Abstract—Forest dieback has become a key threat to Horton Plains (an upper montane forest) in Sri Lanka. Increasing vehicle emissions in the nearby cities and the polluted rain with Pb and Cd falling on forest soils has been the main focus of the study. In the experiment, twenty-four permanent plots were established within an area of 61-80% dieback severity and three soil amendments through addition of (a) compost, (b) montane mycorrhizae, and (c) compost and montane mycorrhizae, alongside the control made up the four treatments used in this study. Treatments were applied to five randomly selected Syzygium rotundifolium saplings of approximate height of 1m and 0.015m diameter breast height (DBH) residing in each plot. Soil organic matter content (SOM) and Pb and Cd were compared from soil samples collected at 0.2m depth. Foliar samples were collected from the ‘treated’ saplings, and were analyzed to investigate the levels of Pb and Cd. These comparisons were done for samples collected at three different stages and during the experimental period, the selected saplings were closely monitored and changes in health were accordingly recorded. The soil analysis shows clear indications of Pb and Cd contamination which impairs plant metabolism leading to dieback. Effect of standard compost and montane mycorrhizae on protecting saplings from Pb and Cd was significant (p = <0.001). The level of soil Pb above ~60ppm appears to be disastrous for the Syzygium rotundifolium saplings. Moreover, compost and mycorrhizae appeared to be effective in reducing the effect of Pb and Cd on sapling’s mortality. Significant decline of Cd (p = 0.01) and Pb (p = 0.01) with the increasing SOM level were observed. A significant inverse relationship between SOM level and the mortality rate of Syzygium rotundifolium saplings was also observed (p= 0.05) and the severity of the mortality sharply increases when the SOM level decreases below ~4%.
Index Terms—Forest dieback, soil organic matter, lead, cadmium.
H. K. S. G. Gunadasa is with Postgraduate Institute of Agriculture, University of Peradeniya, Sri Lanka (e-mail: sajanee2010@gmail.com).
P. I. Yapa is with the Department of Export Agriculture, Faculty of Agricultural Sciences, Sabaragamuwa University of Sri Lanka, Sri Lanka(e-mail: piyapa39@yahoo.co.uk).
S. P. Nissanka is with the Department of Crop Science, Faculty of Agriculture, University of Peradeniya, Sri Lanka (e-mail:nissankasp@yahoo.com).
S. P. Perera is with the Department of Soils and Plant Nutrition, Rubber Research Institute, Agalawatta, Sri Lanka.
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Cite: Gunadasa H. K. S. G., Yapa. P. I., Nissanka S. P., and Perera S. P., "Soil Pollution and Forest Dieback: Will the Compost andMycorrhizal Treatments be Effective in Mitigating Forest Dieback?," International Journal of Chemical Engineering and Applications vol. 3, no. 3, pp. 167-172, 2012.
