Document Type : Research Paper
Authors
1
Assist. Prof., Research Division of Natural Resources, Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education Center, AREEO, Shahrekord, I.R. Iran
2
Senior Research Expert, Research Division of Natural Resources, Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education Center, AREEO, Shahrekord, I.R. Iran
3
Research Expert, Research Division of Natural Resources, Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education Center, AREEO, Shahrekord, I.R. Iran
4
Assoc. Prof., Research Institute of Forest and Rangelands, Agricultural Research, Education and Extension Organization (AREEO), Tehran, I.R. Iran
5
Expert, Chaharmahal and Bakhtiari Department of Environment, Shahrekord, I.R. Iran
Abstract
Oak decline is a complex phenomenon affecting vast areas of Zagros forests. Dust is the most important factors in the decline of Zagros forest. In order to assess the impacts of dust on oak decline, six dust traps were installed in Helen protected area at the beginning of spring 2016. Dust samples were collected using the traps surface in autumn. The weight of dust samples and the amount of heavy metals were measured in the laboratory. Three transects (replicates) with fixed distances were designed in each of northern and southern directions. In each transect, three circular plots (with an area of 1000 m2) were laid out in three altitudinal ranges (1500-1800, 1800-2000, and more than 2000 meter a.s.l.). In each plot, leaf samples of five trees were collected from healthy and unhealthy trees, and the amounts of heavy elements including lead, cadmium, nickel, arsenic and mercury were measured. The results showed that cadmium and lead in leaves of healthy and unhealthy trees had a significant difference and the amount of these elements in the leaves of healthy tree was more than unhealthy trees. Higher amounts of heavy metals were absorbed by oak trees located in the southern aspect compared with those in the northern one. Moreover, the amounts of intercepted cadmium and lead had significant differences. It seems that the stress caused by the absorption of these heavy elements in the leaves of trees is one of the most important factors for oak trees decline.
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