PROJECT DESCRIPTION
BACKGROUND
Acidification of soil and water is considered to be one of the most serious environmental problems in northern Europe. For this reason, reducing emissions of acidifying compounds in Europe has been given priority especially during the last decades. However, progress has not been fast enough even though large scale-liming operations have been carried out in Sweden and other countries to prevent acidification effects in forest and water ecosystems. Existing forest soil liming and freshwater liming methods, however, often have contradictory impacts. Before this project, other liming projects were carried out with a single goal: to improve either water or soil conditions. The objective of this project is develop and demonstrate an integrated liming method in order to accelerate the recovery of both soil and water through a broader vision of the problem.
OBJECTIVES
The objective of the project was to develop and demonstrate an integrated strategy of liming catchments to prevent acidification impacts on forest soil and freshwater ecosystems. The demonstration area was situated 20 km north of the city of Halmstad in the country of Halland, Sweden and was implemented in two small forest catchment areas. One of the plots was treated as a reference area. Whilst, within the treated drainage basin, another three sub drainage areas acted as reference areas. The treatment involved the application of six tons per ha of a mix of granulated limestone (2/3) and wood ash (1/3) and included all soil and vegetation types expect bogs and solid rock. The liming of of the forest recharge area was expected to restore the nutrient supply in the soil and reduce the hydrogen ion and aluminium leaching, while a liming of the discharge area should produce durable neutralising effects in runoff water. The use of wood ash was expected to reduce the risk of nutrient deficiency in acidified soils. Monitoring of water chemistry, forest vegetation and freshwater fauna was intended to demonstrate and verify the effects of the method. As a result, the project expected to assess application prerequisites and the biological and economical advantages of the method . Foreseen results from the project were guidelines for integrated liming measures and integrated liming strategy with a whole-catchment approach that could combine the advantages of forest soil and wetland liming methods.
RESULTS
The project does not present quantified environmental benefits from integrated liming operations. The qualitative environmental benefits, however, are clearly evident. The liming operations carried out in the pilot areas had an immediate effect on water chemistry (pH and aluminium content in runoff water) and fish fauna as well as a gradual recovery of bottom fauna. The project results also have a clear relevance on European level. Acidification is mostly a result of airborne pollution from mainly sulphurous substances emanating from the burning of fossil fuels. Acid rain knows no boundaries and mitigating its effect should quite appropriately be considered jointly by producing and recipient countries. Translating the results of this project into action must take into account differences in acidification impact, soil conditions, vegetation and climate. The design of programmes of integrated strategic liming programmes is therefore primarily a concern for national, regional and local players in the forestry sector. The Swedish National Board of Forestry appears to have some trust in the beneficial and sustainable effects of forest liming, since the Board has decided that a strategic forest liming programme will be initiated in the most acidified areas in Southwest Sweden after a further period of preparation. The project has met its objectives and has successfully demonstrated how to implement an integrated liming strategy on a whole-catchment basis. The demonstrated method is practically replicable, and initial results show that integrated liming has a rather immediate effect on the quality of runoff water from the treated catchments. Specific outputs of the project are as follows: Water chemistry The effects on water chemistry have corresponded well with expectations. The pHvalue rose rapidly after the final spreading in the spring of 1999. The same rapid and clear effect was found for concentrations of calcium. Inorganic aluminium showed a massive reduction immediately following the treatment. Vegetation Where the normal dose has been spread, no particular negative effects on mineral soil vegetation were noted. In some discharge areas a certain shift between species has occurred which may be considered foremost as an effect of the ashes applied. In discharge areas where the lime applications were increased there have been distinct negative effects, mainly among certain Sphagnum species. Bottom fauna The bottom fauna has not revealed any particular changes. Nor was this expected with regard to the ecological factors governing the spreading. However, the results from the last sampling showed a certain increase in the number of species as well as in the total number of individuals in the treated stream, whereas no changes could be detected in the fauna of the reference stream. Fish fauna One of the most positive and distinct ecological effects of the treatment was the return of the salmon trout. Local residents stated that there had not been trout in the stream for the last 40-50 years. During the autumn of the year of the treatment, breeding salmon trout were observed. In the following autumn, breeding again took place. Fry from the previous year were also caught. In November 1998 project management staff arranged a press conference in connection with the project area. The project was thoroughly presented and the liming procedure by helicopter was demonstrated. On this occasion landowners got the opportunity to give their positive attitude to the project. The conference were attended by representatives from two television companies, one radio station and journalists from several newspapers.