Climate Change Hampers Tree Growth, Says New Study

The National Science Foundation has released a study that suggests climate change is having an impact on tree growth and the ability of trees to produce seeds. The study, which was undertaken over an 18 year period and saw the examination of 27,000 trees, concluded that earlier Springs was one of the mitigating factors that was impacting on tree reproduction and growth.

The study also revealed that elm, magnolia, beech and pine trees were some of the most prone to summer droughts, which was another significant risk to trees and their life span. The scientists’ findings could be important in understanding what type of trees will be under threat and why they are more susceptible than other varieties if climate change continues. It is also expected to give scientist and policy makers’ important information when it comes to tackling the problem and finding a solution.

"By quantifying the effects and relative importance of competition and climate variables, including impacts on fecundity, over both time and space, the model we've developed addresses this need and can be used to guide planning," said James Clark who works with Duke University and is the leading author behind the study.

The scientists who conducted the research used a unique bioinformatics analysis that quantified the effects of climate change on trees. Each tree was examined at least once every three years that provided over 280,000 tree years of data.

"In a sense, what we've done is an epidemiological study on trees to better understand how and why certain species, or demographics, are sensitive to variation and in what ways. As climate continues to change, we know forests will respond," said Clark.

"The problem is the models scientists have used to predict forest responses focus almost solely on spatial variation in tree species abundance and their distribution and density over a geographic range,” Clark added.

The study analyzed over 40 different tree types in the US in the south east, the southern Appalachians, the coastal plain and the Piedmont that were subjected to natural and experimental variations.

"That's where the new concept of climate and resource tracking of demographic rates comes in. Trees are much more sensitive to climate variation than can be interpreted from regional climate averages," said Clark.

The study also looked at competition for space and sunlight and the impacts this had with other factors like drought and warmer seasons.

According to Alan Tessier, who is the NSF’s program director in the division of Environmental Biology, “This work demonstrates the limitations of current modeling approaches to predict which species are vulnerable to climate change and illustrates the importance of incorporating ecological factors such as species competition." The study will appear today in the science journal, Global Change Biology.

Photo credit: Geagea