N deposition, balance and benefit in the forest ecosystem of main landscape types of Lithuania

Abstract

Sulphur emissions have declined in Europe by 67% since the early 1980s due to enactment of strict pollution control strategies, whereas nitrogen emissions have remained fairly constant. Consequently, the effect and benefits of nitrogen deposition remain among the most relevant ecological issues. The presented data reveal the trends of nitrate and ammonium concentrations in the air, their wet deposition and concentrations in soil water, ground and runoff water as well as the trends of different components of forest biota in areas where integrated monitoring stations have been operating since 1994. Data on nitrogen concentrations in the soil, ground and surface waters were analysed in relation to air nitrogen concentrations and their deposition. Changes in tree crown defoliation, and abundance, and diversity of the soil micro‐arthropods, stream macro‐invertebrates and small mammals were analysed in relation to concentrations of N compounds in studied substances in an effort to estimate N deposition benefits in forest ecosystems. N balance in areas studied revealed that the amount of nitrogen inflow into the system was very high in comparison with its elimination from the catchments. Approximately 1000 N kg/km² in LT01 and 600 N kg/km² in LT03 are accumulated in the investigated ecosystems per year. But, the relationship between condition of the conifers and air N compounds and their deposition was more significant than between N concentrations in soil and groundwater. N concentration in the studied substances resulted in more significant changes in abundance of soil micro‐arthropods, stream macro‐invertebrates and small mammals than in their diversity.

Keywords:

• N deposition
• Effects on forest ecosystems
• Crown defoliation
• Soil arthropods
• Small mammals
• Stream invertebrates