Comparing plant communities today with a survey taken 50 years ago, a UA-led research team is providing the first on-the-ground evidence for Southwestern plants being pushed to higher elevations by an increasingly warmer and drier climate. In a rare opportunity to directly compare today's plant communities with a survey taken in the same area 50 years ago, a University of Arizona-led research team has provided the first on-the-ground evidence that Southwestern plants are being pushed to higher elevations by an increasingly warmer and drier climate.

The findings confirm that previous hypotheses are correct in their prediction that mountain communities in the Southwest will be strongly impacted by an increasingly warmer and drier climate, and that the area is already experiencing rapid vegetation change.

In a rare opportunity to obtian a "before -- after" look, researchers studied current plant communities along the same transect（横断面） already surveyed in 1963: the Catalina Highway, a road that winds all the way from low-lying desert to the top of Mount Lemmon, the tallest peak in the Santa Catalina Mountains northeast of Tucson.

"Our study provides the first on-the-ground proof of plants being forced significantly upslope due to climate warming in southern Arizona," said Richard C. Brusca, a research scientist in the UA's department of ecology and evolutionary biology who led the study together with Wendy Moore, an assistant professor in the UA's department of entomology. "If climate continues to warm, as the climate models predict, the subalpine mixed conifer forests on the tops of the mountains -- and the animals dependent upon them -- could be pushed right off the top and disappear."

The study, published in the journal Ecology and Evolution, was made possible by the existence of a dataset compiled 50 years ago by Robert H. Whittaker, often referred to as the "father of modern plant ecology," and his colleague, William Niering, who catalogued the plants they encountered along the Catalina Highway.