Input-Output Budgets of Nutrients in Adjacent Norway Spruce and European Beech Monocultures Recovering from Acidification

Abstract

Soil acidification has constituted an important ecological threat to forests in Central Europe since the 1950s. In areas that are sensitive to acid pollution, where the soil buffering capacity is naturally low, tree species can significantly modulate the extent of soil acidification by affecting throughfall deposition and the composition of litter. A principal difference can be expected between coniferous and broadleaf tree species. The aim of our study was to compare long-term trends in element cycling in two stands representing the main types of forest ecosystem in the region (Picea abies vs. Fagus sylvatica). In the period of 2005–2017, we continually measured element concentrations and fluxes in bulk precipitation, throughfall precipitation, and soil leachates. A continuous decline of acid deposition was detected in both bulk precipitation and throughfall. Declining deposition of S and N in both forests has led to the recovery of soil solution chemistry in the mineral soil, manifested by rising pH from 4.25 to 4.47 under spruce and from 4.42 to 4.69 in the beech stand. However, soil water in the spruce stand was more acidic, with higher concentrations of SO42− and Al when compared to the beech stand. While the acidity of soil leachates from organic horizons was driven mainly by organic anions, in lower mineral horizons it was controlled by inorganic acid anions. NO3− concentrations in deeper horizons of the spruce stand have diminished since 2006; however, in the beech plot, episodically elevated NO3− concentrations in mineral horizons are a sign of seasonal processes and of nearby perturbations. Higher output of S when compared to the input of the same element indicates slow S resorption, delaying the recovery of soil chemistry. Our results indicate that, although forest ecosystems are recovering from acidification, soil S retention and the ability to immobilize N is affected by the dominant tree species.

Effects of Moderate Nitrate and Low Sulphate Depositions on the Status of Soil Base Cation Pools and Recent Mineral Soil Acidification at Forest Conversion Sites with European Beech (“Green Eyes”) Embedded in Norway Spruce and Scots Pine Stands

“…Besides NO 3 − , SO 4 2− function as a counter ion for base cations in soil solution and can contribute to strong mineral soil base cation losses [10,20,21]. In some European and North American forested catchments, SO 4 2− accounts even for 68-100% of the acid leaching from forest soils [118].…”

“…Although S depositions decreased strongly over the last decades, even today their legacies are found accumulated in the mineral soil as SO4 2− , predominantly specific adsorbed to iron (Fe) and aluminum (Al) sesquioxides [19]. The desorption and the release of SO4 2− into soil solution is held responsible for mineral soil base cation leaching losses with seepage water [10,[20][21][22], which might decrease pH at deeper mineral soil layers and delay a recovery from formerly induced soil acidification through air pollutants, especially of acidic soils [23]. Although S depositions decreased strongly over the last decades, even today their legacies are found accumulated in the mineral soil as SO 4 2− , predominantly specific adsorbed to iron (Fe) and aluminum (Al) sesquioxides [19].…”

Foliage Biophysical Trait Prediction from Laboratory Spectra in Norway Spruce Is More Affected by Needle Age Than by Site Soil Conditions

“…The concentrations of the main 1980s pollutant, sulphur dioxide, have decreased considerably since the 1990s [15]; the atmospheric acid deposition was reduced and led to the recovery of stream water chemistry at small forested catchments [16]. Although there are apparent signs of ongoing soil recovery (e.g., increasing pH), other parameters (low base cation to aluminum ratios) still indicate unfavorable conditions in the spruce rooting zone [17,18]. The GEOMON network provides a rich variety of data sources related to ecosystem functioning, focusing mainly on soil-stream water chemistry [16,19,20], but recently also supporting the development of remote sensing solutions for forest recovery and biomass mapping [21,22].…”

The legacy of acidic deposition controls soil organic carbon pools in temperate forests across the Czech Republic

“…All these factors, together with organic acids developed through decomposition processes in the forest floor, lead to soil podzolization, with the destruction of clay minerals and translocation of iron and aluminium organic complexes (Lundström, Van Breemen, & Bain, 2000;Sauer et al, 2007), which then leach downward through the soil profile and precipitate in the spodic B horizons. Coniferous forests have been shown to speed up forest soil acidification compared to broadleaved forests because conifers have higher interception of dry deposition (i.e., are able to more efficiently scavenge atmospheric compounds such as SO 4 2− , which are then rinsed to the soil during subsequent rainfall) (Oulehle & Hruška, 2005), and spruce litter leaches more organic acids compared to beech (Augusto, Ranger, Binkley, & Rothe, 2002;Ružek, Myška, Kučera, & Oulehle, 2019). The proportion of acid soils such as dystric Cambisols and Podzols increased with elevation in our study, but as the clay content decreased, the SOC pool increased.…”