Mastering Environmental Science Focus on Figures Video Transcript

This is a transcript of the video on the Educator Features page.

Hi, this is Justin St. Juliana from Cornell University, and in this Focus on Figures video, we'll be looking at this group of graphs to learn what they can tell us about biomes. Biomes are large regions of the earth defined by the plant communities that live there. And as you can see, there are a variety of biomes scattered around the earth. Yet, interestingly, only two factors primarily determine what biome is in a given region -- temperature and precipitation.

Today, we'll explore both this central figure known as the Whittaker diagram as well as the figures on the periphery known as climatographs or climate diagrams. Let's start by exploring how temperature and precipitation interact on the Whittaker diagram.

On the x-axis of this graph, we have average annual temperature. Although temperatures may fluctuate over the course of the year, these values represent the yearly averages. On our graph, as we move from the right to the left, we go from areas of low temperature to areas of high temperature.The second major factor is the average annual precipitation. As we go from the bottom to the top, the amount of precipitation increases.

Now that we know the axes, let's take a look at how this relates to the biome with a given temperature and precipitation combination.

As you might expect, at an extreme, such as areas that are hot and dry, we find deserts. In areas that are hot and wet, we find tropical rainforests. And in areas that are cold and dry, we find tundra. At intermediate values, we find tropical seasonal forests, tropical savanna, grasslands, taiga, and temperate forests.

Now that we know the basics of this graph, we can explore each biome in more detail by looking at something known as a climatograph. Let's examine these graphs using a temperate deciduous forest as an example.

At the top of climatographs, we find some basic information: the name of the biome, the location, average annual temperature, and average annual precipitation. The key aspect of the climatograph is that it allows us to look at the location month by month. So in the graph space on the x-axis, we see the months listed from January to December. On the right axis, we have the temperature in degrees Celsius. On the left axis, we have precipitation in millimeters. For any given month, we see the average monthly temperature indicated with the red line and total monthly precipitation indicated with the blue bars.

In the case of this temperate deciduous forest, temperature fluctuates during the year as seasons change, but precipitation in the form of rain and snow remains fairly constant, at about 100 millimeters per month. A climate diagram will be associated with a given biome. For example, a tropical rainforest has high temperature and precipitation year round, whereas this taiga has highly seasonal temperature and precipitation.

As you can see, the climatographs differ for each biome. Both the graphs we explore today use information about temperature and precipitation to evaluate what biome is in a given region.

Now that you understand this topic, consider where you live. What's the average annual temperature? What's the average annual precipitation? What biome are you in? What would a climate diagram look like for your region?

Thanks for watching.