Plant Biodiversity Field Activity
By Heather Ferguson
What do a 1950s fad and an ecological topic of global interest have in common? This activity— which uses a Hula Hoop® to help your students study biodiversity.
This activity is appropriate for high school students and addresses the following National Science Education Standards for grades 9–12:
- Unifying Concepts and Processes: Systems, Order, and Organization; Change, Constancy, and Measurement
- Life Science: Interdependence of Organisms; Matter, Energy, and Organization in Living Systems
- Science in Personal and Social Perspectives: Environmental Quality; Natural and Human-Induced Hazards
What is biodiversity?
Simply stated, biodiversity is the number and variety of organisms within a particular geographic area. In this activity, students go outdoors and sample the biodiversity of plant species in natural and cultivated areas. Then they compare the biodiversity of plants in the natural areas to that of the cultivated areas. Students measure the species richness, which is the number of plant species per square meter. This exercise requires 50 to 90 min and accommodates students working in groups.
- Hula Hoop®
- Meter Sticks
- Plant Identification Guide (optional)
Note: Students may struggle with identifying distinct plant species during this exercise. If possible, allow them to use a dichotomous key of local plants to aid their species counts. Otherwise, encourage students to identify morphological differences between plants, such as leaf shape and twig color.
- Locate a natural area and a cultivated area where students can sample biodiversity. Any undisturbed or restored area in your region is a natural setting. Examples of cultivated areas are lawns, gardens, and farmers’ fields. Choosing areas close to one another means less time required to complete the activity.
- Secure permission, if possible in writing, to visit the sites.
- Visit each location prior to activity day and perform a safety check. Note any plants, insects, features of the terrain, or anything else that might cause problems during the field trip.
- Make necessary arrangements for your class to visit both locations. It is a good idea to ask other adults to accompany your group on the outing.
- Instruct students to wear appropriate clothes and shoes for the activity and bring water to drink.
- Have students make or purchase a science notebook.
- Procure sufficient Hula Hoops® and meter sticks to provide 1 each per group of students.
- Print out and make copies of the Sample Data Table worksheet and the Questions worksheet.
- Caution students to avoid anything you noted during your safety visit to the site(s).
- Instruct students to record their data and observations in their science notebooks.
- Assign students to working groups.
- Direct students to collect observations from 3 samples at both the first and second locations (6 samples total).
- Upon reaching the testing area, split into working groups.
- By group, randomly select an area to sample.
- In your science notebooks, record a description of this area. Record the physical attributes of the sample area. Describe the amount of sunlight, moisture, relative temperature, and other observations that you make. Be sure to note any signs of human disturbance and if the area appears to be natural or undisturbed.
- Gently toss the Hula Hoop® into the described area. The hoop forms the outer boundary of the area to sample.
- Count the number of plants inside the sample area. Record this number in your science notebooks.
- Count the different plant species you observe inside the sample area. Record this number in your science notebooks.
- Repeat steps 3 through 6 in the 2 additional sample areas at this location.
- At the second location, repeat steps 1 through 8.
- After completing your observations, measure the diameter of the Hula Hoop®. Calculate the area of the Hula Hoop® using the equation below.
- Calculate the total number of plants per m2 that you observed at each sample site.
- Calculate the number of plant species per m2 that you observed at each sample site.
- Organize your data in the data table on the worksheet.
- Answer the questions on the Questions worksheet.
Compile students’ data into a classroom data set. Analyze and discuss the results with the students. This is a good time to describe some of the implications of species richness with your students. For example, when species are lost from an ecosystem, the overall genetic diversity is affected because the genes the species possessed are lost. Additionally, the species’ role in the ecosystem is lost, which ultimately may impact the lives of other organisms or systems, such as nutrient cycling.
Questions with answers
- Using the analysis of your data and observations, answer the following: (a) Did the natural or cultivated area have more plants per m2? (b) Which setting had the greatest species richness, or number of plant species per m2?
Answer (a and b): Answers will vary based on the locations sampled. Restored natural areas undergoing secondary succession have high biodiversity because varieties of plant species are competing to colonize an area. A forest likely has lower biodiversity because the colony of tall trees allows fewer species to compete for sunlight. Disturbed or cultivated area biodiversity also varies based on the amount of human influence, such as the removal of weeds or other invasive plants.
- Compare the class data to the data you collected. (a) Did the natural or disturbed setting have more plants per m2? (b) Which setting had the greater species richness, or number of plant species per m2? Answer: (a) See question 1. (b) The class data contains more samples and therefore presents a more accurate idea of the biodiversity of both the natural and cultivated areas
- Discuss problems with the data you collected. (a) Did you get different numbers from your group members during counts? (b) If so, why do you think that may happen? (c) What can be done to ensure better accuracy?
Answer: (a and b) Answers will vary, but if group members’ count results differed, improve the data by averaging the counts. (c) Students can improve count accuracy by using a dichotomous key to identify the species they are counting.