Will Global Warming Push Trees to Extinction?

Will global warming push trees to extinction?

This question assumes that a tree's range may shrink with rising global temperatures. This assumption in turn assumes that a tree's range is at least in part dependent on temperature. The first question to investigate is; can you demonstrate a relationship between a tree's temperature tolerance and its geographic range?

The United States Geological Survey provides Excel spreadsheets for hardwood and softwood trees. The data in the spreadsheets shows the percentage of trees of a species that are found in areas of different temperature and precipitation.

The table below shows part of that data. The common names of the trees were added to the USGS spreadsheet. The annual temperature spreadsheet was sorted to select trees that grow in the southeastern US. The 5 trees in the table are of the genus Acer. These are the maple trees that are native to the southeastern US.

The column Taxon name is the scientific name for the tree. The column N is the number of trees that were identified out in the forests and used in the study. The 0% column is the annual temperature for the coldest tree that was found. For Florida maple that was 14 degrees Celsius. The 10% column shows the temperature that 10% of the trees grow at or below. For example, 10% of the Florida maple trees grow between 14 and 15 degrees Celsius. In the same way the 50% column shows the temperature that half of the trees grow at or below. The 100% column shows the warmest temperature that a tree was found.

From this data you can calculate the temperature range for each species. Acre barbatum grows in areas with annual temperatures that range from 14 to 20.2 degrees Celsius. This is a 6.2 degree Celsius range. Calculate the range for each species and arrange the species from smallest to largest temperature range.

The second part of our question is, "What is the tree's geographic range." Again the United States Geographical Survey provides maps of the areas where these trees are found.

Florida maple range

chalk maple range

boxelder range

red maple range

silver maple range

You need to determine the north south range for each species of maple tree. This should be an uninterrupted line within the trees range. Use a sheet of paper to help measure the north south range. Put the lower left corner of the paper on the lower left corner of the trees range. Slide the paper to the right keeping the lower edge of the paper on the lowest side of the range. As the paper moves the trees range will move up and down the left vertical edge of the paper. Mark the highest point that the range reaches on the paper. If the range is in more than one block you will need to repeat this for each block selecting the largest distance.

Next you need to convert this distance to miles. The map doesn't have a key but the state boundaries are marked. If you know the north south dimension of a state you can use that state as a key. You can find the dimensions for states by going to netstate.com.

Arrange the maple tree species from smallest to largest north south range.

Compare your two lists.

Do the temperature ranges and geographic ranges list the trees in the same order?

Explain the relationship between a tree's temperature tolerance and its geographic range.

Defend or criticize the statement, "Global warming will cause a shift in the range or the location of a tree species."

Defend or criticize the statement, "Some tree species will be affected more than others by global warming."

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