| Summary: | Bird populations are changing at unprecedented rates in response to human-induced changes to
the global environment, and these rates of change are expected to accelerate over the coming
decades. Changes in the levels of sulphur dioxide (SO2) in the atmosphere through emissions
from power stations pose a potential threat to bird populations. However, avian response to SO2
pollution is poorly understood. Exploring the relationship between avian diversity and SO2
exposure levels will help in determining species sensitive to air pollution.
This study seeks to understand the interactions between avian diversity and SO2 concentration
levels around Matimba power station so as to have more insight on the level of avian vulnerability
to air pollution. Matimba is an important site in South Africa as a second coal fired power station,
Medupi, is currently being constructed with additional stations also a possibility. This study
represents an important baseline assessment of the avian population status before the additional
pollution burden is realised from Medupi.
Ten min repeated point counts were conducted at three sample sites with varying distances from
Matimba and Medupi power stations. These counts were used to calculate bird species density
and diversity. Cloud-free Landsat 8 imagery acquired on 7 January, 2014 was used to derive
habitat structure and productivity variables. Elevation variables were derived using a DEM (Digital
Elevation Model) obtained from NASA Global Data Explorer. The AERMOD dispersion model was
used to characterise spatio-temporal variations in ambient SO2 concentrations around Matimba
power station. Multiple regression analysis was then used to ascertain which of these variables
(SO2, habitat structure, productivity and terrain) contribute most to the observed variation in bird
species density and diversity around Matimba and Medupi power stations.
SO2 polluted air did not have an influence on bird species density and diversity at the community
level. At species level two species (Batis molitor and Streptopelia senegalensis) exhibited some
measure of negative response to SO2 air pollution. However, after further investigation using
multiple regression analysis it was revealed that habitat structure had more influence on the
density of these two species compared with ambient SO2 concentrations. Bird species density
and diversity varied significantly among the sample sites but were not related to the distance to
the source of the SO2 air pollution.
Evidence obtained from this study revealed that continuous monitoring of the interactions
between SO2 polluted air and bird populations is recommended for a more comprehensive
understanding of avian susceptibility towards SO2 air pollution and this will also facilitate in the selection of sensitive and relevant species for future ecology studies at other coal-fired power
stations. Furthermore, it is expected that SO2 concentrations will significantly increase with the
commissioning of Medupi power station thus further necessitating the need for continuous
monitoring of bird species densities around Matimba and Medupi power stations. === MSc (Geography and Environmental Management), North-West University, Potchefstroom Campus, 2015
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