowl and making your best guess. Write this number on a separate piece of paper (or use the space provided on the sheet you can download
in step 2) and label it ESTIMATE.
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Use a table such as the one shown below to record your data. You can draw the table yourself, or you can use the one you downloaded
(it is suitable for working on the computer or printing).
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Using the small cup, “capture” a sample of the beans from the bowl. Do this by dipping the small cup into the bowl, and scooping up beans. DO NOT use your hands or fingers to help push beans into the cup. “Capturing” only some of the beans is perfectly
normal.
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Mark each captured bean with a small X. Count them. This is the ORIGINAL captured amount. Record this number (label it “ORIGINAL”) alongside your ESTIMATE. The chart you downloaded in step 2 has a place at the top
for this.) The ORIGINAL and ESTIMATE numbers are important; you will use them for a math calculation later.
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Put the captured beans that are now marked with an X back in the bowl with the others. Toss and shake the bowl gently for about 20 seconds to mix all the beans thoroughly.
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Capture another sample of beans with the cup. Count all the beans in the cup and put this number in the Sample A block of the chart.
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DO NOT put the beans back in the bowl yet. First, count how many of your Sample A beans have small Xs on them. Put this number in the Recaptured A block of the table. Now, put your beans back in the bowl. Toss and shake the bowl gently
for about 20 seconds to mix all the beans thoroughly.
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Repeat steps 6 and 7 nine more times. You will have 10 sets of data (from A to J).
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Add the numbers in each
of the two columns (Sample and Recapture) to get a total for each column. Put the totals in the TOTAL line at the bottom of the table.
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Now it is time to use the numbers to do a calculation of how many beans (the POPULATION of beans) are in the bowl. This number will be represented by the letter P. This is the math we use to find P:
«math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mstyle mathsize=¨16px¨»«mrow»«mi»P«/mi»«mo»=«/mo»«mfrac»«mrow»«mi»Original«/mi»«mo»§#215;«/mo»«mi»Total«/mi»«mo»§#160;«/mo»«mi»Sample«/mi»«/mrow»«mrow»«mi»Total«/mi»«mo»§#160;«/mo»«mi»Recaptured«/mi»«/mrow»«/mfrac»«/mrow»«/mstyle»«/math»
If that looks complicated, don't worry! It is easy to put into a calculator. On your calculator, you would enter the ORIGINAL number, multiply by the TOTAL SAMPLE, then divide by the TOTAL RECAPTURED.
Writing this as a math equation, it would look like this:
P = ORIGINAL x TOTAL SAMPLE ÷ TOTAL RECAPTURED
For example, let's say you have an ORIGINAL capture number of 38. Your TOTAL SAMPLE might be 330. Your TOTAL RECAPTURED might be 60. So with these example numbers, 38 x 330 ÷ 60 = 209. So P, the calculated population of beans, is 209. Write this number down – note there is a spot to write this number in the bottom right corner of the table.
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Now count all the beans in the bowl. That is the ACTUAL number – the actual population of beans.
You will now have three very important numbers, each representing the number of beans in the bowl:
ESTIMATE = this is the guess you made at the beginning.
P (POPULATION) = this number you got with the Capture-Recapture activity (steps 1–10) and your calculator.
ACTUAL = this is the number you got in step 11 by actually counting all the beans.
After completing this activity, you might be asking the question; "Why did I guess, and go through all the trouble of doing Capture-Recapture and doing calculations, when I could have just counted all the beans in the first place?" That's a
very good question! What you must realize, is that for some populations, it would be impossible to count every single organism. For example, can you imagine how difficult it would be to capture, and then count, every single bee in a hive? It would
be extremely difficult, and even IF you could do it, it would take far too much time. In such cases, it is far better to use a Capture-Recapture technique.
Watch as a scientist describes how he is using Capture-Recapture to estimate the number of bees in a hive:
Watch as a scientist describes how he is using Capture-Recapture to estimate the number of bees in a hive:
Questions:
Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.
Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.
How close you get to the actual number number of beans with your estimate will depend on how good a guesser you are! ...and that is the problem with guessing! Sometimes, you may get it right, but often, you will be way off and get it very wrong. Estimating
can sometimes be useful, but guesses based on very little information often can produce very poor results, and we don’t want poor results when estimating populations in ecosystems.
Generally, the calculated number for the population P will be close to the actual number. It may not be if the sampling is performed incorrectly. But the mark-recapture technique used in this activity generally is quite reliable. Ecologists often use
it in situations counting a whole population of organisms is impossible.
This question depends on your opinion! Remember that using good tools and careful sampling almost always will produce much better results that just guessing. Often, scientists repeat their work several times to try to be sure they obtain reliable results.
If this activity did not work well for you, you might consider trying it again.
Watch More
How Many Snakes?
Sometimes, we can understand easily why people want to protect certain species. Animals such as the caribou are majestic. They symbolize Canada’s wilderness. Other endangered species are less attractive to many people. However, they have vital roles in their ecosystems. Each helps maintain the balance of an ecosystem. For example, several snake species are endangered and need to be protected. Watch this video to learn how snake populations are monitored using the capture-recapture technique.
Sometimes, we can understand easily why people want to protect certain species. Animals such as the caribou are majestic. They symbolize Canada’s wilderness. Other endangered species are less attractive to many people. However, they have vital roles in their ecosystems. Each helps maintain the balance of an ecosystem. For example, several snake species are endangered and need to be protected. Watch this video to learn how snake populations are monitored using the capture-recapture technique.
Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to guide your learning.
Unit A Lesson 7 Self-Check
Instructions
Complete the following 6 steps.
Don't skip steps – if you do them in order, you will confirm your
understanding of this lesson and create a study bank for the future.
- DOWNLOAD the self-check quiz by clicking here.
- ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.
- COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.
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REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct
any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.
- SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.
- CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!
Self-Check Time!
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Self-Check Quiz Answers
Click each of the suggested answers below, and carefully compare your answers to the suggested answers.
If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.
Knowing as much as possible about a population is important. This information can be used to help protect the population. Observing animals in their natural habitats over time is important. This is how scientists determine how the population
is doing in its ecosystem. Estimated population size, interactions with other organisms, and animal behaviours can indicate how well the population is doing. Monitoring can alert scientists to species that are at risk so that they can help
them recover. Population numbers are indicators of an ecosystem’s overall health.
The capture-recapture technique is very useful and it is widely used. However, several factors can affect its accuracy. When scientists capture and recapture, they make several assumptions about the population they wish to measure. If an assumption
is wrong, the accuracy of their population calculation can be reduced. Here is a list of possibilities they look for:
- If new individuals enter a population while it is being monitored, those changes can distort the calculation. For example, birds might migrate into or out of the bird sample area. Or, a population might increase due to births. Scientists assume that the number of individuals in the population does not change while they are being monitored.
- Scientists assume that all animals react the same way to the capture process, but sometimes they do not. For example, some racoons might be shy and avoid traps to tag them. Others might be friendly and allow themselves to be trapped multiple times. When this happens, the samples become less accurate because they are non-random.
- Scientists assume that released animals mix back into the population in a random way. To encourage random remixing, animals generally are given time to spread out before they are counted again. Marked animals might regroup away from the traps. This would mean the sampling is no longer random.
- Scientists assume that the population does not change naturally year to year. In some species, it does. Frog numbers, for example, go up and down naturally every year, depending on how wet each summer is. A dry summer means the population decreases, but this does not necessarily mean the population is in trouble.
- Scientists assume that animals do not lose their marks or tags. If some animals lose their marks, then the accuracy of the population calculation is reduced. The reality of life in the bush is that some might lose their tags!
Researchers want to have a baseline population count of the trout. Then, they can come back year after year, recount, and determine if the population is increasing, decreasing, or staying the same. They can use the trout population data to determine
if the river ecosystem is staying healthy.
Several factors are important.
- Scientists must use the same section of river every year to take their samples.
- They must sample at the same time every year. It would be best to take samples at the same time of day and under similar weather conditions. Scientists want the population sample to be as consistent as possible, year after year.
- They do not want to harm the fish when they catch and release them. If the fish are harmed, they might die.
- The fish might learn to avoid the fishing lures, so behaviour changes could make the sampling less random.
The collar should affect the caribou as little as possible and definitely not harm it. If the collar is too heavy or if it chafes the neck, it could put the caribou at even greater disadvantage in its bid to survive. Either the collaring process
or the collar might change the caribou’s natural behaviour.
Another consideration is how to get the collar device on (or off) the animal. Chasing the caribou by helicopter puts extreme stress on the animal. Usually, caribou are netted from the helicopter, which means they need not be sedated. The sedative would calm the animals, but it could have unknown health effects. Their eyes are covered during collaring to reduce stress. If animals had to be recaptured to change batteries on the collars, that process could add additional stress. The new GPS collars are programmed to send data for a specific period of time. Then, they are programmed to open and fall off. The collars can be recovered and reused. The caribou do not have to be recaptured.
Another consideration is how to get the collar device on (or off) the animal. Chasing the caribou by helicopter puts extreme stress on the animal. Usually, caribou are netted from the helicopter, which means they need not be sedated. The sedative would calm the animals, but it could have unknown health effects. Their eyes are covered during collaring to reduce stress. If animals had to be recaptured to change batteries on the collars, that process could add additional stress. The new GPS collars are programmed to send data for a specific period of time. Then, they are programmed to open and fall off. The collars can be recovered and reused. The caribou do not have to be recaptured.