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Air
Pollution Impacts on Crops and Forests
in
Developing Countries
By: L.D.
Emberson1, M. Agrawal2, A. Wahid3, M.R.
Ashmore4, H. Pleijel5, P.E.Karlsson6
Increases in
air pollution over recent decades have been experienced in many industrial and
urban centres of Asia,
Africa and Latin America primarily as a result of rapid economic growth which
has led to industrialization, urbanization, increases in motor vehicle use and
associated increases in energy demands. To date, relatively little is known
about pollutant concentrations and exposure patterns in most suburban and rural
areas and associated impacts on the local vegetation of developing countries.
The earlier
phase of this RAPIDC project commissioned experts from a number of developing
countries to collate evidence describing local / regional emissions, vegetation
distributions and associated local pollutant concentrations. This information
was related to observations of visible injury in the field and key experimental
investigations describing the direct effects of a number of different air
pollutants on selected crop and forest species. The information collated during
the initial phase of this project has clearly shown that in many developing
country regions, and particularly in parts of Asia, crop yields and forest
productivity are being severely affected by local ambient air pollutant
concentrations.
One of the
main aims of Phase I of the project was to assess the transferability of
pollutant damage assessment methods developed in Europe and North America to
developing country situations. The definition of dose-response relationships or
exposure limits for damage is one component of achieving such an aim.
Preliminary attempts to investigate the potential regional differences in
dose-response relationships have been made by pooling suitable data collected
for sulphur dioxide from exposure studies conducted in China, India, Europe and
Australia. It is evident that large differences exist in sensitivity to
equivalent sulphur dioxide concentrations. However, the data suggest that the
species with higher sensitivities are consistent across regions, for example
both the Indian and Chinese studies identified beans as an especially sensitive
genus. The range of species response to increasing exposures seems broadly
consistent between regions indicating a degree of commonality.
Similar
dose-response data have been pooled for forest tree species allowing the
comparison of responses to varying ozone exposures of Japanese deciduous and
coniferous tree species with equivalent European species. Further, there is
considerable variability in the response of different Japanese tree species to
ozone exposure. Comparison with European beech (a sensitive European species)
suggests that the most sensitive species in Japan have similar responses to
ozone exposure as the most sensitive European species. Similar results are
found on comparison of the Japanese and European coniferous species. Overall,
these data suggest a broad consistency in exposure-response relationships for
sensitive species of both trees and agricultural crops from different regions.
However, much more work is needed to define robust dose-response relationships
that would be appropriate for use in studies to assess the socioeconomic
impacts of pollution damage to vegetation. It is the identification of
appropriate methods to establish such relationships that will form a
significant part of this second phase of the project.
The Regional
Air Pollution in Developing Countries (RAPIDC) programme aims to facilitate the
development of agreements/protocols and to implement measures which prevent and
control air pollution through promoting international co-operation and
developing scientific information for the policy process. The RAPIDC programme
is co-ordinated by the Stockholm Environment Institute (SEI) and funded by Sida
(the Swedish International Development Co-operation Agency). The "Air
Pollution: Crops and Forests" project is a component of the RAPIDC
programme which focuses on assessing damage to agricultural crops and forest
productivity caused by ambient pollution
levels in developing
country regions, with a particular focus on the Asian region. Further details
concerning the overall RAPIDC programme can be found at
To ensure
that appropriate data are collected in Phase II of this project it is important
to consider how these data would be used to inform the implementation of
emission reduction policy initiatives. There is a real need to provide some
indication of the potential risk to which agricultural crops and forest trees
are exposed under current-day air pollution concentrations, and the increased
risk which may arise from future predicted increases in emissions.
Exposure-response relationships can be used to assess the change in the degree
or risk of damage for a given change in pollutant exposure. This requires the
integration of various datasets including regionally mapped pollutant
concentration data and receptor information to show species location. These
data can be overlaid to produce maps capable of highlighting cooccurrence of
sensitive vegetation types and potentially damaging pollutant concentrations
and hence where there may be a risk of crop yield reductions and damage to the
health and productivity of forests. This information may then be used in
socio-economic impact analyses or cost-benefit analyses that estimate the
environmental benefits of investment in measures to reduce pollutant emissions.
The data
necessary to define pollutant impacts on vegetation need to be collected under
careful consideration of the local and regional factors that will no doubt
affect vegetation response to air pollution. For example, are all factors known
to alter plant sensitivity to air pollution and as such will need to be taken
into account when establishing any kind of observational or experimental
protocol to collect exposure-response information.
It may be
possible to use the following options to collect the information necessary to
relate pollutant exposure to damage. It is possible to define two separate aims
and uses for these data: i) to define dose-response relationships or an
appropriate equivalent that can be used to perform socioeconomic pollutant
impact assessments, and ii) to help validate local and regional assessments of
damage produced through the application dose-response relationships.
OBSERVATIONAL METHODS
EXPERIMENTAL METHODS
-
Bio-monitoring using well documented indicator plants.
-
Transect
studies investigating the variability of damage to vegetation along air
pollution gradients.
-
Studies using
chemical protectants.
-
Experimental
studies (e.g. open-top chamber filtration studies, open release systems
etc..).
-
Epidemiological studies investigating statistical relationships between
specific damage parameters and air pollution exposure.
-
Methods to
assess risk of damage by pollutant concentrations
-
Preliminary
semi-quantitative identification of possible risk areas on consideration of
pollutant concentrations, climatic conditions and location of known sensitive
species.
-
Quantitative
estimates of socioeconomic impacts of pollutants. These would require the
establishment of robust speciesspecific relationships relating exposure
indices to damage.
The second phase of the
project will concentrate on identifying which of the above methods will be
suitable for application across the Asian region. Many factors will need to be
considered when trying to select appropriate methods for developing country
situations. Some of the more important will no doubt relate to: i) the
suitability of the experimental methods to developing country conditions; ii)
the ability of the methods to provide information on the response of vegetation
relevant to appropriate, social and economic conditions (e.g. yield and
nutritional status of crops); and iii) the financial and logistical constraints
to establishing and conducting observational or experimental procedures.
MAIN ACTIVITIES
-
Establish a
network of air pollution effects scientists with emphasis on South Asia, but
including practitioners in the rest of Asia.
-
Use of
questionnaire surveys to identify major knowledge gaps and the potential for
developing a common manual describing methods for assessing crop-yield
reductions and loss in forest productivity under Asian conditions.
-
Develop an
experimental protocol for Asian and other developing country conditions to
enable socioeconomic risk assessments to be performed.
-
Produce a
background document, summarising the current status of knowledge of pollutant
impacts on vegetation in the Asian region.
-
Hold a
workshop for the Air Pollution Network in South Asia to assess the current
state of knowledge of air pollution impacts, discuss and agree the proposed
manual/protocol, and bring together regional air pollution experts,
decision-makers and other appropriate stakeholders. Key topics for discussion
at the workshop will be the transferability of European/North American
experience and air quality management tools (including critical levels,
dose-response relationships and air quality guidelines) to the Asian region.
1Stockholm
Environment Institute at York, Biology Dept., University of York, York, U.K.
2Dept.
of Botany, Banaras Hindu University, Varanasi, India.
3Environmental
Pollution Research Laboratory, Botany Department, Government College Lahore,
Pakistan.
4Dept.
of Environmental Science, University of Bradford, Bradford, U.K.
5Goteborgs
Universitet, Goteborg, Sweden
6IVL,
Swedish Environmental Research Institute, Goteborg, Sweden |
