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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.
| HARDWOODS | Annual Temperature (°C) | |||||||||
| Common name | N | 0% | 10% | 25% | 50% | 75% | 90% | 100% | ||
| Acer barbatum | Florida maple | 636 | 14.0 | 15.0 | 16.0 | 16.9 | 17.9 | 18.9 | 20.2 | |
| Acer leucoderme | chalk maple | 191 | 14.1 | 15.3 | 16.0 | 16.6 | 17.1 | 18.4 | 19.9 | |
| Acer negundo | boxelder | 6534 | -2.3 | 2.5 | 6.0 | 10.1 | 14.7 | 17.9 | 26.1 | |
| Acer rubrum | red maple | 4842 | -1.1 | 3.3 | 5.8 | 11.1 | 16.1 | 18.7 | 23.8 | |
| Acer saccharinum | silver maple | 3792 | 1.3 | 5.8 | 7.9 | 11.0 | 14.1 | 16.3 | 20.0 | |
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.