Recovery of Acidified Streams in Forests Treated by Total Catchment Liming

Abstract

Reduced emissions of acidifying pollutants have changed the acidification process, and as a result, forest soils and surface waters are slowly recovering in Sweden. However, model calculations show that some areas may never recover completely unless further measures, such as liming, are undertaken. Liming of surface waters (lakes, rivers and wetlands) has been successfully practised in Sweden since the 1970s, but repeated treatments are necessary. A full recovery of acidified lakes and streams without frequent liming is however not possible until soil acidification is reversed in the most strongly affected areas. In this study, the recovery of acidified streams was examined using 'the total catchment approach' i.e. treatment of both recharge and discharge areas. The aim was to compare the quantitative effect of different treatments on run off chemistry and the recovery of brown trout. Catchments in southwest Sweden were treated with a combination of 2 tons of wood ash and 4, 6 or 12 tons of crushed limestone per hectare in 1998/1999. Treatment of both recharge and discharge areas resulted in fast and significant changes in stream water quality, e.g. increased concentrations of calcium, higher pH and ANC and a decreased concentration of inorganic aluminium. The initial changes were dependent on the distribution of the applied lime between discharge and recharge areas rather than the average dose on the total catchment. Treatment of recharge areas only, resulted in smaller but still significant effects on calcium, pH and ANC in stream water. Furthermore, there was an initial leaching of nitrate but it was only minor compared with the elevated leaching that occurs after a clear-cut. As a result of the treatments, brown trout is now successfully reproducing.

Wood ash as a soil amendment in Canadian forests: what are the barriers to utilization?

“…According to a recent metaanalysis (of predominantly European and North American studies), biomass harvesting can lower the pH and base saturation of surface soils and reduce concentrations of foliar calcium in the regenerating stand, but only when foliage is removed along with tree stems and branches (Achat et al 2015). Research has shown that applications of wood ash can be used to increase soil pH and base saturation, thereby increasing surface water pH, which, in turn, may facilitate the ecological recovery of surface waters (Westling and Zetterberg 2007;Johansson 2014;Huotari et al 2015).…”

Magnesium Isotope Variations to Trace Liming Input to Terrestrial Ecosystems: A Case Study in the Vosges Mountains

“…Liming generally improves the forest nutrition in Ca and Mg (Bonneau et al, 1992;Huettl and Zoettl, 1993) by (i) delivering plant-available Ca and Mg (Wilmot et al, 1996;Moore et al, 2000;Bridgham and Richardson, 2003), and/or (ii) because liming improves humus mineralization (Bridgham and Richardson, 2003;Piatek et al, 2009), which increases the nutrient concentration of soil solution, and/or (iii) because liming raises pH and base saturation and decreases Al toxicity to roots (Cronan et al, 1989;De Wit et al, 2010). The rate and depth of Ca and Mg penetration in soil depends on lime solubility (Hindar, 2005;Westling and Zetterberg, 2007), on climate, and on physical, chemical, and biological soil properties, which are in turn influenced by liming. At the catchment level, the effects of liming on stream water chemistry vary with the proportion of catchment limed (Dalziel et al, 1994;Hindar et al, 2003), soil acidity and buffering capacity (Hindar, 2005;Lofgren et al, 2009), and catchment hydrology (Brahmer, 1994).…”