Download 1 - Fort Lewis College

Plant Community Ecology Course Packet, BIO 390
Fall 2010
Dr. Julie Korb
2445 Berndt Hall
[email protected]
382-6905
1
TABLE OF CONTENTS
Description
Page #'s
Syllabus
Class Schedule
Article Discussion Guidelines
Common Trees in the Southwest
3-5
6-7
8
9-10
In-Class Activities:
Article Discussion Questions Week #1
Article Discussion Questions Week #2
Pinyon-Juniper Worksheet
Mixed Conifer Worksheet
Subalpine Worksheet
Releve Info
Animas City Mountain Species List
Plant Interaction Exercise
Dendrochrono logy
11-12
13-14
15-16
17-18
19-21
22-25
26-28
29-40
41-43
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BIO 390: Plant Community Ecology
Fort Lewis College-Fall 2010
Class Schedule:
T/R 11:15-12:35 p.m.
Rm# Berndt 235, BH #570
Instructor: Julie Korb, Ph.D.
[email protected]
Office: 2445 Berndt Hall
phone: 382-6905
Office Hours: T 10:15-11:10 R 1:25-2:35 or by appt.
Required Texts: There are no required texts for this course. This course does require a
lot of reading of peer-reviewed journal articles that will be located on the O drive under
Korb in a folder labeled Plant Community Ecology.
Course Objectives: This course will introduce students to major themes/theories and
current data analysis techniques in plant community ecology. This course will
emphasize biotic and abiotic variables that affect the distribution and abundance of plant
species including natural and anthropogenic disturbances. We will use native ecosystems
in southwestern Colorado, field collection data, and current scientific literature to explore
these topics.
Class Format: It is imperative for you to be at class in order to learn the course material
and to receive a good grade. This class will focus on using a variety of learning
techniques. Generally, the first half of the class period will be spent on lectures and the
latter half of the class period will be dedicated to group discussions/active learning
exercises.
Reading Assignments: All reading assignments are assigned to prepare you for each
class period and therefore you should do your weekly assignments BEFORE you come to
class. I will draw information from class readings each day and thus it is necessary that
you will have read your assignment so you will be able to participate in class discussion.
Laboratory Format: There is no laboratory associated with this class. We will
however have a required one-day field trip on Sept. 4th starting at 9 am until 4:00 pm to
collect data that we will analyze in class. We will meet at parking facilities (Physical
Plant) near the SW Center. Please dress appropriately by wearing suitable clothes and
shoes, bringing a rain jacket, water, lunch and a notebook.
Evaluation: You will have numerous opportunities to demonstrate your knowledge of
plant community ecology including written exams, oral presentations, group discussion
participation, and assignments. Grading will be done on a point system.
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Evaluation Format
Points
Percentage
Exams (2) @ 100 pts
Discussion Article Leader
Group Discussion Participation
All Day Field Trip
PC-Ord Assignments
Class Assignments (various points/
assignments)
200
100
100
50
100
25.0%
12.5%
12.5%
6.25%
12.5%
50
6.25%
Final Presentation
Final Exam (plant competition)
100
100
800 points total
12.5%
12.5%
100%
Midterm grades: Midterm grades will based up one exam, ½ group discussion
participation, all day field trip and class assignments. If you receive a failing midterm
grade you will be asked to withdraw from the course.
--Exams: No make-up exams will be allowed without prior instructor permission or a note
from a physician. Exams during the semester will cover the material since the first of the
semester or the previous exam. The final exam consists of take-home essay questions.
Discussion Article Leader: Each student will be required to give a 10 minute summary
presentation on a peer-reviewed article related to plant community ecology. Students
will sign up for the article the first week of class. This summary presentation will lead
into a discussion of the article facilitated by the same student presenting the summary
presentation. You will be required to email your classmates with a list of questions a
week before your presentation and discussion of the article. This will allow you to
further develop your skills in scientific reading, interpretation, and presentation. Please
see attached discussion article information in course packet for further details.
Group Discussion Participation: Throughout the semester will we have both small and
large group discussions regarding class lecture material and reading assignments. These
discussions will provide you with the opportunity to explore ecological concepts more indepth with your classmates and myself. For your group discussion grade, you need to be
present on discussion days. If you are absent, it will result in a zero for your group
discussion grade for that day. If you are present you will receive 5 points, if you talk you
will receive another 5 points for the day.
Final Presentation: Each student will give a 12 minute final presentation in Powerpoint
with 3 minutes for discussion based on a topic of the student’s choice related to plant
community ecology. Students must pick one theory/major theme of plant community
ecology (e.g., continuum concept, intermediate disturbance hypothesis, competition
regulation, stress gradient hypothesis, succession theory, facilitation, niche differences,
life-history traits, novel weapons hypothesis, etc.) and illustrate how the theory/major
theme has been advanced/supported through plant community ecology research and
design a study to further test the theory/major theme based on current literature. You
must cite at least four scientific articles for this presentation and tie the various research
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articles into one cohesive presentation. You will be graded on your oral presentation
skills, Powerpoint presentation slides, and most importantly the content of the
presentation. For content you need to include: 1) one theory/major theme, 2) define the
theory/theme, 3) discuss current status of theory/theme based on the current literature—
minimum of 4 scientific articles, and 4) design study to further test the theory/major
theme based on current literature.
Final Word: Enjoy this course. Although learning a new subject is challenging at times,
it is also FUN. If you have problems with anything regarding this course please come
visit me during my office hours or make an appointment at a time convenient for both of
us. I am looking forward to an exciting semester learning about the plant community
ecology!
Students with Disabilities:
“"Fort Lewis College is committed to providing all students a liberal arts education
through a personalized learning environment. If you think you have or you do have a
documented disability which will need reasonable academic accommodations, please
call, Dian Jenkins, the Coordinator of Disability Service, 280 Noble Hall, 247-7459, for
an appointment as soon as possible."
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Course Syllabus (tentative schedule subject to change)
Class: Week of August 30
FIELD TRIP: September 4th
9am-430pm
Class: Week of September 6
Class: Week of September 13
Class: Week of September 20
Class: Week of September 27
Topics (subject to
revision)
T: Course overview &
syllabus , Intro to Plant
Ecology
R: Intro to Plant
Community Ecology/
Article Discussion
Plant Community Data
Collection
T/R: Gradient
Analysis/Pattern
& Process R: Article
Discussion/Intro PC-Ord
T/R: Plant Life History
Traits
R: Article
Discussion/Lab: PC-Ord
T/R:
Competition/Facilitation
R: Lab: Start Plant
Competition Greenhouse
Experiment
T:
Competition/Facilitation
continued
R: EXAM
Class: Week of October 4
T/R: Disturbance and
Succession
R: Article
Discussion/Lab: PC-Ord
Class: Week of October 11
T/R: Fire Ecology:
Pinyon-Juniper
R: Article
Discussion/Lab: PC-Ord
T/R: Fire Ecology:
Ponderosa Pine/Mixed
Conifer
R: Article
Discussion/Lab: PC-Ord
T/R: Fire Ecology:
Subalpine
R: Dendrochronology
Class: Week of October 18
Class: Week of October 25
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Reading
Assignment Due
Kelly and Goulden 2008
(plant migration, climate
change, gradients)
R: Reading
Questions
Lortie et al. 2004
(neutral and niche
theory, plant
interactions)
Fukami et al. 2005
(assembly rules,
alternative states,
succession); Craine 2005
(plant strategies,
competition, stress)
Plant Competition lab
handout
R: Reading
Questions
Callaway et al. 2002
(facilitation,
environmental stress);
Maestre et al. 2009
(competition/facilitation)
T: Reading
Questions
T:Dr. Jeffrey
Mitton, Pine
Beetle Outbreak
NH 125 7 pm
Connell and Slatyer
1977 (successional
theory); Davis et al.
2000 (invasions,
resource availability,
disturbance)
Callaway et al. 2008
(novel weapons
hypothesis, invasions,
mycorrhizae)
Fule et al. 2009
(reference conditions,
fire ecology, restoration)
Scheonnegal et al. 2007
(fire ecology, climate
change,
dendrochronology)
R: Reading
Questions
R: EXAM
R: Reading
Questions
R: Reading
Questions
Worksheet (in
class)
Reading Questions
Worksheet (in
class)
T: Reading
Questions,
Worksheet (in
class)
Class: Week of November 1
T: Restoration & Article
Discussion
R: EXAM
Class: Week of November 8
Class: Week of November 15
T/R: Diversity,
Abundance, Rarity
R: Article Discussion;
complete plant
competition greenhouse
lab
T/R: Climate Change &
Plants/Alpine; Article
Discussion
R: Video
Class: Week of November 22
NO CLASS-Happy
Thanksgiving!
Class: Week of November 29
Student Presentations
Class: Week of December 6
No Class—credit for
field trip
Final Exam: December 15th
MONDAY @ 4:30-6:30 pm
Palmer et al. 1997
(restoration, community
ecology theory); Suding
et al. 2004 (alternative
states, feedback loops,
restoration)
Loreau et al. 2001
(biodiversity/ecosystem
functioning); Levine &
HilleRisLambers 2009
(niche differences,
biodiversity)
Kikvidze et al. 2005
(competition,
facilitation,
environmental stress,
climate change)
R: PC-Ord
report
T: Reading
Questions
R: EXAM
R: Reading
Questions
T: Reading
Questions
R: Video
Worksheet
T/R: Powerpoint
Presentation
Plant Competition
Report
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Presentation of Discussion Articles
About 1/4 of this course will be spent evaluating and discussing papers from the primary
literature. This is a critical skill that students must develop. You need to develop the ability to
figure out the good, bad, useful and useless parts of each paper. You also need to be able to
clearly communicate this to others and to defend your thoughts. This critical thinking, along
with clear enunciation of ideas, is arguably one of the most important skills to get out of your
upper division courses within your major. These skills will also be invaluable for your own
writing, as well as for editing and reviewing.
I want the following questions addressed when papers are presented in class:
1. What is the stated purpose of this paper?
2. What general approach or methods are used to accomplish that purpose?
3. Are the data sufficient and clearly presented?
4. What are the primary stated conclusions?
These first four points are obvious exercises in reading. More importantly, I want you
to be able to apply your critical thinking:
5. Is the main question important (not to be confused with interesting)? Why, why not? (e.g.,
does it tie back to any theory in plant community ecology)?
6. Go back and compare the stated purpose of the paper (#1) with the main conclusions (#4).
Do they match?
7. Do the data support the conclusions? Would another approach have been better? Are the
data over-interpreted or is the interpretation just wrong?
8. What overall contribution does this paper make to community ecology? (can be the same as
question #5)
9. What new questions are raised and what further work is suggested by this study, either
directly or indirectly?
Adapted from http://bio.fsu.edu/~miller/commecol/mss/howtoRead.pdf
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COMMON TREES IN THE SOUTHWEST
JUNIPERS
(Juniperus scopulorum) Rocky Mountain Juniper: Berries: less than or about 1/4
inch across, often pale blue or pale greenish-blue. Usually two seeds in each berry,
sometimes one or three. Trunk: Usually single trunk. Bark: often has reddish-brown
color in places; Tree Characteristics : branches slender and elongate.
(Juniperus osteosperma) Utah Juniper: Berries: more than 1/4 inch across and often
reddish-brown, berries dry and mealy inside. Needles: yellow-grey. Bark: grey with
abundant long shreddy fibers.
(Juniperus monosperma) Oneseed Juniper: Berries: 1/8 to 1/4 inch across with one
seed, dark-blue, reddish-brown or copper colored, juicy inside. Needles: often greygreen. Trunk: Often has several trunks.
PINES
All pines have needles in bundles of two or more. Spruce and fir tree needles are
single.
(Pinus ponderosa) Ponderosa Pine: Needles: over 3 1/2 inches long and in bundles
of two or three) Bark: dark brown/black when young; orange when old-growth;
thick made up of jigsaw puzzle segments. Habitat: Typically found on south-facing
slopes between 7000-9000 ft).
(Pinus edulis) Pinyon Pine: Needles : in bundles of two, rarely three, usually 1 to 1
1/2 inches long. Cones: 1-2 inches; fall soon after maturity; Tree Characteristics:
Tree often stubby, robust, and under 30 feet high. Habitat: Typical of lower
elevations (below 7500 feet) and on dry sites, in arid forests.
(Pinus contorta) Lodgepole Pine: Needles: in bundles of two, usually 1 1/2 to 2 1/2
inches long. Cones: 1 inch; cones persist for several years past maturity; Tree
Characteristics : Tree usually tall and straight with slender trunk. This tree is not
found naturally in the Southwest; it has been planted in revegetation efforts.
(Pinus flexilis) Limber Pine: Needles: in bundles of five, usually 1 1/2 to 3 inches
long. Cones: no bristles on cones, mature cones very pale brown and 3 to 10 inches
long. Tree Characteristics : Trunk branched; not straight; Habitat: usually found on
exposed or rocky and windy sites.
(Pinus strobiformis) Southwestern Pine (Mexican White Pine): Needles: in
bundles of five, usually 1 1/2 to 3 inches long; very few minute teeth near apex;
Cones: no bristles on cones, mature cones very pale brown and 3 to 10 inches long.
Tree Characteristics: tree form upright and straight:
(Pinus aristata) Bristlecone Pine: Needles : in bundles of five, usually 1 to 1 1/2
inches long; speckled with white resin drops; strongly curved; Cones: a long, slender
bristle on the tip of each cone scale; cones less than 3 1/2 inches long.
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SPRUCES
All spruces have single, four-sided needles (square in cross-section). Cones are
lightweight and cone scales are thin and papery. The cones hang downward and fall
intact from the tree after the seeds are mature. Cones with forked papery strips
between the cone scales are not spruces but rather Douglas-fir.
(Picea engelmannii) Engelmann Spruce: Needles: square in cross-section and 1.0
inch in length or less; needles often fairly stiff and sharp pointed. Cones: mature
cones 2.5 inches or less in length; usually 1.5 to 2.0 inches.
(Picea pungens) Colorado Blue Spruce: Needles: square in cross-section and
usually over 1 inch in length; needles stiff and very sharp; pungent odor when
crushed; Cones: mature cones over 2.5 inches in length; often about 3 inches. Bark:
almost always grey.
FIRS
All true fir trees have flat, soft needles about an inch or two long, and upright resinous
cones on top branches which disintegrate on the tree after one season with the scales
and seeds falling to the ground and an upright spike remaining on the branch. NOTE:
The Douglas-Fir is not a Fir at all but is listed here only because of name similarity
(Abies lasiocarpa) Subalpine Fir: Bark: thin Needles: soft and flattened, 1 to 1 3/4
inches long on lower branches except shorter near treeline. Tree Characteristics:
forms tall, narrow, spire-like trees, the narrowest trees of the Rocky Mountain forests.
(Abies arizonica) Corkbark Fir: Bark: thick and soft or corky and broken into
ridges, in color grey, ash-white, creamy-white, or pale- yellowish. Habitat: It is
found only in the southern half of Colorado and northern New Mexico.
(Abies concolor) White Fir : Bark: thick and grooved when older, checkered,
spongy under hand pressure; Needles flattened and soft, 1 3/4 to 3 inches long on
lower branches; attachment to branch looks like a suction-cup; blue-green color.
Habitat: Found below 10,000 feet, in the mountains of central and southern Colorado
and of northern New Mexico.
(Pseudotsuga menziesii) Douglas Fir: Needles: short flat soft needles, only 3/4 to 1 1/2 inch
long that have a pedicle (leaf stalk); Cones: pale brown, and only 1 to 3 inches long, dry
papery scales with papery three-pointed bracts, hang down from the branch, and fall intact
from the tree.
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Discussion Questions: Week 1
1.
Before reading the article, describe in your own words how you think plant communities will
respond to climate change?
2.
Examine the figure below. Which, if any of the diagrams (it can be a combination of any of
them) represents what you described in question 1?
Fig. 1. Types of distributional change for species on an elevation gradient, resulting from changes in
growth, establishment, decline, and/or mortality: ‘‘Lean,’’ where the range remains constant but the
central tendency shifts, as highlighted in a new study (13); ‘‘March,’’ where the entire distribution and its
range moves upslope (5); and ‘‘Crash,’’ where mortality is widespread across the range (10). These types
are not mutually exclusive and could occur in various combinations or sequences to affect distribution
range, central tendancy, and/or skewness.
3.
Which of the diagrams represents what Kelly and Goulden (2008) found in their research in
Southern California over a 30 year period?
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4.
How might the findings from Kelly and Goulden (2008) be applicable to plant communities
in southwestern Colorado?
5.
The authors state four reasons their findings can be attributed to climate change. What are
these four reasons and do you agree with them? Why or why not?
6.
What would you suggest for future research to expand upon the findings of this study?
12
Discussion Questions Week 2
1. Explain the figure below. Is there anything in the figure that should be removed or
added?
2. What makes the “Integrated Community Concept” unique from Clements’ organismic concept
or Gleason’s individualistic concept? Do you agree that the IC concept is a stronger theory for
understanding the structure and function of ecological systems? Explain your response.
13
3.
How does neutral theory and niche theory fit into the IC concept? Describe both of these
theories.
4.
Why is the IC concept important to consider when thinking about plant community responses
to climate change? How, if at all, do the results from Kelly and Goulden (2008) relate to the
IC concept?
5.
What is a research study that could be conducted in southwest Colorado to test the IC concept
and its applicability to climate change?
14
Pinyon-Juniper Class Exercise
Pinyon juniper forests vary in their distribution across elevations (4500-8500 ft).
Answer the following questions regarding their distribution patterns.
8500 ft.
4500 ft
South facing
North facing
1) In the above diagram draw in the elevation bands for the pinyon-juniper forest life zone.
Is there a difference between north and south facing slopes? Why or why not? Why do
pinyon-juniper forests only grow between 4500 and 8500 ft? Hint: what are the limiting
climatic factors?
2) Pinyon pine and Utah juniper are NOT evenly distributed across the elevation gradient
range for pinyon-juniper forests. Which of the two species would be found higher in
elevation? ___________________ Lower in elevation?___________________
What physical characteristics for these two species led you to your conclusions—adaptations
to different climatic environments?
3) Density and basal area are also NOT evenly distributed across the elevation gradient range
for pinyon-juniper forests. Where would density be the highest and why? Where would basal
area be the highest and why?
15
4) Fire is one of the major disturbance agents in pinyon-juniper forests. Is fire behavior
similar in intensity and frequency across the elevation gradient? Fill in the fire behavior
triangle below and think about how these three variables would influence fire behavior and
how they would vary across the elevation gradient. Specifically, look at the leg of the triangle
that you graphed in question #1.
Fire Behavior
Triangle
16
Mixed Conifer Class Exercise
1) There are two types of mixed conifer in the Southwest: warm, dry mixed conifer and
cool, wet mixed conifer. How is it possible for these two different vegetation types to
grow near each other when their names describing their environment are so different?
In the diagram below draw in the elevation bands for these two types of mixed conifer.
10000 ft.
8000 ft
South facing
North facing
2) What tree species is the indicator species for warm, dry mixed conifer?
____________________ What adaptations/characteristics allows this species to
prefer warm, dry areas over cool, west areas?
3) Using the LEGO set, create a warm, dry mixed conifer forest prior to Euro-American
settlement (~1880). When doing this think about the types of tree species (species
richness), density (trees/acre) and biomass (basal area/acre). Also, think about the fire
regime for warm, dry mixed conifer.
What species did you include?
What was the density (low, medium, high)?
What was the diversity of tree diameters--basal area (lots of small trees, lots of large trees,
mixture)?
Using the LEGO set again, create a warm, dry mixed conifer forest after Euro-American
settlement. What impacts did fire suppression, grazing, and logging of old-growth trees have
on the forest structure?
What species did you include?
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What was the density (low, medium, high)?
What was the diversity of tree diameters--basal area (lots of small trees, lots of large trees,
mixture)?
4) Using the LEGO set, create a cool, wet mixed conifer forest prior to Euro-American
settlement (~1880). When doing this, think about the types of tree species (species
richness), density (trees/acre) and biomass (basal area/acre). Also, think about the fire
regime for cool, wet mixed conifer.
What species did you include?
What was the density (low, medium, high)?
What was the diversity of tree diameters--basal area (lots of small trees, lots of large trees,
mixture)?
Using the LEGO set again, create a cool, wet mixed conifer forest now after Euro-American
settlement. What impacts did fire suppression, grazing, and logging of old-growth trees have
on the forest structure?
What species did you include?
What was the density (low, medium, high)?
What was the diversity of tree diameters--basal area (lots of small trees, lots of large trees,
mixture)?
5) Fire is one of the major disturbances in mixed conifer forests. Is fire behavior similar
in intensity and frequency across the elevation gradient for the two different types of
mixed conifer (warm, dry and cool, wet)?
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Subalpine Class Exercise
1) In the diagram below draw in the elevation band for the subalpine. Note, how does
this influence tree line? Where would you first see signs of climate change impacting
tree line?
11500 ft.
10000 ft
South facing
North facing
2) The subalpine is dominated by two tree species: subalpine fir and Engelmann spruce.
Look at the photographs and think about traits for the other common conifers we have
already discussed in class and list four adaptations for each species (some of them can
be the same for both species).
Subalpine Fir
1)
2)
3)
4)
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Engelmann Spruce
1)
2)
3)
4)
3) What other tree species that we have already talked about might also occur in the
subalpine vegetation zone? What adaptations do these species have to live at higher
elevations (colder and wetter than lower elevations)?
4) What type of forest stand structure did the subalpine have prior to Euro-American
settlement? When describing this think about the types of tree species (species
richness), density (trees/acre—low, medium, high) and biomass (basal area/acre-- lots
of small trees, lots of large trees, mixture)?
20
5) What type of forest stand structure did the subalpine have after Euro-American
settlement? When describing this think about the types of tree species (species
richness), density (trees/acre—low, medium, high) and biomass (basal area/acre-- lots
of small trees, lots of large trees, mixture)?
6) Fire is one of the major disturbance agents in the subalpine vegetation zone. Fill in the
fire behavior triangle below and think about how these three variables would influence
the fire regime for subalpine forests. List the fire regime for subalpine forests and the
variables that influence it.
Fire Behavior
Triangle
7) What other natural disturbances play a role in the dynamics of subalpine forests?
How are these similar and dissimilar to fire?
21
Relevé Approach to Vegetation Sampling
The relevé approach to vegetation sampling was developed by Braun-Blanquet for application
to table analysis for vegetation classification. The primary goal of the relevé approach is to
acquire a complete species list from each sample site. If other quantitative site and soil
information is collected, the information can also be used for ordination analysis.
Reconnaissance and Entitation
Reconnaissance is essential. The better your initial knowledge of an area, the better the
subsequent sampling will be. This reconnaissance phase should include the establishment of
the apparent relations of various vegetation types with topography, history, geology, soil
conditions and major disturbance factors (animals, fire, floods, etc.)
The entitation process subjectively subdivides the vegetation into recognizable entities or
vegetation types. The types defined during this process are a starting point for analysis of the
vegetation. During analysis of the data some of these units will likely be subdivided or
eliminated (e.g. they represent transition communities).
Sample Site Requirements for a Relevé
The Braun-Blanquet approach is based on centralized replicate sampling. Plot locations are
chosen in the central areas of homogeneous stands of vegetation and numerous replicate
samples are collected from other similar sites.
Each sample should satisfy the following criteria:
1. Homogeneity of the vegetation canopy
2. Homogeneity of the soil and other site factors
3. Large enough area to contain all the species in the community
4. Should be recognizable as a unit that can be repeated in other areas of the landscape
If the data are to be analyzed using probability statistics, the selection of the sample sites must
be done randomly within an area of homogenous vegetation (e.g. stratified random sampling
approach)
If the data are to be analyzed using ordination methods, then it is necessary to collect
environmental and soils information at each sample site and plant cover estimates.
Plot Size
There are two main methods for determining plot size: the minimal area technique or using
tables based upon previous investigators’ experience.
Minimal area
The minimum mapping area is determined by finding the point where the species-area curve
levels off. Nested plots are used to create this curve. In each plot, a complete species list is
created. Additional plots are added until only one or no new species in the larger nested plots
22
are found. The species-area curve does not level off in tropical and other complex
communities.
Published Tables
The following table is the minimum-area guideline (m2) that has been published by Westhoff
and van der Maarel (1978) for various community types. Only a portion of the table is shown.
Pastures
Alpine Meadows
Chaparral
Scrub Communities
Temperate Deciduous Forest
Mixed Forest
Tropical Secondary Rainforest
5-10
10-50
10-100
25-100
100-500
200-800
20-1000
Data to Collect
Site Factors
You should describe the site as completely as possible using a consistent set of quantitative
variables that can be used in an ordination analysis.
Soils
The soil-vegetation relationship is fundamental to understanding vegetation patterns. Some
recommended soil analyses include pH, percent soil moisture, soil texture, percent organic
matter, soil nutrients (N, P, K) and other physical and chemical characteristics.
Plant Species
You should collect a specimen of every unknown plant species for later verification. Collect
the complete plant including roots, stems, leaves, flowers and fruits. Cover estimates should
be made for each species. Cover estimates can either be exact aerial estimates or coverabundance classes can be used. The disadvantage of using cover-abundance classes is that it
is not possible to determine the average cover of a species for a group of plots (the average
score however can be averaged).
Braun-Blanquet Cover Estimate Scale
R =rare, <<1% cover
+ =common, but < 1% cover
1 =1-5% cover
2 =6-25% cover
3 =25.1-50% cover
4 =50.1-75% cover
5 =75.1-100% cover
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Size of Plots-Minimal Area Method
24
Cover Class Tables
25
Common Plants of Animas Mountain Trail
(partial list)
Trees
Abies concolor (White fir)
Juniperus osteosperma (Utah Juniper)
Juniperus scopulorum (Rocky Mountain Juniper)
Pinus edulis (Pinyon Pine)
Pinus ponderosa (Ponderosa Pine)
Pseudotsuga menziesii (Douglas-fir)
Ulmus pumila (Chinese Elm)
Shrubs
Amelanchier alnifolia (Utah Serviceberry)
Ceanothus fendleri (Buckbrush)
Cercocarpus montanus (Mountain Mahogany)
Fendlera rupicola (Cliff Fendlerbush)
Fragaria virginiana (Wild Strawberry)
Gutierrezia sarothrae (Broom Snakeweed)
Juniperus communis (Common Juniper)
Mahonia repens (Oregon Grape)
Peraphyllum ramosissimum (Squawapple)
Quercus gambelii (Gambel Oak)
Rhus trilobata (Threeleaf Sumac)
Rosa woodsii (Wild Rose)
Symphoricarpos rotundifolius (Snowberry)
Grasses
Achnatherum hymenoides (Indian Ricegrass)
Agropyron cristatum (Crested Wheatgrass)
Aristida purpurea (Three Awn)
Bouteloua gracilis (Blue Grama)
Bromopsis inermis (Smooth Brome)
Bromus tectorum (Cheat Grass)
Elymus elymoides (Squirrel-tail)
Festuca arizonica
Festuca thurburi
Hesperostipa comata (Needle-and-thread)
Koeleria macrantha (June Grass)
Muhlenbergia wrightii (Spike Muhley)
Pascopyrum smithii (Western Wheatgrass)
Poa fendleriana (Muttongrass)
Poa pratensis (Kentucky Bluegrass)
26
Sporobolus cryptandrus (Dropseed)
Forbs/Others
Achillea lanulosa (Yarrow)
Agoseris glauca (Pale Agoseris)
Allium acuminatum (Tapertip Onion)
Allium cernuum (Nodding Onion)
Alyssum alyssoides (Pale Allysum)
Androsace septentrionalis (Rock Jasmine)
Antennaria parvifolia (Pussytoes)
Arabis drummondii (Drummond’s Rockcress)
Artemisia franserioides (Sage)
Artemisia frigida (Silver Sage)
Asclepias subverticillata (Whorled Milkweed)
Astragalus coltonii (Milkvetch)
Bahia dissecta (Ragleaf Bahia)
Calochortus nuttallii (Sego-lily)
Castilleja linariifolia (Paintbrush)
Chenopodium fremontii (Fremont Goosefoot)
Circium tracyi (Thistle)
Comandra umbellata (Bastard-Toadflax)
Convolvulus arvense (Field Bindweed)
Conyza canadensis (Horseweed)
Corallorhiza maculate (Summer Coralroot)
Delphinium nuttallianum (Larkspur)
Erigeron divergens (Fleabane)
Erigeron flagellaris (Fleabane)
Erigeron speciosus
Eriogonum racemosum (Whorled-buckwheat)
Erodium cicutarium (Crane’s Bill)
Galium septentrionale (Bedstraw)
Gaura coccinea (ButterflyWeed)
Gayophytum diffusum ssp. parviflorum (Spreading Groundsmoke)
Gilia aggregata (Scarlet Gilia)
Grindelia squarrosa (Gumweed)
Helianthus rigidus
Heliomeris multiflora (Showy Goldeneye)
Heterotheca villosa (Goldenaster)
Hieracium fendleri (Yellow Hawkweed)
Holodiscus dumosus (Rock Spiraea)
27
Lactuca serriola (False Dandelion)
Lactuca serriola (Prickly-lettuce)
Lepidotheca suaveolens (Pineapple Weed)
Lithospermum multiflorum (Showy Puccoon)
Lotus wrightii (Deer Vetch)
Lupinus ammophilus (Lupine)
Lupinus kingii (Lupine)
Machaeranthera canescens
Medicago lupulina (Black Medic)
Melilotus officinalis (Yellow Sweet-clover)
Opuntia polyacantha (Prickly Pear)
Opuntia whipplei (Rat-tailed Cholla)
Oreocarpa bakeri
Orthocarpus luteus
Packera neomexicana (Groundsel)
Penstemon barbatus (Beardlip Penstemon)
Penstemon linarioides
Penstemon rigens
Penstemon strictus (Rocky Mountain Penstemon)
Penstemon strictus (Rocky Mountain Penstemon)
Polygonum aviculare (Knotweed)
Psoralidium tenuiflorum
Pseudocymopterus montanus (Mountain Parsley)
Pterogonum alatum
Schoenocrambe linifolia (Skeleton Mustard)
Solidago simplex (Goldenrod)
Sphaeralcea coccinea (Globe Mallow)
Taraxacum officinale (Dandelion)
Thalictrum fendleri (Meadowrue)
Thalpsi montana (Candytuft)
Tragopogon pratensis (Salsify)
Thermopsis montanus
Verbascum thapsus (Mullein)
Vicia americana (American Vetch)
Virgulus faclcatus
Wyethia arizonica (Mule’s Ears)
Yucca angustissima (Narrow Leaf Yucca)
Yucca baccata (Datil Yucca)
28
Plant Interaction Lab
INTRODUCTION
Competition in plants may be thought of as “those hardships which are caused by the proximity of
neighbors” (Harper 1961). Hardships may be due to the decreased availability of light, water, or
nutrients to any individual plant when its canopy or root area overlaps with that of another individual.
Therefore, the degree of crowding in an area will have an important effect on the amount of overlap
between individuals and the mean growth of individuals in an area. Competition may be within a
species (intraspecific) or between individuals of different species (interspecific). Differences in
growth form (shape of leaves and arrangement on stem), root depth, development rate, daily pattern of
water and nutrient uptake from the soil, and photosynthetic pathway may all influence the magnitude
of competition.
In this exercise, you will be measuring the effect of competitor density on the growth of plants. You
will be able to design your own experiment to test hypotheses about expected differences in
competitive effects between species under different environmental conditions. You will carry out the
experiment in the greenhouse.
OBJECTIVES
During this laboratory exercise you will

Generate hypotheses regarding the outcome of competition between two plant species.

Design and conduct and experiment to test competition between two potential plant competitors.


Learn how to perform a regression analysis and how to compare the slopes of two regression
equations.
Discover some of the many adaptations that allow plants to survive conditions of differing
temperature and moisture.
29
BACKGROUND
The effect of intraspecific competition in plant populations is usually examined by planting the
species over a range of densities. The most common result is that the mean weight per plant decreases
as density increases (Figure 1) so that total yield (weight per area) approaches some constant value
(Figure 2). This result of diminishing returns is called the Law of Final Yield (Harper 1977). We can
think of this constant yield as the carrying capacity (in terms of biomass) of the environment.
Carrying capacity is the number, or mass, of individuals that can be supported by a particular
environment at any one time. Graphs such as figures 1 and 2, can be used to approximate the optimal
planting density for a particular crop – the density beyond which total yield no longer increases.
Fig. 1
Mean
weig
ht
per
plant
Fig.
2
Total
weig
ht
per
area
Plant
density
Plant
density
You may have noticed that the mean weight per plant decreases in a non-linear fashion as plant density
increases. This non-linear relationship is difficult to analyze statistically. If, however, we transform
the non-linear relationship into a linear relationship, we can analyze the results using a simple linear
regression. A transformation is simply a mathematical manipulation of one or both measured
variables. The best transformation in this situation involves calculating the reciprocal of mean plant
30
weight (1/w). The reciprocal of mean plant weight is related to plant density in a linear fashion
(Figure 3) according to the following formula:
1/w = a + b·D
Where w = mean plant weight, D = density, a = reciprocal of the maximum mean plant weight, and b
= coefficient of competition. This formula is called the reciprocal yield equation. A large (positive)
value of b (steep slope) implies a strong competitive effect.
Fig.
3
1/w
Plant
Density
Most plants, however, do not live in a monoculture but experience interspecific competition from a
number of other species. Even crops must share their environment with various weed species. To
examine the effects of interspecific competition, you can use an experimental design similar to the one
described above for intraspecific competition. In this case, you have two species, an indicator species
(i) and a competitor species (j). If you keep the density of species i constant and vary the density of
species j, you will be able to measure the effect of species j on species i. This type of experiment is
referred to as an additive design because competitors are added to indicators so that the total density
of the mixture increases (Harper 1977).
If the density of the indicator species is kept low enough so that intraspecific competition is weak or
non-existent, we can use the reciprocal yield equation to describe interspecific competition only. In
this situation, w = mean of the indicator species, D = density of the competitor species, a = reciprocal
weight of the indicator when no competitors are present (D=0), and b = competitive effect of species j
on species i.
Using the above design and analysis, students in each laboratory section will conduct experiments to
test hypotheses about the interaction between two likely competitors. The plant species available in
this exercise were chosen because they are potential competitors under natural conditions.
31
SAMPLE EXPERIMENTS
Students will get in groups of two and will conduct two experiments, each consisting of 5 density
treatments. A single treatment consists of one indicator species and one competitor species grown in a
single pot. Each treatment will be replicated three times. Therefore, there you will need 15 pots for
each experiment. You can design experiments to test different combination of species or the same
combination under different environmental conditions. Some suggested designs are given below.
1. Compare intensity of competition (b) for two competitor species on a single indicator species.
Choose your species so that you can develop hypotheses about which species should be the
strongest competitor from knowledge of its morphology or physiology. For example, you could
compare several species of similar growth form but different seed size. If you include the same
species as both indicator and competitor, you can compare the intensity of intraspecific to
interspecific competition.
2. Compare the intensity of competition for two indicator species with the same competitor species.
Again, choose species so that you can develop hypotheses about likely outcomes.
3. Compare the same species pair, reversing which one is the indicator and which the competitor. Is
one species a stronger competitor than the other?
4. Compare the same species pair under various resource levels. Do different levels of fertilizer or
water alter the intensity of competition (b)? What might be the outcome of competition between a
legume and grass under low and high nitrogen fertilization? What might be the difference
between a C3 and C4 grass with mycorrhizae additions?
SPECIES SELECTION
There are two main groups for species selection: eight grass species and two legume species will be
available for experimentation that are cultivars or native mid-elevational species to SW Colorado
which include: four grass species, two legume species and four forb species (see lists below). Consider
the specific adaptations of each species (growth form, seed size, nutrition, and photosynthetic
pathway) as you design your experiments. The seeds of the various species vary in size. How might
seed size affect competition? The legumes are nitrogen fixers. They have symbiotic bacteria
(Rhizobium) in root nodules. These bacteria convert atmospheric nitrogen into a form utilizable by
the plant. How might this affect the outcome of competition with a non-nitrogen fixing species or
another legume? Millet is the least closely related grass species. It has a C 4 photosynthetic pathway
whereas most of the other species have a C3 pathway. The C4 pathway allows a plant to
photosynthesize more efficiently in hot, dry environments. Does millet have an advantage when light
is high and soil moisture low? Lastly some of these plants are allelopathic. Allelopathic plants have
the ability to release chemicals that suppress some other plant species growing around them by
processes such as reduced seed germination or seedling growth. How would this effect competition?
32
Cultivar Species Mix
Legume C-pathway
Allelopathy
Family Fabaceae
Red clover (Trifolium pratense)
Alfalfa (Medicago sativa)
yes
yes
3
3
no
no
Family Legumacae
Green Pea (Pisum sativum)
yes
3
no
no
no
3
3
no
yes
no
no
4
4
no
yes
no
no
3
3
no
no
Family Poaceae
Subfamily Pooideae
Oats (Avena fatua)
Rye (Secale cereale)
Subfamily Panicoideae
Millet (Pennisetum spicatum)
Sorghum (Sorghum sp.)
Family Solanaceae
Tomato (Lycopersicon sp.)
Green pepper (Capsicum annuum)
33
Southwest Colorado Native Mid-Elevation Species Mix
Legume C-pathway
Allelopathy
Family Fabaceae
Lupinus argenteus
Oxytropis lambertii
yes
yes
3
3
no
no
Family Poaceae
Pascopyrum smithii
Bouteloau gracilis
Elymus elymoides
Muhlenbergia wrightii
no
no
no
no
3
4
3
4
no
no
no
no
Family Scrophulariaceae
Castilleja linariifolia
no
3
yes
Family Onagraceae
Epilobium angustifolium
no
3
no
Family Asteraceae
Artemisia ludoviciana
Erigeron speciosus
no
no
3
3
no
no
34
DIRECTIONS
PLANTING PROCEDURE
1. Prepare 15 four-inch pots for each experiment. Use tape to label each pot with indicator name,
competitor name, competitor density, replicate number, and treatment (fertilizer, mycorrhizae).
Remember that there should be 5 density treatments with 3 replicates each. Fill each pot with soil
to the inner rim.
2. Calculate seeding rate. For best results, you should have 2 indicator plants per pot. Competitor
plant densities should be 0, 4, 8, and 16. Because all seed will not germinate, you should plant at
least 3 indicator seeds in each pot (you can thin the plots after they germinate if needed). Plant 0,
6, 11, and 20 competitor seeds in appropriate pots.
3. Plant seeds by distributing them evenly across the soil surface. Plant at a depth of 3 times the seed
size. Place a straw or toothpick next to each indicator seed. This will help you find the plants
after the competitor species germinate as many of them look similar.
4. Put all pots for one experiment in two plastic trays (set 1 and set 2). Label tray with treatment
(“fertilizer”, “mycorrhizae”), if needed. Randomly place pots in trays.
5. Check the pots every week for germination of indicators and later for their survival. If more seeds
than expected germinate, thin plants to appropriate density.
HARVEST
All plants will be harvested and weighed after 7 weeks. Students should harvest their plants only.
1. Carefully pull each plant out of the soil, removing the indicators first.
2. Count the number of surviving indicators and competitors.
3. Note reproductive stage of plants (flower, seeds) and numbers for each species. Also note
anything else unique you see about your plants before you harvest them.
4. Clip the roots from each plant (shoots) and measure the total length (cm) and wet weight (g) of all
indicators and competitors for the roots and shoots. Place in drying oven at 65 ºC for 24 hours and
reweigh to get dry weight (g) of the roots and shoots.
ANALYSIS
1. Calculate the reciprocal mean plant weight (1/w) for the indicator species in each pot. Use dry
weight.
2. Create two graphs for each experiment. On the first, plot 1/w against final competitor density. On
the second, plot 1/w against final competitor weight. Each group should create four graphs.
3. Perform a regression analysis and calculate the reciprocal yield equation for each experiment.
35
4. Compare the slopes of the two reciprocal yield equations (b1 vs b2).
5. Calculate the Root Weight Fraction for all of the species in both experiments. RWF=root dry
weight/total dry weight. Compare the RWF among species and experiments.
6. Calculate average root and shoot lengths (cm) and create figures with means and standard error of
means. Run statistics. Also calculate averages for any reproductive stage data you gathered and
present means and SEMs.
DISCUSSION QUESTIONS
1. What hypotheses were you testing in your experiments? What reasoning led you to develop these
hypotheses?
2. Did your results support your hypothesis? What conclusions can you draw?
3. What abiotic or biotic factors in nature might change the competitive outcome you observed?
How could you design a similar test in the field?
4. What plant community ecology theories are supported and/or refuted or simply are relevant to
your experiments?
5. How would you improve this study to expand its scope or to better address your initial
hypotheses?
References
Begon, M., J. Harper, and C. Townsend. 1986. Ecology: Indivduals, Populations, and Communities.
Sinauer Associates, Inc. Sunderland, MA.
Goldberg, D.E. and L. Fleetwood. 1987. Competitive effect and response in four annual plants.
Journal of Ecology 75: 1131-43.
36
Harper, J.L. 1977. Population Biology of Plants. Academic Press. London. 892 pp.
Krebs, C.J. 1985. Ecology: The Experimental Analysis of Distribution and Abundance, 3rd ed.
Harper and Row, New York.
Spitters, C.J.T. 1983. An alternative approach to the analysis of mixed cropping experiments:
Estimation of competitive effects. Neth. J. Agric. Sci. 31: 1-11.
Adapted from: www.ecogrow.com
37
38
Treatment
Repl.
No. of
indicators
Mean wet
weight root
(g)
Mean dry
weight root
(g)
No. of
competitors
Mean wet
weight root
(g)
Mean dry
weight root
(g)
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
39
Treatment
Repl.
No. of
indicators
Mean wet
weight shoot
(g)
Mean dry
weight shoot
(g)
No. of
competitors
Mean wet
weight root
(g)
Mean dry
weight root
(g)
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
40
Treatment
Repl.
No. of
indicators
Mean length
shoot (cm)
Mean length
root (cm))
No. of
competitors
Mean length
shoot (cm)
Mean length
root (cm))
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
41
Tree Ring Basics
Tree-Ring Basics- From: http://tree.ltrr.arizona.edu/dendrochronology.html; The Laboratory of Tree-Ring
Research, Tucson, Arizona
What is Dendrochronology?
Dendrochronology is the dating and study of annual rings in trees.
The word comes from these roots:
ology = the study of
chronos = time; more specifically, events and processes in the past
dendros = using trees; more specifically, the growth rings of trees
Dendrochronologist
a scientist who uses tree rings to answer questions about the natural world and the place of humans in its
functioning
What do Tree Rings Tell Us?
The practical applications of the study of tree rings are numerous. Dendrochronology is an interdisciplinary
science, and its theory and techniques can be applied to many applications. See our subdisciplines for
examples. These research interests have in common the following objectives:
to put the present in proper historical context
to better understand current environmental processes and conditions
to improve understanding of possible future environmental issues
Why Not Just Count the Rings?
Ring-counting does not ensure the accurate dating of each individual ring. Numerous studies illustrate how
ring-counting leads to incorrect conclusions drawn from inaccurate dating. Dendrochronologists demand
the assignment of a single calendar year to a single ring. Various techniques are used to CROSSDATE
wood samples to assure accurate dating.
Dating Method: Crossdating by Skeleton Plotting
The SKELETON PLOT is one method of crossdating tree rings.
42
crossdating (dendrochronology's fundamental technique)
matching ring-growth characteristics across many samples
from a homogeneous area (area of similar environmental
conditions)
permits identification of EXACT year of formation for
each ring
'skeleton plotting' is one method of crossdating
skeleton plotting (one method of crossdating)
the process of marking a tree's ring width variation on
graph paper strips (the 'skeleton plot')
similar patterns of variation in individual plots
(representing individual trees) are matched among trees
Basics of Ring Formation
Understanding these concepts will help you succeed at this website's skeleton plotting and crossdating
exercises. This page does not attempt to cover the details of wood formation that make tree rings possible,
but rather provides an overview of common wood characteristics and anomalies that you will need to
identify when you are crossdating.
(trans
Conifer Tree Ring
earlywood
verse
appears light in color
or
cells have thin walls, large diameter
crosslatewood
sectio
appears dark in color
nal
cells have thick walls, small diameter
view)
Angiosperm Tree Ring
earlywood
cells have large diameter vessels
(transverse or cross-sectional view)
43
latewood
cells: small diameter vessels
Ring Width Variation
This picture of a conifer wood sample shows
variation in total ring width:
a light and a dark band
variation in latewood width:
just the dark bands
variation in latewood density:
darkness of dark band
The rings display much variation:
Variation in these rings is due to variation in environmental conditions when they were formed.
Thus, studying this variation leads to improved understanding of past environmental conditions
and is the basis for many research applications of dendrochronology.
A key distinction of dendrochronology is that all trees rings being
analyzed are dated to their correct year of formation. At first
glance, it appears easy to date tree rings by just counting them, but
reality is often more complicated than that.
44
45
46