Along with his American colleagues, dendrologist Martin Šenfeldr has studied the relationship between climate and the growth of aspen trees (Populus tremuloides) in the Great Basin region of Nevada, focusing on a period of 100 years. During the research, the scientists used dendrochronological methods. It has been shown that progressive climate change has both a negative and positive effect on the growth of aspen trees, depending on the geographical location of the mountain range and its precipitation pattern. Within the study, the scientists also identified the tree populations most at risk from drought. The conclusions of their research have been published in the prestigious journal Forest Ecology and Management.
Among the vast dry plains of the Great Basin in North America, there are isolated forested islands of mountains, the so-called Sky Islands, where aspen trees grow These trees are of extraordinary ecological importance for the area: “They provide a whole range of ecosystem services, such as water retention, they form so-called hotspots – biotopes with extraordinary biological diversity, and they excel in their aesthetic role. The aspen is an iconic tree species of the North American continent, and when their leaves turn deep yellow in the fall, they create a visually appealing landscape feature,” says Martin Šenfeldr, from the Department of Forest Botany, Dendrology and Geobiocoenology, in explanation of the versatile significance of aspen trees.
The researcher from FFWT MENDELU worked on the aspen study together with scientists from Utah State University, the Western Aspen Alliance and the U.S. Geological Survey. “For scientists, the study of woody plants in an area like the Great Basin is incredibly interesting. The key question for us was how the trees in this region react to the changing climate. It is getting warmer, and this means that the intensity of drought is also increasing. These are all key factors in the survival of aspens in these conditions,” Šenfeldr explains his research interest. For their research, the scientists applied the dendrochronological method of studying tree growth rings. They studied growth ring series from 1910 to the present day in about three hundred trees. They compared the relationship between growth ring width and various climate variables. “The results indicated a highly variable growth response between the three mountain ranges within the Sky Islands. Aspen growing in the drier Ruby and Jarbidge Ranges showed growth depression and increased sensitivity to worsening drought due to ongoing climate change. On the other hand, in the slightly wetter Santa Rosa mountain range, aspen trees showed an acceleration of growth as a result of the gradual increase in temperature since 1970. This means that progressive climate change can have both a negative and positive effect on the growth of aspen trees,” said Martin Šenfeldr in summary of the research.
The scientists were very surprised by this contrasting growth response. They began their research with the hypothesis that the response would be very similar in all mountain ranges. Thanks to this welcome variability, they were able to identify the aspen populations most likely to be threatened by progressive climate change in the future, and vice versa, those which will benefit from rising temperatures.
“The way to ensure the greatest support for aspens in times of climate change is to maintain the complex age structure of tree populations, i.e. to have trees of different ages: young, mature and veteran. For the healthy growth of trees, it is also necessary to regulate the presence of animals. In this area, mainly various species of deer and elk that nibble on seedlings and saplings and thereby inhibit natural reproduction,” concludes Šenfeldr.
Detailed research results and conclusions in the journal Forest Ecology and Management
Contact for further information: Ing. Martin Šenfeldr, Ph.D., Department of Forest Botany, Dendrology and Geobiocoenology FFWT MENDELU, +420 545 134 500, martin.senfeldr@mendelu.cz