FAO Forestry DepartmentThis article is adapted from a paper prepared by the FAO Forestry Department as a basis for discussion on forest protection at the Fourteenth FAO Regional Conference for Europe in Reykjavik, 17-21 September 1984. Significant contributions were received from P. Bazire Chief of the French National Forest Inventory Service, with inputs from Giancarlo Calabri (forest fires), Chief of Italy's Forest Fire Service, Ministry of Agriculture and Forests; Manlio Mariani (long-range air pollution), a forest inspector with the Italian Ministry of Agriculture and forests; and Tran Van Nao (insects and diseases), a former FAO Forestry Officer. Daniel Liefgreen is a special correspondent for the Wall Street Journal in Milan, Italy, and was public relations officer for the Navajo Indian tribe in Window Rock. Arizona USA.
· Europe's forest resources include forest lands per se, as well as other lands covered with various types of woody vegetation - such as heaths or maquis formations - which can be grouped under the term "other woodlands". Table 1 indicates the proportion of land occupied by various woodlands in the different subregions. The "forestation rate" shown in the last column is the ratio of the land area occupied by forests and "other woodlands" to the total land area.
Overall, broad-leaved and coniferous forests and other woodlands cover almost exactly one-third of Europe's total land area. Also notable are (a) the high forest cover rate and the large proportion of coniferous forests in the Nordic and Central European countries; (b) the relatively large area of "other woodlands" in Southern Europe; and (c) the preponderance of broad-leaved forests in the European Economic Community and Southern European countries.
The quantity of wood harvested yearly gives an idea of the economic importance of European forests (Table 2). In all the subregions, the quantities of both round-wood and softwood represent between 1.6 and 2.8 percent of corresponding total standing volume. Even considering harvesting losses, or frequently underestimated rural self-consumption, these values show that forest resources are being rationally exploited and that removals are lower than average annual growth.
In recent years, damage of considerable intensity and scale attributable to long-range air pollution has occurred in Europe. Well-known examples are the decrease of fishery resources in many Scandinavian lakes and the thinning of thousands of hectares of forest in Central Europe. Occurrences like these have served to emphasize the worldwide danger to forest resources and have helped lead to the proclamation of the International Year of the Forest, 1985. The suddenness of these phenomena, together with their wide scope and visibility, has struck public opinion and drawn the attention of governments. Technicians, meanwhile, have pointed out that the degradation caused by one agent - air pollution - has made the forest more vulnerable to the attacks of others, such as insects and diseases, thereby setting off a multiplying effect with a potential for damage of incalculable magnitude. In this sense, long-range air pollution - popularly but somewhat imprecisely known as "acid rain" - cannot be examined in isolation.
Table 1. Forests and other woodlands in Europe (Areas in thousands of hectares)
|
Subregion
|
Total land area excluding water
|
Area as proportion of total European land area |
Total forest area
|
Forest area as proportion of European total |
Area covered by hard-woods
|
Hard woods' share of forest area |
Area covered by soft-woods
|
Soft woods' share of forest area |
Area of other wood-lands
|
This as proportion of European total of other wood-lands |
Forestation rate |
|
(%) |
(%) |
(%) |
(%) |
(%) |
(%) |
||||||
|
Nordic countries 1 |
112503 |
20.5 |
54597 |
34.9 |
5505 |
10.1 |
49092 |
89.9 |
5790 |
22.6 |
53.6 |
|
EEC (excluding Greece) 2 |
146384 |
26.7 |
31130 |
19.9 |
17835 |
57.3 |
13295 |
42.7 |
3607 |
14.1 |
23.8 |
|
Central Europe 3 |
12250 |
2.2 |
4754 |
3.0 |
939 |
19.8 |
3815 |
30.2 |
124 |
0.5 |
39.8 |
|
Eastern Europe 4 |
96934 |
17.7 |
26654 |
17.0 |
11390 |
42.7 |
15264 |
57.3 |
1307 |
5.1 |
28.8 |
|
Southern Europe 5 |
174814 |
31.9 |
37962 |
24.3 |
18390 |
48.4 |
19572 |
51.6 |
14523 |
56.7 |
30.0 |
|
Other Mediterranean countries 6 |
5697 |
1.0 |
1316 |
0.9 |
1019 |
77.4 |
297 |
22.6 |
255 |
1.0 |
27.6 |
|
Europe |
548582 |
100.0 |
156413 |
100.0 |
55078 |
35.5 |
101335 |
64.5 |
25606 |
100.0 |
33.2 |
Source: FAO unpublished data.
1 Finland, Iceland, Norway. Sweden. 2 Belgium, Denmark, Federal Republic of Germany, France, Ireland, Italy, Luxembourg, Netherlands, United Kingdom. 3 Austria, Switzerland. 4 Bulgaria, Czechoslovakia, German Democratic Republic, Hungary, Poland, Romania. 5 Greece, Portugal, Spain, Turkey, Yugoslavia. 6 Albania, Cyprus, Israel.
Table 2. Quantities of wood harvested in 1982 (Roundwood volumes)
|
Subregion
|
Hardwoods |
Softwoods Hardwoods/softwoods |
|
||||
|
Total (thousands of m3) |
Share of European total (%) |
Total (thousands of m3) |
Share of European total (%) |
Share of total hardwoods/ softwoods (%) |
Total (thousands of m3) |
Share of European total (%) |
|
|
Nordic countries |
17051 |
13.2 |
82153 |
35.9 |
82.8 |
99204 |
27.8 |
|
European Economic Community (excluding Greece) |
37714 |
29.3 |
46710 |
20.4 |
55.3 |
84424 |
23.6 |
|
Central Europe |
3807 |
3.0 |
13680 |
6.0 |
78.2 |
17487 |
4.9 |
|
Eastern Europe |
35065 |
27.2 |
49823 |
21.8 |
58.7 |
84888 |
23.7 |
|
Southern Europe |
27266 |
21.2 |
33845 |
14.8 |
55.4 |
61111 |
17.1 |
|
Other Mediterranean countries |
7823 |
6.1 |
2594 |
1.1 |
24.9 |
10417 |
2.9 |
|
Europe |
128726 |
100.0 |
228805 |
100.0 |
64.0 |
357531 |
100.0 |
Source: 1982 yearbook of forest products (FAO, 1984).
The market value of wood production may seem small when compared with that of agricultural crop and livestock products. However, wood as a raw material (its role as an energy source in Europe is small, although not negligible) serves as a base for large industries and a varied artisan sector employing considerable numbers of people, without counting those employed in the forest itself for silviculture and forestry enterprises. In Europe, these jobs are numbered in the millions and have a considerable share in the rural activities and economy of regions that are often disadvantaged owing to the quality of their soil or the harshness of their climate.
However, the woodlands are not only wood producers. They play a fundamental role in the protection of soil, the regulation of water regimes, the mitigation of climatic extremes, and the protection of plant and animal wildlife and of environmental stability in general.
Woodlands also play a leading role in the recreation sector. The growth of urban life has intensified the need felt by human beings to rediscover contact with nature. The growth in access to transport and in leisure time has made for increased use of wooded areas. The forests of the Paris green belt, for example, receive a yearly average of several tens of millions of strolling tourists, far more than all the monuments of the capital combined.
Until recently, there was a tendency to forecast a slight expansion of wooded areas and a substantial increase in standing volume and wood production for Europe as a whole. However, these positive tendencies could be reversed by the degradation of forests observed in some regions in Europe, and by the various threats to which forests are subject, if protection, prevention and control measures are not sufficiently strengthened.
The relationship between forest degradation and air pollution has sound statistical bases.Long-range air pollution remains a serious threat to the future of forests, to the soil, and to all the functions and services that forests perform.
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Biotic factors: pests and diseases Insects or diseases can attack different parts of the tree and either cause its death or diminish its growth. They even eliminate fructification and hence the natural regeneration of forests. The wood itself can be modified to some extent and lose all or part of its utilization value. The death of trees can also have a considerable influence on landscapes. This happens in the case of the famous Dutch elm disease, which affects moat of the Northern Hemisphere and has proved disastrous for the rural and urban landscapes in most European countries. The diseases that have recently affected the Mediterranean plane and cypress trees, together with the caterpillar (Mastococcus feytaudi) - which in 20 years destroyed the maritime pines of Provence and has affected Italy in the past few years - have gravely modified the urban and rural landscapes of what are predominantly tourist areas. The present situation varies widely from country to country and from year to year. A particular insect or disease may suddenly acquire great importance for a few months or years and then disappear, or return in a milder form. Reducing the area of European forest ecosystems with the aim of more intensive use for production purposes has shown the importance of only a small number of insects or diseases. The lowering of tree vitality caused by this reduction in area can often lead to epidemics that affect a significant portion of productive capacity. An example is the large Bostrychidae group, insects endemic in conifer populations and ever ready to proliferate at the first favourable opportunity, especially if tree vigour has been undermined (by drought, storms, air pollution). Some Bostrychidae species attack hardwood trees: for example, the bark beetle propagated by the fungus Ceratocystis ulmi, itself responsible for elm disease. Also to be mentioned in this regard are the pine processionary caterpillar, which mostly affects southern areas from the French Atlantic coast to Spain and Cyprus; the gypsy moth, which attacks oaks, especially in southern regions; the nun tussock-moth (Lymantria monacha), which, having ravaged the German spruce forests at the end of the last century, has devastated the Polish spruce and wild pine forests on more than 2 million ha for several years. These attacks may be the result of trees weakening from the effects of air pollution. Among fungi, Fomes annosus is the deadliest. Every year it causes the loss of about 20 percent of the production of spruce and other conifers. Ink disease and blight in the chestnut are the source of the considerable decline of this fine species, once the base of a civilization. As with the elm, it is the association of an insect, the beech-scale caterpillar Cryptococcus fagisuga, with a fungus, Nectrus coccinea, that has greatly damaged the beech; beech bark disease is widespread in Western Europe, especially since the 1976 drought. Fungi are also the source of the degradation of the Mediterranean plane and cypress trees. Although these different factors may be mentioned separately, they are closely interrelated. A forest population struck down by storm or destroyed as a result of drought or air pollution is an ideal prey for insects and fungi. Conversely, by weakening the root system of trees, air pollution or a severe drought makes them more vulnerable to wind (by lowering the automatic resistance of roots) and cold (because of the poor nutrition of soft tissues). The degradation or mere weakening of trees makes them more vulnerable to attacks from pests (either insects or diseases). Moreover, these different factors act not only separately but also in synergy. |
Long-range air pollution is produced by the transformation of gaseous components, emanating primarily from combustion, during their transport in the atmosphere under the influence of the sun's radiation, and by gases in the atmosphere - especially water vapour. The most widespread of these are sulphur dioxide (SO2) and nitrogen oxides (NOx). The products of their transformation are varied and complex, but they include ozone, heavy acids (sulphuric and nitric) and peroxidants.
Owing to volcanic eruptions, discharges of electricity during storms, or the activity of soil microorganisms, these components already exist naturally in the atmosphere in varying, usually small, quantities. However, industrial development in the Northern Hemisphere, and especially in Europe, has led to great energy consumption, especially during the past 30 years, which has significantly increased the emissions of these components in the atmosphere.
The first occurrences of long-range air pollution in Europe were reported in Scandinavia, where many lakes that had suffered high acidification caused by heavily acid-charged precipitations (rainfall, snow) gradually lost all aquatic life. During the past few years, alarming phenomena have been observed in the Central European forests, rapidly increasing both in area impacted and in intensity. Countries such as Austria, Czechoslovakia, the Federal Republic of Germany, the German Democratic Republic and Poland, and, more recently, Belgium (northeast), France, Luxembourg and Switzerland, have also reported grave forest damage.
The relationship between forest degradation and air pollution has sound statistical bases. In fact, the primary pollutants (SO2 and NOx) and the products of their transformation act synergistically among themselves and with meteorological factors.
Initially, pollution affects the leaves, where it arrests the regulation of evapo-transpiration and damages the chlorophyll system which is the source of photosynthesis, thus weakening the plant by making it vulnerable to hydric "stress" and reducing its nutrition. This causes damage to the root system, further reducing the nutrition of the organism. In the long term, changes in the composition of the soil made by acid precipitation can release harmful substances.
The initial manifestations are reflected by a decrease in annual tree growth. This can pass practically unnoticed unless detailed inventories are made: the Nordic countries are still at this stage. Pollution levels that have been fatal to Scandinavian lakes have not yet caused real degradation of the forests.
This growth slowdown caused by a lowering of photosynthesis also occurs in farm crops. Here, it is not perceived until the pollutants cause leaf necroses (death). In fact, the experimental establishment of "open-top chambers" freely fed by "ambient" or filtered air in the midst of crop fields has demonstrated that atmospheric pollution, especially ozone and (SO2 can reduce crop yields by between 15 and 25 percent.
Under these conditions, it is sufficient that the forest be subject to an unfavourable circumstance like a heavy drought for visible symptoms of degradation to appear. These can take the form of a premature falling of needles, which makes tree crowns abnormally thin and irregular, or discoloration or yellowing of green tissues. The droughts of 1976 and 1983 and the high temperatures in the summer of 1983 conducive to ozone production have had an influence on the sudden expansion of degradation observed recently.
In the Federal Republic of Germany, the forest area affected by long-range air pollution increased from 562000 ha in 1982 to 2500000 ha in 1983, or 34.4 percent of the country's total wooded area; heavily degraded areas increased from 35000 ha to 64000 ha, or 1 percent of total woodlands, during the same period. In the Vosges forest massif in France, which covers about 400000 ha, 15 percent of trees were affected and 3 percent degraded in the autumn of 1983. Similar percentages apply to Swiss forests.
On the other hand, the Mediterranean or far western areas of Europe seem little affected as yet. In Greece, Ireland, Italy, Spain and the United Kingdom, there have not yet been reports of serious damage or even weakening of growth, with the exception of such special cases as pollution along the sea coasts or areas located near pollution sources.
It is difficult as yet to draw up an accurate tally of the damage caused by long-range air pollution to forest resources. The volume losses in annual growth, in the few cases where they can be evaluated, can reach 15 to 25 percent, and they can therefore be counted in several hundreds of thousands of cubic metres of wood. The survey undertaken by the Joint ECE/FAO Agriculture and Timber Division and the Economic Commission for Europe is attempting to evaluate the impact on the wood market but has not yet been able to assess it accurately. For now, it can be said that the quantity of pollution damage is less than that of large storms, which can strike down several million cubic metres of wood in a few hours.
Whatever its immediate effects, long-range air pollution remains a serious threat to the future of forests, to the soil, and to all the functions and services that forests perform.
AIR POLLUTION AND TREES a troubled coexistence
The state of prevention and control varies widely according to countries, but generally there is a need to raise consciousness at the international level. Unlike local air pollution, whose source can be identified, long-range air pollution comes from emission sources that are not easy to identify. In fact, this is a trans-boundary problem requiring the adoption of international measures. Its prevention and control are more difficult because they must be exercised not in forests but at the sources of the emissions, especially industrial ones, which throw back the products of combustion - SO2, NOx, dust, unburnt fossil fuels - into the atmosphere.
Drastic reduction of pollutant emissions, which is the only effective means of prevention, should be widespread and include not only ordinary gas components (SO2, NOx, fluorine) but also acids, heavy metals, fossil fuels and oxidants. In fact, the interactions between different pollutants increase their harmfulness. For example, the toxicity of heavy metals and SO2 increases in the presence of acids. NO2, which in its pure state is not toxic for the chlorophyll system, becomes toxic in the presence of SO2, which destroys the enzyme that can reduce it to ammonia.
The effect of air pollution on forests cannot be deduced from the concentration of a few components like SO2. A complete network of air pollution measures is necessary in the forest itself, permanently recording the concentrations of SO2, NOx, ozone, and dry or humid acid deposits, the degree of acidity of precipitations and their anion-cation balance, etc. Continuous measurement can record the pollutant emission "peaks", which may be 10 to 20 times above average levels. For example, (SO2 recordings in the Black Forest showed an average level ranging between 25 and 80, micrograms per m3 of air, but reaching 600 micrograms per m3 during "peaks".
Delays in detection of the effects of long-range air pollution on the forests have demonstrated the need for the continuous monitoring of forest ecosystems. Such monitoring includes the establishment of a' network of stations observing the state of trees' health, permanent forest-inventory stations for monitoring tree growth at frequent intervals, and global control based on colour aerial photographs in infrared emulsion, or even high-resolution satellite images (for example, the Landsat 5 satellite's "thematic mapper" and the sensors of the future Spot satellite).
Certain national measures cannot be adopted in isolation if they are to be effective.Regional and international agreements on acceptable air pollutant content should be broadened in scope and in their objectives.
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Forest fires The role of fire in shaping forest landscapes is well known. There exists a danger of aggravation, since the vegetation that grows afresh following a forest fire is itself extremely vulnerable to fire. In fact, it is not in the trees that fires start, but rather in the understorey vegetation occurring in open formations, or in "other woodlands" such as heaths, moors and maquis, or under sparse forest populations such as those composed of pines, flex and cork oaks. But whereas the regressive evolution from a dense and closed forest formation to a sparse and open one is usually rapid, the opposite evolution, from an open to a closed forest, requires decades. The seriousness of the danger of fire varies widely according to region. In Europe it increases from north to south and reaches a maximum in the Mediterranean area. In northern, central and western Europe, the most dangerous time is usually the end of winter, before the new vegetation starts to grow; further south, periods of acute drought, together with tourist visits - both occurring during the summer - present the greatest danger. In 1981, 85 percent of the total number of forest fires in Europe and about 99 percent of the total area burnt were concentrated in nine Mediterranean countries. In average years, the forest areas affected by fire in France, Greece, Italy and Spain exceed 200000 ha, not including "other woodlands" such as maquis and moors. (See "Fighting fires in Mediterranean forests" by Giancarlo Calabri in Unasylva 141 [1983]:14-21.) However, lengthy droughts like that of 1976 in the non-Mediterranean part of Europe can cause forest fires that are all the more grave since these areas are poorly prepared to prevent and combat them. Thus, no area of Europe is really safe from the risk of forest fires. In the Mediterranean areas, climate is not the only unfavourable factor. The decline of the farming and harvesting of wood or forest products (cork, tanning bark) has facilitated the development of highly combustible, low understory vegetation which has eliminated the natural fire-breaks created by well-tended crops, grazing areas, chestnut groves and cork stands. Damage due to forest fires is not confined to losses of wood and forest products. The destruction of an ecosystem through fire bares the soil and permits a further degradation which is often more grave than that caused by the fire itself, if only because of the economic consequences. A heavy rainfall occurring after a forest fire on sloping stony ground, for instance, can remove all of the topsoil. The beneficial effects that forests have on the climate, the regulation of water regimes, and soil protection are then reduced or eliminated. Consequently, it is difficult to evaluate natural losses due to forest fires in monetary terms. For example, European statistics for the 1979-81 period record an annual average loss of US$567 million. But when such estimates are made, they are confined to the value of the wood or forest products. The costs of re-establishing the forest are therefore largely underestimated. |
The protection of European forest resources has, first, a national dimension. The different levels of international cooperation - subregional, European, interregional - have no basis unless they already exist within the framework of national policies.
DOES ACID RAIN KILL TREES? the evidence is mounting
In most European countries, forest protection has been subject to specific, often very strict national regulations. What may sometimes be lacking is the political will to enforce them. As a rule, this kind of protection is in the public interest and may therefore conflict with private interests. In other sectors, regulations must still be worked out. Other measures, adopted following insufficiently thorough studies, have occasionally had perverse effects. For example, it was supposed that by raising the height of factory chimneys the concentration of pollutants such as SO2 and fluorine would be reduced below a threshold harmful to local plant life. While this did eliminate the effects of localized pollution, it created long-range pollution, whose effects are different, more complex, and spread over much wider areas.
Certain national measures cannot be adopted in isolation if they are to be effective. They must be designed in concert with neighbouring countries, especially in the case of industrial policy, where measures should be subject to intersectoral consensus. Final decisions should be harmonized through international agreements. The harmonization should start at the subregional level so as to take into account affinities between groups of countries sharing similar environmental conditions and confronting the same problems.
International cooperation already plays a major role, especially in the research sector, in harmonizing national legislation, in human resources training and in data circulation. This is true, for example, in the case of border monitoring and control over the introduction of parasite or predator plant and animal organisms or those likely to harbour pests. Severe measures have been adopted, first in the agricultural field and then in the forestry sector. Nevertheless, their effectiveness has not been able to prevent the spread of such major epidemics as those of Dutch elm disease or the pear-tree fire blight. In fact, the speed of modern means of transport and the volume of international trade make monitoring and control very difficult.
The magnitude of the problems related to long-range air pollution, its transboundary character, and the variety of sectors affected-from public health to crop yields, from the degradation of forests to the death of aquatic life, from the degradation of buildings to the corrosion of metals-demand global awareness of the phenomenon, first at the government level in each country, then at the European regional level. And finally at the interregional level, and between Europe and North America in particular.
International cooperation has already been a reality in this sector for about ten years, especially in Europe. Concerning destruction of forests specifically, mention could be made of the following:
· the organization by the Commission of the European Communities of a symposium at Karlsruhe, Federal Republic of Germany, between 19 and 21 September 1983;· special meetings under the auspices of the FAO European Forestry Commission at Geneva in April and again in December 1983, and at Freiburg im Breisgau, Federal Republic of Germany, between 18 and 20 June 1984.
However, cooperation in the field of European forest resources protection has so far been confined within limits that are too narrow both geographically and in terms of content. The main concern has been with the effects of local pollution, particularly plant necrosis, near emission sources. The maximum content thresholds adopted have addressed concentrations of pollutants, especially SO2, likely to cause necrosis These thresholds, to be sure, were based on serious trials, but trials that were short-term in scope and that did not include pollutant transformation products such as ozone, sulphuric and nitric acids, and photo-oxidants. They did not take account of the indirect effects of those pollutants on the soil microfauna and microflora - which play a fundamental role in consolidating life cycles. Nor did they consider their long-term effects in subnecrotic doses, effects that are now being observed.
If international research is to operate more effectively, it must be expanded to include new areas: the transformation of pollutants during their transmission in the atmosphere; forms of physiological effects on plants; impact on soil evolution; air circulation; technological research to reduce pollutant emissions; evaluation of new toxicity thresholds; and so on.
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Should acid rain worry developing countries? Robin Levingston, former FAO Senior Forestry Officer, and other forestry officials say that while acid rain may be affecting forests in the Third World, documentation of its occurrence is scarce in comparison with that in Industrialized countries. Some evidence, nevertheless, is emerging. Tropical forests in Venezuela have reportedly been affected by acid rain, which in Peru has killed vegetation on thousands of hectares of mountains near mines and refineries - causing heavy soil erosion. Emissions of sulphur dioxide have tripled since the early 1960s in India. Cities there and in China have reported pH rain levels of 4.5 and below, the same levels reported in the sections of Europe and North America where acid rain's impact on forests is believed to be the highest. Moreover, large regions of Brazil, southern India, Southeast Asia and eastern China feature the soil types most vulnerable to acidification. In southwestern Venezuela, studies conducted by scientists from the University of Georgia and Pennsylvania State University in 1982 detected the presence of acid rain in the remote Amazon rain forest. These studies suggested the possibility that this was the result of long-range transport of industrial pollutants to the region-although at relatively low levels. Scientists reported pH levels of 4.7 averaged over 70 storms during a one-year period at the small settlement of San Carlos de Rio Negro, located about 900 km from industrial areas in Venezuela and 5000 km from industrial areas in Brazil. Because of prevailing winds in the Amazon basin, pollutants originating in industrial regions of Venezuela, Guyana and Brazil could be carried to the San Carlos location, the scientists concluded. Given the nature of such precedents, documented reports of the effects of acid rain in Third World regions could therefore become more frequent. Daniel Liefgreen |
Regional and international agreements on acceptable air pollutant content should be broadened in scope and in their objectives; they should not be confined to SO2 and "black dusts" but should also include nitrogen oxides and heavy metals. Moreover, they should prescribe maximum and average content levels decidedly below those accepted so far. Although SO2 emissions in Europe are now tending to become stabilized or even to decrease, the average content observed is still above the threshold that can be borne by sensitive species such as silver fir or common spruce. On the other hand, nitrogen oxide emissions are steadily increasing, mainly owing to the rise in automobile traffic, which is responsible for about 50 percent of total NOx in the atmosphere.
A drastic reduction of pollutant emissions, which is the only practical long-term solution, raises serious problems of industrial technology. The sums that will have to be invested will be considerable. However, the direct and indirect costs of the effects of long-range air pollution are still far higher, not to mention those that cannot be evaluated in monetary terms. Of course, the greatest difficulties lie in the industrial problems that must be solved, and it is here that intersectoral and international cooperation is most necessary.
Cooperation between neighbouring countries at the subregional level, at the European level, or at the interregional level can considerably strengthen the impact of national programmes.
Atmospheric pollution measurement methods must be harmonized so as to make the results obtained comparable in time and space and to enable meaningful maximum and average pollutant levels to be established.
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The debate: is acid rain harmful? "The question is not whether acid rain affects our forests, but rather to what degree, and it the effects are irreversible." That is the opinion of Professor Hubert W. Vogelmann, Chairman of the Botany Department at the University of Vermont Burlington, Vt., United States. "We know that present-day rains contain sulfuric and nitric acids, copper, lead, zinc, cadmium, hydrocarbons, fluorocarbons, organic acids... and lots more. It is ecologically inconceivable that this complex of substances cannot have some effect on tree growth," Vogelmann wrote in a 1983 article. After years of research, however, the scientific community still finds itself divided on the Issue of acid rain's effect on forests. Continuing research only seems to cloud the issue further and intensify the debate. "The problem facing legislators and the public", Vogelmann says, "is that we cannot also demonstrate unequivocally a clear, lawyer-proof, cause-and-effect relationship between acid rain and alterations in forested ecosystems viewed as a whole. Just because these interactions haven't yet been nailed down does not mean that they don't exist. As every biologist knows, such relationships do exist. But ecosystems are so remarkably complex that acid rain's guilt has not yet been proven." FAO's ad hoc Working Group on the Impact of Air Pollution on Forests of the European Forestry Commission concluded in its December 1983 meeting: "Although it has yet to be scientifically proved, there are strong indications that the damage to forests is, at least in Central Europe, mainly due to air pollutants: not only sulphur dioxide, which has been receiving particular attention, but also nitrogen oxide, heavy metals and photo-oxidants." The Worldwatch Institute, an environmental research group based in Washington, D.C., stated in a recent report: "Decades of additional research may be needed to prove precisely how pollution causes damage. But like cigarette smoking and cancer, the evidence linking fossil-fuel pollution to forest damage is overwhelming." But the voice of dissent is still strong. The Hudson Institute, a US think-tank, concluded last year that "the popular notion that acid rain is threatening forests in the Eastern US, and indeed all across the earth's temperate zone, is based less on substance than upon ill-informed conjecture and is probably wrong". J.P. Lanly, Director of FAO's Forestry Resources Division, says the need to curtail air pollution is universally accepted, but adds: "No forest researcher can tell you he has demonstrated that dieback is solely caused by atmospheric pollution... It is air pollution on top of other things, like insects, disease and drought, that leads to harmful effects." Lanly nevertheless is among those who say remedial action must not be delayed while research continues. "We can't wait for research to provide definitive results before doing something; we have some presumption that air pollution is at least one of the causes (of dieback)," he says. Peter Baum of the Council of Europe's committee for the conservation of nature and natural resources says to the doubters of acid rain's impact on forests: "Go into the forests and have a look; go into the Black Forest and see the effects. It's difficult to say if (acid rain) is the primary factor, but it is certainly significant enough to establish anti-pollution programmes. The problem is under-stated. Since 1983, damage has doubled in Germany - and all species are being affected." Others believe that calls for additional research are a veiled attempt to table the issue. Says Canada's Minister of Environment, John Roberts, "I say we do have enough information to act; it's not a matter of science any longer, it's a matter of political will. We have reached the point where a decision to stall and drag our feet on the pretext that we need more research is, in fact, a decision to do nothing." Meanwhile, research into the causes of acid rain and its effects on forests continues. For example, the International Institute for Applied Systems Analysis (IIASA) in Vienna is developing computer models for governments to use in evaluating various air-pollution control measures. The work is carried out with the cooperation of the UN Economic Commission for Europe. In February, the organization began studying direct impacts of air pollution on forests. "There's enough information to take action, but it's a question of what action to take," says Joseph Alcamo of IIASA. He adds that the aim of IIASA's research is that it serve as a "common technical ground" in the hopes of reaching an international agreement on air pollution abatement. Daniel Liefgreen |
The destruction of forest resources is perceived as something endangering a natural environment that provides a balancing factor in the face of the tensions produced by modern life
IN THE FEDERAL REPUBLIC OF GERMANY...
... AND IN SWEDEN dying trees among the healthy
Health control criteria for forest stands and research methods in the forest itself must also be harmonized to allow comparison of on-site observations. The distribution of sites should provide a representative sample of the populations concerned. Through a series of observation networks, the identification of forests suffering initial damages due to long-range air pollution can provide agriculture with indicators of the presence of pollution, which can easily have cumulative and negative effects on human health.
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Acid rain in Italy? Fabio Clauser peers outside the window of his office nestled in a wooded area on the outskirts of Florence. Clauser, forest administrator for the lush forest region of Vallombrosa, points out yellowing needles on pine trees that he says are ailing because of acid rain. A native of Florence, Clauser remembers a period "when the trees used to look so healthy". He and other Italian forestry officials believe the forest regions of Vallombrosa, Trentino-Alto Adige and Abruzzo in the north, and Calabria in the south, are showing the same symptoms of suffering from acid rain fallout as those in the Federal Republic of Germany. The forests of Bavaria are similar in composition to those of the Vallombrosa region - rich in conifers of all types. "We don't have the same acid rain problem as Germany and Poland and some other countries, but we do have cause to worry," says Alfonso Alessandrini, Director-General of the Italian Forest Service. This past October, the Forest Service completed an investigation which revealed that 400000 ha of Italy's forests (5 percent of the total) have now been affected by acid rain. In May 1985, a government study group issued a map indicating the chemical characteristics of precipitation in a 60000 km2 area in the north of the country. Within the study area, the city of Turin showed the greatest presence of acidic precipitation (pH 4.09-4.26). Romano Gellini, professor of forest biology at the University of Florence, has conducted studies of the effects of atmospheric pollution near Florence. His experiments found pH rain levels below 5.6 in three zones in and around Florence. A pH level of 5.6 is considered slightly acidic. (The lower the pH number, the greater the acidity.) In Vallombrosa, Gellini's tests found pH levels ranging from 4 to 5.5, with particularly high levels of sulphur. "The fact of finding acid pH levels in a mountain locality like Vallombrosa, more than ten kilometres from any urban-industrial zone, is a further indication of the transportation of pollution from distant areas," Gellini says. But what would be the source of the pollution? Gellini and others can only speculate. "We don't know exactly where the pollution is coming from, but forest damage has been reported in all regions of the country - north, central and south," says Professor Mario Pavan of the Institute of Entomology at the University of Pavia. Depending on the outcome of the state Forest Service's investigation, Italy could be one of the first Mediterranean countries to document forest damage from acid rain. (The effects of acid rain on monuments in Athena have been widely publicized.) Adds Eliodoro Runca, former air pollution director with IIASA in Vienna: "I think there is an acid rain problem In Italy, but there are not enough data to demonstrate it." The effects of acid rain on monuments in Italy are well documented, Runca says, and it can reasonably be assumed that the forests are being affected, too. "Italy is a heavily industrialized country. We have a lot of sulphur emitted, and with relatively sunny weather and a lot of cars there probably Is a high degree of oxidant pollution," he says. "It is evident, unfortunately, that even in Vallombrosa, one has to speak, if not of the death of the forest... at least of its deterioration," says Gellini. Daniel Liefgreen |
Damage to the growth and even existence of the European forests from long-range air pollution undermines not only their productive capacity but also their other, no less important functions: soil conservation, regulation of water balances, genetic resource conservation, recreation, and improvement of the quality of life. At the same time, forests constitute a basic feature in the life-styles of many of Europe's inhabitants. The destruction of forest resources is thus perceived as something endangering a natural environment that provides a balancing factor in the face of the tensions produced by modem life.
Prevention, monitoring and control measures have been adopted at the national level, but they are not always adequate or sufficient. Nor are they always coordinated with neighbouring countries adopting similar measures. Cooperation between neighbouring countries at the subregional level, at the overall European level, or even at the interregional level can considerably strengthen the impact of national programmes, both on basic and applied research and on the implementation of operations.
Consequently, two levels of action - national and international - need to be considered.
LONG-RANGE AIR POLLUTION an unwanted export
At the national level, the countries of the European region could consider strengthening their action in the following sectors:
· improvement of data on the magnitude and extent of degradation phenomena, in particular by systematic surveys allowing measurement of damages to forest resources and evaluation of their impacts on the production of raw materials, the protective role of soil and water, etc.;· research programmes aimed at better knowledge of long-range air pollution, its origin and dissemination, and control and prevention mechanisms;
· prevention policies and measures taking into account, among other things, the need to coordinate actions through intersectoral liaison, i.e., industry, urbanization, environment, agriculture and forests.
At the international level, two types of measure should receive attention:
· rapid exchange of information and data collected according to agreed methods, not only affording improved knowledge of pollution and its impacts but also effectively taking into account its transboundary character;· harmonization of prevention, combat and control measures from the centre of origin to their place of impact.
International cooperation can be organized at the subregional level according to need, but cooperation within a whole region or even with other regions is at least as important. In this context of cooperation at the global, regional and interregional levels, FAO is well placed to provide its collaboration if countries wish it. Indeed, it is especially well placed to promote regional or interregional cooperation in the exchange of information and the study of appropriate measures.
