Challenges to Anticipate and Solve:
I have identified 5 challenges that commonly arise:
- making field observations: Students who are not used to making observations in the field will need some help
and special training. One way to do this is to show slides of field sites in class and work with students on making observations
first (we call this "page one") and developing explanations for these second ("page two"; see essay on this in the
Teaching section. Many students have a difficult time distinguishing
between observations and interpretations. Another idea is to go outside near your building and have students write down
observations of what they see, and back in class to discuss their observations. The next step is to help students develop
specific questions based on their observations.
- using their observations and questions: Another skill is to use their observations and questions in the field site to
develop a project that you have already have sketched out. You need to be open to their ideas, but the project needs focus
and must meet your course objectives. This is a very tricky balance. For the first project of the semester especially, I tend the
guide the questions a fair amount.
- dealing with large data sets: An issue for students will be dealing with a fairly large data set. You will have to decide
how much creative chaos you find useful for your students and how much you need to own and orchestrate to effectively
accomplish data reduction. Students who don't how to use the spreadsheet and graphics package should be taught this
ahead of time. You can do this in class or perhaps a student assistant can do a session outside of class.
- focusing their data set: Many students have trouble finding a focus for their paper from this large data set. I ask
them to ask specific questions that require use of only part of the data so that they can develop a few ideas in more detail.
For instance, some students may analyze the temperature data in more depth than others or focus on one tree species.
During lab time you can ask students who have a more focused idea to describe it to other students as an example.
- writing a research style paper: How much time you spend teaching students how to write scientific style research
papers depends on their prior experience with this. If they have not written such papers before take class or lab time to explain
the structure of research papers and how to write them. If the class is small enough and if you have time, ask your students to
rewrite this paper. They will benefit enormously by doing this.
Comments On the Lab Description:
This lab is a multi-week field project that I use in my undergraduate second semester basic ecology class during February in
Massachusetts. I have found that this a good first investigation because it is based on students' own observations of tree types
and also common-sense environmental characteristics such as air temperature. In addition, this project gets them working
in the field in groups right away. Another reason why I use this as the first investigation is because the question the students
address at the onset is fairly straightforward. The question concerns contrasts in tree species on two very different, adjacent
sites - the north and south aspects of a small mountain. This topic also fits well with the opening of my course on autecological
approaches to ecology such as discussed in Ricklefs' chapters on "Organisms in Physical Environments." During the course
of this lab, the students start to work on the most obvious questions related to climate difference, and their thinking becomes
more sophisticated as they consider more subtle issues such as disturbance history.
Questions Addressed and Ecological Context
The structure of this ecology class is bottom-up, and I use this investigation to stimulate student thinking about physical-chemical factors
contributing to local tree distribution in a site where there is a sharp climatic gradient. In this domain, I would expect a student to
consider, for example, adaptations that might allow hemlock to grow in colder climates. In addition, I hope that students will begin
to think about other factors affecting trees in this location. Many students quickly recognize the limitation of the
"tree-is-there-because-it-likes-it" thinking because they see evidence of prior land use such as grazing (e.g., juniper bushes
in the woods), and they read about the 1938 hurricane that flattened trees on south facing slopes in our area. My hope is that
each student will consider the importance of additional factors such as disturbance in addition to climate and soil in influencing
tree type and size in our study site.
Time Commitment and Expected Product.
This is a largely student-developed investigation which requires a significant amount of time. We spend two lab sessions in the field
(3 hours each) and two more labs working with computers to process the data. The students work outside of class to write
individual research papers. I provide background primary particles.
Comments On Questions for Further Thought:
Comments on Q1. Consider local vs. regional distribution of tree communities...
Comment for instructors: what you are looking for here is not necessarily
the correct answer but rather evidence of good ecological and scientific
thinking. Help students further develop statements and questions
like: how do I know what tree communities look like north and south
of here? Is there such a thing as a typical community for a region?
If some trees are the same but others are missing, does that mean
the communities are different? What about animals; would we think
they would have distributions like the plants, and if they don't
would that make a difference? Is the weather on the south slope
really like weather south of here? To prevent the discussion from
being too diffuse, follow some lines of thought with further questions
about how students would test their assumptions or get more information
to address their questions.
Comments on Q2. Design a year round study to address the questions we are asking...
Comment for instructors: the kind of thinking you are looking for
here is targeting data collection to address specific questions
and hypotheses (as opposed to a shot gun approach) and more focus
on critical data sets (such as more frequent sampling of temperature
in spring when changes are rapid or in mid summer when extremes
Comments on Q3. Students in beginning ecology courses when asked why....
Comment for instructors: this questions leads to the realization
that the actual distribution of organisms is much narrower than
the potential distribution (or niche if you choose to use that term).
Have students consider what factors might limit the distribution
of a plant or animal and how they would test that.
Comments on Q4. Ecology texts are often divided into sections called....
Comment for instructors: this might be a good review question towards
the end of the semester. It is important for students to recognize
that the types of question an ecologist asks depends on the type
of topics that interest them.
Comments on Q5. Suppose you noticed a typically northern tree....
Comment for instructors: again you are looking for sound scientific
thinking and so strong answers would include: I would see where
else hemlocks are found on the south slope and measure their abundance.
I would look to see if anything was different about the places where
hemlocks were growing, come up with a hypothesis based on those
observations, and then test the hypothesis with field studies.
Comments on Q6. Consider a totally different ecological situation where zonation....
Comment for instructors: This could be a class-wide activity in
which you discuss other locations where zonation is clearly evident.
For example, seaweeds and invertebrates are sometimes found in distinct
zones on rocks in the intertidal or wetland plants are often sharply
zoned. Show slides of these places and have students first describe
the patterns they see and then develop ideas as to why these patterns
exist. Have them design experiments to test their assumptions and ideas.
Additional discussion questions to use in your class:
1. Locate a data set comparing ecological communities among different habitat
types from previous student projects or published data from one of the references for this lab or from some other source.
Show and discuss data. For instance, show the air column temperature data the students collected and ask them
to predict what the soil temperature profile might look like. Xerox
temperature data from a relevant research paper and ask students
to discuss how they might use this information in their own papers.
Propose that the abundance of tree species X is related to soil
moisture, and ask students to draw figures that describe this relationship.
2. Community vs "other" ecologies: This study concerns some classic
aspects of community ecology including measures of relative abundance
and diversity and their physical-chemical correlates, the role of
disturbance in community structure, and gradients. However, depending
on your personal interests and when during the course you do this
lab, you can also emphasize other aspects of ecology that typically
are found in chapters called "organisms in their physical-chemical
environment" (adaptations, abundance as a function of soil moisture).
Population ecology also could be emphasized such as age distribution
of trees. This points out of course the artificial separation of
these "ecologies" in our textbooks. It is important that you clearly
think through the focus of your particular study and explain this
very clearly to the students. I use this as an opportunity for then
to practice "thinking like" ecologists with differing interests.
3. Trained ecologists would quickly recognize the important of
disturbance (in our location primarily hurricanes) in this field
site, but most students are slow to see disturbance as critical.
Instead of telling them about hurricanes, I hope for the "ah-ha"
by giving them reference material for their research papers that
includes data about New England hurricanes. I also lead a discussion
in class about the role of disturbance in other communities such
as fire out west or wrack in salt marshes. After the students hand
in their papers, I ask them to talk about what disturbances might
be important in out study and the evidence they would look for.
This also leads us to discussion of the role of humans in New England
forests, including native Americans and also settlers who lived
here in the 1700 and 1800's and cut down the forests for pasture
and firewood. To enrich this topic, I often bring students to a
local museum at the Harvard Forest in Petersham, MA, where there
is a wonderful diorama depicting a New England forest from pilgrim
times on and dramatic photos of hurricanes.
4. The students in my class are freshmen and sophomores and so
they are just taking or haven't yet had a statistics course. For
this study I set up the excel spreadsheet so that they can very
easily do chi-square analyses of their tree data and we talk in
lab about what these numbers mean. In my experience, most students
fairly quickly understand the definition of "significance" sufficiently
to use these data in their papers.
Comments On the Assessment of Student Learning Outcomes:
Student assessment is based mainly on the quality
of the research paper as outlined in the "report format" section -
Description: Tools for Assessment of Student Learning Outcomes.
Effectiveness of students as group members and leaders
is also important in this class and is noted in a written summary
by me at the end of the semester of each student's performance in my course.
Comments On the Evaluation of the Lab Activity:
Comments On Translating the Activity to Other Institutional Scales:
This lab should provide a useful model for any ecology lab faculty to adapt and use to study the effects of locally accessible
major environmental gradients on organisms and communities. This activity would be amenable to any field situation where contrasting
environments and communities of organisms exist in close proximity (e.g. for vegetation in dry/wet fields, young/older forest,
grazed/ungrazed or mowed/unmowed fields, polluted/less polluted wetland). In the Synopsis
I list several www sites concerning sampling plants in other habitats. However, avoid the temptation to compare x area to y area
"just because it is there". The project must be based on interesting and important ecological concepts.
Reading research papers is difficult in large classes. Here, students could do posters instead of writing papers (for an example rubric see