| United Nations | E/CN.17/IPF/1996/3 |
Economic and Social Council
Distr. GENERAL
21 February 1996
ORIGINAL: ENGLISH/FRENCH
COMMISSION ON SUSTAINABLE DEVELOPMENT
Ad Hoc Intergovernmental Panel on Forests
Second session
11-22 March 1996
Item 2 of the provisional agenda*
* E/CN.17/IPF/1996/1.
IMPLEMENTATION OF FOREST-RELATED DECISIONS OF THE UNITED NATIONS
CONFERENCE ON ENVIRONMENT AND DEVELOPMENT AT THE NATIONAL AND
INTERNATIONAL LEVELS, INCLUDING AN EXAMINATION OF SECTORAL AND
CROSS-SECTORAL LINKAGES
Programme element I.4: Fragile ecosystems affected by
desertification, and the impact of air-borne pollution
on forests
Report of the Secretary-General
SUMMARY
General
The present document reports on implementation of decisions of the
United Nations Conference on Environment and Development related to the fourth
programme element of category I, "Implementation of the United Nations
Conference on Environment and Development decisions related to forests at the
national and international level, including an examination of sectoral and
cross-sectoral linkages", of the work programme of the Ad Hoc
Intergovernmental Panel on Forests. It is presented in three parts. Part one
deals with the experience with afforestation, reforestation and the
restoration of forest systems, where appropriate, particularly in countries
with fragile ecosystems and those affected by desertification and/or drought,
particularly in Africa. Part two presents a synthesis of the impact of
air-borne pollutants on forests, in particular those in Central and Eastern
Europe. It includes a general overview of the issue, and a short update of
the current status, and is followed by a description of the range of
considerations for the substantive discussion of this programme element at the
second session of the An Hoc Intergovernmental Panel on Forests. Part three
suggests items to be discussed by the Panel.
Part one: Fragile ecosystems affected by desertification:
monitoring actions to support afforestation,
reforestation and the restoration of forest
systems, particularly in Africa
The earth's fragile ecosystems, which are situated mainly in arid,
semi-arid and dry sub-humid regions, are most affected by these phenomena,
which are largely due to: (a) the population pressure associated with poverty
and the resulting efforts to produce more food crops from less and less
suitable soils; (b) inappropriate methods of developing forestry resources and
grazing lands; (c) the impact of man-made or natural catastrophes, such as
forest and brush fires, insect plagues, diseases and frequent, prolonged
droughts.
The development of the forestry sector over the past 20 years,
particularly in the countries with less forestry resources and the arid
countries, has resulted in a form of forestry which is more open and
responsive to the needs of populations and to the multi-purpose use of trees
and forests in the different natural or man-made systems.
The general information section focuses on the need for reforestation
because of land degradation, a process which is described and explained and
whose consequences are analysed.
The section on current status focuses on poverty and its constituent
elements, namely, unemployment (including or resulting from the scarcity of
land in rural areas) and the lack of food security. The need for firewood,
which represents the only available source of energy for the poorest groups,
generally exceeds the production capacities of rural woodlands. These factors
lead to strong pressure on tree and forest resources. The resulting
deforestation is analysed; it strongly affects arid regions, particularly in
the drylands of tropical Africa, where 2.22 million hectares are lost each
year. Afforestation and reforestation can offer solutions to these problems,
but the results to date have been poor, particularly in Africa, where the
ratio of afforested/reforested to deforested areas is only 1 to 32; the
conditions under which afforestation and reforestation are conducted, from the
planning stages to the enjoyment of the goods and services which they provide,
are still far from being satisfactory.
The report indicates numerous gaps and areas in which improvement is
needed. Those which are of particular importance from the policy standpoint
include: (i) the need to recognize both the potential and the limitations of
afforestation and reforestation and to plan such programmes against a
background of sustainable development, particularly in rural areas; (ii) the
need to plan afforestation and reforestation programmes in close collaboration
with and with the participation of the populations concerned; (iii) the
promotion of technologies and species that are both suited and familiar to the
populations; (iv) the integration of tree planting into conservation
programmes, particularly those concerned with the conservation of
biodiversity, with all the related considerations regarding reforestation
options as opposed to the management of natural stands, and choice of local
species.
Part two: The impact of air-borne pollution on forests,
particularly in Central and Eastern Europe
Forest declines and dieback of trees occur as a world-wide phenomenon.
In addition to being widespread geographically, forest declines can be caused
both by natural factors and by human influences. Indeed forest dieback may be
part of a normal ecological succession. Human activities that can contribute
to forest decline include pollutant depositions, overgrazing when woodlands
are used for pastoral purposes, insensitive harvesting operations, use of
plantations with low genetic diversity, accidental introduction of pest
species, fire, alteration of hydrology and, finally, anticipated climate
change associated with the burning of fossil fuels and increased concentration
of greenhouse gases.
In the late 1970s and early 1980s, public attention was drawn to the
deterioration of forest condition in Germany and subsequently in some other
European countries and in parts of North America. By the early 1980s, these
symptoms seemed to be widespread and public concern focused on whether such
declines were new and pollutant-related. The terms "Waldsterben" and
"neuartige Waldschaden" meaning "forest death" and "new-type forest decline"
respectively were introduced and there was fear that the deterioration was
irreversible.
Recent inventories show roughly stable levels of emission of nitrogen
oxides from European countries between 1980 and 1993, and a moderate decrease
in ammonia emissions from 7,649 thousand tons per annum in 1980 to 6,573
thousand tons per annum in 1993.
It is clear that the Central European area which includes areas of
Poland, the former German Democratic Republic (East Germany), the Czech
Republic and Slovakia have the largest proportion of defoliated trees. This
is the area of Europe that has been referred to as "the black triangle"; in
this area there have been large sulphur emissions from heavy industry and the
combustion of high-sulphur-content coal.
The International Institute for Applied Systems Analysis has recently
undertaken a study of forest resources of Western and Eastern Europe with the
objectives of looking at the potential developments of the forest resource,
illustrating the effects of forest decline caused by air pollutants on this
resource and identifying policy options for dealing with these effects. The
study represents a unique attempt to provide predictions on the way in which
sulphur and nitrogen depositions might affect the development of forest
resources and of wood supply in Europe. The results are of considerable
interest and indicate the importance for European countries of formulating new
forestry policies to address the new conditions caused by the decline if they
are to maintain current forest resources.
The concern over a single novel forest decline throughout Europe
undoubtedly resulted from misinterpretation of the results of forest condition
data (Forest Health Surveys), combined with lack of awareness of historical
records of forest declines and lack of understanding of forest science,
particularly nutrient-cycling and forest pathology. It is now clear that many
of the statements that were made concerning the effects of pollutant
deposition were appropriate on the local scale only.
CONTENTS
Paragraphs Page
INTRODUCTION ............................................... 1 - 5 7
PART ONE. FRAGILE ECOSYSTEMS AFFECTED BY DESERTIFICATION:
MONITORING ACTIONS TO SUPPORT AFFORESTATION,
REFORESTATION AND THE RESTORATION OF FOREST
SYSTEMS, PARTICULARLY IN AFRICA ................ 6 - 53 8
I. INTRODUCTION ......................................... 6 - 8 8
II. GENERAL INFORMATION .................................. 9 - 16 8
A. Objectives of the study .......................... 9 8
B. Description of the problem ....................... 10 - 16 9
III. CURRENT STATUS ....................................... 17 - 30 11
IV. GAPS IN KNOWLEDGE AND INFORMATION .................... 31 - 34 14
V. APPROACHES AND EXPERIENCES: SUCCESSES AND FAILURES .. 35 - 41 15
A. Positive experiences ............................. 35 - 36 15
B. Negative experiences ............................. 37 16
C. Summary of lessons learned ....................... 38 - 41 17
VI. FUTURE TRENDS ........................................ 42 - 53 18
A. Identification of challenges for the future ...... 42 - 46 18
B. Priorities ....................................... 47 - 53 19
PART TWO. IMPACT OF AIR-BORNE POLLUTANTS ON FORESTS,
PARTICULARLY IN CENTRAL AND EASTERN EUROPE ...... 54 - 103 21
I. INTRODUCTION ......................................... 54 - 61 21
II. CURRENT STATUS ....................................... 62 - 81 23
III. EXISTING GAPS IN KNOWLEDGE AND UNCERTAINTIES ......... 82 - 88 28
IV. APPROACHES TO ADDRESSING THE ISSUE: EXPERIENCES,
SUCCESSES AND FAILURES ............................... 89 - 96 29
V. FUTURE TRENDS AND PERSPECTIVES: THE WAY AHEAD ....... 97 - 103 31
PART THREE. ITEMS FOR DISCUSSION .......................... 104 -105 32
MAPS*
1. Approximate locations of decline events .......................... 22
2. Percentage of trees damaged in 1994 .............................. 25
3. Location of the European sites mentioned in the text ............. 34
* The boundaries shown on the maps do not imply official endorsement
or acceptance by the United Nations.
INTRODUCTION
1. The present document reports on implementation of the decisions of the
United Nations Conference on Environment and Development related to the fourth
programme element of category I, "Implementation of the United Nations
Conference on Environment and Development decisions related to forests at the
national and international level, including an examination of sectoral and
cross-sectoral linkages", of the work programme of the Ad Hoc
Intergovernmental Panel on Forests. It is presented in two parts. Part one
deals with the experience with afforestation, reforestation and the
restoration of forest systems, where appropriate, particularly in countries
with fragile ecosystems and those affected by desertification and/or drought,
particularly in Africa. Part two presents a synthesis of the impact of
air-borne pollutants on forests, in particular those in Central and Eastern
Europe. It includes a general overview of the issue and a short update of
current status, and is followed by a description of the range of
considerations for the substantive discussion of this programme element at the
second session of the Panel.
2. The work under this programme element (I.4) is guided by the decisions
taken at the third session of the Commission on Sustainable Development and
further elaborated at the first session of the Ad Hoc Intergovernmental Panel
on Forests.
3. The Commission on Sustainable Development, at its third session, defined
programme element I.4 as a need to "monitor actions to support afforestation,
reforestation and the restoration of forest systems, where appropriate,
particularly in countries with fragile ecosystems and affected by
desertification and/or drought, particularly in Africa. Within this context,
also consider specific actions in countries whose forests are affected by
pollution, particularly those with economies in transition in Central and
Eastern Europe". 1/
4. Subsequently, the Panel, at its first session, emphasized the need for "a
report on the experience with afforestation, reforestation and the restoration
of forest systems, where appropriate, particularly in countries with fragile
ecosystems and those affected by desertification and/or drought, particularly
in Africa, including links to the implementation of the United Nations
Convention to Combat Desertification in those Countries Experiencing Serious
Drought and/or Desertification, particularly in Africa. A synthesis of the
impact of air-borne pollutants on forests - in particular, those in Central
and Eastern Europe - and an assessment of ongoing activities and proposals for
an assessment of the expansion of all types of forest cover due to
reforestation and afforestation". 2/ At the first session of the Panel, it
was decided to schedule programme element I.4 for substantive discussion at
the Panel's second session, to be held in Geneva (11-22 March 1996).
5. The present report was prepared by the Food and Agriculture Organization
of the United Nations (FAO), as lead agency for programme element I.4, in
consultation with the secretariat of the Ad Hoc Intergovernmental Panel on
Forests in the Division for Sustainable Development of the Department for
Policy Coordination and Sustainable Development of the United Nations
Secretariat. In addition, contributions and comments were received from the
Forestry Commission of the United Kingdom of Great Britain and Northern
Ireland, from the Centre for International Forestry Research (CIFOR) and from
the Global Forestry Policy Project. Part one is based on the report of a
consultant in French and part two on the report of a consultant in English.
Both reports contain valuable information that could not, however, be
accommodated within the limits of a report of the Secretary-General, but will
be available as regards consultation to support follow-up activities related
to this programme element.
PART ONE. FRAGILE ECOSYSTEMS AFFECTED BY DESERTIFICATION:
MONITORING ACTIONS TO SUPPORT AFFORESTATION,
REFORESTATION AND THE RESTORATION OF FOREST
SYSTEMS, PARTICULARLY IN AFRICA
I. INTRODUCTION
6."The impacts of loss and degradation of forests are in the form of soil
erosion, loss
of biological diversity, damage to wildlife habitats and degradation of
watershed areas, deterioration of the quality of life and reduction of the
options for development." 3/ This is the conclusion contained in chapter 11
of Agenda 21.
7.The earth's fragile ecosystems, which are situated mainly in arid, semi-arid
and dry
sub-humid regions, are most affected by these phenomena, which are largely due
to: (a) the population pressure associated with poverty and the resulting
efforts to produce more food crops from less and less suitable soils; (b)
inappropriate methods of developing forestry resources and grazing lands;
(c) the impact of man-made or natural catastrophes, such as forest and brush
fires, insect plagues, diseases and frequent, prolonged droughts.
8.The development of the forestry sector over the past 20 years, particularly
in the
countries with less forest resources and the arid countries, has resulted in a
form of forestry which is more open and responsive to the needs of populations
and to the multi-purpose use of trees and forests in the different natural or
man-made systems.
II. GENERAL INFORMATION
A. Objectives of the study
9.This part contains a synthesis of part one of programme element 1.4 of the
programme of
work approved by the Commission on Sustainable Development for the open-ended
Intergovernmental Panel on Forests. The document focuses on afforestation and
reforestation programmes and their various functions. To this end, it recalls
facts relating to degradation, studies the role of afforestation and
reforestation in preventing and combating desertification, highlights gaps in
knowledge, describes the experience gained and lessons learned and, lastly,
identifies the challenges and the priorities for the future and proposes a
list of priority actions which are of common interest to all the countries
concerned.
B. Description of the problem
Elements and processes of desertification
10. Many civilizations have foundered as a result of their failure to control
the population growth that is responsible for disrupting the balance between
the degree of pressure (human and animal) placed on the land and the latter's
capacity to absorb it. The traditional users of arid lands succeeded in
developing land-use systems that were sustainable and compatible with their
environment because they were careful to renew the fertility of the soils,
their land-use options were characterized by flexibility and solidarity, and
their land occupation density was low.
11. The considerable increase in population has changed the parameters
without any corresponding change in the traditional systems of production so
as to increase production on a sustainable basis. The constraints resulting
from the increasing need to exploit resources and the reduction in the amount
of available land have led to expansion towards forested and marginal areas
and to competition which has spurred the widespread conduct of mining
operations on lands that are now undergoing increasing degradation.
12. Sustainability of production, whether in agriculture, cattle farming,
firewood or any other sector, depends on agrarian land-use systems capable of
maintaining soil fertility and reducing all forms of land degradation. The
vulnerability of land, however, is an additional constraint to sustainable
exploitation, since the risk of desertification may increase, above all in a
period of climate change and particularly in regions where poverty is endemic.
Degradation and desertification may be brought about by inappropriate land-use
systems or by a combination of the latter with recurrent drought at frequent
intervals.
13. The expansion of agricultural zones is without doubt the main cause of
deforestation in tropical drylands and in the Middle East. Reforestation,
when integrated into forest management as an alternative to natural
regeneration, can contribute to the conservation and development of forests.
Measures to combat desertification
14. In combating desertification, each type of landscape and each system of
land use requires a different approach. There are, however, certain common
measures that are prerequisites for the conservation and restoration of land
in dry areas. These include:
(a) Adopting appropriate policies and legislative measures;
(b) Making an inventory of land resources and identifying both their
potential and the constraints on their use;
(c) Choosing suitable approaches to sustainable development;
(d) Improving land-use methods and developing appropriate technologies;
(e) Ensuring user participation in all stages of planning and execution;
(f) Conducting research in rural areas;
(g) Training of managers and rural dwellers;
(h) Introducing incentive measures (price of agricultural and forest
products, markets, subsidies, taxes, and so on) to encourage land users to
adopt sustainable land-use methods;
(i) Diversifying employment, and so on.
The technical measures proposed below are general in nature and concern the
principal uses of rural drylands as described above.
The economy and the role of reforestation in combating land degradation
15. Tree planting in various forms can constitute an effective means of
combating soil degradation and, more particularly, desertification. In arid
zones, trees are planted for the following reasons:
(a) To protect and maintain the balance within production systems. Trees and
forests are critical to the preservation of the ecological and biological
functions required for sustainable agricultural production. They help to
preserve and improve soil productivity;
(b) To satisfy social and economic needs. Forests and trees constitute an
important resource base which is essential to sustainable social and economic
development, inasmuch as they provide a wide range of wood and non-wood
products and services;
(c) To protect the habitat and to provide aesthetic value and shade. This
function of trees has to do with enhancing living space, providing greater
comfort for people and protecting human settlements. Significant progress has
been made in this area in arid countries, and particularly in the Sudano-
Sahelian region of Africa;
(d) To produce cattle fodder. Cattle raising in arid zones depends for a
part of the year on wooded areas in the form either of fallow land, in the
case of sedentary farming, or of fallow land and forests, in the case of
transhumant cattle farming. In the Sahelian region, food for cattle consists
on average of 25 per cent aerial fodder (up to 45 per cent at the end of the
dry season). In the driest areas of the Brazilian savannah, aerial fodder
accounts for 60 per cent of cattle food.
Evolution of the concept of the role of reforestation
16. There has been a considerable evolution in the concept of the role played
by reforestation in the forestry industries of all continents, particularly in
dry regions. In the past, forestry experts often tended to conduct
reforestation as a means of demonstrating its technical potential. Gradually,
however, efforts to meet needs for firewood, construction wood and utility
wood also came to be emphasized. In addition, protection of the environment
and improvement of the habitat, and nowadays respect for and conservation of
biological diversity, are becoming increasingly important in the design and
planning of afforestation and reforestation projects.
III. CURRENT STATUS
Scope and impact of the problems
17. According to 1992 estimates by the Food and Agriculture Organization of
the United Nations (FAO), nearly 500 million people, including 50 million
cattle farmers, live in the drylands (annual rainfall of under 500 millimetres
(mm) - period of growth less than 120 days per year) and regions characterized
by uncertain rainfall (including sub-humid zones with light and irregular
rainfall) which cover 20 million square kilometres of the earth's surface.
These regions are also affected by severe degradation of resources,
particularly through water and wind erosion: 60,000 square kilometres of land
are lost each year.
18. The African continent is particularly affected, as a result of several
factors which include:
(a) A large proportion of arid land (65 per cent of the continent);
(b) Strong population pressure relative to the productive capacity of the
land;
(c) A combination of socio-economic problems and frequent institutional
deficiencies;
(d) Consequently, a large proportion of affected land.
19. According to an assessment carried out in 1992 by the United Nations
Environment Programme (UNEP), 74 per cent of the arable land in Africa is
affected by various forms of deterioration. Seventy-three per cent of grazing
land, 61 per cent of rain-fed agricultural land and 18 per cent of irrigated
land on the African continent are undergoing desertification and, according to
the assessment, have already lost 25 per cent of their fertility.
Reforestation as a response to deforestation
20. Reforestation campaigns over the last 10 years have been evaluated within
the framework of the 1990 assessment of forest resources (FAO Forestry Paper
No. 128, 1995). Plantations in countries located in the arid regions have
most often been devoted to the production of firewood and, in the wettest
regions, construction and utility wood. The goals of environmental
preservation and desertification control have gained importance since the
1970s, but their vagueness, together with relatively lax planning and, often,
a governmental approach to their establishment, have affected their
sustainability.
21. It is impossible to overemphasize the difficulty and hazards of assessing
man-made forests; it would seem simple to monitor plantations, but the
difficulties are numerous. These difficulties include the following:
(a) Plantations have not in all cases been well planned;
(b) In cases when planting is unsuccessful, reuse of the same land
compromises assessments based on field reports;
(c) Assessment methods vary widely from one country to another;
(d) The use of variable conversion factors when estimates of surface area are
made a posteriori, on the basis of the number of trees planted, introduces
other uncertainties.
Reforestation campaigns in tropical regions (in estimated net surface area)
22. In tropical countries, which accounted for approximately 17.5 million
hectares of man-made forests in 1980, those areas have increased by 150 per
cent to a total of 43.9 million hectares in 1990, with an average annual
growth rate of 2.6 million hectares. In the breakdown of reforested land by
major geographical region, tropical Africa accounts for only 7 per cent of
planted areas, whereas tropical America accounts for 20 per cent and the Asian
and Pacific region 73 per cent of such areas.
The evolution of reforestation campaigns in tropical Africa
23. From 1960 to 1980, African forestry services made major efforts at
reforestation, with the help of outside financing. From 1961 to 1975,
priority was given to industrial afforestation (61 per cent of the areas
planted). From 1976 to 1980, a scaling back of industrial plantations, and
therefore of large-scale plantations, was begun as a result of the frequently
mixed results of massive plantations, the major drought and the development of
more integrated and participatory approaches.
24. Despite the efforts devoted to afforestation and reforestation, the total
surface area of man-made forests in tropical Africa is barely 3 million
hectares, or less than the average area deforested annually, which amounts to
4.1 million hectares. In terms of increase in the average area planted
annually, the campaign has been unable to narrow the enormous gap between
afforestation and deforestation, the proportion of which was in the ratio of
1:29 in 1980 and 1:32 in 1990.
Reforestation campaigns in the non-tropical developing countries
25. Reported plantations accounted for 42.1 million hectares in 1990 (a
surface area similar to that in the tropical countries), while the rate of
annual planting amounted to 1.46 million hectares (2.61 for the tropical
countries). The Asian temperate zone displayed the highest annual rate of
reforestation (1.25 million hectares), whereas progress in the African
subregions remains insufficient. North Africa accounts for a total of 1.79
million hectares of reforestation with an average annual rate of 72,400
hectares, while the southern portion of the continent accounts for 1,492
hectares of plantations at an annual growth rate of 23,000 hectares of planted
area. China alone accounts for 31.8 million hectares (75.5 per cent),
followed by the Republic of Korea (2.1 million hectares) and Chile (1.45
hectares).
26. The average area deforested annually is 850,000 hectares, while
reforested areas total 1.46 million hectares. This generally encouraging
picture conceals various realities, including:
(a) The major efforts in the Asian temperate zone, with 1.25 million hectares
planted annually, compared to a deforestation rate of some 400,000 hectares
per year;
(b) A net loss for southern Africa, which loses 40,000 hectares of forest
annually;
(c) Near-equilibrium for North Africa (deforestation: 70,800 hectares;
reforestation: 72,400 hectares).
Reforestation as a response to the population's needs: Consumption of wood
products
27. The urban populations of developing countries are experiencing growth on
sites which are sufficiently productive. Plantations are best able to respond
to the increasingly heavy demand for wood in built-up areas. The consumption
of roundwood in developing countries will rise sharply in the coming years,
reaching 300 million cubic metres in 2010. Between 1990 and 2010, the
consumption of all wood products will require, together with other demand for
such products, the establishment of between 50 and 100 million hectares of
additional industrial plantations on productive sites by 2010.
28. With regard to the supply of firewood in developing countries, as early
as 1981, during the preparations for the United Nations Conference on New and
Renewable Sources of Energy, FAO drew attention to the energy wood crisis. A
study of the problem led to findings which included the following:
(a) A firewood shortage of 972 million cubic metres by the year 2000
(500 million in Asia; 337 million in sub-Saharan and north Africa; 137 million
in Latin America);
(b) A population of 2.4 billion people (including 600 million in sub-Saharan
Africa and north Africa) affected by the shortage.
29. It is clear that current reforestation efforts, while praiseworthy in
view of the economic situation of the developing countries and the high levels
of investment which the plantations represent, fall far short of current and
future needs. In the short and medium term, reforestation has little chance
of replacing natural stands as a means of satisfying the growing energy needs
of developing countries. It is also clear that afforestation and
reforestation must be greatly accelerated and the number of plantations
greatly increased through intensified forestry activities and widespread
forestry management.
Reforestation as a response to environmental problems
30. With regard to the environment, it is generally recognized that
reforestation plays the same roles as natural forests in contributing to the
stability of the environment. Owing to the rapid deforestation of vast areas
throughout the world, the role of reforestation in the protection of catchment
basins and, through dune fixation, of production infrastructures, the
protection of animal life, soil and water conservation, and the conservation
of genetic resources and biological diversity, while difficult to quantify, is
more important today than ever before.
IV. GAPS IN KNOWLEDGE AND INFORMATION
31. In the area of policies, a number of improvements are possible and,
indeed, urgent.
32. Many of the shortcomings identified are due to a basic orientation
towards the production of industrial wood products, which are, by their very
nature, less suited to the needs of the populations of arid areas whose
systems of forestry production are inseparable from other land-use systems.
Among the many matters requiring further study are the following:
(a) The conversion of forest land;
(b) The practical implementation of the integration of forest plantations
into agrarian systems and their effective and sustainable management;
(c) With regard to land devoted to rain-fed cultivation, the integration of
forest plantations into cropland and the restoration of permanent
agro-forestry park systems are of growing importance and call for the use of
previously seldom-used and little-known species;
(d) Silvicultural techniques and large bodies of practical and concrete
knowledge are available, even where they need improvement. However, it must
be said that they are usually unknown to the general population and poorly or
incompletely applied by technicians;
(e) Community and individual plantations, in addition to their role as a
response to deforestation, must take into account the social consequences they
entail.
33. There are numerous gaps at the research level, particularly in relation
to the following topics:
(a) Conflicts and power struggles between customary law, forestry
legislation, traditional land ownership, rural or land ownership codes and the
administrative, traditional or religious authorities;
(b) Improvement of forest regeneration and enrichment techniques in secondary
forests and improved fallow land, better knowledge of local species and
methods of perfecting their artificial regeneration;
(c) Systematic research designed to achieve the optimum balance between
trees, farming and cattle;
(d) Studies of the changes in soils in reforested areas and potentially
beneficial effects on their productivity depending on species and plantation
type;
(e) Durability and productivity of newly planted growths;
(f) Protection of the diversity of genetic stock by identifying and managing
noteworthy stands, sites of origin and specimens;
(g) Greater knowledge and more focused utilization of traditional knowledge
and local practices in reforesting and managing plantations.
34. We still need to identify these "local advanced technologies" and assess
their performance and their advantages in comparison with modern technologies
from the technical, environmental and socio-economic standpoints; if
appropriate, we can then work with their originators to perfect such
technologies and integrate them fully into "technical packages" for
popularization purposes.
V. APPROACHES AND EXPERIENCES: SUCCESSES AND FAILURES
A. Positive experiences
35. Assessment of positive experiences should not be based merely on
considerations of the scale of the achievements, but also on their
significance in the countries concerned and the impetus they have provided to
other experiments. The following are examples of at least partially
successful experiences:
(a) Development of social forestry in Peru. This was started in 1982 as part
of a project to develop community forestry on the Andes plateau;
(b) Project to rehabilitate grazing land in the south of Khorasan Province
(Islamic Republic of Iran). The project, initiated in order to rehabilitate
grazing lands that had been degraded by the concentration of Afghan refugees,
made it possible to rehabilitate more than 20,000 hectares of badly degraded
grazing lands and stabilize approximately 27,000 hectares of dunes between
1990 and 1994;
(c) Reforestation and fixation of large dunes in the Islamic Republic of
Iran. For over 30 years this country has also been engaged in a number of
projects designed to renew forest cover by planting, sowing and propagation.
A total of 4 million hectares of arid land has been directly sown (2 million
hectares) or planted and propagated (2 million hectares);
(d) Large-scale reforestation in China. The People's Republic of China has
devoted significant human resources to halting deforestation and renewing its
forest cover, which is projected to increase from 14 to 17 per cent between
now and 2010, reaching 20 per cent by 2050;
(e) India and reforestation. The average annual reforestation rate between
1980 and 1990 was 1.45 million hectares, of which more than 400,000 hectares
per year were industrial and 1 million hectares were non-industrial
reforestation;
(f) Plantations in Cape Verde. This island country of volcanic origin, whose
vegetation is highly degraded as a result of over-felling and repeated
droughts, has undertaken a series of reforestation initiatives since 1970 with
the help of FAO, the United Nations Development Programme (UNDP) and the
Government of the Kingdom of Belgium;
(g) Dune fixation in Mauritania. Based on a purely technical approach to
dune fixation, planting projects initially aimed at adapting and improving
biological and mechanical fixation techniques in order to protect habitat,
production zones and infrastructure; the approach has gradually shifted
towards the successful use of local materials and local practices;
(h) Improvement of land use in the Keita valley, Niger. An imaginative
integrated rural development project is helping to restore the balance by
combining traditional production systems with modern technology.
Non-forest-related advances and successes outside the scope of projects
36. In addition to the examples cited above, there have been many successful
activities in rural areas arising out of spontaneous, collective or individual
non-governmental initiatives. Small rural woodlands and amenity plantations
which improve the village environment, line roads and demarcate the boundaries
of fields are increasingly dotting the landscape in a number of Sahel
countries.
B. Negative experiences
37. There are still many deficiencies and difficulties regarding plantations
which demonstrate the need to improve the level of expertise and put further
effort into research. All too often, officials dealing with reforestation
still lack qualifications, and reforestation programmes are characterized by
bad planning (in terms of programming, land use, pair matching of species and
sites, etc.). The following shortcomings should be mentioned:
(a) Plantations in Africa. Planting is the preferred activity of African
foresters, particularly in sub-humid to arid countries, and forestry services
are often judged by the success of their plantations. However, in addition to
the shortcomings described above, one of the biggest drawbacks is the limited
variety of species used;
(b) Afforestation for production purposes. Industrial afforestation has too
often been carried out in marginal site conditions in the form of single-
species plantations extending over a large area;
(c) Reforestation versus management of natural stands in arid zones. Until
recently, development projects have too often overlooked the rational
utilization of natural stands and their management;
(d) Non-timber forest products. Despite their potential importance and their
contribution to the local economy in tropical regions, the past 20 years have
seen a sharp decline in the production of and trade in a number of non-timber
forest products which used to be very important.
C. Summary of lessons learned
38. While significant progress has admittedly been made over the past decade
in policies and in the legislation enacted, they still do not allow country
people to organize their future with sufficient confidence and purpose; nor do
they allow them to establish mechanisms for wielding the tools and investment
resources that would enable them to take charge of their development.
39. International aid, and particularly official development assistance, has
not always lived up to perhaps overly high expectations; it has often lacked
focus, with one programme having to compete against another, and without
sufficient coordination and an adequate targeting of efforts which could have
ensured greater efficiency. Moreover, aid has often been allocated for
relatively short periods, without any guarantee of extension. All of these
factors hamper effective planning and continuity that is essential in all
matters pertaining to reforestation and forestry.
40. In terms of knowledge and information, much remains to be done in the
following areas:
(a) Improving training for technicians by adapting it to the conditions of
their ecological, social, political and economic environment;
(b) Strengthening and improving the focus of research, which has hitherto
made insufficient progress in the service of rural areas with regard to
participation;
(c) Improving documentation of participation which, mutatis mutandis, has
nevertheless made great strides in the implementation of community planting
programmes;
(d) Improving documentation of the economic consequences of
reforestation.
41. The involvement of non-governmental organizations in forest resource
management operations over the past decade has been remarkable in the pursuit
of objectives involving (a) satisfaction of household energy needs;
(b) improvement of the inhabited environment; (c) the structuring of rural
land occupancy and improvement of fertility; (d) in general, the campaign
against land degradation and desertification. Non-governmental organizations
have encouraged cooperative work.
VI. FUTURE TRENDS
A. Identification of challenges for the future
Substantial common ground coinciding with or approximating to the objectives
highlighted by the forest principles 4/ and chapter 11 of Agenda 21
42. These include the following elements:
(a) Reforestation projects should be integrated into development and be
planned to take account of this fact. In particular, there is a need to adopt
an intersectoral approach and attack the problems of poverty and the causes of
soil degradation "in the context of efficient and coherent national forestry
projects and programmes";
(b) More substantial support should be provided for research. There are
still many areas in which research has to provide additional tools to enhance
reforestation activities, including (i) systematic evaluation of reforestation
needs;
(ii) better matching of the site and types of reforestation;
(iii) improvement of technologies designed for arid regions, greater
international scientific cooperation between the countries
concerned being of particular importance; (iv) taking into account and using
local knowledge and technologies.
43. Principle 9 of the Rio Declaration on Environment and Development 5/
calls for the strengthening of "endogenous capacity-building for sustainable
development by improving scientific understanding through exchanges of
scientific and technological knowledge, and by enhancing the development,
adaptation, diffusion and transfer of technologies, including new and
innovative technologies". This approach must be applied in its entirety,
which at the same time drawing to the greatest possible extent on all
technologies available locally.
Challenges in the areas of policy, strategy and legislation
44. General policy. The introduction of shrubs, bushes and trees into
production systems is an important stage in maintaining or restoring the
fertility of the land and remains one of the preferred tools for combating
against desertification, when it is integrated into a coherent package of
measures. The campaign against land degradation, in particular in arid
regions, is now clearly identified with the drive against poverty and for
development, the major objective being to achieve food security and ecological
security. Therefore, all rural development policies must aim at solving
simultaneously the three key problems of:
(a) Restoring and increasing soil fertility;
(b) Restoring herbaceous and aerial fodder; and
(c) Controlling deforestation.
45. This is, without doubt, a huge task, and it is hoped that action may be
taken concomitantly on such problems as controlling population growth,
stemming migration flows and transforming production systems. Accordingly,
initiatives on the ground will need to be defined in terms of multisectoral
development and integrated into geographical and human units, with a view to
achieving a socio-economic and environmental equilibrium.
46. Role of non-governmental organizations. Despite the significant advances
made, too many delays and constraints hamper the administrations and technical
services of the poor countries in their attempt to generate a renewed impetus
stemming from the debate on sustainable development and the programmes of
Agenda 21; by combining the desire for progress felt by the communities and
Governments with the potential of non-governmental organizations, many
advances could be made in reforestation, which is viewed as a primary and
obvious area for the involvement of non-governmental organizations.
B. Priorities
Participation, partnership with the State
47. Participation is the final phase in local populations awareness of their
skills and of the fact that responsibility is shared between the State, the
rural communities and the other major groups. Thus, it is a phase of
partnership between equals which must be regulated within a legal, economic
and ownership framework which is defined jointly on the basis of clearly set
out contracts and which takes into account the need to increase the access of
the greatest possible number to land and resources.
48. Therefore, States will rapidly have to improve the institutional and
legal framework capable of tapping the public's commitment to reforestation,
including:
(a) Increased access to land (ownership or extensive rights);
(b) Clarification of the status of new plantations;
(c) Improvement of the contractual arrangements between the State and
communities regarding planting on forest land;
(d) Availability of products and assistance with their marketing, and so on.
49. Lastly, all decisions regarding afforestation and reforestation projects,
particularly large-scale ones, must be taken openly and with the full
participation of the groups concerned or potentially affected.
Role of pilot projects leading to wider impact
50. Pilot projects generally extend beyond the context in which they are
implemented, even when they are successful in terms of achievements and
innovations. It is important to analyse the factors which account for this,
and to determine clearly the socio-economic and technical objectives of pilot
projects and the situations targeted, so that, in the future, they may fully
perform their role in the communities they are intended to serve. Defining
easily adaptable reforestation techniques matched to the skills of the local
population and compatible with their social aspirations remains the chief
function of pilot projects, if further progress is to be made in response to
the objectives set out in Agenda 21. The results derived from such
experiences will have to be carefully recorded and better presented so as to
enable them to be used more widely and disseminated more rapidly.
Methods of integrating and managing afforestation and reforestation projects
51. Knowledge of the various traditional systems of agroforestry must be
increased and the reasons for their success or failure analysed, in order to
improve our ability to integrate and manage wooded areas within existing
production systems.
Ongoing follow-up and analysis of past and future projects from a physical,
economic, social and ecological standpoint: lessons learned and their
application
52. It is a necessity and a top priority to help the developing countries
acquire the tools needed for monitoring, ongoing follow-up, surveys and data-
processing and analysis which they are unable to put in place using their own
means and skills and without which there can be no planning in line with and
of relevance to the socio-economic reality. It is equally important to
develop appropriate tools and mechanisms for data-gathering and exchange;
subregional groupings could constitute the political basis for such
cooperation. It is crucial therefore to set up databases on plantations at
the country level in order to compensate for the lack of knowledge on the
relationship between growth and production on the one hand and on the matching
of forest species to the sites involved on the other. To achieve this it is
necessary to design methods of inquiry which can be used with ease by the most
decentralized units and by members of the community with only limited
training.
53. During the first session of the Panel, the Government of Portugal made a
proposal to sponsor, jointly with a developing country to be identified, an
"Expert meeting on desertification and reforestation of degraded forest
lands". The expert meeting, co-sponsored by Cape Verde, will take place in
Lisbon, Portugal, 24-28 June 1996. A report will be published prior to the
third session of the Panel in Portuguese, English, French and Spanish. The
expected results of the meeting are to:
(a) Collect and analyse the experiences of afforestation, reforestation
and restoration of forest systems, especially in countries with fragile
ecosystems affected by desertification and/or drought;
(b) Identify the main constraints and present the most relevant
studies/cases;
(c) Contribute to the identification of practical measures and potential
solutions and their impact on development and efficiency of future action.
PART TWO. IMPACT OF AIR-BORNE POLLUTANTS ON FORESTS,
PARTICULARLY IN CENTRAL AND EASTERN EUROPE
I. INTRODUCTION
54. Good forest health is essential to the continuous flow of goods and
services from sustainably managed forests. However forest declines and
dieback of trees occur as a world-wide phenomenon. The approximate location
of decline events as described in FAO's 1994 global overview of decline and
dieback of trees and forests is shown in map 1.
55. Forest decline is defined in this overview as an episodic event
characterized by premature, progressive loss of tree and stand vigour and
health over a given period without obvious evidence of a single clearly
identifiable causal factor such as a physical disturbance or an attack by an
aggressive disease or insect.
56. In addition to being widespread geographically, forest declines can be
caused by both natural factors and human influences. Indeed forest dieback
may be part of a normal ecological succession. Human activities that can
contribute to forest decline include pollutant depositions, overgrazing when
woodlands are used for pastoral purposes, insensitive harvesting operations,
the use of plantations with low genetic diversity, the accidental introduction
of pest species, fire, the alteration of hydrology and, finally, the
anticipated climate change associated with the burning of fossil fuels and
increased concentration of greenhouse gases.
57. In Europe, there have been historical regional declines in forest
condition dating back to at least the eighteenth and nineteenth centuries.
There were rarely single, undisputed causes of decline, but drought, extreme
winter temperatures, late frost, insects, fungal pathogens and pollution were
all suggested as important causes. Silvicultural practices, particularly
clear-felling and inadequate thinning, and low potassium availability were all
identified as causal factors. Arguments over which factors were primary or
triggering and which were secondary go as far back as 1928.
58. In the late 1970s and early 1980s, public attention was drawn to the
deterioration of forest condition in Germany and subsequently in some other
European countries and parts of North America. By the early 1980s, these
symptoms seemed to be widespread and public concern focused on whether such
declines were new and pollutant-related. The terms "Waldsterben" and
"neuartige Waldschaden" meaning "forest death" and "new-type forest decline"
respectively were introduced and there was fear that the deterioration was
irreversible.
59. Similarly to what happened in developed countries, the rapid economic
growth now occurring in some developing countries is largely based on energy
generation through the burning of fossil fuels. For example, over the last
20 years energy use in South and East Asia has doubled, and there are
currently no international conventions or other instruments in place to limit
emissions of acidic substances. Continued development over the next 30 years
could bring a fourfold increase in emissions of sulphur dioxide in countries
such as Japan, China and India.
Map 1
[not shown]
60. Concerns over forest health were also being expressed in North America in
the 1970s, although in the United States of America and Canada the regional
diversity in the combinations of causal factors of such problems was
acknowledged from the outset. Coordinated and comprehensive national and
international programmes of forest monitoring and research were established to
address forest health and the role of pollutant depositions in both North
America and Europe.
61. The results of many of these programmes have led to a general scientific
consensus on the degree to which pollutant depositions contribute to poor
forest condition in Europe, a review of ongoing activities (monitoring,
research and coordination), identification of gaps in understanding, provision
of informed comment on the degree to which pollutant depositions threaten
sustainable forest development, and consideration of possible future actions
and the implications for other parts of the world.
II. CURRENT STATUS
Europe's forest resource
62. Among the 35 countries that participated the 1994 International
Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on
Forests (ICP Forests), 29.8 per cent of the land area is forest. Ten climatic
regions have been identified covering the 35 countries that participate in the
Economic Commission for Europe (ECE) and European Union (EU) surveys of forest
condition.
Pollutant emissions in Europe and the European climate record
63. In parallel with silvicultural influences, pollutant emissions and
depositions have been changing both qualitatively and quantitatively.
European sulphur emissions have risen from under 5 million tons (of sulphur
dioxide (SO2)) in 1880 to a peak of nearly 60 million tons in 1975 with the
geographical pattern of emissions (and thus of depositions) also changing
substantially. By 1990, emissions had declined to about 48 million tons per
year and the levels continue to fall (the data quoted above include
contributions from the former Union of Soviet Socialist Republics (USSR) and
Turkey). Trends are not as clear for nitrogen compounds, but emissions have
also increased substantially with industrialization and the increase in road
traffic.
64. Recent inventories show roughly stable levels of emission of nitrogen
oxides from European countries between 1980 and 1993, and a moderate decrease
in ammonia emissions from 7,649 thousand tons per annum in 1980 to 6,573
thousand tons per annum in 1993. The most recent Pan European inventory of
pollutant emissions was undertaken in 1990 and emission data are now available
from the European Environment Agency as CORINEAIR 1990 summary tables. These
tables cover the emissions of SO2, the oxides of nitrogen (NOx), volatile
organic compounds (NMVOC), methane (CH4), carbon monoxide (CO), carbon dioxide
(CO2), nitrous oxide (N2O) and ammonia (NH3) from 29 European countries.
65. All of these pollutants and others, notably heavy metals, have the
potential to influence plant growth either directly, through their effects
(those which are greenhouse gases) on climate or via soil-mediated effects
(for example, contamination, soil acidification, accelerated weathering and
the leaching of nutrients).
66. Over the period for which instrumental records of European climate exist
(about 300 years) and, indeed, within historical time, the climate record has
been relatively uniform, and there have not been major shifts in vegetation
cover associated with climate change.
Forest surveys and monitoring of forest conditions
67. Because of concern over forest decline, a steadily increasing number of
countries have been making annual assessments of forest condition since 1984.
ICP Forests was established along with the other International Cooperative
Programmes of the Working Group on Effects of the Convention on Long-range
Transboundary Air Pollution which had been ratified by 39 countries in 1985
and is administered by ECE. The main activity of ICP Forests has been to
coordinate forest monitoring and this has been undertaken in conjunction with
the EU Standing Forestry Committee, the Working Group on Air Pollution (DG
XVI) and the 15 member States. A special report on the condition of forests
in Europe has been prepared as a contribution to the work of the Ad Hoc
Intergovernmental Panel on Forests.
68. Within EU, forest monitoring and associated pilot and demonstration
projects are under EU Council regulation (EEC) No. 3528/86 and its subsequent
amendments. In 1994, 29 countries participated in these monitoring programmes
and in recent years the ECE and EU have published joint annual reports on the
condition of forests.
69. The annual reports of these programmes date back to 1987 and represent a
thorough record of forest condition since then. However, the symptoms that
are recorded are non-specific, and therefore determination of the extent to
which the recorded damage is caused by pollutant depositions is not easy. A
number of useful attempts have been made to address the question and it is
certain that these reports present the most appropriate data from which to
assess the overall damage to European forests, including that caused by
pollutant depositions.
70. The percentage of trees of all species in each defoliation class is shown
in map 2, which is derived from the EU/ECE source Forest Conditions in Europe:
Results of the 1994 Survey. Maps of this type are available for every year
from 1987 onwards and thus the reports give insight into the spatial
distribution and temporal development of forest condition in Europe. The
general spatial pattern as seen in map 2 is similar to that in most years of
the period, although some anomalies have occurred.
71. It is clear that the Central European area that includes areas of Poland,
the former German Democratic Republic (East Germany), the Czech Republic and
Slovakia has the largest proportion of defoliated trees. This is the area of
Europe (referred to as "the black triangle") in which there have been large
Map 2
[not shown]
sulphur emissions from heavy industry and the combustion of high-sulphur-
content coal. However there are other areas, such as parts of central
Romania, the eastern Pyrenees and some plots in Norway and Sweden, with
defoliation that stands out on a European scale. It is important to interpret
this with reference to the national accounts in ECE and EU reports. There is
no doubt that local forest-based research programmes are able to inform
discussion of the extent to which pollutant depositions can be regarded as
causal agents.
72. The changes over time of these data are important in determining whether
long-term deterioration or improvement is occurring. The annual reports do
present information on plots that are worsening, stable or improving.
Unfortunately, the most recent report shows a general worsening of crown
density over the period 1990-1994. A series of dry years with drought and
high summer temperatures is thought to be the main cause of worsening
conditions.
The International Institute for Applied Systems Analysis Forest Study 1992
73. The International Institute for Applied Systems Analysis (IIASA) has
recently undertaken a study of forest resources of Western and Eastern Europe
with the objectives of looking at the potential developments of the forest
resource, illustrating the effects of forest decline caused by air pollutants
on this resource and identifying policy options for dealing with these
effects. The study represents a unique attempt to provide predictions of the
way in which sulphur and nitrogen depositions might effect the development of
forest resources and of wood supply in Europe. The results are of
considerable interest and indicate the importance for European countries of
formulating new forestry policies to deal with the new conditions caused by
the decline if they are to maintain current forest resources.
Research and identification of forest declines (where and when do problems
occur)
74. Over the last 20 years, there has been a substantial amount of research
into the effects of pollutant depositions on trees and on the role of
pollutant depositions in forest declines. Within Europe much of this work has
been within national programmes such as the French De'perissement des fore^ts
et pollution atmosphe'rique (Forest Decline and Atmospheric Pollution)
(DEFORPA) and the Dutch Priority Programme on Acidification (DPPA). Many
national programmes are now complete, with results being available in
scientific journals and in programme reports.
75. In many cases, research projects have enjoyed funding from successive EU
research programmes, and activities have been coordinated through EU Concerted
Actions. Data are available in a series of ECE Air Pollution Research
Reports. International coordination has also been carried out through the
International Union of Forest Research Organizations (IUFRO), which involves a
project group on The Impacts of Air Pollution on Forest Ecosystems and a
special task force on Forest decline and air pollution (followed by a second
task force on Forest, climate change and air pollution in 1991).
76. The overriding conclusions of the extensive research and forest studies
can be considered to be:
(a) Recognition of the geographical extent over which pollutant inputs
can affect forest condition (a recognition of the role of long-range
transboundary air pollution);
(b) Identification of the considerable variety of stress combinations
and thus forest responses that can occur;
(c) An understanding of the processes by which many of these factors
influence forest condition.
77. Few of the original hypotheses that were proposed as explanations of
forest decline have been rejected; however, the different factors have been
put into context on the basis of their importance in particular regions. The
role of virus infections, for example, has proved to be insignificant,
although plant viruses might be present. In contrast, the importance of
drought has become clear, with water deficit often being a major factor in the
development of a decline.
78. In some regions, such as the Ore mountain of the Czech Republic and the
Silesian region of Poland, the direct effects of gaseous SO2 are a major
factor. However scientific consensus now suggests that, other than in the
so-called black triangle of Central Europe, the main emphasis can be placed on
the soil-mediated effects of pollutant depositions (primarily sulphur and
nitrogen). These have also been referred to as constituting the indirect
effects of pollution in contrast to the direct effects on foliage.
79. A clear understanding of the long-term effects of continued, perhaps low,
rates of sulphur and nitrogen deposition on soil condition and tree
nutritional status is valuable in determining policy for pollution abatement
and forest management. It has become clear that both these issues
(atmospheric elemental inputs and tree nutrition) need to be addressed if
forest resources are to be sustainable.
The critical loads approach
80. Based on the last 20 years of research on European forest scientific
understanding has been formulated as policy through the critical loads
approach. The importance of this approach has been recognized by the
signatories of the current sulphur and nitrogen protocols of the 1979 Geneva
Convention on Long-range Transboundary Air Pollution. The Convention was
signed by all countries of Eastern and Western Europe and by Canada and the
United States, and came into force in 1983. ECE was charged with supporting
cooperation in air pollution control. An important activity by ECE towards
achieving this aim has been the support of the Cooperative Programme for the
Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in
Europe (EMEP).
81. For the purposes of the nitrogen protocol (Sofia, 1988) and the second
sulphur protocol (Oslo, 1994), a critical load was defined as follows: a
quantitative estimate of the exposure to one or more pollutants below which
significant harmful effects on specific sensitive elements of the environment
do not occur according to present knowledge. The basic obligation of the
second sulphur protocol is that parties shall endeavour to control emissions
so that long-term depositions do not exceed defined critical loads. A
reduction in the difference between the deposition of sulphur in 1990 and
critical sulphur depositions (the critical load corrected for base cation
deposition and uptake) by at least 60 per cent is required. The mapping of
critical loads for Europe has been undertaken by the Coordination Centre for
Effects which was created by the Executive Body of the Convention. Critical
loads maps have been published for the protection of aquatic ecosystems and
soils (1991 and 1993). However, some countries including Switzerland and the
United Kingdom have also published critical loads maps specifically for forest
soils.
III. EXISTING GAPS IN KNOWLEDGE AND UNCERTAINTIES
82. A degree of scientific consensus has been reached on the question of
European forest declines and this consensus view has been presented and
justified here. Over the long term, continuing small inputs of sulphur and
nitrogen and gaseous pollutants, such as ozone, will exert an influence on
forest ecosystems. However, it is also clear that the widespread and
catastrophic forest death that was feared in Europe has not occurred. Wide-
scale effects of pollutant depositions are subtle and, at least in the short
term, often have little commercial impact relative to the effects of extremes
such as windthrow, drought and outbreaks of fungal or insect pests.
83. In managed forests, the nutritional problems that depositions create can
be addressed by using fertilizers, provided that pollutant inputs are not
excessive and that direct damage from pollutants in the atmosphere is not
occurring. However, in the long term these responses may be difficult to
maintain and the abatement of pollutant emissions is clearly the preferred
option. Critical levels for forest damage have been exceeded in many areas of
Europe and elsewhere in the world, and it is clear that pollutant depositions
must be considered one of the abiotic factors that have a significant impact
on forest ecosystems. In spite of this, the forecast or prognosis for forest
condition, stability and growth remains difficult, because gaps remain in
understanding the processes, and hence uncertainties are attached to even the
best causal explanations of specific forest declines. In some cases, the
specific gaps in understanding that remain are important in terms of current
and future policy.
84. Some more general but equally important uncertainties remain that need to
be addressed. These include the extent to which the critical loads approach
has provided deposition targets that will effectively protect the target
ecosystems, the degree to which elevated CO2 concentrations have affected
forest ecosystems and the way in which they may be affected in the future. It
remains difficult to predict forest growth for a given site with confidence.
85. For European forests, many of the specific gaps in knowledge that were
listed above can be addressed effectively within the structure of the level
III network of forest plots, and this is an objective of ICP Forests. The
entities concerned are detailed research forest plots for which the objective
is to understand the processes occurring therein. Many countries have forest
plots with the detailed measurements required for those plots to constitute
the basis of a level II network but, in general, the full establishment of the
level III network, and the effective use of the data that it is now providing,
must be seen as a priority. Data are now being submitted from the level II
network and a data coordination centre is being established under the guidance
of a scientific advisory panel.
86. The ongoing analysis of the level I data is also important. The
indication up to 1994 of a general continuation of the worsening condition of
trees throughout Europe means that it remains important to continue these
monitoring activities and, in particular, to develop an understanding of the
relative importance of the various factors now known to influence crown
density.
87. For countries not participating in EU and ECE (Convention on Long-range
Transboundary Air Pollution) coordinated activities, other, more general, gaps
in knowledge may exist, as follows:
(a) The ecosystem nutrient and elemental budgets may not be known;
(b) Pollutant emission inventories may be lacking and pollutant
transport patterns in the atmosphere may not be understood;
(c) Critical loads maps for forest soils may be absent;
(d) There may be no environmental monitoring system, including
monitoring of forest condition.
88. Without these data, it is likely to be impossible to evaluate the extent
to which pollutant depositions, forest management and other anthropogenic
factors threaten forest sustainability.
IV. APPROACHES TO ADDRESSING THE ISSUE: EXPERIENCES,
SUCCESSES AND FAILURES
89. In the last 20 years, a considerable amount has been learned about the
status of forests in developed countries where pollutant depositions with
moderate or small values (depending on one's perspective) are the norm rather
than the exception. A change in the condition of the silver fir and the
Norway spruce did occur in the late 1970s and early 1980s in Central Europe
but it is now clear that, to a large extent, this was synchronized with a
period of climatic stress. It has been suggested that interactions among the
effects of climate and pollutant depositions are important. The acceleration
of nitrification rates in forest soils in warm years is a good example of a
mechanism that can result in such interactions.
90. The examination of changes in crown density over time supports the view
that weather is an important factor in explaining year-to-year fluctuations in
crown density. However, it has now been established that above certain
critical values, continued pollutant depositions will result in widespread and
long-term effects. The separating out of pollutant from other effects in
forest ecosystems is the main challenge for the newly established level II
monitoring network of EU and ECE countries.
91. The concern over a single novel forest decline throughout Europe
undoubtedly resulted from the misinterpretation of the results of forest
condition data (Forest Health Surveys), combined with a lack of awareness of
historical records of forest declines and a lack of understanding of forest
science, particularly nutrient-cycling and forest pathology. Perhaps the main
lesson learned has been that the results of surveys of crown density and
discoloration must be interpreted objectively. These symptoms are not
specific for pollution damage. Similarly, it is misleading to place too much
emphasis on temporal changes in mean values for Europe or other large and
diverse geographical regions.
92. It is now clear that many of the statements that were made concerning the
effects of pollutant deposition were appropriate on the local scale only. The
wide-scale or overall status is assessed more clearly on the basis of the
critical load exceedance and, for forests, exceedance of soil critical loads
proves particularly relevant in assessing sustainability. This is because of
the requirement of quantifying nutrient inputs, budgets, fluxes and outputs in
the calculation of soil critical loads. A knowledge of nutrient budgets over
successive rotations is also essential in determining whether the site will
become impoverished as a result of forest harvesting.
93. Tree mortality and growth rates represent alternative indicators for
evaluating forest condition. Neither a consideration of mortality rates nor a
consideration of growth patterns supports the view that European forests are
in a threatened condition, but mortality rates have been large for specific
species on a local scale. Similarly, a consideration of growth patterns leads
to a different view of the future.
94. Experience has been gained on the restoration of damaged forests
throughout the world. Since most European forest declines are associated with
nutritional disturbances, the emphasis of restoration work has been on the use
of mineral fertilizers, especially magnesium (Mg) and potassium (K) salts, and
the use of compensation liming. Where the nutritional imbalances have been
understood correctly these techniques have proved effective. The use of
dolomitic (magnesium containing) limestone in spruce forests throughout
Germany is a particularly clear example of such a technique.
95. The use of more tolerant tree species where direct damage from gaseous
air pollution has been a problem has also been tried. An example is the use
of blue spruce (Picea pungens) in the Ore mountains of the Czech Republic.
However, the fact that this approach has not been general probably reflects a
preference for emission abatement as the desired course of action.
96. At least two overall and related general lessons have been learned.
First, that it is important to consider sustainability in forest planning and,
second, that it can be achieved if appropriate policies are adopted.
V. FUTURE TRENDS AND PERSPECTIVES: THE WAY AHEAD
97. Achieving deposition levels of less than the critical loads is clearly
important if damage to forest ecosystems is to be prevented. The continued
monitoring of forests is thus an important priority along with the extension
of monitoring to regions not covered by effective programmes. Access to
survey information and the integration of different monitoring activities are
also important. These objectives can be achieved by the proper coordination
of monitoring activities across the various sectors, a goal that has not
always been achieved in the past.
98. It is important that in future the knowledge that has been gained in
Europe and North America be put to use on a global scale in the management of
pollutant emissions and forest resources. After the recognition of the
transboundary nature of air pollution problems, the significance of the
critical loads approach cannot be overstated. The experience of Europe has
shown that this approach allows scientific understanding to be expressed
quantitatively and thus to influence agreements on emission abatement.
99. Ecosystem sensitivity to acidification is affected by sulphur dioxide
depositions from the burning of fossil fuel. The mapping of sensitive areas
helps to develop measures to counteract potentially harmful effects of
pollutant depositions. As in Europe, so in other parts of the world: a good
knowledge of the location of sensitive areas and of the threshold deposition
values above which damage occurs (the critical load) would allow measures to
be taken before problems attained the proportions seen in some areas of Europe
in the past. Initial conclusions for South and East Asia indicate the need
for early action, since critical loads have probably been already exceeded in
parts of Japan, China and India.
100. The sensitivity maps that are being produced for developing countries
need to be developed and evaluated by local scientists who are better able to
undertake this task, and the maps need to be verified using international
assessment and monitoring schemes. It is also important that the general
public be kept informed. Approaches and parameters developed in Europe will
require modification for application in other parts of the world and local
scientists are best able to formulate the needs for their countries.
Technology transfer has a role but European technologies may not always be
directly applicable. Liaison and cooperation are clearly important.
101. There is a clear relationship between the amount of light intercepted by
forest canopies and the growth rate of the forest. This relationship forms
the basis of a number of process-based growth models. It had been assumed
that loss of crown density resulted in decreased growth rates; and if
defoliation was severe enough and was sustained, this would certainly be the
case. Indeed, a reduction in growth rate associated with loss of crown
density had been an assumption of the IIASA study discussed earlier that
predicted subsequent financial losses.
102. However, in recent years a number of reports of increased growth rates
have been published. Possible explanations for enhanced growth are the
effects of nitrogen deposition, improvements in silvicultural practice, the
use of improved plant material (selected genotypes), increases of atmospheric
CO2 concentrations and improved climate (especially temperature). It is clear
from the Dutch Priority Programme on Acidification and other studies that for
nitrogen depositions below a certain threshold, effects on tree growth are
beneficial. This particular explanation of improving growth trends is thus
well supported on a regional basis. The precise quantification and
explanation of the improving growth trend on a broader basis is much more
difficult to achieve and this represents one of the challenges for forestry
research in the next few years.
103. European and North American research has shown that there is a strong
link between pollutant depositions and sustainability: at its simplest,
elemental loss or leaching from forest ecosystems, particularly of nutrient
base cations which are essential for tree growth, is caused and driven by the
deposition of acidic compounds. This fundamental link is quantified in the
mass balance and dynamic model critical loads calculations. In Europe, the
critical loads approach combined with effective forest monitoring has provided
a framework for guiding international abatement commitments. Where direct
damage from gaseous air pollutants to forest ecosystems has occurred locally,
the required action was often obvious. On a global basis, the overriding
requirement is to see that the benefits derived from the research and from the
frameworks for coordination of actions are available wherever they are
required.
PART THREE. ITEMS FOR DISCUSSION
104. In relation to part one of this report, the Panel may wish to consider
the following items for discussion:
(a) The need for an integrated approach to reforestation and the restoration
of forest ecosystems within the overall social and economic development of
countries with fragile ecosystems affected by desertification and/or drought;
(b) The need to assist developing countries in increasing their capacity for
continuing analysis and monitoring of past, present and future experiences,
including biophysical, economic, social and ecological aspects;
(c) The strengthening for partnership arrangements among local communities,
Governments, non-governmental organizations and other interested groups,
including long-term institutional and legal arrangements;
(d) The establishment of a closer relationship between reforestation and
management of existing forest ecosystems, including the in-depth study of
traditional agrosylvopastoral systems, for the purpose of benefiting from
existing knowledge and integrating management of new forests into traditional
production systems.
105. Concerning part two of this report, the Panel may wish to consider the
following items for discussion:
(a) The lessons to be learned from the experience of forest decline world
wide and from pollutant-related declines where they have occurred;
(b) The need for national commitments and international agreements on
pollutant emissions for countries not within the Convention on Long-range
Transboundary Air Pollution;
(c) The link between pollutant and elemental inputs from the atmosphere and
sustainability and the extent to which pollutant depositions (and aerial
elemental inputs, rates of mineral weathering and elemental losses from
leaching by ground- and surface water and in forest harvesting) are considered
in forest planning and management;
(d) The need for continuation in EU and ECE countries, and for geographical
expansion, of monitoring programmes where required;
(e) The need to develop the use of the critical loads approach within the
context of sustainability world wide;
(f) The coordination of these activities, the dissemination of information to
the public and the access of potential users (managers and policy makers) to
data;
(g) Specific research and field data collection to support the above-
mentioned activities, including work on ecosystem function where pollutant
depositions threaten sustainability.
Notes
1/ See Official Records of the Economic and Social Council, 1995, Supplement
No. 12 (E/1995/32), chap. I, annex I, sect. III (I.4).
2/ See document E/CN.17/IPF/1995/3, sect. II, para. 18 (I.4).
3/ See Report of the United Nations Conference on Environment and
Development, vol. I, Resolutions Adopted by the Conference (United Nations
publication, Sales No. E.93.I.8 and corrigendum), resolution 1, annex II,
para. 11.10.
4/ Ibid., annex III.
5/ Ibid., annex I.
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