0450-B3

Forest ecosystem monitoring - a contribution to environmental policy and science

Thomas Haussmann, Richard Fischer, Allen Riebau ¹ and Hiroyuki Sase

Abstract

Networks for the monitoring of air pollution and their effects on forests are presented from the United States of America, East Asia and Europe. The USDA Forest Service does not directly carry out air pollution monitoring but relies on existing networks. Sulphate and nitrate wet acid deposition are highest in the northwest of the USA. The Acid Deposition Monitoring Network in East Asia (EANET) has only been operating since 1998 with 40 sites located in 11 participating countries. First results are presently available. Under the UNECE, the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) in cooperation with the European Commission, has been monitoring forest condition for 16 years. Deposition monitoring has been carried out on large parts of the 860 Level II plots since the beginning of the 1990s. Recent results show excess nitrogen deposition on up to 90% of the plots. Critical Loads were most heavily exceeded in central and Western Europe.

The results are an important basis for political decisions at different levels. In the United States the Forest Service relies on air quality data for the approval or disapproval of air pollution permits. The data and results of EU/ICP Forests are used as a direct input in formulating Protocols under the UNECE Convention on Long-range Transboundary Air Pollution (CLRTAP) and the programme pursues objectives of several resolutions of the Ministerial Conference of the Protection of Forests in Europe (MCPFE). In recent times an increasing demand from other political processes has been recognized, including the United Nations Forum on Forests (UNFF), the implementation of the Convention of Biological Diversity (CBD) and the Framework Convention on Climate Change (FCCC).

1. Introduction

Throughout most continents forests are one of the most widely used renewable resources, providing recreation and enhancing the environment. In particular in industrialized regions forest ecosystems are however affected by the deposition of atmospheric pollutants and air pollution has been recognized as a threat for the functioning of these ecosystems in many countries. Due to the transboundary character of the pollutants monitoring networks have been installed across the borders in Europe, North America and East Asia. A main task of these extensive programs is to bring the state of the forests and the role of atmospheric pollutants to everyone's attention. This includes the challenge to bridge gaps between scientists and politicians and to facilitate an effective communication of the desired policy relevant information. Only if this transfer is guaranteed, scientific results can serve as a requested basis for decisions in the fields of environmental and clean air policies.

2. Air pollution monitoring systems

2.1 Forest and rangeland air quality monitoring in the United States, with particular emphasis to wilderness areas managed by the Forest Service

Legal framework

In the United States managers of federal lands have a special responsibility for protection of natural resources from air pollution. Under the US Clean Air Act (CAA) e.g., National Parks and Wilderness Areas are designated as Class I areas which are specially protected for air quality The US Forest Service manages vast tracts of land as CAA Class I Wilderness and has thus a need for reliable data on air quality in these areas.

Monitoring systems

At present, there is no USDA Forest Service national monitoring program solely dedicated to forest air quality or AQRVs. The Forest Service participates in the Interagency Monitoring of Protected Visual Environments (IMPROVE²) for collection of national background visibility values and the constituents that add to visibility impairment. There are approximately 150 IMPROVE sites across the United States.

The Forest Service also participates in the National Atmospheric Deposition Program (NADP³) for wet acid deposition information, but because NADP relies on mechanical devices for collection of samples, sites cannot legally be placed within a Wilderness. This program operates more than 200 sites. For dry acid deposition measurements the Forest Service relies on the Clean Air Status and Trends Network (CASTNET⁴). This Network runs approximately 70 stations. In addition there are internal and localized programs and networks of the Forest Service and National Park Service ⁵⁶⁷⁸.

Results

From its monitoring sites the NADP calculates Isopleth maps (Figure 2). For sulphate as well as for nitrate they show comparatively high wet deposition inputs in the north east and much lower inputs in the western United States. The monitoring sites are not exclusively located in forests and a general comparison with e.g. ICP Forests data is therefore limited.

Outlook

Even though that there is a magnitude of different programs, it is an imperative to develop site specific information and apply it consistently agencywide throughout the United States. Recently the Federal Land Managers' AQRV Work Group (FLAG⁹) has been constituted, being an interagency workgroup whose objective is to achieve greater consistency in the procedures Federal Land Managers use in identifying and evaluating AQRVs. Indeed, scientific issues faced by ICP Forests (see following chapters) have great parallel and are a complement to this group. A workshop in the near future has been proposed to assess the applicability of the ICP Forest methods to US Wilderness air quality monitoring.

2.2 Acid Deposition Monitoring Network in East Asia (EANET)

A new network

With the creation of the Acid Deposition Monitoring Network in East Asia (EANET¹⁰) transnational monitoring activities in this region started in 1998. Presently eleven countries are participating in the programme, namely Cambodia, China, Indonesia, Japan, Malaysia, Mongolia, The Philippines, Republic of Korea, Russia, Thailand and Viet Nam. The Acid Deposition and Oxidant Research Centre (ADORC) located in Niigata-shi, Japan was designated as network center. The UNEP Regional Resource Centre for Asia and the Pacific (RRC.AP) was designated as the Secretariat for EANET and started its function in 2002. This centre is situated within the Asian Institute of Technology (AIT), Bangkok, Thailand. The regular EANET monitoring phase began in January 2001.

The monitoring of EANET is presently based on 40 sites (Figure 3).

Results

Comprehensive wet deposition data from the EANET sites are available for the year 2000 (Network Center for EANET, 2001). The results show that the median sulphate deposition on 35 plots was around 10 kg SO₄-S per ha and year. For the sum of NO₃ and NH₄ it was approximately 7 kg N. Due to the fact that 13 sites are located in urban areas, comparatively high values are included. Thus the distribution is right skewed; (Table 1). Annual sulphur inputs of more than 30 kg per ha were measured in Manila, The Philippines and on 5 sites located in China. Nitrogen inputs were exceeding the 30 kg margin on the Petaling Jaya site in Malaysia and on 3 Chinese plots.

Table 1: Wet deposition on 35 EANET plots in the year 2000 (N = NO₃-N + NH₄-N). Results of the preparatory phase.

Note: Sites were excluded when monthly values were missing or were not in line with the quality criteria. In cases of five or less monthly values missing or not in line with the criteria the monthly values were filled in or replaced by the mean of the previous and following month.

2.3 International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests)

Set up of the monitoring system

Supported by the United Nations Economic Commission for Europe (UNECE) and the European Commission (EC), 39 European countries are presently taking part in the joint EU/ICP Forests Monitoring Programme. Implemented since 1986, the integrated environmental monitoring programme is today one of the largest in the world.

The objectives of the programme are implemented by a systematic large scale monitoring network (Level I) and an Intensive Forest Monitoring Programme (Level II) (Table 2).

At Level I approximately 6000 permanent plots are systematically arranged in a 16 x 16 km grid throughout Europe. Since the beginning of the 1990ies more than 860 Level II plots have been selected for intensive monitoring in the most important forest ecosystems of the countries participating. A larger number of key factors are measured on these plots.

Table 2: Surveys carried out on Level I and Level II plots

Results

On Level I crown condition assessments are a major activity. Annually more than 120 000 trees are assessed and classified into damage classes according to their needle and leaf loss, called defoliation. Latest evaluations (Fischer et al., 2002; Lorenz, M. et al. 2002; De Vries, W. et al., 2002) show that the percentage of plots with increasing damages in the last years is slightly higher compared to the percentage of plots with a decrease. However, there is no uniform trend throughout Europe, but changing conditions in different regions and also for different tree species.

Results of regression analysis for Pinus sylvestris and Fagus sylvatica plots show that high precipitation is related to relatively healthy tree crowns (Table 3). With respect to biotic damage factors, insects (and on beech plots also fungi) are related to high or increasing defoliation. Sulphur deposition was also correlated in all four models with high or increasing defoliation. The correlations between nitrogen inputs and forest condition reveal ambiguous conditions. This might confirm current knowledge, as nitrogen inputs on one hand eutrophy forest ecosystems but on the other hand may have acidifying effects.

Table 3: Relations between temporal and spatial variation of defoliation of Scots pine and common beech and various explaining variables as results of multivariate regression analyses. The R² value indicates the percentage of variance explained by the model.

Critical loads and levels define thresholds for the effects of air pollution. Based on Level II data critical loads for nitrogen were calculated which aim at no further net accumulation of nitrogen in the soil. The calculations are based on a nitrogen threshold in the soil solution of 0.28 g.m^-3 (0.02 mol_c.m^-3). For sites with higher values, increased leaching is to be expected. Critical loads were compared with actual deposition in order to derive the extent of excess deposition.

The average nitrogen deposition from 1995 to 1999 on 234 assessed plots is 19kg.ha^-1.yr^-1. The respective 5% and 95% percentiles are 3.5 and 39 kg respectively. High nitrogen inputs above 22.4kg.ha^-1.yr^-1 (1600 mol_c.ha^-1.yr^-1) only occur on plots in central Europe (Figure 4). Total nitrogen input is generally found to be much lower on plots in northern and southern Europe.

The average critical load aiming at no further nitrogen accumulation in the soil was near 8kg.ha^-1.yr^-1 . These critical loads were exceeded on 92% of the evaluated Level II plots. Results confirm that forests in northern Europe are more sensitive to nitrogen inputs as the net uptake of nitrogen by trees is low in these regions.

Critical nitrogen loads related to effects on tree foliage were higher than those related to the soil. These loads were exceeded at 45% of the evaluated conifer plots indicating an increased vulnerability to drought stress, frost, pests and disease. Critical loads requiring no changes in the ground vegetation were exceeded on 58 % of the plots. This shows that changes in plant diversity are very likely in European forests.

3 Policy relevance

Direct local needs: an example from the US

In the United States land managers have to approve or disapprove an air pollutant emissions permit whenever a new emission source, such as an electric power generation plant, applies for a permit to operate. As can be readily imagined, the forest supervisor must have quite some information at his disposal as a basis for his decision related to the question whether a particular air pollution increase can be allowedPerhaps most important in this context arethe existing state and trends for visibility in the potentially impacted wilderness.

Thus, air quality has become an argument that has to be considered in daily economic, administrative and political life and its monitoring as well as scientifically approved knowledge on its effects are basic needs for sound decisions.

Input to transnational and global processes

The results of ICP Forests are used as a direct input in formulating Protocols under the UNECE Convention on Long-range Transboundary Air Pollution (CLRTAP) and to verify the successful implementation of the Protocols. The latest Protocol is the Protocol to Abate Acidification, Eutrophication and Ground-level Ozone and was signed in Gothenburg, Sweden in 1999.

The monitoring activities also pursue the objectives of the Resolution S 1 of the first Ministerial Conference of the Protection of Forests in Europe (MCPFE) (Strasbourg, 1990) and contribute to the Resolutions H 1 and L 2 of the same process.

As a direct input the data of ICP Forests are introduced in the process of indicators for sustainable forest management an activity which is carried out in Europe within the MCPFE process. The section of forests health is regarded as a very important aspect in this context. In Northern America this process is known under the Montreal process while similar processes for the tropical forests are steered by FAO.

At global level the installation of the United Nation Forum on Forests (UNFF) was an important milestone to discuss issues of general importance. Forest health was one of the three key issues on the agenda for the 3rd session of UNFF (May 2003). ICP Forests also contributed to this important event.

The mandate of ICP Forests was expanded in 2000 (UNECE, 2000) in order to contribute also to aspects of biodiversity and climate change and the implementation of the Convention of Biological Diversity (CBD) are of importance. The soil data of the programme are expected to be important for the assessment of carbon sinks in the frame of the Kyoto Protocol under the Framework Convention on Climate Change (FCCC).

4. Conclusions

The influences of atmospheric deposition on the environment and on forests have been widely recognized and related monitoring networks have been implemented in North America, East Asia and Europe.

The Acid Deposition Monitoring Network in East Asia (EANET) is comparatively young and therefore only preliminary results are available. In the United States there are several monitoring systems related to different pollutants such as wet and dry deposition and constituents that add to visibility impairment. As legally responsible land manager of wildernesses and other areas the US Forest Service relies on these data for the approval or disapproval of air pollutant emissions permits. Through these permits air quality plays an important role in local and regional developments.
The EU/ICP Forests in Europe is one of the largest biomonitoring networks world-wide. Still concentrating on its main task - monitoring of air pollution effects on forests - ICP Forests has recently widened its objectives and is now in a position to contribute also to other processes in the field of environmental policy. With growing data bases and increasingly complex evaluation methods the need of effective communication structures has been realized. The interpretation and transfer of scientifically sound but complex results into correct messages understandable for non experts is a continuous task not only within the program but in principal for the whole scientific community. Only if this permanent challenge is overcome, EU/ICP Forests and other programs can claim to be cost effective multi-purpose monitoring systems.

5. References

De Vries, W., G.J. Reinds, H. van Dobben, D. de Zwart, D. Aamlid, M Posch, J. Auee, J.C.H. Voogd and E. Vel. Intensive Monitoring of Forest Ecosystems in Europe. Technical Report 2002. UNECE and EC, Geneva and Brussels, 105 pp. http://www.icp-forests.org/RepTecII.htm

Fischer, R., De Vries, W., Barros, M., Van Dobben, H., Dobbertin, M., Gregor, H.-D., Larrson, T.-B., Lorenz, M., Mues, V., Nagel, H.D., Neville, P., Sanchez-Pena, G., De Zwart, D., 2002: The Condition of Forests in Europe. 2002 Executive Report. UNECE and EC, Geneva and Brussels, 35 pp. http://www.icp-forests.org/RepEx.htm

Lorenz, M., Mues, V., Becher, G., Seidling, W., Fischer, R., Langouche, D., Durrant, D., Bartels, U.: Forest Condition in Europe. 2002 Technical Report. UNECE and EC, Geneva and Brussels, 69 pp. http://www.icp-forests.org/RepTecI.htm

Network Center for EANET, 2001: Data Report on the Acid Deposition in the East Asian Region 2000. Internal report

UN/ECE. 2000. Strategy of ICP Forests for the period of 2001-2006. UNECE, Geneva, 19 pp. http://www.icp-forests.org/pdf/strategy.pdf

Figure 1: Data from the IMPROVE visibility network site collected near the Jim Bridger Wilderness Area in Southwestern Wyoming (courtesy of Colorado State University)

Figure 2: Location of NADP monitoring sites and nitrate wet deposition in the United States, 2000

Figure 3: Locations of EANET Sites in 2000

(Note: "Xi'an" includes 3 sites, and "Chongqing", "Xiamen", "Zhuhai" includes 2 sites, respectively. "Jakarta" includes also nearby "Serpong" and "Bandung" sites, and "Bangkok" includes also nearby "Samutprakarn" and "Patumthani" sites. "Metro Manila"/"Los Banos" and "Hanoi"/"Hoa Binh" are described as one point, respectively.)

Figure 4: Top map: average present deposition load of nitrogen (N = NH₄-N plus NO₃-N) Middle map: critical nitrogen loads related to nitrogen concentration in the soil. Bottom map: excess deposition above critical loads. 234 Intensive Monitoring Plots, average 1995-1999.

¹ Chairman, ICP Forests, Federal Ministry of Consumer Protection, Food and Agriculture, Rochusstr.1, D - 53123 Bonn, Germany. [email protected]; Website: www.icp-forests.org

² http://vista.cira.colostate.edu/improve
³ http://nadp.sws.uiuc.edu/
⁴ http://www.epa.gov/castnet/
⁵ http://www.fs.fed.us/biology/
⁶ http://www.fs.fed.us/r6/aq/lichen/
⁷ http://www2.nature.nps.gov/ard/
⁸ http://www.na.fs.fed.us/spfo/fhm/
⁹ http://www.aqd.nps.gov/ard/flagfree/
¹⁰ http://www.adorc.gr.jp