Scientists from Bonn University have recently verified the link between air pollution and forest cover decline. The particulate matter, particularly salt compounds, seemed to promote dehydration in plants and trees, decreasing their leaf cover and directly causing a decline in the forest cover.
These salt deposits also seemed to decrease the tolerance of trees to drought, which further added to the forest decline.
The surface of the leaves of a plant contains a waxy sheet, which helps retain moisture and prevents the plant from withering away due to loss of water. This waxy covering is destroyed due to its exposure to particulate matter, the researchers claim.
"Our study reveals that so-called wax degradation on pine needles may develop from deposited particulate matter," Dr. Jürgen Burkhardt, the Institute of Crop Science and Resource Conservation, explained. "Wax degradation was addressed by many studies in the 1980s and 90s, but sound explanations for both the degradation mechanism and the high correlation with forest damage have yet been missing,"
Co-author Shyam Pariyar further emphasized on how the deposition of these salts could decrease the tolerance of the trees to extreme conditions like drought.
For the study, the scientists sprayed salt solutions on Scots pine needles, and evaluated their weight loss after they were cut. Close observation of the pine needles revealed that those exposed to salt solutions dried and shrunk much faster than the needles that weren't exposed to the salt solutions. This revelation clearly explained the link between the exposure of particulate matter from air pollution to the forest decline and a lowered resistance to drought conditions.
"This newly described mechanism was not considered in earlier explanations of Central European forest decline," Dr. Burkhardt added.
Earlier studies have stressed on how climate change has affected forest cover, but this study seems to specify the effects of air pollution on forest decline.
This study is now published in 'Environmental Pollution'