A new model may predict how forests will respond to climate change, and scientists have found that drought may cause the northeast's mixed forests to be unsustainable after 2050.

Scientists have long known that climate change is likely to cause drought in certain areas. This, in turn, may have a major impact on forests. That's why researchers decided to take a closer look at forests with the use of a new type of mathematical model.

The new model is called the Tolerance Distribution Model (TDM) and is the first to ever use the tolerances of different types of forests to drought, flood and shade to see how these forests may respond to climate change. In contrast to existing methods, the new findings can actually be applied on a continental scale.

In order to actually create the new model, the researchers collected data on the ability of U.S. tree species to cope with drought, sunlight levels and flooding. They then assigned tolerance rankings to each of the 400,000 forest plots based on the composition of the trees in each plot.

"Until now, our ability to predict exactly how and where forest characteristics and distributions are likely to be altered as a result of climate change has been rather limited," said Jean Lienard of WSU Vancouver, first author of the study. "With our model, it is possible to identify which forests are at the greatest risk from future environmental stressors. Forest managers and private landowners could then take steps like planting drought tolerant seedlings and saplings to prepare."

The new model predicts that in the northeastern U.S., forests of maple/beech/birch, spruce/fire and white/red/jack pine combinations will have a hard time withstanding the predicted drought conditions. Other forested areas at risk from drought include the northern Great Plains and higher elevations of the Rocky Mountains. In addition, low altitude areas of Texas may actually eventually host tropical dry forests that are similar to those found in the regions of eastern Mexico. In addition, moist, deciduous forests like the ones in Cuba could be found along the U.S. Gulf Coast.

The results reveal a bit more about what's in store for the forests in the U.S., which is particularly important to note in the face of continuing climate change.

The findings were published in the April 26 issue of the journal Global Change Biology.