Case Study: What's Been in Your Backyard Over the Past Centuries?

Ancient Plant Pollen Tells Tales

Have you ever wondered if the trees in your backyard have always been there? Although plants don't actually move, the wind, birds, and insects distribute their seeds, which allow new trees to grow in different areas. To pollinate the flowers that produce the scattered seeds, many plants release large amounts of pollen in the air. Some pollen gets buried and preserved in sediments of nearby lakes, ponds, swamps, and bogs. By sampling the sediments and extracting this pollen, scientists can track the movements of plant species around North America.

The goal of this particular investigation is to see how plant populations change over time in an area of personal interest. In this chapter, you'll create graphs of plant abundance over time for selected areas based on a time series of maps to answer questions like the one asked in the first sentence.

Data exist in numerical, written, and image form, and, in any form, data are the backbone of scientific research. In this activity, we will be dealing with numerical and image data. Two common tools to visualize data are maps and graphs. Maps display the spatial relationships within a field of data. Graphs show the time trend of variables or the relationship between variables. We will be taking advantage of digital versions of maps so that the numerical data used to create the colors of maps may be recovered using software tools and then graphed to study time trends.

In this chapter, you'll learn about plant response to changing climate conditions across North America. With software tools, you will convert the visual data of maps into graphs to study the change of plant distribution in a selected region.

Keep the following questions in mind as you progress through the chapter:

  • Have all plant species responded the same way as the ice sheets retreated northward?
  • In addition to climate, are there other factors that have affected the distribution of plant populations?