Biological Diversity at the Dunes

Background

Biological diversity, or biodiversity, refers to the variety and variability of living organisms on the planet. Ecologists tend to focus on three levels of biological diversity: genetic, species, and ecosystem diversity. This activity will focus on species and ecosystem diversity.

Species diversity is the most common level of biological diversity. Species is a word used in biology to refer to a type of organism different from all others. Species diversity is a measure of the number of different species at a location.

An ecosystem is a community of organisms and the physical environment in which they interact. Each ecosystem contains characteristic plants and animals. Some examples of ecosystems are grasslands, deserts, rain forests, conifer forests, and deciduous forests. Great Sand Dunes has high ecosystem diversity where there are a great variety of ecosystems (or community types).

It is also important to note that some ecological systems are less diverse than others. Ecosystems that are in the later stages of succession, such as an old-growth forest, may have low biodiversity. Yet they also have what some ecologists call process integrity. Ecosystems where nutrients are being passed efficiently and where the nitrogen and carbon cycles are intact are considered to have high process integrity.

Procedure

Find an area outdoors where students will be able to set up measuring plots. A good place for this may be in the sparse vegetation near Medano Creek. Each group should have string, four stakes, and a yardstick. Each group should set up a one meter by one meter plot. As students are setting up their plots, caution them not to step inside, or this may damage or destroy what they are looking for.

Groups should systematically search their plots for any and all signs of life. Sketch and categorize each organism or sign of life. Categorizations should be simple, such as: beetle, butterfly, spider, small animal track, etc. Please remind students not to hurt any living organism and to return their plots to their original form. Students should have about 25 minutes to search, sketch, and categorize their organisms.

It might be interesting to set up plots perpendicular to the Medano creekbed, to see how biodiversity might change as you move from sandy creekbed into the grasslands. Watch out for cactus, if you go into the grasslands.

After each student in a group has documented all the organisms they can find, they are to combine their lists into a group list for their plot. The list should have two columns: Category, Quantity. Under Category, they should list all the different categories they found. Similar categories may be combined, but define some broad
categories, such as "bug," more specifically.

Back at school, on a piece of butcher paper create a large graph. The x-axis of the graph should contain all the categories from all the groups. Work together with the groups to decide what all the categories should be. Again, similar categories should be combine and ones that are too general should be defined more specifically. After the x-axis is complete, students may then need to re-categorize their group lists to match. The y-axis should go from zero to the highest quantity listed within each of the group's categories.

Have one person from each group plot their quantities as a bar graph on the butcher paper. Each group should draw their vertical bars with a different colored marker.

This graph shows species diversity. It shows how many kinds of organisms were found, as well as how many of each category were found.

Ask the following kinds of questions:

• Which category did we find the most often?
• Which category did we find the least often?
• Which group had the highest and lowest diversity of categories? Where were these plots?

Critical Thinking

1. Is biological diversity important to you?
2. Are areas with low biological diversity, such as sand dunes important too?

Adapted from Biological Diversity Makes a World of Difference, by the National Park Service.