Using Plant Surveys to Study Biodiversity
Summary
This is an extended field investigation that is intended as launch into several concepts in environmental science including biodiversity, human impacts on natural systems, and energy transfer in ecosystems.
Students will work in small groups of 3-4 students to conduct plant surveys in two study areas, looking and the type and relative proportions (approximate) of each plant found. Students will also make general observations about the conditions at each site (moisture, light level, or other factors they feel are important).
Students will graph the relative frequency of the plants found at each site and compare the composition of the plots by calculating Species Richness, Dominance, and Sorensen numbers (a correlation coefficient).
After conducting the survey, student will attempt to identity several plants from each plot using a guide books to determine whether or not the plant types found indicate a difference in growing condition between the two plots. Students will study the natural history of the local area to determine how the area has changed over time/how the current plant communities reflect a change.
Students will also generate questions for further study at the plots. (ex. How do the soil types differ? Does the insect community differ? Which plot is has the most biomass? Etc.)
Learning Goals
Students will practice data analysis by constructing simple frequency graphs and calculating biodiversity indices given an algebraic formula.
Students will critically analyze one document that give information about the natural history of the area studied.
Students will write a state that synthesizes field observation and document analysis findings.
Skills emphasized each day:
Days 1 & 3 – Data Collection and Observation Skills
Days 2 & 4 - Graphing and Data Analysis (qualitative)
Day 5 – Data Analysis (quantitative)
Days 6 & 7 – Writing, Critical Thinking, Questioning
Context for Use
The activity requires two study plot areas, fairly distinct in vegetation (ex a pond and a field or wooded area). Time requirement is seven 50 minute periods (days 6 & 7 are optional, but work towards stands is done on day six). If the format is 90 minute block periods, all of the collection could be done in one period. Graphing and plant identification could be done in a second period, Dominance and Sorensen could be combined into one period.
Description and Teaching Materials
The teacher should select two general study plot areas that contain enough plant diversity to make counts interesting, but not overwhelming. Student will work in groups of 2-4 students.
A pre-activity brainstorming session is recommended during which student determine what controls and general methods they will use during the investigation. A class discussion should lead to the following conclusions:
Study plot areas should be the same size
Plants should be counted by the same method in both area
When estimating the number, the same method should be use for both areas
Plants in the field should not be destroyed
The area studied should be disturbed as little as possible during the activity
(Other)
Day One – Plot One Data Collection
Field Work Day
Student work in groups of 3-4 at the first study area. Data collection site should be 1m x 1m or smaller. Each group records the following in the science notebook:
Date
Time
Weather Condition
Plot Location & Description
Data Table with Plant Description and Frequency for each plant type found
Other Observations
Students need not identify plants in the field, but if field books are available, team members can work on this part in the field. If plant identification will happen in the classroom, students should take digital photos, do rubbings, sketches, or collect samples.
(Sample pages in Attachments)
Day Two – Plot One Graphing and Plant Identification
Students work in their groups to determine the best way to present the plant survey data graphically. (Usually a pie chart or bar graph is best, but other graphical representations are possible). 20-30 minutes
Student use field guides to identify as many plants as they can in the time allotted. If possible, they should note any information about native/non-native status and growing condition requirements. This can be difficult with flowering plants that are not in bloom at the time of collection. (To speed this up, groups could share information by posting sketches or picture on a central whiteboard or bulletin board.)
At the end of the period students should have completed:
1)graphical representation of plant frequencies in study plot one
2)plant identification and information for plot one (at least a few plants)
(Sample graphs in Attachments. Hand drawn may be preferable).
Day Three – Plot Two Data Collection
(Repeat of day one, second plot. Hopefully students have done some problem solving on the first day and collection will go more quickly).
Day Four – Plot Two Graphing and Plant Identification
(Repeat of day 2, second plot)
Day Five - Biodiversity Analysis (Dominance and Sorenson)
This is a structured day. Use the page on Biodiversity Calculations or the handout "Joe's Jungle: Exploring Biodiversity" (see teaching notes) to guide students through examples of each of the quantities: Species Richness, Dominance, and Sorensen number. The goal of the activity is that student will investigate ways of quantifying data, specifically to answer the question "how biologically diverse are the study areas?"
At the end of the period students should have completed the following in their science notebook:
1)Calculate the Species Richness for each study area and discuss what is indicated by the two values.
2)Calculate the Dominance number for each study area and discuss what is indicated by the two values.
3)Calculate the Sorensen number for the two plots and discuss what is indicated by the value.
Day Six – (Optional) Elements from the Natural History of the Area
This lesson can include elements of geologic history, but here it is written having students look mainly at changes in vegetation.
Students work in the same groups to answer the question "How natural are your study areas?"
Each group of 3-4 students received a set of documents that contain information about the general biome characteristics, pre-settlement native landscape, and land use history of the area.
Group members jigsaw the material and share their finding with one another.
Possibly, students have found some non-native plants in their study areas and will grapple with what the term "natural" really means. This is encouraged.
At the end of the hour student should have completed the following in their science notebook:
1) Compare/contrast the plant communities in each plot to the pre-settlement landscape as they can best determine.
2) A bulleted list of factors that have influenced changes in the area
A set of documents designed for Apple Valley, MN can be found in the attachments. Many are taken from websites that contain information about other areas in Minnesota.
Day Seven? – Generating Further Questions for Study/Work day to finish report pieces
It is important that students consider sources of error in the investigation and generate questions for further investigation of the study plots. Hopefully they may already be questioning whether studying plants only is a valid method of studying biodiversity.
Sample questions: Is the soil different in the two study areas? What kinds of life exist in the soil? How are the insects different in the two areas? What food chains does each area support? Etc.
At the end of the investigation each student should at the following to their science notebook:
1)A list of SEVERAL questions and
2)at least a suggestion for how to improve the investigation. Sample Notebook Page (Acrobat (PDF) 2.2MB Aug21 09) Biodiversity Calcuations - Day 5 (Microsoft Word 23kB Aug21 09) Plant Survey - Sample Frequency Graphs (Excel 32kB Aug21 09) Documents for Investigating Pre-settlement habitat (Microsoft Word 297kB Aug21 09)
Teaching Notes and Tips
Keep study areas small, not larger than 1m x 1m. It can be difficult to count plants in dense vegetation. Survey plots should be smaller in very dense vegetation.
Note: Grassy areas can be difficult to study when estimating the number of plants. Students have to grapple with questions about what constitutes one grass plant? How can I count them all? This is a good exercise for brainstorming ways to estimate the total number of plants. Back in the classroom, the class can take a look at what a rhizome is, but for the survey, students can make their own judgment about what constitutes one grass plant and therefore how does one estimate. In this case, the field notes should contain a justification for the estimate.
Unfortunately, a direct life science standards match for grades 9-12 from the survey activity itself is hard to find. But the plant survey serves as a great launch into concepts covered in the standards, so the standards match really comes through the extension and analysis activities (day 6). The plant survey becomes a concrete example to which students can refer when studying concepts in ecology throughout the year including energy transfer in ecosystems, factors affecting carrying capacity, and further investigation of human impacts on natural systems.
Assessment
Site Observations & Sketches/Rubbings/photos (both sites) (4 pt)
Plant Survey Data (number & types of each plant) (4 pt)
Graph of Plant Frequencies (one for each plot) (4 pt)
Plant Identification List (when possible) (2 pt)
Correlation Analysis (Dominance/Sorensen Number Calculations) (4 pt)
Discussion of Natural History/Apparent Changes to the Ecosystem (3 pt) (Optional)
Questions for Further Study (2 pt)
Standards
The Nature of Science and Engineering/Interactions Among Science, Technology, Engineering, Mathematics, and Society
Science, technology, engineering and mathematics rely on each other to enhance knowledge and understanding.
9.1.3.4.3 - Select and use appropriate numeric, symbolic, pictorial, or graphical representation to communicate scientific ideas, procedures and experimental results.
9.1.3.4.6 - Analyze the strengths and limitations of physical, conceptual, mathematical and computer models used by scientists and engineers.
Interdependence of Life – The student will describe how the environment and interaction between organisms can affect the number of species and the diversity of the species in an ecosystem.
2) The students will predict and analyze how a change in an ecosystem, resulting from natural causes, changes in climate, human activity or introduction of invasive species, can affect both the number of organisms in a population and the biodiversity of the species in the ecosystem.