Lab 1 Land Use Change
(30 mins)
Lab 1 will make use of Google Earth. If you haven't used the program before, consider spending time
at: https://support.google.com/earth/topic/22361?guide=22358 (link is external)
Once you feel you are ready, download the Deforestation file from the link below.
Deforestation
Note: the Deforestation file above is a Google Earth file. To open it make sure you have:
1) Downloaded Google Earth (http://www.google.com/earth/ (link is external))
2) Double click on the 'deforestation' link above and it will open automatically in Google Earth
Next, answer the questions in Part 1.
Part 1. Global Deforestation
For all countries in North and South America (including the Caribbean countries), observing all different
layers of the deforestation database, answer the following questions:
1.
In what country is the largest total percentage loss of natural forest (hint, the large number in red)?
2.
What is the percentage lost in the country in Question 1?
3.
In what country is the largest total gain of natural forest?
4.
What is the percentage gained in the country in Question 3?
For all countries in Asia (including the Middle East and the East Indies see map below--not including
Africa or Australia), observing all different layers of the deforestation database, answer the following
questions:
5.
In what country is the largest total percentage loss of natural forest?
Afghanistan
6.
What is the percentage lost in Q5?
7.
In what country is the largest total percentage gain of natural forest (Egypt is not in Asia)?
8
What is the percentage gained in Q7?
Part 2. Land use in Africa
Anthromes are the globally significant ecological patterns created by sustained interactions between
humans and ecosystems, including urban, cropland, rangeland and woodland anthromes. They provide a
great basis for studying the impacts of humans on land use patterns. Here we will study the distribution of
anthromes in 1900 AD and 2000 AD maps and summarize the changes.
First open the two google map anthrome maps for 1900 and 2000 in different windows.
Anthrome map for 1900 (link is external)
Anthrome map for 2000 (link is external)
You might also want to open google maps in a separate window to help you find locations. Legend for
land use is given below maps.
9. Focus on the land use changes in the Democratic Republic of the Congo between 1900 and 2000 AD.
Is the following statement true or false? Between 1900 and 2000, there has been a large increase in
residential woodlands in the Democratic Republic of the Congo.
10. Next look at the population changes in Nigeria between 1900 and 2000 AD.
Is the following statement true or false? The amount of residential rangelands in Nigeria increased
between 1900 and 2000 AD.
11. Now focus on the complex land use changes in Ethiopia. Focus in particular on the changes in cropland
between 1900 and 2000 AD.
Is the following statement true or false? The number of pastoral villages in Ethiopia decreased between
1900 and 2000 AD.
12. Next look at the land use changes which occurred in the region around Johannesburg in South Africa.
Is the following statement true or false? The amount of dense settlements around Johannesburg
increased between 1900 and 2000 AD.
13. Finally, look at the Sahara desert in North Africa and see how land use has changed there and in its
immediate surroundings. What does this tell you about the potential for this land to sustain population in
the future?
Hint: focus on the changes that occur in the Sudan and in Mauritania
Is the following statement true or false? The amount of barren, inhabited land in the Sahara desert
decreased between 1900 and 2000 AD. If this trend continues, this land will be able to sustain a much
smaller population in the future.
14. So looking at Africa as a whole, what are the main changes in land use over the last century?
Lab 2 Simple Population Growth
(30 mins)
To begin with, let’s try to understand a few basic things about population growth by exploring a very
simple model of the global population. The model looks like this:
Population starts out with 7 billion people; it increases due to births and decreases due to deaths — what
could be simpler? The birth percent is a constant and gets multiplied by the population to give the number
of people born each year; likewise, the death rate is also constant and is multiplied by the population to
give the number of people who die each year. Log Population is just a converter that gives the logarithm of
the population, which is sometimes a useful thing to look at when studying population growth (remember
that log(10) =1, log(100)=2, log(1000)=3, etc.). Sometimes population growth follows an exponential
curve, and the log of an exponential curve is a straight line.
The initial birth percent at present is about 1.91% per year, while the death percent is about 0.88%, so the
net growth rate is 1.03% per year — more people are born each year than die each year and thus our
population grows.
Let’s do a couple of experiments with this model to get a better feel for population growth.
1. Run the Global Population Model (link is external) and observe what happens. Note that the Population
itself is an exponential curve (slope keeps getting steeper and steeper), while the log of the population is a
straight line that could be extrapolated out into the future to predict the population. From the model, what is
the population in the year 2200? Remember, you can click and hold your cursor on the graph to display the
values of the data that you are clicking on.
Note: write your answer as a full number not in shorthand form. The the terminology e+# just means you
add that number of zeros to the initial number. For example:
3e+3 = 3000
7e+6 = 7000000
2. Look on graph 3 and describe the difference between births and deaths as time goes on.
3. Now make the birth percent .01 (1%) and the death percent .02 (2%) and observe what happens. What is
the population by the year 2200?
Population and Food
Your answer to question 1 above should strike you as absurd — the Earth surely cannot support that many
people. This means that there are some natural constraints on the size of the population, and one of those
constraints is food. But another could be something like diseases that become much more effective as the
population becomes very crowded. Another constraint might be pollution, as represented in the model
diagram below:
So we turn to some models where food provides a constraint on population growth — just as Malthus
suggested long before the age of computers. This model is also pretty simple, but it will allow us to explore
the possible consequences of the future of food production as predicted by the Food and Agriculture
Organization of the United Nations. The FAO notes that in recent times, global food production has
increased at an annual rate of about 2% per year, but this rate of increase has been declining over time and
they expect it to continue that trend in the future. The reason for this is that as we have increased
agricultural yields from the land, we have approached a sort of maximum value that is possible and as we
approach that limit, it gets harder and harder to make the same gains in food production that we have
obtained in the past.
Here is what the model looks like:
In this model, the amount of food produced each year determines the amount of food per capita, and that
affects the life expectancy, which in turn affects the death rate. Total Food represents the food produced
each year, and it assumed that all of this is consumed that year; it increases following a food production
growth rate that is essentially the percent per year by which our food production increases. This growth
rate, as mentioned above, declines according to a parameter called the production growth decline. The
model also includes waste — it turns out that at present, almost 30% of the food we produce is wasted due
to the imperfect distribution of the food to places where it is needed. The model is initially set up with a
production growth decline factor of 2% per year.
This model also includes something that will decrease the global birth percent per year, following the best
estimates of demographers — this will limit the rate at which the population increases.
4. Run the Population Growth Limited by Food Production Model (link is external)with all of the
parameters in their initial states (i.e., don’t change anything) and observe what happens. The population
levels off at about 25 billion by the year 2400, and it gives us something close to the expected 9 billion by
the middle of this century. This leveling off, or approach to steady state means that the birth and death
percents must be just about equal, but at the beginning, the birth percent is certainly higher than the death
percent since the population increases. The question here is: How does the food production history
contribute to the leveling off of the population? Study the Total Food reservoir, the food per capita, the life
expectancy, and the death percent as you search for an answer.
5. What if we eliminate waste? Change the waste value from 0.3 to 0.0 and run the model, comparing the
results to the initial model with waste set at 0.3.
6. Restore all the parameters to their beginning values, and then change the production growth decline from
0.02 (this is 2%) to 0.0. This is like saying that we will somehow be able to continue our increasing rate of
food production indefinitely — a very optimistic outlook. Run the model and describe what happens in
terms of the ending population, the general form of the population curve, and the food per capita.
7. Next, change the production growth decline from 0.02 to 0.04, which is like saying that our ability to
increase food production will diminish even faster than the FAO predicts. Run the model and describe what
happens in terms of the ending population, the general form of the population curve, and the food per
capita.