Mark A. Davis

Professor of Biology
Macalester College


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Syllabus AssignmentsUFIs (Useful Flyers of Information for students)

BIOL 180 Ecology (4 Credits)
Fall 2005
Professor Mark Davis
Office: OlinRice 219; 696-6102
Office Hours    M: 1:30-3:00, W: 1:30-3:00


Biology 180 (Ecology) is a comprehensive introductory ecology course.  Students will be introduced to the principal ideas and theories currently engaging population, community, and ecosystem ecologists.  Students also will examine a variety of environmental problems from an ecological perspective.  The course encompasses both terrestrial and aquatic systems, however it emphasizes terrestrial systems.  Plant and animal ecology receive approximately equal treatment.  In addition to reading and hearing about ecology, students will have the opportunity to conduct field sampling and research.  During several field problems, students will learn field techniques used by ecologists--observation, measurement, sampling, and analysis.  Students will also be introduced to other ecological tools, e.g., experimental design, statistics, and computer modeling.  

REQUIREMENTS SATISFIED:  This course is required for a Biology Major. It also meets course requirements for a Biology Minor, one of the natural science requirements for an Environmental Studies Major, and 4 credits of the college’s Natural Science Requirement.

TEXTS: Stiling (2002) Ecology: Theories and Applications; and other readings to be assigned.

LECTURES/DISCUSSIONS: MWF 9:40-10:40 a.m. in OlinRice 250.   Please come to class before 9:40.  Coming to class late is disruptive and inconsiderate, and you will miss important information.

LABORATORY/FIELD TRIPS: Th 8:30-11:40 a.m.; Th 1:00-4:15 p.m.  We will use the weekly laboratory time to engage in a variety of activities, including field studies, field trips, workshops in statistics and computer modeling, student presentations, and exams.

WRITING, EXAMINATIONS, AND GRADING: There will be 3 exams--2 exams during the term and a final exam (100 points each).  Several of the laboratory activities will require write-ups and these will be graded as well.  There will be a final project resulting in a 2 page executive summary and an oral presentation.  In addition, students will write several memos to one another on  issues raised in the course.  Students will be evaluated on their performance on exams (50%), their laboratory writeups (30%), their final project (15%), and their participation in class discussions and memo writing (5%).  Attendance at labs/field trips is required and any missed labs will result in a 20 point deduction from the semester total.  Attendance at lectures and class discussions is highly recommended. Each missed discussion will result in a 5 point deduction from the semester total.  The final exam is scheduled for Thursday, December 22, 8:00-10:00 a.m.. Students must arrange their end of the semester travel arrangements so that they can take the exam when it is scheduled.  Note: if you have need for special test-taking or note-taking accommodation, please feel free to discuss this with Professor Davis.

SCHEDULE OF TOPICS (Readings from Stiling; page numbers indicated)

September      7    Introduction                            1-18


9    Population Genetics                        19-29
12    Population Genetics (continued)
14    Natural Selection
16    Evolution and Speciation


19    Environmental Gradients                    89-107, 227-230
21    Succession                            303-312, 314-317
23    DISCUSSION (Memos Due)
26    Disturbance, Equilibrium, Climax Communities, and         289-302
        the Idea of Scale
28    Competition and Resource Partitioning            108-122, 127-134
30      Patterns of Species Diversity                    249-270, 273-276, 344-346
October 3    Island Biogeography                        318-334
  5    Biological Invasions
  7    DISCUSSION (Memos Due)
10    Population Growth                        66-88
12    Review for Exam #1 


13    (EXAM #1)
14    No Class (International Roundtable)
17    Population Growth (continued)
19    Limits to Population Growth                    206-225
21    DISCUSSION (Memos Due)
24    Persistence and Extinction                    30-41
26    Predation/Herbivory                        160-169, 180-188
October 31    Living in Groups                        42-53
2     Coevolution, Parasitism, and Mutualism            135-144, 147-149, 189-205


  4    Energy Budgets and the Principal of Allocation
  7    Life Histories                            54-55, 59-64
  9    Reproductive Syndromes, Dispersal and Dormancy
11    DISCUSSION (Memos Due)


14    Primary and Secondary Production and Energy Flows    348-355, 336-341
16    Review for Exam #2
17    EXAM #2
18    Primary and Secondary Production (continued)        355-359
21    Nutrient Cycling                        360-371
23    Landscape Patterns at Global and Multiple Scales        230-248



28    DISCUSSION (Memos Due)


30    Restoration Ecology
December 2    Acid Rain
 5    Cultural Eutrophication Global Atmospheric Issues
 7    Global Atmospheric Issues
 9   Global Atmospheric Issues (cont)
12   DISCUSSION (Memos Due)
14   Toxic Wastes
16   Final Thoughts

22      FINAL EXAM (8:00-10:00 a.m.)


Date        Site                        Objective/Focus

9/15        Ordway                Field Study #1.  Ecological change over time and space (Orientation and field data collection)

9/22        Ordway                Field Study #1. (Field data collection continued)

9/29        Ordway                Field Study #1. (Field data collection completed)

10/6        Ordway                Field Study #2. Diversity and Distribution (Orientation)

10/13      OlinRice               Exam #1

10/20     Ordway                 Field Study #2. (Field data collection completed)

10/25     OlinRice               Biostatistics and Graphics Lab

Fall Break

11/3        OlinRice             Work on Data Analysis for Field Study #2

11/10        OlinRice            Introduction to Ecological Modeling    

11/17        OlinRice            Exam #2

12/1        OlinRice            Management and Habitat Restoration Exercise (Orientation for Final Project)   

12/8        OlinRice             Student Oral Presentations of Final Project

<>12/15        OlinRice           Student Oral Presentations of Final Project    

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 Forest Succession Lab Diversity and Distribution LabStatisticsFinal Project


On this and the next field trip to Ordway, you will study an oak woodland and forest, a habitat located near the border of the North America grasslands to the west and the eastern deciduous forest to the east.  During this field exercise, you will be examining both temporal and spatial patterns of the forest.


I.  Temporal Change.  One of the primary interests of forest ecologists is whether forests are regenerating, and if they are regenerating, whether the next generation of mature trees will be of the same species composition as the current generation of trees.  If the next generation differs from the current generation, ecologists often call this change >succession=.  If the next generation is basically the same as the current generation of trees, ecologists refer to the tree community as being in an  >equilibrium= state, sometimes referred to as a >climax=.

II.  Spatial Patterns.  Ecologists have always been particularly interested in how organisms are distributed across the landscape since non-random distributions (e.g., clumping or regular dispersion) usually mean that some biological and/or physical mechanisms are working to produce these patterns, mechanisms such as competition, predation, dispersal mechanisms, and underlying substrate patchiness.  Recent studies in six species rich tropical forests in Central America, South Asia, and Malaysia  have shown that most tree species are clumped, that the degree of aggregation declines with distance, that small trees are more aggregated than large trees of the same species, and that rare species are more aggregated than common species.  To date, only one study has been conducted in a temperate forest (a species-poor oak woodland at the Cedar Creek Natural History Area, located 35 miles north of the Twin Cities) and the results are remarkably consistent with the tropical findings, raising the possibility that diverse forest types may be subject to common organizing processes.

Objectives:  You have two objectives in this field exercise.  Your first goal is to sample the Ordway oak woodland  and determine whether you believe the woodland is in a climax state or whether it is undergoing succession.  Your second goal is to quantify the spatial patterns of trees in the woodland and provide a second temperate data set to compare with tropical forest findings.

Methods:  You will work in groups of 4 individuals.  As a group you will collect data in the field at Ordway.  You will be assigned to a site in the woodland and sampling should approximately three to four  hours (spread over two to three lab days).  When you return to Macalester, you will compile and analyze your data in order to make your conclusions as to the successional status of your site and the spatial patterns of the trees.  Each group will write up their results and conclusions in a summary report.

I.    (Temporal Change)  To determine whether a forest community is in a climax state or undergoing succession, you need to sample several generations of trees in the forest, including the mature trees, the juvenile trees (saplings and small trees), and seedlings.

A)  To sample the mature trees (>10 cm dbh [diameter at breast height), you will use the point-quarter method (see attached description of this method).  Include 12 points in your transect.  Use Table 1 to record your data in the field.

B)  To sample the saplings and small trees (>2 cm and <10 cm), set up a 2.24 x 4.47  m plot (10 m2) centered at each of the 8 points (12 points if there is enough time) and count the number of trees of each species in this size class in each plot. To sample the seedlings, count the number of seedlings (<2 cm dbh) of each species in each of the same 8 (or 12) plots.  Use Tables 3 and 4 to record your data in the field.

C)  To gain some insight as to the frequency of small scale disturbance at each sites, e.g., tree falls, and to determine whether certain species representing the juvenile or seedling cohort are more common under canopy gaps, estimate the percent canopy cover by mature trees over each 10 m2 plot.  Use the canopy sighting device (densitometer) at five locations for each plot (one at each corner and one in the middle of the plot) and record either a 1 (if sighting point intersects tree canopy) or a 0 (if the sighting point intersects the sky) for the five sightings at each of the 8 (or12) transect points in Table 4.

II.  (Spatial Pattern)    Standing at each of the 48 trees (>10 cm dbh) encountered in the point-quarter sampling, find the nearest tree at least 2 cm dbh (this is now your target tree), identify it (it may be the of the same or different species as the 10 cm tree), record the species on Table 1, and record the number of other trees of the same species (any size) within 5 m of the target tree.  Record this number on Table 1 for each of the 32 (or 48) trees.

SUGGESTION:  In a group of four, it will probably be most efficient if, once a point along the transect has been established, two group members collect the point-quarter data (IA, using Table 1 to record raw data) and the spatial  pattern data (II) while the other two members set up the 10 m2 plot  and collect the plot sample data (IB, using Tables 3 and 4 to record raw data).  Whichever group finishes first at a point can then collect the canopy cover data (IC, using Table 4 to record the data).

Data Compilation and Calculations:

I.    (Temporal Change)

1)  For the point quarter sampling of mature trees, complete Table 2, or an EXCEL spreadsheet in the same format.  Express tree density as number of trees per hectare.  (A hectare equals 10,000 square meters and 10,000 should be used as >unit area= in the equation for total density.)  Follow the instructions for the point-quarter calculations carefully (see page 5).

Important Notes:  A special time will be arranged for those who would like to learn how to do these calculations using EXCEL.  Be sure to do the calculations in the prescribed order.  Basal area for an individual equals the area of the trunk at breast height. In making this calculation, remember that you are recording diameter not radius. Also, to convert cm2  to m2, divide cm2  by  10,000. In completing Table 2, you will calculate a single number for each species called the Importance Value.  This number, which incorporates the density, distribution, and size of trees of each species, describes the prominence of each tree species in the community.

2)  For the plot sampling, calculate an estimate of density for each species in each of the two small size classes (sapling and seedlings) and record these estimates in Tables 5 (saplings) and 6 (seedlings). Express density as number of stems per hectare.   (Note: the total area sampled in your 8 plots is 80 m2 (120 m2 if you completed 12 plots)  Thus, you will need to convert density (number of stems) in your 12 plots to density per hectare (10,000 m2.)).  Also, include the frequency (0.0-1.0) of occurrence in the 8 (or12 plots) for each species in each size class in Tables 5 and 6.  (If a species were present in half of the plots, its frequency would be 0.50.) For each species in each of the two size classes, calculate relative density (sum the densities of all species encountered in a size class and divide the density of each species in the size class by this number) and relative frequency (sum the frequencies of all species encountered in a size class and divide the frequency of each species in the size class by this number) and include these results in the two tables as well.  Finally, calculate an Importance Value (IVi) for each species based on relative density (RDi) and relative frequency (RFi), i.e., IVi=(RDi+RFi)/2.

(3) Calculate the mean canopy cover for each of the 8 (or12) plots (0.0, 0.2, 0.4, 0.6, 0.8, 1.0) and then the mean canopy coverage for your transect.  The means will tell you something about the average amount light reaching the lower vegetation layers in individual plots and the woodland as a whole.

II.    (Spatial Pattern)

1)     For each species encountered in your sample of 32 (or 48) trees, calculate the total area (A) in meters squared of  all the 5 m radius plots censused for that species (= 78.54 * no. of 5 m radius plots for that species) and the total number of neighboring stems of the same species (N) in all the plots of this species.  For example, if 10 of your trees sampled for spatial pattern were bur oaks, A = 785.4 m2.  If in all ten of the 5 m radius plots centered around these 10 trees you counted a total of 25 other bur oaks 2 cm dbh or larger, N = 25.

2)    Then, calculate the neighbor density (ND) for each species (N/A).  In the example above, ND = 25/785.4 = 0.0318.  This number will represent the number of neighboring stems per square meter in the 5 m radius plots.  To convert this to density per hectare, multiply ND by 10,000.  In the example above, ND = 0.0318 * 10,000 = 318.

3)    To calculate the Aggregation Index (AI) for a species, divide the neighbor density (ND, expressed in stems per hectare) by the estimated absolute density (AD) of the species along your transect (also expressed in stems per hectare), that you calculated using the point-quarter and plot data.  (The estimated total density of a species is simply the sum of the density of the large trees (> 10 cm dbh), calculated from the point-quarter data, and the density of the small trees (2-10 cm dbh), calculated from the plot data.)  If  your estimated density was 100 trees ha-1 for large bur oaks, and 50 trees  ha-1 for small bur oaks, the summed density for bur oaks 2 cm dbh or larger would be 150 trees ha-1.  Using the example above, AI = 318/150 = 2.12.

An aggregation index >1.0 means that a species is clumped at the 5 m spatial scale, i.e., more trees of the same species are found within 5 meters of an individual tree than would be expected if the trees were randomly distributed.  An index <1.0 means that the species is more evenly dispersed than predicted from a random spatial distribution of the trees An index approximately equaling 1.0 (e.g., 0.8-1.2) means that there is no or very little clumping or regular dispersion present and that trees of this species appear to be randomly distributed throughout the landscape.   In the example above, the bur oaks would appear to be clumped.  Enter your calculations, including your Aggregation Indices on Table 7.

Writeup: Summarize your results in a scientific report.  The report should include an introduction in which you introduce the issues of succession and spatial patterns in forests and state the objectives for your study, a methods section in which you briefly describe the study habitat and the methods you used, a results section in which you verbally summarize your results and include Tables 1-6, and a discussion section (two to four pages) in which you present your thoughts regarding whether the oak woodland is in a successional or climax (equilibrium) state and whether the spatial patterns in the Ordway forest are similar (or different) to the patterns found in the tropical forests and the oak woodland at Cedar Creek.  (More information will be provided as to how to write a scientific paper.) You should also include a bibliography of any works cited in the text.

  In your discussion, you should explain how your results support your conclusions. If you conclude that the woodland is in a climax state, what events or processes (e.g., disturbances or climate change) could cause the woodland community to move into a successional state. If you conclude that the woodland is in a successional state, what would you predict the woodland will be like in 50 or 100 years, assuming the current disturbance and climate regime continues?  Was the percent canopy cover quite similar from one plot to the next, or where there distinct light gaps?  Were some species in the juvenile or seedling stage more likely than others to be found in light gaps?  What ecological factors might be responsible for light gaps?   If the uncommon species are more spatially aggregated than the more common species (as was found in the tropical and one temperate study), can you think of what ecological mechanisms might be responsible for this pattern?  (By the way, no ecologists have yet established what these mechanisms are, or why the spatial patterns of trees in species-poor temperate forests should be so similar to those in species-rich tropical forests, so your brainstorming will be very much appreciated.)  In your discussion, provide a concluding paragraph in which you summarize your results and conclusions.

Suggested Readings (On reserve)

Abrams, M. D. 1992. Fire and the Development of Oak Forests. Bioscience 42:346-353.

Runkle, J.  R.  1985. Disturbance regimes in temperate forests. in Pickett and White.  The ecology of natural disturbance and patch dynamics.  Academic Press, New York.

Condit R. et al. 2000.  Spatial patterns in the distributions of tropical tree species. Science 288:1414-1417.


Field Component.  The point-quarter method is a plotless method of estimating tree density.  It is commonly used by foresters and forest ecologists.  Data collection in the field is quite simple.  A line transect is established in the site to be sampled.  Points along the line transect are established using a random number generator of some sort.  At each point, an imaginary line is established perpendicular to and crossing the line transect to produce four quadrants.  In each quadrant, the tree nearest the point of intersection on the line transect is identified, its dbh (diameter at breast height) is measured, as well as the distance (in meters) of the center of the tree to the point of intersection.  When these three bits of data are recorded for all four quadrants, the field team moves along to the next point.

Use the attached sheet of random numbers to generate the random distances between points by doubling the first two numbers in a 5 digit set and dividing by 10.  (For example, if the 5 digit number is 61329, take 61, double it [=122], and divide by 10 yielding 12.2 meters.)  If your result is less than three meters, repeat the procedure with a new 5 digit set.

Calculations.  Follow the steps below to complete Table 2.

1.  For each tree, calculate the basal area (last column, Table 1)

2.  Calculate the mean point-to-tree distance (in meters) based on all trees (e.g., 32 trees if your transect consisted of 8 points).  Square the mean point-to-tree distance.  Divide 10,000 (the number of square meters in a hectare) by the square of the mean point-to-tree distance.  This represents the estimate for total tree density (TD) for all species combined per hectare.

3.  Calculate the relative density (RD) for each species (divide the no. of trees encountered of each species by the total number trees you sampled, e.g., 32 trees if your transect consisted of 8 points.

4.  Calculate the estimated absolute density (AD) per hectare for each species (RD*TD).

5.  Calculate the absolute frequency (AF) for each species (i.e., count the number of points that contained at least one tree of that species and divide this number by the number of points in your transect).  Note that frequency is based on number of points, not number of quadrants.

6.  Calculate the relative frequency for each species (divide AF by the sum of AFs for all species).

7.  Calculate the mean basal area (MBA) for each species.

8.  Calculate the estimated total basal area (TBA) per hectare for each species (MBA*AD).

9.  Calculate the relative basal area (RBA) for each species (divide TBA by the sum of TBAs for all species).

10.  Calculate the Importance Value (IV) for each species (RD + RF + RBA)/3.Return to Assignments Return to Main Menu


No one knows how many species inhabit the earth.  Estimates range from three to more than one hundred million.  What is known is that these species are not distributed evenly across the Earth=s surface.  Some species are very widespread, while others are found only in one small location.  Some species occur in a wide variety of habitats, while others are restricted to a single habitat type.  And some are abundant in the communities they inhabit, while others are always uncommon.  Some of these patterns are obvious to any observant person, while others are more subtle and must be documented more systematically.  In any case, describing these patterns is the first step in understanding what factors influence species diversity.  The patterns often suggest hypotheses, and hypotheses prompt curious scientists to conduct field studies to determine if their intuition is correct.  In addition, knowing patterns of species diversity and understanding the causes behind these patterns enables us to make wise conservation decisions.

One commonly found species pattern in nature is that species richness increases with the area sampled, often in a very predictable way (see Stiling pp. 322-328 for more information on the species?area relationship). Interestingly, this trend has been found to exist at widely divergent scales, from small mangrove islands several meters across to entire continents.  Although limitations of the species?area relationship have been pointed out, this mathematical relationship
continues to be used as an important guide for conservation biologists engaged in real efforts to preserve biodiversity. In this field study, you will determine whether the patterns of species abundance in the Ordway grassland are consistent with the species?area relationships that have been documented in numerous other studies, often at much larger spatial scales, in other parts of the world.

    The System Under Investigation  and Research Objectives

The grassland habitat at Ordway consists of a wide variety of grasses and wildflowers, the latter sometimes called forbs.  At first glance, and to the untrained eye, a grassland habitat often appears to be a uniform and homogeneous environment.  In fact, like most habitats, grasslands are spatially quite heterogeneous.  Some plant species are common and apparently distributed throughout the habitat, while others are much less common and are patchy in their occurrence.  This is the case at Ordway.

Your objectives are:

    Learning Objectives

By conducting this study, students will gain experience in:

1.    Observation and description (in this exercise this includes careful observation and inspection of individual plant species and naming and describing the plant species)

2.    Quantification of ecological phenomena (in this exercise this involves the quantification of species abundance via cover and presence/absence frequencies)

3.    Recognizing ecological patterns (in this exercise, the patterns are spatial patterns involving species abundance and area size)

4.    Comparative ecological analysis (in this exercise you will be comparing your observed abundance patterns with those in the literature)

5.    Recognizing the practical value of theoretical ecology (in this exercise, this will involve seeing the potential value to conservation biology of insights gained from species-area theory)


The class will be divided into groups of 4 individuals per group.  Each group will be assigned a portion of Ordway to study.  As a group, you will collect data in the field during the laboratory sessions at Ordway.  Later, you will compile and analyze your data, and then write up your results in a scientific report.  The entire project will take approximately two months to complete.

Sampling Procedures.  Given time constraints, you will not be able to exhaustively search your entire assigned area in order to compile your species list.  Instead, you will sample your area using plots of different sizes.  Specifically, you will identify herbaceous plant species in three very small plots (.25 x .5 m), three slightly larger plots (.5 x 1 m), three large plots (1 x 2 m) and three very large plots (2 x 4 m).  You will be provided with stakes, string, and a tape measure to lay out your plots.  The plots should be positioned randomly, with the provision that no plots overlap.  As a group, you will need to develop a procedure to position your plots in your area.

Since the focus of the current study is patterns of abundance, it is not necessary that you know the scientific names of the species you identify.  In fact, you will have the opportunity to name the species you find in your plots.  As is customary, the person finding a new species should have the honor of naming the species.  Normally, species are named by using an adjective and a noun, although sometimes a person=s name or a place is used instead of the adjective.  Examples from a species list might include names such as:  long-leaved yellow sunflower, Bob=s grass, short grass, sticky flowered forb, etc.  In order to determine whether your group has come across a new species for your habitat, you will need to compile a Afield herbarium@ of your specimens, against which you can compare new specimens.  Instructions for compiling your field herbarium will be given at Ordway on the first day of the project.

You will need to do your best to search each plot thoroughly for new species.  Begin with the smallest plots first.  These will be easiest to search exhaustively and will give you an opportunity to become familiar with the different species growing in your plot before getting to the larger plots.  Include in your plot censuses only forbs 5 cm tall or wide and only grasses that are flowering.  For each species in each plot, record its abundance on a scale of 1 to 3, with 1 being rare to uncommon (<5% cover), 3 being abundant (>25% cover), and 2 being somewhere in between (5-25% cover).  Keep a record of which species you found in each of the 12 plots along with the abundance index for each species.  After completing the censusing of your12th plot, divide this plot into sixteen 1 x .5 m subplots and estimate percent cover for each species in each subplot using six abundance categories (<1%, 1-2%, 2-5%, 5-25%, 25-50%, >50%); also determine the frequency of occurrence of each species in the 16 subplots, i.e., the number of subplots that contain each species. Finally, using the cover categories for each species in each of the 16 subplots, develop a method to calculate a percent cover for each species for the entire large plot.

    Timetable and Logistics

Thursday, October 6    Trip to Ordway.  Groups are formed and are assigned a portion of the field station to sample.  Groups spend some time familiarizing themselves with the system and develop a methodology to randomly position the plots.  Sampling and development of the Afield herbarium@ begins.

Thursday, October 20         Complete all necessary field work

Thursday, November 3        Biostatistics and Computer Lab

Thursday, November 10        Work on Ordway Analysis and Writeup

Monday, November 7        First Draft of Final Report Due

Monday, November 21    Final Report Due
    Final Report

Your final report will consist of six sections:

--An Abstract: a one paragraph summary of the objectives, methods, results, and implications of your research.

--An Introduction, in which you review some of the relevant literature, set the context for your study, and state your objectives.

--A Methods section, in which you describe your sampling and other field procedures and also your methods of data analysis.

--A Results section, in which, along with a verbal summary, you present the following data and graphs:

A summary table (Table 1) showing which species are found in which plots, with totals showing the number of species and area per plot, and cumulative totals of area and species number as each new plot is added.  (For the cumulative totals, begin with the smallest plots and add successively larger plots).

A species-area scatter graph showing the relationship between cumulative number of species and cumulative area.  Add a linear regression trendline to the graph. The graph should also contain the r2 and p values for the linear regression.

A species-area scatter graph with log transformed x and y axes showing the relationship between cumulative number of species and cumulative area. IMPORTANT:  Before creating this graph, multiply the area values by 10.  (Since the log of a number less than 1.0 is a negative number, multiplying each of the area values by 10 makes sure that all the transformed numbers will be positive while preserving the relative magnitudes of the differences between areas.)  Add a power regression trendline to the graph after you have log transformed both axes. Include on your graph the r2 value and the p value, as well as the power equation (which you will compare with other similar equations from the literature). See Stiling pp.  322-328 for more information on species area relationships, species area curves using log axes, and the species area equation.

A table (Table 2) showing cover, relative cover, frequency, relative frequency, and Importance Value for each species in your 12 plot (the 3rd largest plot).  In order to calculate per cent cover for the different species in your plot, you will need to decide on a way to convert cover classes (e.g., 5-25%) to a specific cover value.  To calculate the relative cover for each species in the plot, divide the cover value you calculated for each species for the entire plot (i.e., mean of the 16 subplot cover values) by the summed cover value for all species. The frequency value for a species is the number of subplots (1?16) in which the species was found. Relative frequency for a species is the frequency value for that species divided by the summed frequency values for all species.

The Shannon Diversity Index for your 12th plot.  (Use the relative cover estimate of each species as pi).

Make a rank-abundance column graph using the data from your 12th plot.  The x-axis should be abundance rank (e.g., 1-12 if you had 12 species in this plot), and the y-axis should be the actual percent cover (e.g., 0.5, 3.5, 37.5, except that you will multiply each cover value by 10 so that 0.5 becomes 5.0, 37.5 becomes 375, etc.  After you have created the graph, log-transform the y-axis.  Does your transformed rank-abundance distribution look most like a geometric distribution or one of the more equitable distributions (e.g., broken-stick or lognormal)?  See Stiling pp 280-284 for more information.

A table (Table 3) listing your species, the abundance index (1-3 scale) of each species in each plot, and the Ararity type@ you determined for each species.  You have four potential forms of rarity: 1) high coverage in most plots and found in all/most plots (not rare at all, actually); 2) found in one/just a few plots but abundant when present; 3) found in all/most plots but never/seldom abundant; 4) found in one/just a few plots and never/seldom abundant.  Along with your chart, provide the objective criteria you used (e.g., based on the abundance indices and presence or absence in plots of different sizes) to assign species to different rarity types.

--A Discussion section in which you thoughtfully interpret your results and discuss some of their implications.  This is also the time to point out any weaknesses or limitations of your study and
conclusions. In your discussion, you should address the following questions in your discussion:

Are your species-area curves (and z values) similar to those found in the literature?

Use your species area power equation (from your species area graph based on cumulative area and cumulative species) to answer the following questions:

How many plant species do you estimate are in the entire area you sampled?

If habitat area in your site declined by 90%, approximately what proportion of species would you expect to be lost?

Based on projections from your species area graph and data from your plots, which would you expect to yield more species at your site--a single large plot of 4 x 4 m or sixteen 1 x 1 m plots?  Explain your conclusion.  What insights might this give you regarding efforts to try to preserve as many species as possible in a landscape?

On the basis of your data and experience, what practical recommendations can you draw regarding measuring diversity?  For example, if one were cataloging bird species on a tropical island, how could you use a species-area curve to determine if further time spent looking for additional species were warranted (i.e., likely would turn up many additional species)?  If 90% of area of tropical forest was to be cleared leaving a small patch for a reserve, what would be your prediction regarding the number of plant species likely to persist in the site, based on your knowledge of species-area relationships?

What do you expect would happen to your species-area curves (plotted on linear axes with cumulative area as the independent variable) if the area of your plots continued to get larger and began to include other habitat types, e.g., forests or wetlands?  Draw a hypothetical species-area curve showing what you mean.

Which species in your habitat do you believe should be the targets of conservation efforts if we were interested in preserving species richness in your habitat?  What criteria did you use to come to this conclusion?  Is there any other information you might want before you make this decision?

--Acknowledgments (optional) in which you acknowledge the additional help provided by people outside your group, e.g., people who reviewed an initial draft of your paper, or someone who helped you with computer problems during a late night session in the computer lab.

--Literature Cited, in which you list sources actually cited in your paper.

Relevant Readings:
Stiling (pp. 322-328)
Cox 1993. The Design of Natural Preserves (5 pages, on reserve)
Meffe & Carroll 1992. Patterns of Species Vulnerability (5 pages, on reserve)
Vankat 1992 The Natural Vegetation of North America; pp158-169, 171-179 (on reserve)Return to Assignments Return to Main Menu


For each of the first three problems, state the null hypothesis and the alternative hypothesis.

Use Excel to perform these analyses and to make your graphs 

1.  It is hypothesized that the mean running speed of lizards in a group of related species is associated with the mean size of the respective species.  The following data were collected in a study to test this hypothesis.  First, state the null hypothesis and the alternative hypothesis.  Then, conduct a linear regression analysis to test these hypotheses and state your conclusion.  According to the results of your analysis, what proportion of the variation in running speed is attributed to variation in size?   Create a scatter graph of the data that includes the linear trendline, the r2 value, the significance level (p value), and the regression equation.  Be sure to edit the graph so that text, data points, and trendline are clearly readable.  If a new species were discovered with a mean annual size of 11 g, what would you predict the running speed of the new species to be?

                                    Species                        Mass (g)           Running Speed (

<>                                         A                                  10                                10
                                         B                                     2                                20
                                         C                                  18                                  3
                                         D                                    6                                12
                                         E                                     3                                15
                                         F                                   15                                  6
                                        G                                   13                                  7
                                        H                                     8                                11

2.  It is hypothesized that the mortality rate of a specific insect species is density dependent.  The following data were collected in a long-term population study.  State the null and alternative hypotheses.  Then, conduct a linear regression analysis to test these hypotheses and state your conclusion.  According to the results of your analysis, what proportion of the variation in mortality rate is attributed to variation in population size (density)?   Create a scatter graph of the data that includes the linear trendline, the r2 value, the significance level (p value), and the regression equation.  Be sure to edit the graph so that text, data points, and trendline are clearly readable.


                                                Population Size             Mortality Rate (%)

<>                                                            100                                          50
                                                            200                                          70
                                                            100                                          20
                                                              50                                          30
                                                              30                                          80
                                                            300                                          30
                                                            160                                          80
                                                              80                                          70

3.  It is hypothesized that seed dispersal distance is a function seed mass.  State the null and alternative hypotheses.  Using the data below, conduct a linear regression analysis to test these hypotheses. What is your conclusion?  According to the results of your analysis, what proportion of the variation in dispersal distance is attributed to variation in seed mass?   Create a scatter graph of the data that includes the linear trendline, the r2 value, the significance level (p value), and the linear regression equation.  Be sure to edit the graph so that text, data points, and trendline are clearly readable.

Then, log transform both axes, and add a power regression trendline to the new scattergraph.  According to this analysis, what proportion of the variation in dispersal distance can be attributed to variation in seed mass?   Create a scatter graph of the data with the log transformed axes, the power trendline, the r2 value, the significance level (p value), and the power regression equation.  If you wanted to predict dispersal distance on the basis of seed mass, which equation would you want to use, the linear or power equation?  If you came across a seed with a mass of 15 mg, what would you predict its dispersal distance to be?


                                    Seed Mass (mg)                                   Dispersal Distance (m)

<>                                                10                                              800
                                                  6                                              900
                                                30                                              150
                                                  2                                            6000
                                                26                                              100
                                                36                                                20
                                                33                                                50
                                                20                                              300
                                                  4                                            2000  <> 

4.  Using the following data, create a column graph showing the mean seed production for plants growing in the different habitat types.  Add a title to the graph.  Be sure to edit the graph so that axes labels are clearly readable.

                                    Habitat Type                            Seed Production

<>                                                A                                             1000
                                                B                                              2000
                                                C                                               350
                                                D                                             1500
                                                E                                                800
                                                F                                              1200

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Background:  Ecology has become the intellectual foundation for the new field of Restoration Ecology, a discipline that applies ecological theory and principles to efforts to restore species, communities, and ecosystems in Minnesota and throughout the world.  It has become clear that although each restoration effort has its unique aspects, there are some common issues and concerns that must be addressed in virtually all restoration efforts.  In this assignment, you are assuming the role of a restoration consultant.  An expert in ecology and restoration, you have

been hired to provide some initial guidance to a proposed restoration project involving an isolated patch of tall grass prairie that has been colonized in recent decades by woody plants and by herbaceous species new to North America while at the same time losing some of the plant species inhabiting the prairie prior to 1900.  The town that has hired you wants to conduct a restoration of this habitat to enhance the diversity of both the plant and animal communities.  The town plans to add plant species to the site by seed and also transplants.  The town and the prairie patch are surrounded primarily by agricultural lands.  The nearest other prairie habitat is 35 miles away.  The patch to be restored is approximately 25 acres in size and is adjacent to and down hill from a corn field.  Your job is to draft and present a Preliminary Ecological and Restoration Assessment (PERA) of the proposed project in which you identify six important ecological concerns that you believe must be satisfactorily addressed if the restoration effort is to be successful.

Objective:  To demonstrate that you understand fundamental ecological principles and theory and can apply these ideas to practical concerns.

More Information:  Your PERA should consist of a two page Executive Summary in which you list in turn each of the six ecological concerns, with each concern followed by a condensed rationale.  Your rationale should explain the ecological principles that are the basis for your concern.  You should conclude each rationale with some advice as to how to proceed with the design and implementation of the restoration plan to best meet the concern.

    In addition to turning in your Executive Summary, you will prepare a 12-15 minute oral presentation which you will present during one of the last two laboratory periods.  You will receive additional information regarding your oral presentation about a week before your presentation.  Your Executive Summary is due and must be turned in at the time of your scheduled oral presentation.  NO EXCEPTIONS!  PERAs must be turned in on a single sheet of paper, i.e., double-sided.  Due to the space limitation, you will probably need to single-space your entries.  Font sizes can be either 10 or 12.  To save space, do not include an introduction to your Executive Summary.

Evaluation:  Your PERA will be evaluated on how well you were able to apply a variety of ecological ideas and principles from the course (e.g., ideas related to evolution and population genetics, dynamics of populations, species interactions in biological communities, disturbances, life histories, mutualisms, and flows of nutrients in ecosystems) to the specific task of restoring an historical prairie at this site.  The degree to which your analysis and recommendations reflect an understanding of a broad range of basic ecological theory will be the primary basis for the evaluation.

Sources of Information:  This is not a research paper.  Your information and perspective should come primarily from the lectures, text book, assigned outside readings, discussions, and field trips.  You do not need to provide a bibliography with your executive summary.  This is not an exam!  While each student needs to write up their own Executive Summary, feel free to talk over ideas with other members of the class.  Although this is not an exam, you should view this assignment as a very important opportunity to show how much ecology you have learned in this class.

Points:  The Executive Summary is worth 60 points and the oral presentation is worth 30 points.  Together, they are worth nearly as much as one of the exams!

Supplemental and Optional Readings:  The following readings have been put on reserve to give you more background regarding restoration ecology, prairie ecosystems, and design of natural reserves.

 <>Primack 2002. Restoration Ecology (6 pages)
Meffe and Carroll. 1994.  Restoration of native prairies. (3 pages)
Bakker and Berendse. 1999.  Constraints in the restoration of ecological diversity in grassland and heathland communities. Trends in Ecology and Evolution 14:63-68.

BAD EXAMPLE:  Ecological Concern #X:  The environment might not be the right one for the desired species.  All species require a particular environment.  It is important that the right ecological conditions be created for the prairie grasses….. [This is a bad example because it is obvious; one did not need to take this class to know this; no specific ecological principles or theories covered during the class are incorporated into the response.]

GOOD EXAMPLE:  Ecological Concern #X:  Nutrient runoff from the adjacent corn field into the prairie habitat.  Corn fields are very open ecosystems because....It is very important to prevent the export of substantial amount of nutrients from the adjacent corn field into the restored prairie because.....  According to the principle....or.... as the xxx study showed, increases of nutrients into an ecosystem can affect community composition by....Nutrient export can be prevented by....

Yes, you may use this example as one of your concerns as you wish.Return to Assignments Return to Main Menu