Summary of the International Meeting on Restoration of Forest Soils in Polluted Areas Organised

International conference

RESTORATION OF FOREST SOILS IN POLLUTED AREAS

26 – 28 May, 2004

Prague, Czech Republic

Summary of the International Meeting

Pollution of forest soils through human activities in central and western Europe has a long history but has undergone changes during the last few decades. Previously pollution occurred on specific areas affected mainly by the mining activities which became non-specific type due to long-range transport of pollutants affecting large land areas. During the last 10 years the nature and level of pollution has changed due to special measures taken by the industry to decrease mostly air pollutants. These measures have resulted in reduced acidity inputs. In addition special efforts have been made to compensate for the acidity inputs to soils by the application of liming materials. Despite these measures, restoration of already polluted (acidified) soils has been slow. This meeting had the following objectives: 1. To provide the present state of emission inputs to forest soils, especially in different parts of Europe. 2. To describe and assess the success of various ameliorative measures so far undertaken. 3. To include information from long-term experiments on liming materials and fertilizer additions. 4. To provide a report with recommendations for future activities including policy matters. In order to accomplish the above objectives five plenary sessions were held, each one of that included one key note address and additional presentations in oral and poster form. The sessions included: (a) Soil acidification – where the status and present situation of soil acidification in Europe and U.S.A. were presented. (b) Liming as ameliorative measure – the results from long-term liming experiments indicating their success and limitations were presented. (c) Fertilization to improve nutrition – amelioration of soils through fertilization practices and their long-term effects were considered. (d) Other measures of amelioration – discussion included the use of other materials including wood ash and other management practices. (e) Biological measures of soil amelioration – where the role of trees, microbial and faunal activities was the subject of discussion. In addition to the above presentations, a whole day scientific excursion to the Ore Mountains provided a useful opportunity to discuss the problems of soil pollution and the ameliorative methods which were undertaken to establish the forest stands in the Litvinov forest district. Scientists from most of the European countries and also from USA participated in the meeting. At the concluding session an open discussion was conducted under the following headings: I. Present status of soil acidification in EUROPE and USA and how far it is still a problem in relation to environmental issues and economic losses. II. What are the possibilities of countermeasures in forestry and other land uses, and neighbouring ecosystems? III. Recommendations for – future issues of research pertaining to science, forest management, and for policy and decision makers.

Details of the observations and remarks made are given below:

Re. I. Present Status of Soil Acidification

1. In general the atmospheric inputs of SO2 to forest ecosystems have decreased during the last decade, but the inputs of NOx and NHx have not changed. This poses two future issues – (a) to advise decision makers to develop policies to reduce N emissions, and (b) to develop forest management strategies where for a long-term these high N inputs would continue (especially under conditions of low inputs of S and salt).

2. Despite the decrease in atmospheric inputs of acid (together with SO2), the impacts of acid inputs causing acidification of soil (and high heavy metal inputs) will stay for a long time in future. The threat of high acidity in soils on functioning of soil processes remains. This warrants special measures of ameliorating soils by addition of lime or alternative liming materials. 3. There are major regional differences in the atmospheric inputs of pollutants (the so called ‘hot spots’ compared to areas of usual inputs). Many factors including the level of emissions, type and density of vegetation, climatic conditions, exposition, altitude etc. interact to determine the amount of inputs. Due to differences in the management practices it is important to distinguish ‘hot spot’ areas from others on a regional scale. 4. In addition to the spatial differences in the inputs of pollutants, there are additional factors requiring site specific management practices due to differences in tree species, tree mixtures, undergrowth, stand age, and stand density, 5. Major research efforts have been made into the areas of pollution inputs, their effects on soil and ecosystem processes and the methods to counteract the deteriorating effects, especially the role of ameliorative measures. The research so far conducted has shown that: a) Tree growth and nutrition (measured as nutrient levels in leaves, or nutrient turnover rates) have been affected by pollutant inputs. N inputs have probably removed N as limiting growth factor and have enhanced the growth of many tree species but that has caused other nutrients (Mg, P, K, Ca) to become sub-optimal. b) Intensity and depth of tree roots has been affected by high input of pollutants leading to stand instability against diseases and windthrow. c) Leaching of dissolved organic C, nitrates and the associated cations have increased, causing deterioration in chemical and biological soil processes and also affecting quality of leached water. d) Quality of ground water and river water has been affected by processes related to pollutant inputs. e) Health and stocks of fish in lakes and rivers have been affected by the deterioration in the quality of water. f) Content and form of soil organic matter and biodiversity of ground vegetation and soil components have been affected by pollutants. g) Decline in soil aggregate structure has been observed in some instances, affecting water percolation, surface water flow and preferential flow pathways. 6. The above mentioned deteriorating effects of pollutant inputs to various ecosystems have a number of consequences relating to their functioning and may lead to following economic losses: - Reduction of tree growth at a regional level, due to reduced health, dieback, and hazards to windthrow will cause economic losses. - Reduced level of stable forest ecosystems would need additional funds to gain degree of sustainability especially for landscape stability (landslide and erosion control). - Increased risk of greenhouse gas emissions, requiring funds to develop measures to counteract the emission levels. - Overall increase in forest management costs relating to high pollutant inputs. - Costs involved in amelioration of soils, ground water, and river water quality. - Costs involved in establishing aquatic biota as ameliorative measures. - Increased level of dangers of floods and their consequences on the economics of a region. - Additional financial efforts as required to offset decline in landscape values for recreation e.g., hunting and fishing, and tourist purposes.

Re. II. Possible Countermeasures A number of countermeasures to offset the effects of pollutant inputs to forest ecosystems and to improve the health, productivity and stability of forest ecosystems were discussed at the meeting. It was observed that there are both benefits and problems associated with any countermeasure and appropriate importance or significance should be given to each measure. Some of the important outcomes are given below: (a) Plant succession – in some of the polluted areas measures to promote appropriate species following succession patterns may be a useful method to restore ecosystems. However, to achieve functional efficiency and stability of forest ecosystems additional measures, alone or in combination, may be required. (b) Liming and fertilization – alone or in combination, are required to compensate for the losses of proton buffering and nutrients due to pollutant inputs. In some areas where trees of high quality wood are produced additional measures may be needed to ameliorate the deep soil acidity. (c) Soil cultivation is an essential component of soil amelioration, especially when deep soil placement of liming material is warranted. Soil cultivation is also important on some sites to obtain better regeneration of tree and understorey species. (d) Depending on the level and nature of pollution selection of species is an important parameter to establish and restore site specific forest ecosystems. For example, there may be a need to increase the components of broadleaves at the site specific and regional levels, either alone or in combination with other species forming mixtures. In addition, a change of stand density may form an important practice in the site amelioration process. (e) Combination of countermeasures – In many cases single counter-measures may not be possible in practice or economically efficient to ameliorate a site, but may need of a number of them in combination.

Re. III. Recommendations It was realised that the recommendations must be directed to various groups due to differences in their need and usefulness. Three groups were outlined – future science issues, future forest management issues and future policy measures.

1. Future Science Issues: They include additional studies on: (a) Additional research efforts are needed to describe the effects of ameliorative measures on soil morphological parameters, soil structure changes, and water flow pathways. (b) Effects of ameliorative measures on the biological processes are not properly understood, especially in terms of the long-term effects, microbial population changes and biodiversity effects. Additional research efforts are required which may even include the use of techniques involving molecular genetical markers. (c) There had been insufficient study of assessing the ameliorative measures at the landscape level e.g., the catchment studies. Data from many catchment studies have not been properly evaluated. Additional measures are required to develop catchment models to evaluate the already available data and for any studies which may be established in future. (d) The multiphased and multicomponent effects of any ameliorative measure on forest ecosystem need collaborative efforts of a number of scientific disciplines. Special research efforts are required in future to develop such teams to study the effects of pollution and of ameliorative measures. 2. Future Forestry Issues Forest management aims to achieve the site specific tree growth with optimum nutrition and health state, and minimum harm to the neighbouring ecosystems through any measures undertaken. There are many issues outlined below which would require attention in future: (a) Future strategies would need site specific measures in terms of their management under high inputs of pollutants (‘hot spots’) or under usual atmospheric inputs of N which are expected to continue for a long time. Such measures should be considered in terms of their effects at the landscape level. (b) Future management should provide detailed instructions for the ameliorative measures, including their effectiveness, cost and limitations.

3. Future Policy Issues There are a number of policy related issues concerning ongoing pollutant inputs to forest areas and their effects on various ecosystems which decision makers need to consider in future. Some of these issues are given below: (a) Value of wood production as renewable source (also for energy production) needs appropriate recognition in the existing and future economic frame work, which may involve additional resource allocation for future forest management and for research and development work. (b) For achieving sustainable forest ecosystems and an optimum productivity level, additional efforts are required to ameliorate soils (restore to its pre-industrial initial state), which would mean making available additional resources. (c) One of the most important environmental issues of the future is the availability of good quality water, most of which has its direct or indirect source in forest land. Quality of water from underground, rivers and lakes affect directly the survival and growth of aquatic biota. Policy measures directed at maintaining the water quality through forest management should be taken to provide appropriate frame work for future development. (d) Maintaining biodiversity is the other important social need which requires appropriate measures of short term and long term nature under continuing high atmospheric inputs of certain elements which pose threats to biodiversity in forests, soils and water. (e) Demands by Kyoto protocol to reduce GHG emissions would need policy decisions relating to the use of forest products as renewal resource for alternative energy production and for using ameliorative measures to improve C-sequestration in forests and forest soils and to decrease direct and indirect emissions of GHG. We, representing many research institutions of central and western Europe (list of participants is attached) participated in the International conference on ‘Restoration of Forest Soils in Polluted Areas’ organised at Prague, Czech Republic, 25-29 May, 2004, present the following jointly agreed resolution:  There has been major decrease in the atmospheric depositions of acidifying and toxic elements on forest land in recent years. Despite this decrease there are major areas where depositions exceed the total critical loads for many areas, especially so on the so called ‘hot spots’, needing further measures to decrease emissions, especially of nitrogen compounds.  Areas with ‘hot spots’ may continue to need application of liming materials to compensate for the atmospheric depositions of acidity.  Despite the general decrease in atmospheric depositions, recovery of already affected functions and properties of soils to pre-high-deposition state would need further soil management under forests with suitable measures (liming and fertilization).  There are many forest areas where regularly or periodically the deficiencies of Mg and K are observed, which would need further site specific treatments to sustain and improve forest health and growth.  We recommend that suitable policies with appropriate law enforcement and financial support to encourage research and development be undertaken to sustain the following: a) Forest health b) Forest nutrition and nutrient cycling c) Quality and quantity of underground water d) Biodiversity e) Recreation f) C-sequestration following Kyoto protocol Details on each of these are provided in the attached document.