GLOBAL ENVIRONMENTAL CHANGE AND VULNERABILITY
ECOSYSTEMS: FROM LOCAL TO REGIONAL AND GLOBAL SCALES
OF
Mečislovas Žalakevičius
Institute of Ecology, Akademijos 2, 2600 Vilnius, Lithuania; e-mail: mza@ekoi.lt
Key words: climate change, global warming, bird migration, population state,
breeding range shift, distribution areas, vulnerability of ecosystems
Many processes occurring on the Earth are climate-related. Seasonal fluctuation in
temperature determines the existence of the Earth's climatic zones and ecosystems,
which have a unique environment with specific plants, animals, and precipitation
amount.
Air temperature in the last two hundred years was not stable around the world and in
the Baltic region as well. Since XIX century the mean annual temperature has
increased approximately by 1 o C in Lithuania, and in the course of XX century – by
0.7 o C. The registered temperature increase in winter and spring seasons during this
period was more apparent, whereas changes in summer and autumn seasons were not
so obvious. Increase in mean air temperatures in winter and spring seasons has been
more significant since the 1960s (up to 1.7-2 o C).
Recent global environmental change raises new problems and targets for ecology and
human being. This process covers the entire planet. Under the effect of global
warming the world suddenly became small. Unfortunately, the consequences of the
planet's warming have not received sufficient investigation yet, while this kind of
research is of both theoretical and practical importance. Under the above mentioned
circumstances research into biodiversity and dependence of different characteristics of
flora and fauna upon changing environmental temperatures, as well as the related
modeling is crying out for attention.
Due to universal processes, that regulate functioning of ecosystems with wildlife as
one of its components, local investigations have assumed not only narrow regional but
also international importance and application. So, results of local research activities
can be successfully adapted on a regional or global scale. Science does not recognise
frontiers. It is similar to birds which breed in certain countries, feed and accumulate
fat deposits for migration in other countries and winter in the third countries,
migrating over large territories and continents.
Human being is closely related to wildlife and depends on its state. Ecosystem is as a
living organism the components of which are closely interrelated. Thus even the
slightest environmental alteration can result in a negative feedback for all the mankind
and its future generations. Not without reason such great attention has been recently
paid to environment and wildlife conservation in the world.
Recently the effect of climate change upon wildlife has become obvious and this
effect has significance for different branches of economy: civil and military aviation,
agriculture, forestry, environmental protection, fishery, transport and hunting. Herein
we deal with sensitivity and vulnerability of the country or region.
Among the indications of climate change impact on wildlife the following can be
mentioned: changes in bird population state or trends, their breeding ranges, staging
and wintering territories. They are of extreme importance for environmental
protection and different sectors of economy not only in Lithuania, but in the Baltic
region, Europe and all over the world as well. Here I must stress that changes in
wildlife first of all are expressions of changes in habitats and ecosystems. Wildlife
could be used as an indicator of global climate change and anthropogenic impact.
Reclamation of lands and forests, canalization of rivers and streams, increasing
thermal and chemical pollution, expansion of seaports and transport infrastructure
have become crucial to birds in the process of global climate change.
Efforts are made to preserve wildlife, its habitats and ecosystems for humanity and its
forthcoming generations by allotting sufficient financing for that purpose. Large
amounts of international money resources are assigned for environmental protection
whereas global processes taking place in the world bring changes into the possibilities
to preserve biological diversity in certain earlier designated strictly protected
territories.
My presentation deals with the impact of global warming on wildlife which is based
on the example of the avian annual cycle: timing and characteristics of migration,
breeding, staging, and wintering.
Bird migration.
It is known that bird strikes as a rule are registered in civil and military aviation
during bird migration periods and on migration territories. Different kinds of forecasts
are applied to prevent this great danger.
Our results of recent investigations (performed from 1966 up to 2001) indicate that
under the conditions of more expressed global warming (1990-2001 in Baltic region)
85% of short-distance migrant species investigated in spring and 74% of investigated
long-distance migrants arrived at the Žuvintas Strict Nature Reserve much earlier.
This regularity was reiterated in Vilnius environs: 88.2% of short-distance and 82.8%
of long-distance migrant species arrived in spring earlier. As you know long-distance
migrants winter in Africa, short-distance migrants - in Western Europe and in
Mediterranean region. This regularity was statistically significant in 26.7% cases for
short-distance migrant species and in 58.3% cases for long-distance migrants (p<0.050.001).
The study of spring arrival into the entire territory of Lithuania (to more than 130 sites
of registration), as well as Central and Eastern Europe shows that the course of arrival
of the selected model species (Skylark, Starling, White Stork, Swallow, and Cuckoo)
directly depends upon the rise in air temperature. Higher temperatures were associated
with earlier arrival (a significant relationship was obtained in four species: p<0.010.001).
Migratory take-off.
Undoubtedly, of all migration processes and its constituent parts the most sensitive to
climate change is migratory take-off. We defined that birds try to take off under
particularly favourable and ideal for the flight conditions. It helps them to avoid
extreme flight conditions in a great part of their migratory passage.
We established that the take-off with subsequent migration of maximum and high
density associated with increasing air temperature in spring and with falling air
temperature in autumn. Furthermore, the greater the increase in air temperature in
spring and the greater the fall in autumn, the greater the density of the take-off. Thus
climate change induces certain shifts in take-off periods, influencing alterations in
staging areas and formation of bird accumulations in them, and eventually
conditioning the timing and number of migration waves, migratory distances, and
species characteristics of migratory course.
Bird migration control.
In bird migration control, climate change acts both through the endogenous
programme, readiness for flight, changing its periods, and through changes in
environmental conditions. The existing models with the set-up range of transition
from the endogenous programme to the environment and vice versa may shift to one
or another side. Thus bird migration control may only change the ranges of dynamic
balance, which are essential for the practical use of the mechanisms controlling
migration.
Very interesting data were obtained when analysing bird breeding cycle. When
verifying the hypothesis of global climate change impact on bird breeding areas, data
confirming it were obtained. Besides that, different impact of climate change was
established on short-distance and long-distance migrants, breeding in the region of
three Baltic states - in the territory eastward from the Baltic Sea.
It is known, that conditions most favourable for the species life and their successful
existence are as a rule observed in the central part of their distribution ranges
(Timofejev-Resovskij, Jablokov, Glotov, 1973). In that part of ranges, habitats that
are most favourable for the species are found, as well as the greatest mean abundance
of the population. In the peripheries of ranges, where the complex of abiotic and
biotic conditions is often extreme, mosaic-like, fragmentary spread of individuals
within the populations is usually observed, thus populations are found in low density.
It is confirmed by the analysis of the ranges of the bird species enlisted in the Red
Data Book of Lithuania that almost all bird species are outside the limits of their
entire distribution ranges - in the periphery of the fragmentary ones. And, the state of
as much as 1/3 of the populations of the bird species included in the Red Data Book is
stable or they are increasing. The remaining 2/3 of the populations are decreasing in
Lithuania. As for the populations of the remaining 147 bird species not included into
the Red Data Book of Lithuania, the analysis of their distribution ranges within the
Western Palearctic shows that even 57.83% of these species breed in the central part
of their ranges and only 42.17% of them breed in the periphery. Populations of 84%
of the species not included into the Red Data Book and breeding in the central part of
their ranges are increasing and stable and only 16% are decreasing.
The species and populations that expand their ranges in a certain direction show
higher population abundance in the periphery of this direction.
So, if the range expanded in the northeastern direction because of climate change the
bird populations that are in the northern-northeastern-eastern periphery of their
Western Palearctic ranges ought to get under optimal conditions and their abundance
ought to increase, whereas in the western-southwestern-southern periphery due to the
contracting range the conditions ought to become more unfavourable and population
abundance ought to diminish. On testing the above hypothesis it was established that
the species which are both included and not included into the Red Data Book of
Lithuania show a clear tendency towards a rise in population abundance and stability
in the northern-northeastern-eastern periphery and a drop in the southernsouthwestern-western periphery of the ranges. These regularities observed in recent
years confirm our hypothesis about the impact of climate change on the population
ranges of birds breeding in Lithuania.
The species analysed belong to various ecological groups and breed in habitats of
various ecosystems. Anthropogenic effect does not explain these differences as it is
similar to different species on the investigated territory.
Besides, no differences have been found between sedentary and migratory species.
The above regularities established for Lithuania show that the Western Paleartic
ranges of breeding species are undergoing a shift to the northeast. This could be
attributed to only one reason: a northward (north-eastward) shift of climatic zones due
to global climate change.
During our research an interesting regularity was established: the impact of global
climate change or the shift in distribution ranges is better expressed in birds of
terrestrial and wetland ecosystems. Meanwhile, in water ecosystems habitats are not
so strongly influenced by global climate warming. Water acts as a buffer. This law is
interesting not only from the theoretical but also from the practical point of view as
far as environmental protection and various branches of economy are concerned. In
environmental protection this factor is acute when choosing the areas for the
protection of certain species in which the habitat state undergoes changes under the
effect of climate warming. The changes in habitat state are followed by the change in
the preserved species state. As a result of that, protected areas stop meeting the
requirements that they should and therefore their status should be altered. However,
that is not an easy task to do.
Analysis of 129 migratory bird species reveals distinct differences between
populations of long- and short-distance migrants breeding in Lithuania. It has been
established that in the northern part of the ranges short-distance migrants are most
abundant among the increasing populations, but in the southern part long-distance
migrants predominate in decreasing populations. The populations that are in the
central part of the ranges are markedly growing for short-distance migrants, but they
are diminishing for the long-distance ones. Statistically significant association
between certain parts of bird species ranges and their migratory categories: short- or
long-distance was obtained. This attests the hypothesis of some scientists in Europe
about different impact of global climate change on short- and long-distance migrants.
Short-distance migrants gain from this process eliminating long-distance migrants and
reducing their possibilities in competition.
Staging, wintering and migratory-resident state.
One of the signs of climate change impact upon migratory process of birds is the
regulation of migratory-resident state, which has developed in the course of evolution
as a response to periodical global processes of the rise and fall in temperature,
including global warming of recent years. Global warming causes shortening of
migratory routes of birds breeding in Lithuania, their winter quarters coming close to
breeding sites.
Recently shortening of migratory routes of birds breeding in Lithuania has been
observed, new wintering sites and new staging concentrations have been determined.
Our analysis revealed that the migratory routes of Starling, Mallard, Mute Swan,
Merganser, sea ducks, White-fronted Goose, ringed in Lithuania after 1989, to their
wintering sites has shortened.
These changes cause quite a number of urgent environmental problems in the
Lithuanian coastal zone of the Baltic Sea, where huge accumulations of wintering
water birds, that have the status of international protection, have formed. Meanwhile,
in this area oil export and import is being expanded, the huge sea oil terminal has
been constructed, the sea port is being extended and fishery is intensifying. All the
above mentioned factors have a disastrous effect on wintering water birds – many of
them perish here.
So, in this work, a new viewpoint of Lithuanian ornithologists on the global processes
occurring on the planet and in the country is reflected. Until now the bird distribution
and population change were related first of all to other reasons (such as habitat
succession, anthropogenic loading, land-reclamation, agricultural practices,
environmental pollution, resource utilisation, etc.). However, these reasons are not the
only and the most important factors. After the volume of land-reclamation works in
Eastern Europe had been reduced and intensive collective agriculture had been
destroyed, industrial and agricultural pollution became less intense and the areas of
monocultures decreased.
Unfortunately, global climate change impact on wildlife and biodiversity has been so
far insufficiently investigated. The perspective of such research is evident. We hope
that this subject will not be avoided by researchers, and new valuable results will be
obtained in the future.
So, in conclusion we must recognize that global warming impact on wildlife
influences economic activities, and raises new environmental problems. Due to the
sustained warming of winter seasons, the majority of species have shifted east- and
northwards; the main stop-over areas of migrating populations have changed; the
number of resident birds in different populations is rapidly increasing, the migratory
distances have diminished. These changes reveal new urgent practical ecological
problems on the science-policy interface basis. They are the audit of the net of old
strictly protected areas, establishment of new protected areas, optimisation of the
usage and protection of biological diversity and its resources, land privatisation and
use practices, new commitments in relation to the international conventions, revision
of ecological preservation strategies, action plans and programmes. Knowledge of
these changes has a direct influence on success in the bird strike problem
management: ways of solution, applicability of concrete measures, their effectiveness,
etc.