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| Scientists' Contributions | ||
LARGE-SCALE AIR POLLUTION AND CLIMATE CHANGE IMPACTS ON TERRESTRIAL
ECOSYSTEMS:
MONITORING, RESEARCH SYNTHESES AND ASSESSMENTS IN RUSSIA
Serguei SEMENOV,Gregory INSAROV Background
Amongst thousands of anthropogenic factors that may affect terrestrial
ecosystems there are few of large-scale ones, i .e. acting on the regional, continental or
global scene. Changes in atmospheric concentrations of carbon dioxide (CO2),
ozone (O3), sulphur dioxide (SO2) and nitrogen oxides
(NOx, i.e. NO and NO2) are of the major interest with this regard.
While elevated CO2 leads to a certain increase in plant growth and productivity,
enrichment of the atmosphere with O3 and SO2 causes significant
inhibition of these functions. NO and NO2 have no direct (i.e. through
penetration via stomata) effect on terrestrial plants at contemporary regional to global
levels. However, they are important as chemical precursors of ozone as well as the agents
leading to acidification and nitrogen fertilisation of soils. Both latter factors
potentially affect terrestrial plants. In addition to the above, changes in climate,
especially in temperature, precipitation, and ground-level flux of solar radiation form
another group of factors that can seriously affect terrestrial plant species and
communities.
Potentially factors of both groups can substantially alter structure
(species composition) and function (productivity) of natural terrestrial ecosystems as
well as affect production of agricultural crops and wood. Therefore, large-scale air
pollution and climate change effects on terrestrial plants was one of the major focus of
monitoring, research and assessment activities in the last decades of XX century. An
interest to these issues is becoming even higher nowadays due to increased understanding
of importance of combined effects of the above factors in view of projected climate change
in XXI century.
This interest is especially serious in Russia, because there are vast
territories at which trends in air pollution of regional to global scale as well as
global climate change are the major impacts to which natural as well as artificial plant
communities are exposed. In response to increasing necessity for investigation of these
issues, monitoring, research synthesis and assessment activities have been initiated in
1970th within Hydrometeorological Service by Professor Yuri Izrael (Head of the agency
that time). Namely, a core research group was established in Moscow at the Institute of
Applied Geophysics (IAG) in 1974. The main task of the group was to provide scientific
support for monitoring and assessment activity in the field of large-scale air pollution
and climate change impact on terrestrial ecosystems and, especially, plant communities.
This group was initially headed by the late Dr. L. M. Filippova. Since 1985 and to
present Professor S. M. Semenov leads the group. Due to administrative reorganisations,
the group moved from IAG to Laboratory of Environment and Climate Monitoring (LAM) in
1979 and then to the Institute of Global Climate and Ecology (IGCE) in 1991. Parent
agencies of LAM and IGCE are Hydrometeorological Service1
and Russian Academy of Sciences (RAS) The group constitutes now Terrestrial Ecology and
Bioclimatology Department of IGCE.
This paper is devoted to brief description of activity in Russia
aiming at monitoring and assessment of impacts of large-scale air pollution and climate
change on terrestrial plant communities. This activity includes the projects directly
conducted at the IGCE as well as projects conducted at co-operating institutions under
Russian Academy of Sciences and some other agencies formally or informally contributing to
this work. IGCE has no formal co-ordination function, i. e. the projects are implemented
autonomously and have their own goals. However, integration of information and its
analysis from the perspective of large-scale impacts of air pollution and climate change
on terrestrial ecosystems are performed mostly at the IGCE. High level of mutual
understanding of the groups carrying out the projects makes possible efficient
co-operation (mainly informal) and exchange of information.
It should be mentioned that the results are not aimed only to
description of a situation in Russia. They relate partly the situation in adjacent
countries and some other countries as well. This activity is currently being maintained
in Russia despite of contemporary difficult economic circumstances in the country. The
main goal of this paper is to present philosophy and major components of the work, and to
give a brief overview of ongoing activities and the prospects.
Philosophy
Concerns of scientists, public and, hence, policymakers on changes in
state of the environment and climate have resulted first of all in increasing demand for
reliable information on existing and future trends. Such information is produced through
MONITORING, RESEARCH SYNTHESIS, and ASSESSMENT activities. In all of them MODELLING plays
an important role.
MONITORING programmes produce long-term series of data over spatial
networks of observational stations (a synonym to a "site"). These data could be both of
abiotic nature (emission rates or concentrations of certain substances, temperature or
precipitation, depth or acidity of snow cover, etc.) and biotic nature (phenological
dates, occurrence and abundance of indicator species, crop yields, tree growth rates,
etc.). Some types of environmental variable is very difficult or/and expensive to measure
in the field, however they can be calculated with models from other monitoring variables
which are easier to measure. For instance, EMEP2 programme produces, in particular,
seasonal and yearly means of sulphur and nitrogen atmospheric deposition over 50x50 km
grid in Europe through model calculations using routine monitoring data on emissions by
countries. It is typical example of secondary monitoring product, i. e. obtained through
calculations from the measured values. The final information product of any monitoring
activity is a field of certain environmental variable (biotic or abiotic), i. e. the
current value of an environmental or climatic variable as depended on latitude, longitude
and altitude, as well as statistical characteristics of this field allowing comparison of
such fields in space and time. Such a field can be produced either through extrapolation
of primary monitoring data over geographical space or through conversion of another
observed field with models. Sometimes the primary information can be obtained also from
publications or reports from large-scale research projects.
Results of some experimental research projects as well as of monitoring
programmes often contain so called cause-response data. These data characterise species
response to a certain change in long-term (chronic) air pollution level or change in
climate. Searching such data through scientific publications, organising them into
databases and further synthesising them using models constitute RESEARCH SYNTHESIS. Its
main information products are so called cause-response relationships, i. e. simplest
mathematical data-based models that can convert a given long-term change in a level of air
pollution or in climatic variable into species response. Different variables can be
employed in characterising the response. However, usually net photosynthetic rate, net
primary production or biomass growth rate are applied. The usage of such information
products, namely cause-response models, is very wide. In between, they can be directly
used in large-scale assessments for converting a perturbation of a field of certain
abiotic variable (gas concentrations in the surface layer of the atmosphere, surface
temperature, etc.) into respective changes in productivity (e.g., in crop yield or wood
production). On the other hand, they are very efficient in quantifying sensitivity of
plant species to a given factor as well as for comparative analysis of sensitivity of
species from a certain group, for instance, serial crops, lichens, etc.
ASSESSMENT is the final stage of any activity aiming at delivering
environmental information produced by monitoring and, partly, research programmes to
consumers. The main goal of this stage is to convert environment and climatic information
into specific format usable for managers and understandable for public, and, therefore,
applicable in decision-making process as well as in informing the public. Typical
information products at this stage are maps characterising distribution of priority
biotic and abiotic environmental and climatic variables over space, their averages over
globe, continents, countries and provinces, as well as their trends in time. Such
distribution may describe the current situation, or a situation may emerge in accordance
with some scenario. The ultimate goal of such assessments is to evaluate whether the
observed or projected tendencies are dangerous or favourable for human health,
life-supporting systems of humans, and ecosystem health.
Monitoring activities
A large-scale monitoring activity with respect to terrestrial
ecosystems, especially in Russia having so vast territory and currently the economy in
transition, should consist of very few priority items to be realistic. Therefore, data
related to large-scale air pollution and climate change impacts on terrestrial ecosystems
collecting by IGCE itself or providing by co-operating institutions are limited to three
major types of biotic variables, namely, lichenological, phenological and
dendrochronological ones.
Lichen monitoring. It is widely accepted that epiphytic
lichens are very sensitive to an increase in long-term air pollution and climate change.
They serve as "early warning" detectors of such changes in a state of the environment and
climate. Epiphytic lichen monitoring programme is in operation since 1978. A network for
this type of measurements is based mainly on a system of Russian nature reserves, i. e.
any lichen monitoring site is located within a reserve. These areas are usually located
far from pollution sources, and status of nature reserve minimises influence of such
anthropogenic factors, as land use, forestry, construction, etc. Major information
products of lichen monitoring are quantitative estimates of occurrence and cover of
lichen species characterising a given site at a year when survey was made. These values
may further be subjected to an assessment procedure, in particular, aiming at detection of
a trend in time at a given site, or at comparison of sites with respect to lichen species
abundance and cover. IGCE is fully responsible for this activity in Russia.
Epiphytic lichen sampling procedure consists of selection of sample
plots within a site, selection of model trees within plots, and lichen measurement on
trunks of the trees selected (Insarov, 2001). Sample plots at a site (7-50 in practice)
and model trees at each sample plot (4-10 in practice) are selected evenly within as much
narrow stratum as possible with respect to substrate (tree species), tree age and/or size,
as well as altitude, slope, aspect, shading and moisture conditions. This allows us to
reduce uncertainty of over-site averages quantifying a state of lichen community. A
distance between trees should be considerably less than distance between plots. Forest
edges and maritime situations are to be avoided. Trees are to be selected with no a
priori information on lichen presence and abundance on their trunks. They should have
near vertical trunks and have no severe visible damages of bark or crown. To exclude
effects of tree age, further surveys at the same site are to be conducted within the same
stratum, in particular, on trees of nearly the same age/size as model trees selected for
the first survey. Thus, model trees to select for the next survey should be as a rule
different from those used in the previous ones to fit the latter requirements. Cover of a
lichen species at a given tree is quantified as total length of the species thalli
intersections with measuring tape placed around the tree trunk at 1.5m height from the
tree base (1.0 or 0.5m can be used for phorophytes with numerous dry snags). This is a
major variable for further processing.
Lichen thalli unidentified to species in the field are collected for
further identification in the lab. Computer-aided multi-access keys for lichen
identification are elaborated for a number of reserves, see, for instance, (Insarov et
al., 1997). The keys allow non-lichenologists to identify common lichens in the on-line
mode. They also allow to identify specimens lacked some characters which presence is
compulsory for traditional identification procedure using dichotomous keys. Lichen
monitoring data are stored in special database (Zeltyn, Insarov, 1993). Data quality
assurance as well as data export into format needed for future calculations are available.
Since 1978, initial lichenological surveys have been undertaken at 28
nature reserves in Russia and adjacent countries on the territory of former Soviet Union,
see (Insarov, Pchiolkin, 1990) and future references there. Region list includes European
part of Russia, Belarus, Ukraine, Caucasus, Central Asia, Siberia, Russian Far East,
including Kamchatka peninsula and Kurile Islands. Typical size of nature reserve area is
50 - 100 km2. Total number of sample plots surveyed is over 600, total number of model
trees belonging to 42 species is over 4,500. Total number of lichen species recorded is
over 500. Beside, a number of surveys have been undertaken in Sweden, Portugal and Israel;
in the last case epilithic lichens have been surveyed.
Phenological monitoring. First observational network was
established under Russian Geographical Society in 1885. This type of observations
occurred of significant importance nowadays in connection with air pollution and climate
change issues. The beginning and ending of vegetative period (synonym to "growing season"
for plants) can be considered as limits of a period of plant exposure to air pollution. On
the other hand, well-known dependence of these phenological dates on within year course
of climatic variables (predominantly of surface air temperature) makes the dates valuable
indicators of climate change. Primary large-scale phenological data on natural vegetation
originates from monitoring activity both of state institutions and the volunteers. Forest
Experiment Stations routinely collected the data on the annual basis and reported them to
the All-Russia Research Institute of Forestry and Mechanisation (Pushkino, Moscow
Province). Staff of nature reserves was and still is yearly reporting phenological data
to the All-Russia Research Institute of Nature Protection (Moscow). This activity is under
Ministry of Nature Resources of Russia. The data are stored in respective institutions.
However, majority of phenological data is resulted from activity of the volunteers and/or
recorded during biological field training of schoolchildren. These data are then sent to
the Phenological Centres where data are stored and processed. There are two centres
working under the patronage of Russian Geographical Society, namely, in Moscow, within the
IGCE, and in St. Petersburg, within the V. L. Komarov Botanical Institute (BIN, under RAS).
Methodologies for phenological observations have been comprehensively
developed in 1970th, and their modern versions are also available, see, for instance,
(Bulygin, 1974, 1976; Elagin, 1975; Bulygin, Yarmishko, 2000). Although the phenological
network in Russia has been notably declined during last decade due to economical situation
in the country, it still consists of several hundreds of sites. Their spatial distribution
is not even, most of them are located within European Russia. Dozens of phenological
dates are monitored over the network on the annual basis. However, the most universal
amongst easily observed ones with respect both to plant response to large-scale air
pollution and climate change, appear two of them, namely, leave development (emerging) in
spring and leave colouring in autumn in deciduous trees. The analogues dates in conifers
limiting the growing season are observed rarely. The dates associated with a given site
and a certain year are the major information products of this section. Since 1999 the
IGCE has been developing phenological database on natural vegetation containing, in
particular, the dates on trees of the following genera: Acer, Aesculus, Alnus,
Armeniaca, Berberis, Betula, Carpinus, Cerasus, Corylus, Fagus, Larix, Malus, Padus,
Picea, Populus, Prunus, Robinia, Quercus, Salix, Sorbus, Tilia, Ulmus.
Dendrochronological monitoring. The major
dendrochronological information products of this section are series of annual tree size
increments (e. g., radial increments, tree height or branch length increments). Such
series reflects all kind of changes in the environment and climate in the integrated
manner, and, therefore, serve as biological indicator of the combined effects. It contains information both on long-term trends and inter-annual variations.
Amongst dendrochronological observations the most known and widely
performed in Russia are tree ring measurements. This work on the large scale was and is
mainly carried out by research institutes of RAS. V. N. Sukachev Institute of Forest
(Krasnoyarsk) and Institute of Plant and Animal Ecology (Ekaterinburg) are concentrated
mainly on measurements at Siberian sites and within Ural region, respectively. V. L.
Komarov Botanical Institute of RAS (St. Petersburg) mainly deals with dendrochronological
studies at the forest/tundra ecotone and upper edges of forest zone in the mountains. Till
1991 Botanical Garden of Lithuanian Academy of Sciences (Kaunas) has been conducting tree
rings studies over European part of the USSR. Dendrochronological data are stored at these
institutions at their own databases. However, developing the All-Russia
Dendrochronological Data Bank has been recently started at V. N. Sukachev Institute of
Forest (RAS) in Krasnoyarsk.
It should be emphasised that the above mentioned institutions pursue
mostly their own academic goals, namely, to update the fundamental knowledge, and to
develop and improve methodologies (Bitvinskas, 1974; Vaganov et al., 1996; Lovelius,
1997; Vaganov, Shashkin, 2000). However, large-scale data on tree rings series obtained
in these studies are very valuable monitoring products as well. Tree species mainly used
for tree ring measurements are Larix sibirica, Larix gmelinii, Larix cajanderi, Pinus
sylvestris, Pinus sibirica, Picea obovata. A network for dendrochronological
measurements in Ural region, Siberia and Far East already contains several hundreds of
sites (Vaganov et al., 1996) and tends to expanding. According to methodological
requirements samples from about 15-25 trees of the same species have been taken at each
site using the increment borer. These trees should be under similar growth conditions and
represent different age groups of trees, namely, old, middle-age, and young. The samples
are further processed in lab using tree-ring scanners and special computer programmes
dating tree rings and producing verified tree-ring series.
In addition to traditional dendrochronological activity described
above a new one has been initiated by IGCE in 2000. It is aimed at measuring annual
linear increments of trees, i. e., increments of stem height and branch length. As in the
case of epiphytic lichens (see above), each monitoring site is located within a nature
reserve and represents a certain stratum with respect to tree life conditions. The
juvenile trees of Pinus sylvestris of 2-2.5m height are used for such measurements.
Twenty to fifty sample plots are selected within the site as evenly as possible. Three to
ten trees of different age/size with no visible damage from animals (insects, elks, etc.)
are selected within each plot in a random manner. The sample plots are not to be
permanent, i. e. the plots to use in future surveys of the same site should be within the
same stratum, but selected independently of selections made in previous surveys. Annual
segments of stem and of three branches of each selected tree are measured starting from
the most recent one till the last one reliably distinguished. The branches should be of
the first order and of the same direction (for instance, south direction), and represent
the upper, middle and lower parts of the crown. All three branches are to be alive
(growing), and the age of the upper one is to be 5 years or more. The major
characteristics of the site and the results of measurements are documented.
This type of dendrochronological observations was decided to start,
because such data appears the most informative for short- to middle-term assessments,
namely, for periods of 5-25 years, due to the following reasons. Twig growth is more
directly affected by a change in chemical composition of surface layer of the atmosphere
and climate than radial tree growth and, therefore, twig response has more chances to be
early detected. Such measurements are simple, enough precise, do not require complex
equipment, and can be carried out by trained technicians of monitoring stations or
expeditions. And last, but not least reason is that the increment borer damages to a
certain extent last 5 tree rings that might be of particular interest in short- to
middle-term assessments. Such type of measurements was named "horpexometry"
(Koukhta, 2001; Koukhta, Semenov, 2002), since the Greek "horpex" in English means a
"twig". The basic surveys of this type were accomplished by IGCE expedition in 2000-2001
at monitoring sites located in Kandalaksha State Reserve (North of European Russia, White
Sea region), Pechoro-Ilych State Reserve (North-East of European Russia),
Prioksko-Terrasny State Reserve (Moscow Province) and Central-Forest State Reserve
(central Russia, approximately at the midway from Moscow to St. Petersburg). A database
containing the data has been developed and is being maintained at IGCE.
Research synthesis
Two examples of research syntheses will be described in this section.
Both relate to an estimation of sensitivity of species or groups of species to a change
in chemical composition of the atmosphere, in particular, in a level of air pollution.
The second one also relates to climatic effects. The organisms to consider are the higher
plants (trees, crops) and epiphytic lichens.
Sensitivity of higher plants. In the last quarter of XX
century a chamber experiment technique (using close chambers, open-top chambers, etc.)
has been widely employed in studies of the effects of various agents (e. g.,
CO2, O3, SO2) on higher plant growth. A typical
experiment with an agent was conducted under controlled conditions, i. e. all
environmental variables except concentration of the agent were kept constant or had the
similar course over exposure period in all treatments of a series, while concentration of
the agent was specific in each treatment. Such concentrations of the agent were maintained
in chambers several days a week over a part of day, and the schedule was common for all
treatments of the series. Seedlings or small plants were exposed to the agent from a
certain day after emerging (planting). Plant biomass or biomass of its parts (leaves,
root, stem etc.) or yield were measured and documented several times during the experiment.
Sometimes, other conditions (light, soil, watering, etc.) were also recorded. Height was
also often employed in characterising experimental tree growth. Measurements could be
continued, in particular, after finishing a treatment. Such cause-response data have been
obtained in various experiment research projects conducted in many countries (mostly in
USA and of Western Europe) in the last quarter of XX century. The data have been searched
through world scientific literature and collected at IGCE. They are stored in special
database and subjected to further processing with statistical means. Trees are
represented, in between, by plants of the following genera: Acer, Betula, Fraxinus,
Liquidambar, Liriodendron, Pinus, Populus, Quercus. Crops are represented, in between,
by the following species: Allium cepa (bulb onion) , Arachis hypogaea
(peanut), Brassica napus (turnip), Brassica rapa (rape), Glycine max
(soybean), Lactuca sativa (cutting lettuce), Lycopersicon esculentum
(tomato), Nicotiana tabacum (tobacco), Phaseolus vulgaris (kidney bean),
Triticum aestivum (spring wheat), Zea mays (maize).
Concentration of an agent averaged over period of growth (c) is
often applied in characterising a state of the environment with respect to chemical
constituents. Besides, integral of an excess of some threshold level by concentration of
the agent over growth period is also successfully used. For instance, AOT40 index (that
means Accumulated Over Threshold of 40 ppb) is alternatively used in quantifying ozone
impact on plants (F(hrer, 1996).
Cause-response models are widely employed for synthesising results of
cause-response experiments. Such models are simple relationships between a change in a
state of the environment (Dc) and corresponding change in plant productivity (total
biomass production, yield, etc.) from P to Po.
Exponential function Sensitivity of lichens
Sensitivity of lichens to air pollution. Because of slow
growth, very few lab cause-response experiments with low and moderate pollutant levels
have been undertaken with lichens (Insarova, Insarov, 1989). The main set of data we used
to assess lichen sensitivity to air pollution are numerous published results from field
gradient studies containing data on a change in lichen community structure and species
characteristics along air pollution gradients. The majority of such studies have been
accomplished in various regions of Northern Hemisphere with respect to SO2,
NOx, H2S, CO, dust, and heavy metals. A typical study is designed as
follows. Characteristics of lichen communities and species are observed within sample
plots placed along a certain transect starting from a source of pollution (city centre -
outskirts transect, for example) (Richardson, 1988). List of lichen species is compiled
for each plot, and lichen species occurrence and cover are documented. Such information
comprises a basis for estimation of lichen sensitivity for pollutants. For instance, a
rate of decline of occurrence/cover of a species with decreasing distance to the source of
pollution roughly quantifies sensitivity of the species. Species can be further
quantitatively compared with respect to sensitivity using such values. So far, a series of
so called lichen sensitivity scales has been developed (Hawksworth, Rose, 1970; Hultengren
et al, 1991; Insarova et al., 1992). A database containing estimates of lichen
sensitivities to various pollutants has been also developed (Insarova et al., 1992). At
present it contains estimates of sensitivities for more than 250 lichen species in
different localities of the Northern Hemisphere. The values are transformed into a unified
100-degree sensitivity scale. Information on localities, tree phorophytes and their bark
pH-class, and literature sources is also stored.
Sensitivity of lichens to climatic factors could be
estimated through a) gradient studies, b) analysis of lichen species
ranges, and c) analysis of experimental data on an influence of climatic stress on
lichens.
In order to filling the gaps in knowledge on sensitivity of some
lichen species at a region, an extrapolation procedure can be applied (Roitman, 1989).
Such procedure uses a hierarchical system of the Earth floristic regions as well as
phylogenetic system for describing lichen taxonomy. Existing data on sensitivity of
lichen species to certain factors at various regions of the Earth is an input information
for such procedure. Output contains the estimates of sensitivity for species to factors
and for regions requested, and their uncertainties (Insarov, Insarova, 1996).
Assessment activities
An assessment is roughly of two types, namely, "status assessment" and
"trend assessment". A status assessment is aimed at characterising field(s) of given
variable(s) in space at a certain moment or time period. Such a field can be actual or
hypothetical one, i. e., constructed in accordance with a scenario. The main aim of a
trend assessment is to detect a trend in actual series of monitoring data on given
variable(s) characterising a certain location or territory. Some examples of assessments
of these types are given below. The assessments are widely demanded within scientific
community as well as by policymakers and public. Specially formatted (in particular,
written in common language) assessments oriented to the latter two groups of users are
annually published in Russia by Hydrometeorological Service (see, for instance, (Survey
of pollution of the environment in the Russian Federation in 2000, 2001)).
Status assessments. Ground-level concentrations of
O3 and SO2 in Europe in the last quarter of XX century
significantly exceeded their "pre-industrial" levels. Meteorological Synthesising
Centre-East (MSC-E) of EMEP calculated these values for each cell of so called EMEP grid
with a routine model. In co-operation with MSC-E these calculated fields for 1991-1994
were then used at IGCE for comparative assessments of sulphur dioxide and ozone fields and
for estimation of O3 - and SO2 -caused reductions in cereal crop
yield and growth of biomass of deciduous trees over Europe for 1990th (Semenov, Koukhta,
1996; Semenov et al., 1998).
At the first stage fields of excess (Dc) of surface concentration of
ozone and sulphur dioxide over their pre-industrial levels averaged over vegetative season
were computed. The lower and upper limits of vegetative season for each cell of EMEP grid
were calculated using a data-based model quantifying their dependence on latitude. The
model was developed through research synthesis of published phenological data (Semenov et
al., 1997). These two averaged fields, namely, of O3 and SO2
occurred essentially different. Concentrations of O3 everywhere significantly
exceeds concentrations of SO2. Maximal concentrations of SO2 (up to
35mg/m3) are characteristics of some regions of Germany (East), Poland and
Czech Republic (West), while outside them as a rule the values are several times lesser.
Ozone field has several peaks (from 30 to 40mg/m3) within territories of the
following countries: Great Britain (eastern England), Netherlands, Belgium and Luxembourg,
Germany (South), Austria, Czech Republic. Ozone concentrations in some locations of
Greece (25mg/m3) nears the peaks.
At the second stage the above fields (Dc) for SO2
and O3 were converted into the fields of percentage decline in the annual
biomass increment of deciduous trees using a formula Thus, SO2 direct effect on biomass increment of terrestrial
plants (i. e., through penetrating into leaves via stomata) is a problem of regional
scale, not of continental one. It is mostly the problem of three countries: Germany,
Poland and Czech Republic. Contrary to this, anthropogenic ozone in the troposphere
constitutes a continental problem. Averages of its concentrations over vegetative season
in Western and Central Europe almost everywhere significantly exceeded their
pre-industrial levels in 1990th.
The same model was applied for conversion of the excess (Dc) for
ozone into reductions in cereal crop yield. It was shown that such reduction had exceeded
20% in some regions, while overall ozone caused annual losses in crop production in
Europe had exceeded 2 billions US dollars (Semenov et al., 1999).
Trend assessments.
Lichens. A methodology for the most efficient detection
of changes in a state of lichen communities at a site caused by an increase in background
air pollution or climate change has been proposed in (Insarov, Semenov, 1993; Insarov et
al., 1999). The main idea is construction of Trend Detection Index (TDI), namely, a
weighted sum of species cover with special weights. The weights have to be chosen so as to
ensure the highest resolution of TDI in detecting changes in lichen communities. In a
monofactorial case, i. e., if a change in lichens is mainly determined by one
environmental or climatic variable, two pieces of information are needed for calculating
such weights. The first one is information on species sensitivity makes it possible to
quantify how each species cover will change in response to projected change in the
variable. Such information is derived from databases on lichen sensitivity through
research synthesis procedures. The second one is information on natural variability, i. e.
variances of lichen species cover at the site. Such information is derived from initial
and further field surveys at the site using computerised statistical procedures.
Mathematically the weights for calculating TDI are to be computed so as to achieve
maximum possible value of signal-to-noise ratio, namely, a ratio of square of expected
trend to natural variance. It was shown that resolution of such TDI is several times
greater than resolution of each of the widely used indices, e. g., total cover of all
species, Index of Atmosphere Purity, Index of Poleotolerance, or cover of one, even the
most sensitive species. In many cases this allows to detect trends undetectable with
traditional methods. For instance, estimation of potential efficacy of TDI-based system
for monitoring and assessment of climate change with epilithic lichens proposed for the
Ramon nature reserve (Negev Desert, Israel) showed that 0.8oC change in the annual mean
surface air temperature will be detectable (Insarov et al., 1999). Such resolution appears
sufficient in view of global warming by 1.4 to 5.8oC predicted by the
Intergovernmental Panel on Climate Change for the end of the 21st century (Houghton et
al., 2001).
Phenology. An analysis of changes in major phenological
phases for some tree species in European part of the former USSR occurred in 1966-1995
were accomplished at IGCE (Minin, 2000). It was shown that leave development (emerging)
in birch has shifted backward by 5-10 days in North, while in South-West it occurs now
several days later. No trends in the date has been detected in central part of European
Russia. The similar and even more distinct trends were found in mountain ash and bird
cherry tree. Litter-fall in birch has shifted forward in North and South-West, and
backward at Upper and Middle Volga regions. Vegetative period has increased by 10-20 days
in Baltic part of the former USSR territory, and within boreal and sub-boreal zones. A
certain decrease in duration of vegetative period has observed in Tambov and Pensa
provinces. No changes in duration of vegetative period have been detected in the Upper
Volga region, while its beginning has shifted backward. Duration of vegetative period has
slightly increased in Carpathians, while its ending has shifted forward.
Prospects
A set of contemporary activities aiming at evaluating the consequences
of large-scale air pollution and climate change impacts on terrestrial ecosystems in
Russia is not yet a system. This means that many important segments of "technological
chain" of evaluation procedure "from monitoring to assessments using a research synthesis
results" are still not properly established or needed to be seriously improved. The
problem has scientific, financial and institutional aspects. The major points could be
outlined as follows.
Although lichenological, phenological and dendrochronological
observational activities in Russia pursue their particular goals, respective networks
could have a common part that may constitute a Large-scale Background Monitoring (LBM)
network. This will ensure, in particular, more high resolution of trend detection
procedures. Such common LBM areas are expedient to select within state nature reserves
due to the following reasons. The reserves are typically located far from big sources of
air pollution, represent various climatic and floristic zones, have a permanent scientific
staff, and also have a certain protection regime minimising local land use caused impacts
and, thus, ensure possibility of long-term observations. Such LBM network, similar (by its
aims and character of the sites) to LTER networks in many countries, is to be decided.
Initial surveys of epiphytic lichen communities have been accomplished
at a number of nature reserves located in different climatic and floristic regions and
provinces in 1970th and 1980th. These areas are considered as a basis of LBM network. Now
it is time to repeat the surveys at the same sites that will give data needed for trend
assessments. Initial surveys should also be made at some new areas of LBM. This
lichenological work have to be accomplished by IGCE expedition. Phenological dates have to
be routinely observed at nature reserves belonging to LBM network by their permanent
staff and reported to Phenological Centres where the data are to be stored and processed.
The staff has also to collect wood samples using the increment borer and send them to a
dendrochronologocal data lab (for instance, to V. N. Sukachev Institute of Forest,
Krasnoyarsk) for further processing, and verifying and storing the tree-ring series.
Linear increments of young trees have to be measured by IGCE expedition, and then stored
and processed at IGCE.
The priority task for research syntheses with respect to trees and
crops is estimation of tree and crop species sensitivity to atmospheric deposition to the
land surface of certain substances, in between, of nitrates and ammonia, and to changes
in climate. Search of chamber experimental data through scientific publications,
developing special databases and cause-response models are needed for accomplishing this
task. New literature data on lichen sensitivity to air pollution should be also searched,
standardised, incorporated into existing lichen database and processed using a model
means. Gradient studies are also needed for estimating sensitivity of higher plants and
lichens both along climatic gradients and gradients in concentration of atmospheric
compounds, including pollutants. In these studies different types of biotic variables, in
between, phenological dates and rate of growth (both radial and linear) of trees as well
as species composition of lichen communities and species cover are to be explored.
Although research synthesis activity in Russia is still going on, it is seriously suffered
by limitations in availability of new scientific publications. A number of scientific
periodicals available in Russia have substantially declined during last decade. Access to
electronic library resources and reference materials is far from being perfect. Field
expeditions for extended gradient studies are also needed, but difficult to organise due
to budget circumstances.
There are two major issues which rectification is very important for
assessment activities. First issue relates to developing specific indices for integration
of monitoring data having high resolution, e.g., signal-to-noise ratio. This is important
for early detection of large-scale trends in lichenological, phenological and
dendrochronological variables. Such indices depend on a biotic variable and particular
factor(s) affecting it. The second issue is developing approaches for attribution a change
in biotic variables, e. g., explaining it by influence of certain air pollution or
climatic factor(s). There is certain experience with respect to the first issue (see
above, namely, assessment section, about trends in lichen communities). The second one is
still at research stage.
Unfortunately, funds available in Russia for monitoring, research
synthesis and assessment activities have been heavily lacking in the last decade that
created serious obstacles for evaluating the consequences of large-scale and log-term air
pollution and climate change impacts on terrestrial ecosystems. This has seriously
affected, first of all, field expeditions needed for routine field observations and
gradient studies, as well as library access, computer facilities and manpower needed for
carrying out research synthesis projects and assessment procedures.
References
Institute of Global Climate and Ecology,
Glebovskaya str., 20B, 107258 MOSCOW, RUSSIA
Contents of the document
P=Poexp(bDc)
is convenient for this purpose from many perspectives. Model parameter b
(coefficient of sensitivity, positive for CO2 and
negative for O3 and SO2)
is estimated from the results of cause-response experiments with a statistical procedure
using special computer FORTRAN programs developed at IGCE. Such estimations have been
accomplished with respect to CO2,
O3, SO2 for groups of
deciduous and coniferous trees, and cereal crops (Semenov, Koukhta, 1996; Semenov et al., 1999).
(1 - exp(bDc)).100%
(see Research Synthesis section for explanation of b, i. e. sensitivity value). As
it became clear from the results of these calculations, a role of sulphur dioxide is very
modest as compared with ozone role. Maximal value of anthropogenic effect of
SO2 (8%) is localised at the border between Germany and
Poland. The values quickly decline with distance from this location down to 1% and lower.
Contrary to this, anthropogenic effect of ozone exceeds 8% practically over all
continental part of Western and Central Europe as well as in eastern England and southern
Sweden. Decrease by 10% and more in the annual increment of biomass of deciduous trees
occurred in some regions of Austria, Great Britain, Hungary, Germany, Greece, Netherlands,
Poland, Romania, Slovak Republic, France, Czech Republic, Slovenia and Switzerland
(Semenov et al., 1996, 1997).
Serguei Semenov & Gregory Insarov
Serguei.Semenov@mtu-net.ru
insarov@chat.ru
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