Correlation of atmospheric purity index to the diversity of lichens in the Horton Plains National Park, Sri Lanka

R G U Jayalal,V Karunaratne,P Wolseley,D S A Wijesundara,O A Ileperuma

doi:10.4038/cjs.v46i2.7426

Abstract

Horton Plains National Park (HPNP) has been declared as a world heritage site, because of its unique biodiversity. Die-back of certain areas of this park is widely believed to be due to acidic precursor depositions carried over from other parts of the country and also from neighboring countries. Air pollution data for the two pollutants, NO2 and SO2 were obtained from the passive air sampling method. The data revealed that the concentrations of ambient NO2 and SO2 were very low in the HPNP. The variations of ambient NO2 and SO2 concentrations during the study period showed insignificant positive correlation (p≥ 0.05) with the rainfall data. Considering the variations of these two pollutants with Relative Humidity and the number of vehicles visiting HPNP, both pollutants had insignificant positive correlation. The Index of Atmospheric Purity (IAP) value obtained for the whole area of the HPNP was 54.22. This value belongs to the quality level 5 which represents the ‘very low’ pollution level. The results including lichen distribution and air quality data could confirm that the ambient air quality at HPNP is very high. The high diversity of lichens and the minimum levels of air pollutants suggested that the forest health of HPNP is at a favorable level. Therefore, it is essential to maintain at least the current air pollution level of HPNP in order to conserve the forest and its biodiversity.

Highlights

Horton Plains National Park of Sri Lanka, a cloud forest, recently designated as a World Heritage Site by UNESCO
In one of the rare studies related to the atmospheric pollution at the Horton Plains National Park (HPNP), Gunawardena et al (1998) reported the possibility of acid deposition in the fog which arrives predominantly from the Indian continent and from the western parts of the country where more than 50 % of the vehicle population and the major industries are located
Chemical analysis to determine the atmospheric purity is important and would derive baseline information, biomonitoring attempts to evaluate the presence of air pollutants are not reported from HPNP

Summary

Introduction

Horton Plains National Park of Sri Lanka, a cloud forest, recently designated as a World Heritage Site by UNESCO. Because of the unique climatic and physiographic features, it ranks high among the biodiversity super hotspots within the Western Ghats and Sri Lanka. Chemical analysis to determine the atmospheric purity is important and would derive baseline information, biomonitoring attempts to evaluate the presence of air pollutants are not reported from HPNP. Biological monitoring of air pollutants can be passive or active. Passive methods involve observing plants growing naturally within the area of interest. Active methods detect the presence of air pollutants by introducing test plants of known genotypes and its response within the study area (Mulgrew and Williams, 2000)

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