Geography 102 Lab 1
Teaching Notes
N. Salant
LAB 1: ATMOSPHERIC ENERGY TRANSFER
Preparation
- Write name, email address (optional), lab section, lab time, and personal LAC hours
on board
- Set up overhead projector, check overhead pen
- Get overheads out of binder, including assignment questions and pictures of two
different sites
Introduction
- Pass out attendance sheet
- Ask students if they have questions from previous week regarding the introductory
material and the math review in their lab manuals
- Give brief outline of how lab will generally be conducted:
1. Review basic concepts of the week’s topic
2. Go through assignment together
3. Complete exercises in pairs or groups (and come check answers when
finished)
Main points
- Solar radiation is the main source of energy to the Earth
- Ask students: Why is energy important?
- Answer(s): Energy is essential for life; drives biological systems, weather
patterns, and climate
- This lab: We will learn the ways in which this energy is received and transformed
and the ways by which we describe it
1) Radiation budget
What is a budget?
= what goes in – what goes out
Examples
Money ($)
Income – Expenditure
Energy (Q*)
Q* = net radiation = incoming radiation – outgoing radiation
(Draw diagram)
Incoming
Outgoing
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Geography 102 Lab 1
Teaching Notes
N. Salant
There are two different kinds of incoming and outgoing radiation
K = shortwave radiation = radiation from the sun
L = longwave radiation = radiation from the earth or atmosphere
(Have them identify each kind on diagram, beginning with K↓)
If radiation is ‘bounced’ or reflected
If radiation is absorbed and re-emitted it becomes L↑
So where does L↓ come from? The atmosphere – clouds!
Radiation from the ground (K↑ or L↓) or
from the sun (K↓) absorbed by clouds and reemitted
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Geography 102 Lab 1
Teaching Notes
N. Salant
(How to compute net radiation)
A. Radiation balance equation
Q* = incoming – outgoing
Incoming =
Outgoing =
(Walk them through each term starting with K↓)
L↓
L↓
K↓
K↓
Putting them together
Q* =
If Q* is positive?
If Q* is negative?
(K↓
(Get them to identify each term)
+
L↓)
–
(K↑
Incoming > outgoing
Incoming < outgoing
+
L↑)


Warming
Cooling
Two things that determine the amount of K or L we have
1. Albedo
= proportion of radiation reflected by the surface (K) ~ ‘reflectivity’
α = K↑/K↓
light coloured surface = high albedo
(e.g. snow)
dark coloured surface = low albedo
(e.g. black pavement)
reflects most of the energy
absorbs most of the energy
So why does black pavement feel so hot in the summer?
2. Stefan-Boltzman Law
= amount of radiation emitted by a surface (or object) (L) is directly proportional
to the temperature of the surface (or object)
L = σ T4
σ = Stefan-Boltzmann constant = 5.67 x 10-8 W m-2 K-4
T = surface temperature, in degrees Kelvin (K = ºC +273.15)
(Make clear that the ‘K’ in the S-B constant is NOT shortwave radiation, it is a
unit – Kelvins – and the temperature used in the equation must be in Kelvins)
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Geography 102 Lab 1
Teaching Notes
N. Salant
Therefore, the warmer the surface, the more energy emitted
2) Energy balance
Q* = net radiation
= excess energy that can be partitioned into three different heat transfer mechanisms
QH = sensible heat flow to and from the atmosphere by conduction and convection
QE = latent heat transfer from the surface by evaporation, and to the surface by
condensation and reverse sublimation (vapor-to-solid change of state) requires water
QG = sensible heat flow to and from the ground by conduction
The sign (positive or negative) of the terms in the energy balance equation is important:
Positive = flow of energy is away from the surface
(heating the air or subsurface)
Negative = flow of energy is towards the surface
(heat comes from the subsurface or out of the air, or condensation occurs)
(Draw diagram to demonstrate. Most important is to remember what the ‘surface’ is – it is not
the ground, but rather the contact between the ground and the air)
- = towards
+ = away
SURFACE
- = towards
+ = away
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Geography 102 Lab 1
Exercises: Tips
N. Salant
3) Lab exercises
Question 1
Filling in Table 1.1
- Put up overhead of Table 1.1
- Write out radiation budget equation
- Go through example calculation using values in table for one of the times that has
all the values filled in– demonstrate that the radiation budget works
- Go through an example calculation for the Stefan-Boltzman law
Remember to first convert temperature to Kelvin (ºC plus 273.15)
Drawing figure
- Remind them to first read graphing guidelines in the lab manual (p. 5)
Most important is to USE PENCIL
- Suggest the following steps to constructing graph:
1. Choose scale for y-axis (radiation flux) and x-axis (time)
Look at the range for each axis
y-axis: 2 – 24 W/m2
x-axis: -22 – 800 W/m2
Count boxes on graph
Choose appropriate interval so that all boxes are used
y-axis: 4 boxes = 100 W/m2
x-axis: 1 box = 1 hour
2. Pick symbols for each term
Recommend they use the same symbols as used in Figure 1.1 (next page)
3. Plot values
Start plotting Q* to show them how
4. Connect values with smooth line
5. Label axes (with units)
Question 2
- Remind them that L↑ comes from the earth and L↓ comes from the atmosphere
- Recall Stefan-Boltzman law (relationship between L and temperature)
- Ask them to consider which is warmer (earth or atmosphere) and why?
Question 3
- Explain that uniform, low cloud cover can be considered like a thick blanket over
the surface
- Draw diagram
-
Suggest that they go through each term one-by-one, starting with K↓
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Geography 102 Lab 1
Exercises: Tips
N. Salant
Question 4
- Put up overhead of Figure 1.1
- Point out that these measurements were taken on a cloudless day in July
- Put up overheads of two sites – grassy park (the figure they constructed) and
residential site (Figure 1.1)
- Remind them that both were taken on cloudless day, but ask them to consider
what is different between the two sites
Season
Grassy park – September (autumn)
Residential site – July (summer)
Albedo
Grassy park – higher (dark grass)
Residential site – lower (light materials)
- To answer the question, tell them to go through each term, one-by-one, starting
with K↓, explain what graph values show and explain why using differences
noted above
Question 5
- Write out energy balance equation; simple calculation to determine values
Question 6
- Recall that QG is energy received and emitted by the ground, but remind them that
the ground is not the ‘surface’ (diagram on p. 103)
- Recall that a positive sign indicates flow away from the surface and a negative
sign indicates flow towards the surface
- 0400 is the middle of the night, 1200 is middle of the day
- Heat will flow from high temperatures to lower temperatures
Question 7
- Remind them that QE requires water and this site has green grass – what does
green grass require?
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Geography 102 Lab 2
Teaching Notes
N. Salant
LAB 2: ATMOSPHERIC PRESSURE, WIND AND CIRCULATION
Preparation
- Write name, email address (optional), lab section and lab time on board
- Set up overhead projector, check overhead pen
- Get overheads out of binder (lab exercises)
Introduction
- Pass out attendance sheet
- Ask students if they have questions from previous week
- Reminders regarding schedule: no labs during next 2 weeks; weather project
assigned in lecture this week; project data collection begins next week
- Reminder regarding LAC hours: come with questions on project write-up or any
previous labs, also to make up labs missed
1) Air pressure
= weight of the atmosphere
i.e. higher air pressure reflects a larger mass of air
Air will always move from areas of high pressure to areas of low pressure
 horizontal air movement = WIND
Barometers = instruments used to measure air pressure
Several different possible units of measurement:
mm Hg
millimeters mercury
in Hg
inches mercury
mb
millibars
kPa
kilopascals
Converting between units:
1 in Hg = 25.4 mm Hg = 33.9 mb = 3.39 kPa
- This conversion is provided in your book, would be provided on an exam
- We will review a technique for converting when we go through the assignment
2) Forces that create air movement (i.e. wind)
Three forces:
1. Pressure gradient force (PGF)
2. Coriolis force (Fc)
3. Frictional force (Ff)
The resultant sum of these 3
forces determines the magnitude
and direction of the wind
1. PGF
- Horizontal force
- Always goes from high to low pressure
= difference in pressure (i.e. pressure gradient)
horizontal distance
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Geography 102 Lab 2
Teaching Notes
N. Salant
2. Coriolis force
- Due to the Earth’s rotation
- Causes a deflection of the PGF
Northern hemisphere – deflection is to the right
Southern hemisphere – deflection is to the left
Provide visual or conceptual example
Visual example: Using the overhead projector (and have the students try the same thing with a piece of
paper), try drawing a straight line down the middle of the page while rotating the paper or the overhead to
the right; if you are careful to draw the line straight towards you while rotating the paper, the line will
become deflected to the left
or
Conceptual example: Imagine spinning to the right on a playground ‘roundabout’, then trying to throw a
ball to your friend across the roundabout. You throw the ball in a straight line, but because you and your
friend are spinning to the right, the ball appears to deflect to the left and misses your friend.
- The amount of defection depends on 2 things:
- Magnitude of the PGF force
- Amount of surface friction
Higher friction (e.g. mountains, cities): deflection from 0 – 45°
Lower friction (e.g. ocean surface): deflection increases to 90°
Geostrophic wind (e.g. upper atmospheric winds)
Essentially no friction (because no surface)
Maximum 90° deflection of PGF
3. Friction force
- Exerted by the ground (therefore only when there is surface friction)
- Acts in direction opposite to motion
e.g. imagine pushing a block of wood across grass versus ice
which surface exerts a stronger friction force against you?
How to draw these 3 forces and the resultant wind (step-by-step procedure)
1. Draw the PGF
- H to L pressure
- Perpendicular to isobars
- Length of arrow = magnitude of force
- Relative magnitude important only – don’t worry about length unless there are 2
diagrams to compare
PGF
1000 mb
PGF
980 mb
1000 mb
2
960 mb
Geography 102 Lab 2
Teaching Notes
N. Salant
2. Draw the wind vector (‘resultant’)
- In northern hemisphere, wind is deflected to the right
- If there is friction (assume high friction) deflection is 45°
PGF
Wind
- If there is little or no friction deflection is 90°
PGF
Wind
3. Draw the Coriolis force (Fc)
- Always 90° to the right of the wind vector
PGF
Fc
Wind
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Geography 102 Lab 2
Exercises: Tips
N. Salant
4. Draw the friction force Ff (ONLY if friction is present – see #2)
- Always opposite to motion of wind
Ff
PGF
Fc
Wind
Bottom line: Draw arrows in this exact order and you can’t go wrong
3) Isopleths (Isolines) = lines connecting places on a map with the same value
Examples
Data value
Isopleth
Elevation
Contour line
Temperature
Isotherm
Precipitation
Isohyet
Pressure
Isobar
Rules for drawing isopleths (provided in lab manual)
- Drawing isopleths can be subjective, but never WRONG if you follow these rules
Have individual students read the first sentence of each rule, may seem tedious, but gets them involved and
paying attention; add explanations to the rules that are not as obvious
1. Self-explanatory
2. One side of the isopleth will be higher than the isopleth value, the other side will be lower – determining
where the isopleth goes in between actual data points may require ‘interpolation’ (essentially,
estimating its location)
3. Spacing at equal intervals is important to remember, especially the fact that these intervals will be the
same across the ENTIRE map (they do not change). It is best to determine what each interval is before
drawing the isopleths.
4. Spacing is determined by data, but in this class the intervals are normally provided
5. Spacing distance indicates the rate of change – use example of two sets of stairs
Wide spacing – small rate of change (shallow)
Tight spacing – fast rate of change (steep)
6. Lines never cross! Very important
7. Self-explanatory
8. Smooth closed shape (‘circular’) UNLESS lines go off page
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Geography 102 Lab 2
Exercises: Tips
N. Salant
4) Lab exercises
Question 1
- Do one example with them (‘sea-level’)
- Provide method for keeping units straight (dividing by same unit cancels it out)
- At each step, the unit on top is the unit you’ve converted to
760 mm
x
1 in Hg
25.4 mm Hg
x
33.9 mb
1 in Hg
x
3.39 kPa
33.9 mb
=
Question 2
- Suggest they think about how the effect of gravity changes as you move farther from the
Earth’s surface (increasing altitude)
Question 3
- For both parts of Question 3, refer them back to the step-by-step procedure you
presented during the lecture
- For the first part (3a and 3b):
- Point out that the two diagrams are from the same area, so they can be compared;
thus the length of the arrows should reflect the difference in pressure gradient
between the two diagrams
- Point out that they correspond to mountainous areas, implying friction
- Remind them that the PGF always goes from high to low pressure
- For the second part (3c):
- Get them to recognize that ‘geostrophic flow’ and the ‘middle troposphere’ imply
no friction
Question 4
- Most importantly, reassure them of the following:
Drawing isobars is difficult, subjective, and takes a lot of practice to get good at
On an exam, the area and the amount of data would be much smaller and more
straightforward
There really is no ‘right’ answer; interpolating requires some degree of approximation
However, there are rules that must be followed (refer back to lecture and/or the lab
manual)
- Suggest they start by writing down the intervals: beginning with 992, add 4 each time
(992, 996, 1000, 1004, 1008, 1012, 1016). Remind them that these intervals are the
same across the entire map.
- Suggest they start at the lowest data point, 992 mb, (lower right hand side of the map)
and draw the first few circles for them
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Geography 102 Lab 3
Teaching Notes
N. Salant
LAB 3: ATMOSPHERIC HUMIDITY AND ADIABATIC PROCESSES
Preparation
- Write name, email address (optional), lab section and lab time on board
- Set up overhead projector, check overhead pen
- Get overheads out of binder, including psychrometric table, Figure 2.1 and
exercises
- Set up psychrometers
Introduction
- Pass out attendance sheet
- Ask students if they have questions from previous week
1) Atmospheric humidity
Definitions
Humidity = amount of water vapour in the air
Relative humidity (RH)
= amount of water vapour in air, divided by maximum amount of water vapour air
can hold
=
water vapour content
water vapour capacity
We measure water vapour in terms of vapour pressure, so that this equation can also be
written in terms of the vapour pressure of the air and the maximum or saturated vapour
pressure
=
ea x 100
es
(in percent)
ea = vapour pressure = pressure exerted by water vapour molecules within a given
volume of air (actual content)
es = saturated vapour pressure = pressure exerted when amount of water vapour is at its
maximum (theoretical capacity)
Saturation = when level of water vapour in air is at its maximum
Dew point temperature (Td) = the temperature to which air must be cooled for saturation
to occur
i.e. when the air temperature T equals Td, the air is saturated and ea = es
and RH = 100%
(Put up Figure 2.1 overhead)
(Tell them it may be difficult to follow, so pay attention and ask questions)
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Geography 102 Lab 3
Teaching Notes
N. Salant
Figure 2.1
Graph of es versus temperature
Theoretical relationship that does not change
Line on the graph represents saturated conditions
Thus for any given T, we know the es – in other words, the capacity of the air
Note that if T increases, capacity increases
(Show them how to use graph)
Consider, you walk into a room and air temperature is 20 °C
What is es?
~ 23 mb
You then raise the temperature to 25 °C
What is es?
~ 31 mb
Thus raising the temperature increased es
But has ea changed?
No
How could we change ea?
Only by adding or removing water from the air
Let’s assume we don’t change ea, so ea stays constant
At what temperature will ea = es?
In other words, at what temperature will air become saturated?
Dewpoint temperature (Td)
So when the temperature reaches dewpoint (when T = Td), ea = es
Now we can replace the axes of the graph
Replace T with Td – what must we then replace es with?
ea
So if you know the dewpoint temperature, you know how much water is in the air (ea)
Example)
Why do we get dew in the morning?
OK?
Because air has cooled overnight to Td
Great, but how do we measure humidity?
2) Psychrometers
Wet
Tw
Dry
Ta
Two bulbs measure temperature
- dry bulb measures air temperature
- wick keeps wet bulb wet
- evaporation from wet bulb cools wet bulb to lower
temperature than surrounding air
- therefore Tw < Ta
- amount of evaporation that can occur depends on
humidity of air
- therefore difference between Ta and Tw is a measure of
relative humidity
Ta – Tw ~ humidity
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Geography 102 Lab 3
Teaching Notes
N. Salant
Large difference (Tw << Ta) = low RH
Small difference (Tw < Ta) = high RH
lots of evaporation/cooling
little evaporation/cooling
(Put up psychrometric table)
When Ta –
Tw = 0, RH = 100%
no cooling of wet bulb, so temperatures are same
When Ta – Tw = 10, RH as high as 53%
lots of cooling of wet bulb
3) Atmospheric stability
If COOL air lies above
WARM air
Why?
atmosphere is unstable
Because warm air rises, and cool air sinks
Therefore instability  air movement
What does air movement produce?
WEATHER!
Parcel theory
= how we describe behaviour of air parcel as it moves through the atmosphere
(Draw diagrams)
Sun heats parcel at surface
Warm air rises
(Walk them through what happens as air rises)
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Geography 102 Lab 3
Teaching Notes
N. Salant
2
As air rises, it expands and cools
19 °C
For every 100 m that it rises it cools by 1°C
This rate of cooling is called the DALR
100 m
= Dry Adiabatic Lapse Rate
1
20 °C
When does air parcel stop rising?
When it is no longer warmer than the surrounding air
2
Now let’s assume the dewpoint
temperature of this parcel is 19 C
19 C
What will happen at 100 m?
Air will condense (forms clouds!)
100 m
Recall from lab 1 that condensation leads
to a gain in energy (heat)
1
So, air is both rising (losing heat)
and condensing (gaining heat)
20 C
The result?
Air will continue to drop in temperature as
it rises, but only at 0.6 °C/100m
Clouds will rise
until they cool to
the surrounding
temperature
= Saturated Adiabatic Lapse Rate (SALR)
Environmental Lapse Rate (ELR) = the actual temperature profile of the atmosphere
(i.e. what the air parcel is rising through)
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Geography 102 Lab 3
Teaching Notes
N. Salant
How to use parcel theory:
1. Plot the ELR on a height versus temperature graph
ELR
SALR
Dew point – Clouds form
Height
(m)
DALR
‘Hot spot’
Temperature (°C)
2. Start at the hot surface temperature
3. Plot DALR if air is dry (for every 100m up, decrease temperature by 1°C)
Parcel will rise and cool at the DALR until it reaches its dewpoint temperature
4. At the dewpoint temperature, parcel will rise and cool at the SALR (for every 100m
up, decrease temperature by 0.6 °C)
5. Parcel will stop rising when the theoretical DALR/SALR line crosses the ELR
Clouds will form up to the height when the SALR line crosses the ELR
Free convection = air rises or falls according to atmospheric stability
Forced convection = air is forced to rise over obstruction (i.e. mountain
ridge)
Parcel will cool and warm
according to DALR/SALR
ELR does not matter
5
Geography 102 Lab 3
Exercises: Tips
N. Salant
4) Lab exercises
Question 1
- Use psychrometer to get wet and dry bulb temperatures
- ‘Wet bulb depression’ is Ta – Tw
- Use psychrometric table with Tw and Ta-Tw to get RH
Question 2
- Do 1st example with them
- Use Figure 2.1 (put up overhead)
Knowing T = 12, es = 14
Then replace T with Td, es with ea
Knowing Td = 2, ea = 7
Calculate RH from ea and es
Question 3
- Remember, what happens when T increases? es increases
- But ea remains the same
- Consider, what happens to RH when es increases but ea stays the same?
Question 4
4a. Remind them of graphing guidelines (PENCIL!)
This data is actual data measured from weather balloons (= ELR)
4b. Plot DALR when parcel is warmer than dewpoint
Plot SALR when parcel reaches dewpoint
‘Condensation level’ is the height when T = Td
4c. ‘Maximum height’ is when the SALR crosses the ELR
Cloud thickness will depend on what height clouds form and rise to
4d. Remind them that they only plot the SALR if the T cools to Td
Question 5
- Example of forced convection
- ‘Moist’ air does not mean saturated air, use the DALR at first
- Start at 15 °C, rise at DALR until the T reaches Td, then rise at SALR
- Rising continues until top of mountain
- Rain occurs at top of mountain and all water is lost from air
- Air descends at DALR
1
Geography 102 Lab 4
Teaching Notes
N. Salant
LAB 4: VEGETATION IN THE FIELD
Preparation
Pick up measuring tapes and waterproof plant keys
In class:
Get some students to carry measuring tapes
Make sure everyone has proper clothing (rain gear, warm clothes, etc.)
Remind them to bring their lab manual
Offer them to leave their bags behind (lock in room 129 or 229 closet)
Tell them, however, they are free to leave directly from the field trip site
At entrance to UEL:
Stop just inside gate and wait for people to catch up
Introduction to UEL:
- Large area that surrounds the UBC campus, contains woods, bogs, walking and biking
trails; terrific place to get a dose of nature, go for a walk, take a break, etc.
- Originally endowed to UBC by the government and used for logging to generate
income
- The area we will walk through today was all logged in the 1920s, so the trees are 80
years or younger – no old growth
Introduction to the lab:
- Main objectives of the lab are to 1) learn about the history of disturbance in the UEL
and 2) learn to identify tree species using a plant identification key
- As you walk, take the time to look around and ask any questions about what you see
- We’ll stop periodically to talk more about the forest and the trees; first stop is just ahead
1st stop: Wind-thrown tree along side of trail
- In addition to the logging that occurred in the 1920s, this areas was cleared a second
time in the 1950s for a planned residential development
- The trees were logged, the slash was burned, and most importantly, the soil was heavily
compacted and disturbed – as a result, the seed bank was destroyed
- The residential development was never built, however, and the forest was allowed to
recover
- Without seeds in the soil, how do you think these trees around us first started growing?
(Note: they were not planted)…
… these trees have wind-dispersed seeds, so that’s how they got here
- Most of the large trees around us are red alders: these are considered ‘early-succesional’
species, which means they come in soon after a disturbance; they are fast-growing and
need lots of sunlight
- Trees that need lots of sunlight to grow are ‘shade-intolerant,’ which means that
younger alders will not be able to grow underneath the full-grown ones; instead, the
alders will be replaced by ‘later successional’ species (we will be introduced to some
shortly)
- We’ve mentioned two types of disturbances (logging and construction), what are some
other types of disturbances that might occur in these forests (either human or natural)?
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Geography 102 Lab 4
Teaching Notes
N. Salant
Possible answers: insects, disease, fire, wind-throw
(point out the wind-thrown tree)
- We can see a couple other trees here that look very different from the alders (point out
the English hollies); do you recognize these trees? From where? How do you think they
got here?
Hints: hollies are grown in people’s gardens; they have red
berries that birds like to eat; birds fly and poop!
These are what we call ‘invasive’ or ‘exotic’ species; they aren’t native to this area,
but they have become ‘naturalized’ which means they can now reproduce on their
own in the wild
Invasive species can cause huge problems for natural ecosystems because they use up
valuable resources and can spread diseases
Head farther down trail to first right-hand turn and wait
2nd stop: First right-hand turn
- Look to your left (students’ right) and you will see a small vine maple whose leaves are
turning red; does anyone know why they are turning red? (Preparing to lose leaves for
winter) What do we call trees that lose their leaves during the winter? (Deciduous) What
do we call trees that don’t? (Evergreens; for example, the holly is an evergreen tree)
- Talk about layers of the forest (from top, downward):
Overstory or canopy layer (e.g. red alders)
Understory or sub-canopy layer: including young trees and shrubs
Young trees will eventually become as tall as the canopy, shrubs will not
(e.g. trailing blackberry, huckleberry, salal)
Fern layer (e.g. bracken fern, sword fern)
Herbaceous layer (e.g. grasses, horsetails)
Moss layer (e.g. moss!)
Take right-hand turn and head downhill, past gate to second junction
3rd stop: Junction with large big-leaf maple
Plant identification:
- Gather around the red alder at the centre of the junction
- Take out lab manuals and turn to the plant identification keys
- Go through identifying the red alder as a group to demonstrate how to use the key
- Use pictures on next page to define the terms such as ‘toothed’ vs. ‘lobed’, ‘compound’
vs. ‘simple’
If possible, pick a leaf from the elderberry to show what a compound leaf looks like
- Determine the circumference of the tree using the measuring tapes (have 1 or 2 students
do it) and use the equations in your manual to find the area and the diameter of the tree
(suggest they do it when they get back and ask questions if they don’t know how)
- ‘Diagnostic features’ are those features in the identification key that helped you
determine which species it was
Put flags at 3 additional trees to identify in pairs or groups, including:
1) Big leaf maple (straight ahead)
2) English holly (just down left-hand trail)
3) Elderberry (just past English holly)
4) Black cottonwood (very tall, black and furrowed bark across trail on the right)
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Geography 102 Lab 4
Teaching Notes
N. Salant
Once everyone is done, continue downhill
4th stop: Bridge with beaver dam on the right
- Beavers and the dams they build are examples of natural disturbances that can cause
major changes to the forest
- Just before the bridge, there is a small spruce tree, planted by forest managers in an
attempt to provide young trees to replace the full-grown alders when they die;
replacement would have occurred naturally had the seed bank not been destroyed;
because the seeds were destroyed, replacement species will either have to be planted or
will gradually encroach from surrounding areas
- Just past the bridge, on the right, you can see dark green shiny rhododendrons; most
likely these also came from nearby gardens
Continuing further down trail towards coniferous area
- On left, large patches of salal (dark green, oval leaves, shrub), beaked hazelnut,
huckleberry, more rhododendrons
5th stop: At crest of hill in coniferous area, next to yew
- What was the first thing you noticed as we walked into this area? What’s different?
Darker, colder, shadier
- Many of these trees are ‘shade-tolerant’ which means they can grow in the understory
- This area was logged in the 1920s (see the large stumps) but was not cleared in the
1950s, thus the trees here are much older and represent a later-successional stage
Flag 4 more trees for them to identify, including:
1) Red cedar (just before stop on right-hand side)
2) Vine maple (just before stop on left-hand side)
3) Western yew (at stop on right-hand side
4) Western hemlock (just past stop on left-hand side, small tree)
5) Douglas fir (pick one of the large trees but place a branch with needles next to it)
Tips to help them identify (and additional info about each:
1) Red cedar has scale-like leaves and cones, not berries (point out cones on the ground)
3) Western yew has distinctively red bark, which contains a chemical used in ‘taxal,’ a
newly developed breast cancer drug; an example of why forest biodiversity is important
4) Western hemlocks are shade-tolerant, thus they can be both in the over- and
understory; they have needles that vary in length and relatively finely furrowed bark
5) Douglas fir are shade intolerant, thus they are only tall trees in the overstory; they have
needles of all the same length and deeply furrowed bark
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Geography 102 Lab 6
Teaching Notes
N. Salant
LAB 5: LAND COVER CHANGE
Preparation
- Write name, email address (optional), lab section, lab time, and personal LAC hours
on board
- Set up overhead projector, check overhead pen
- Get topographic map of Fraser Valley with four areas delineated
- Put out overhead grids and overhead pens
- Put Windex and toilet paper in separate area of room
- Set up piles of photos, in order: Langley, Port Moody, Richmond, West Vancouver
(separate piles for 1946 and 1994)
- Get overheads out of binder, including 8 photos (1946 and 1994 of 4 different
areas), assignment questions and tables
Introduction
- Pass out attendance sheet
- Ask students if they have questions from previous week
Main points
- Lab has 3 main parts:
1. Learn how to interpret air photos for different land cover types
2. Calculate actual areas based on the scale of the photos
3. Determine changes in land cover from 1946 to 1994 (using photos, in pairs)
1) Air photos
- Allow us to study natural systems at a larger scale than can be covered on land
- Taken from planes
- Affected by weather conditions (e.g. clouds), time of day, and season
For example, if we flew over Vancouver in the winter, how might it look different
than in the summer or spring?
Some trees lose leaves, snow on mountains
Have students pair up
Pass out photos – one 1946 and one 1994 to each pair
Tell them: DO NOT WRITE ON PHOTOS
Show each area on the topographic map
Put up overheads for each area one by one and point out certain features
Have them guess what certain things are (e.g. trees in Lighthouse Park, agricultural fields, Cypress
Bowl Road)
- Identifying land cover types; basic rules:
Vegetation types
Forests: Dark, coarse textured, evergreen trees darker and denser, deciduous have
no leaves in winter
Grasslands: Lighter, more uniform texture
Agricultural fields: Geometric shapes, colour varies with crop type
Bare soil: Very light, uniform
Sports fields/Golf courses: Identifiable shapes (e.g. ovals, sand pits)
Residential areas: Houses, grid-like streets
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Geography 102 Lab 6
Teaching Notes
N. Salant
Industrial/commercial areas: Parking lots, large buildings
Roads/Highways: Uniform width
Water: Light or dark depending on sun direction, smooth, shiny
- Looking at the 1946 and 1994 maps you can probably see differences right away
- Today we will quantify these differences by determining the percent cover in
vegetation, residential areas, etc. for both years
2) Scale
- In order to quantify areal changes based on photos, we need to be able to scale the
map into ‘real life’ distances and areas
3 main types of scale:
1. Verbal scale
Most familiar scale (e.g. 1 cm on map = 2 km in real life)
2. Bar scale
Found on maps, pictorial representation of scale
10 km
3. Representative Fraction (RF)
Actually most common and most useful scale for interpreting maps/photos
Unitless fraction – doesn’t matter what units you use
For example, if the RF is 1:25,000
1 pen cap on the map = 25,000 pen caps in real life
1 inch on the map = 25,000 inches in real life
1 cm on the map = 25,000 cm in real life
1:25,000
or
1
25,000
no units are specified
How to calculate actual areas from the RF scale:
(Remember, whatever unit you choose is the same for both the photo and real life)
1. Measure the length on the photo and convert to the ‘real’ length
L on photo x 25,000 = L in real life
e.g. 10 cm on photo x 25,000 = 250,000 cm in real life
(converted to meters)
= 2,500 m in real life
2. Measure the width on the photo and convert the real width
W on photo x 25,000 = W in real life
e.g. 10 cm on photo x 25,000 = 250,000 cm in real life
(converted to meters)
= 2,500 m in real life
3. Calculate the real life area as real life L x real life W
(L on photo x 25,000) x (W on photo x 25,000) = A in real life
Multiply by 25,000 TWICE
e.g. (10 cm x 25,000) x (10 cm x 25,000) = 250,000 cm x 250,000 cm
or 2,500 m x 2,500 m
Units of area will be cm2 or m2
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Geography 102 Lab 6
Teaching Notes
N. Salant
3) Lab exercise
Pass out overhead grids and pens
- One person in each pair does the 1946, the other does the 1994 photo
- First, calculate area of photo and single quadrat on grid using RF scale and ruler
- Second, identify land cover types:
Lay overhead grid on photo
Use pens to mark which of 8 categories for each square (see Table 5.1)
Choose category that covers most of the square
However, call the square a road/highway if it crosses through square
- Third, count the number of squares in each category and fill in Table 5.1
- Lastly, compute the percent change from 1946 to 1994
% change = # squares in 1994 - # squares in 1946
# squares in 1946
x 100
Note: If there were 0 squares in 1946 and some in 1994, it is a 100% increase
- As a class we will fill in Table 5.2 (put up overhead) and discuss results
4) Discussion (Questions 5 and 6)
For each site, put up overhead photos and have each pair discuss what they observed
Have students suggest possible implications
General changes/implications (Question 5):
- Increase in residential and industrial areas, decrease in forest and agricultural land
- Destruction or reduction of natural habitat for wildlife
- Isolation of wildlife in smaller areas (e.g. Richmond nature park, Lighthouse Park,
riparian corridor along Coquitlam River)
- Migration barriers caused by roads; fragmentation of landscape
- Increased conflicts; wildlife compete for resources (including space) both with humans
and other animals
Other effects (Question 6):
- Pollution of water by fertilizers from agriculture, oil from roads
- Increased traffic on waterways, increased noise pollution
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Geography 102 Lab 6
Teaching Notes
N. Salant
LAB 6: INTERPRETING VEGETATION COMMUNITIES
Preparation
- Get vegetation maps: ‘Vegetation of the Southwester Fraser Lowland, 1858-1880’.
Put either at front of room or place one on each table (one per pair of students).
- Write name, email address (optional), lab section and lab time on board
- Set up overhead projector, check overhead pen
- Get overheads out of binder, including examples of toposequence and
chronosequence, blank templates, and Table 6.1
Introduction
- Pass out attendance sheet
- Ask students if they have questions from previous week
Main points
- Describe the distribution of historic (pre-industrial) vegetation communities in the
southwestern Fraser Lowland
- Relate plant distribution to topography, soil, precipitation and disturbance
1) Factors that influence vegetation
VEGETATION = f(CL+O+R+P+T)
(Make clear this is not an equation)
‘CLORPT’
(Get them to identify what each letter stands for)
CL = Climate
O = Organisms
R = Relief (topographic)
P = Parent material
T = Time (since disturbance)
Examples)
Climate – Precipitation, temperature
(Have them think of examples)
e.g. Deserts vs. Tropical rainforests
Organisms – Animals or plants
e.g. Earthworms, beavers, birds
(Have them think back to the field trip
and the evidence of animal influence we saw there
– beavers creating a swamp, birds bringing in hollies
Relief – 3 main components:
1) Elevation
2) Slope angle
e.g. Steep vs. gradual; mountainside vs. floodplain
3) Aspect (N, S, E, or W)
Insolation effect (S receives more sunlight)
Parent material – Original material that soil came from
e.g. Bedrock vs. river deposit
Time – since disturbance, stage of succession
e.g. Fires, flooding, humans
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Geography 102 Lab 6
Teaching Notes
N. Salant
(Again, think back to field trip – alders were ~50
years old, more recent disturbance, earlier succession; conifers were older)
2) Describing vegetation
Toposequence
(Put up overheads – examples)
One moment in time (NO succession, a ‘snapshot’)
Change over space
Vegetation communities differ in topography and soils
Chronosequence
One place
Change over time (succession)
3) Vegetation map
Vegetation of the Southwester Fraser Lowland, 1858-1880
Pre-agricultural, pre-industrial
Limited human development
Natural vegetation distribution
LOTS of information in maps, margins, text
A. Large map = Plant communities
Identified by colour – see margin:
Colours = Plant communities (8 communities)
Lists = Vegetation types (3-9 different types per community)
Regular font = Common species
Underlined = Dominant species
(Brackets) = Minor species
B. Left-hand small map = Topography
Lowland (e.g. floodplains)
Upland (e.g. mountains)
[Burned areas (NOT a topographic classification, imposed on existing elevation)]
(Example of disturbance)
C. Right-hand small map = Soils and precipitation
Gleysolic – Associated with prolonged saturation (e.g. flooding)
Organic (Histosols) – High organic content, common to bogs, wetlands (e.g. peat)
Podzolic – Well-drained, stained with Fe oxides, moderate leaching, common to
coniferous forests
D. Text between maps = History of disturbance in area
–
(Encourage them to read material in text of all maps
lots of information they will need to complete the exercise)
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Geography 102 Lab 6
Exercises: Tips
N. Salant
4) Assignment
3 parts:
- Toposequence – using maps directly
- Chronosequence – not directly from map, using your own inference
- Table – using info from maps an your own inference
A. Toposequence
Template is scaled to the small inset maps –
- Fold toposequence template along ‘Topography’ line (tear out paper, if needed)
Position on inset left-hand map:
Line up edge to edge of map; make sure to cross Annacis Island (in Fraser River)
Tick mark when topography changes (lowland switch to upland)
Draw schematic of what topography cross-section looks like
Example:
Upland
Island
Lowland
River
- Refold template on ‘Soil order’
Position on right-hand inset map:
Line up edge to edge of map; make sure to be in same location
Tick mark every time soil changes
Write in names of soils
- Determine the scale of toposequence from bar scales on small maps
Choose interval (e.g. 2 km), measure ‘map distance’
Tick mark each interval, just like a graph
Example
Scale
(km)
2
4
6
8
10
12
14
B. Chronosequence
For an upland forest starting immediately after a disturbance (e.g. fire)
ONE place over time – show succession of plants
Recall field trip, use example from lab manual, use communities from map
1
Geography 102 Lab 6
Exercises: Tips
N. Salant
Consider, how large are plants when they first start growing, how many years to a
full-grown tree, how do forests change composition over time?
(Get them to think about this)
C. Table
Column 1: Communities
List communities (correspond to colours) from most dominant to least dominant
(i.e. which colour covers most of the map) – 8 total
Column 2: Number of vegetation types
Count the number of different vegetation types listed (each box in key)
Column 3: Dominant species
Write down underlined names only
Column 4: Topography
Upland or lowland
Column 5: Soils
Gleysolic, organic, or podzolic
Column 6: Historic disturbances
Use text, logic (e.g. what sort of disturbance affects a low-lying floodplain?)
Column 7: Successional stage
Use logic (size of plants, location and frequency of disturbance)
Remember, the more frequent the disturbance, the younger the plant
BOTTOM LINE: Emphasise the correspondence in space and time between the factors
(topography, soil type, time since disturbance) and the vegetation communities
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