In this lesson, appropriate for middle through high school, students practice skills essential to all scientific investigation: carefully observing and collecting data. Students become field biologists in a series of hands-on activities to collect and identify specimens, and survey and calculate the diversity of plant species in their local environment.

Background
Researchers exploring biodiversity (short for biological diversity) want to understand the variety of life. This includes the kinds and numbers of organisms on Earth, their genetic relationships, and their ecological roles (sometimes set apart as species diversity, genetic diversity, and ecological diversity). The first step in understanding biodiversity is to find out what organisms exist.

The work of cataloging life on Earth is ancient, much older than the first rock paintings. Despite intensive exploration over hundreds of years, the total number of organisms present today is an educated guess. Only 1.5 million species have been identified and named. Anywhere between 14 and 100 million species may exist worldwide-it's difficult to estimate the unknown. Most of the undiscovered species are small, difficult to observe organisms: viruses, bacteria, fungi, algae, and invertebrates. Taxonomists have the large job of naming organisms according to the rules of binomial nomenclature and classifying them.

Botanists estimate about 320,000 plant species exist worldwide; about 270,000 are known so far. Many of the new plant species will be found in the tropics, well known for dazzling high diversity.

What about North America? The discovery of the New World sparked excitement around the world. A strong tradition of botanical exploration in North America soon followed. By the 1660s, American plants were an important part of European collections and grown in European gardens. During the 1804-1806 Corps of Discovery expedition, Lewis and Clark collected more than 230 plant specimens along their historic route to the West. North America might appear well explored, but the pace of plant finds isn't slowing much. Over 1,190 vascular plants were discovered between 1975 and 1995. That's about 41 new taxa per year. As many as 1,900 vascular plants are undiscovered in North America. Mosses, liverworts, and marine macroalgae are also waiting in the wings to be discovered.

Ready for more surprises? You don't have to be a professional biologist working in a remote area to discover a new species. Consider these examples. Lowell Ahart wanted to know all the plants growing on his sheep ranch in the Sacramento Valley, California, and his survey revealed two taxa new to science. Bill Ott found an unknown species of terrestrial leech while mowing his lawn in New Jersey. And many volunteers are making significant contributions to survey all organisms in the Great Smoky National Park. In three years of sampling, 427 species are new to science and more than 2,000 species are newly recorded in the Smokies. Who will be the next lucky person to extend a distribution range, find a new species, or rediscover one thought extinct?

The diversity we see is the result of 1.5 billion years of evolution since life emerged on Earth. Biodiversity is not static: It varies from place to place, and over time. Field biologists conduct surveys in hopes of finding new species, but also to

1. map patterns of diversity - e.g., California and the Southeast are species-rich areas.
2. track the spread of introduced species -; Introduced species make up at least 25% of the U.S. flora. Almost 400 species, including saltcedar, kudzu, water hyacinth, cheatgrass, and purple loosestrife, are invasive in North America.
3. monitor the health of endangered and threatened species - Of the 1,263 species on the 2002 U.S. list of endangered and threatened species, 745 are plants. Thirty U.S. plants were confirmed to be recently extinction on the 2003 I.U.C.N Red List.

Rapid species loss has spurred biologists to complete the catalogue of life as soon as possible. Today's extinction rates are faster than those recorded before modern times. Mass extinctions occurred 440 million years ago, 370 mya, 255 mya, 200 mya, and 65 mya. Experts place the responsibility for the current 6 th mass extinction squarely on human shoulders. Some 0.2% of plants around the world have become extinct since 1600. We live in a new age of exploration. But the time available to discover new species is critically short.

Hands-on Activities and Worksheets

Several class periods are needed to complete all of the class or team activities. The plant collecting and surveying activities may be done together, perhaps by separate teams. If possible, repeat the activities at different times of year and locations, or with new classes over several years. That would enhance students' ability to observe variation in nature and make comparisons.

• Collecting and preparing plant specimens (Student Handout)
• Using and writing identification keys (Student Handout)
• Conducting and analyzing biodiversity surveys (Student Handout)

See also the Plant Ecology and Plant Identification sections of the Biodiversity Counts curricula, which cover using a key, collecting, and surveying. It is available from the American Museum of Natural History at http://www.amnh.org/education/resources/
biocounts/ecology.php]

Enrichment Activities

• Many American plants have been named in honor of important pioneer naturalists, e.g., Lewisia and Clarkia immortalize Lewis and Clark of the Corps of Discovery. Select a naturalist who has been honored this way. Use library or internet resources to prepare a brief profile about his/her contributions (time period, regions explored, species discovered, etc.).
• With a classmate create an illustrated portfolio on extinct or endangered plants and new discoveries. Include at least two plant species that are now locally or globally extinct (or currently endangered): map where they once occurred and describe the factors that lead to their extinction (or the threats they currently face). Include at least two species discovered in recent decades: map where they occur and describe how they were found.
• A new field of bioinformatics has emerged to manage today's vast wealth of biological information. Links to several online biological databases are given below. Search the web to describe at least four kinds of biological data. Prepare a brief profile on the skills and background needed for a career as a bioinformatics specialist.
• Natural history museums, botanical gardens, zoos, aquariums, and herbaria are storehouses of information of Earth's biodiversity. Hardly musty relics of the past, they address vital social issues such as climate change, public health, biological invasions, and environmental contaminants. Visit a local institution and find out how their biodiversity studies serve society. Present your view on the value biodiversity in a 1-page editorial for your school paper.
• In today's world, the management of biodiversity is as much a concern as its discovery. Contact your state department of conservation, local chapter of the Nature Conservancy, or other conservation organization. Ask about the cost and effectiveness of removing invasive species, restoring native habitats, and reintroducing endangered species. Choose a local project. Evaluate its success and propose two concrete ways the project could improve.

Explore more!
Organizations conducting diversity surveys and studying biodiversity
All Taxa Biodiversity Inventory (ATBI)
Approximately 200 scientists and volunteers are documenting all species living in the Great Smoky National Park. The ATBI website provides updates on their discoveries.

Suggested Readings and Resources
Eldredge, N. 2003. Life on Earth: An Encyclopedia of Biodiversity, Ecology and Evolution. ABC-Clio.
Ertter, B. 2000. Floristic surprises in North America North of Mexico. Annals of the Missouri

Students might enjoy these general audience pieces.
Allen, W. H. 1993. Reintroduction of endangered plants. BioScience 44: 65--68.
Gibbs, W. W. 2001. On the termination of species. Scientific American 285: 40--49.
Gibbs, W. W. 2002. A search for all species. Scientific American 287: 92--94.
Lundmark, C. 2003. BioBlitz: Getting into backyard biodiversity. BioScience 53: 329.
Milius, S. 2002. Are they really extinct? Science News 161(11): 168.
Mulford, K. 2004. Leech found in Salem County may be scientific breakthrough. Courier-Post

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