A comparison of the first on-the-ground evidence between today and 50 years ago at a specific plant community in Arizona shows that southwestern plants are being forced into higher elevations by an increasingly drier and warmer climate.
A University of Arizona research team confirmed previous hypotheses which stated that mountain communities of the Southwest U.S. will be strongly impacted (vegetation changes) by the increasingly drier and warmer climate.
This study was made possible by the existence of a plant dataset compiled in 1963 by Robert Whittaker on a tract of land along the Catalina Highway northeast of Tuscon, Arizona.
The research team found that three quarters of the 27 catalogued plant species have shifted their range significantly higher and as much as 1,000 feet in some cases. Plants were also found to be growing in a narrower elevation range than what they were 50 years ago.
Key excerpts from the University of Arizona News story...
According to the authors, the main point emerging from the study is that plant communities on the mountain were different 50 years ago because plant species do not necessarily move toward higher elevations as a community. Rather, individual species shift their ranges independently, leading to a reshuffling of plant communities.
Based on studies done by other scientists, including UA researchers, the researchers believe that a "thirstier" atmosphere might be a major driver behind the shifts in plant distribution, possibly even more so than lack of precipitation. As the atmosphere becomes warmer and drier, plants loose more water through their leave openings and become water-stressed.
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