Sulfur inputs and outputs for two European beech forests growing on different soil substrates

Abstract

Using a flux-balance approach, the S budget of two heavily polluted beech (Fagussylvatica L.) forest ecosystems growing on acid and calcareous soil substrates was investigated. Total S deposition (dry and wet fall) at both sites was large (2.3 and 3.2 kequiv.•ha−1•year−1 at the calcareous and acidic beech forest sites, respectively). The contribution of dry deposition to the total S deposition in both stands was significant; dry deposition of S exceeded the deposition of S even in bulk precipitation. The atmospheric input of S exceeded, at both sites, the forest S requirements by 6–7 times. Consequently, at the acidic beech forest site, phytotoxins like Al3+ (2 kequiv.•ha−1•year−1) were released with seepage water, neutralizing the acid input. At the calcareous beech forest site, leaching of huge amounts of Ca2+ (15 kequiv.•ha−1•year−1) and HCO3− (12 kequiv.•ha−1•year−1) was significant enough to offset the effects of acid precipitation. About 20% of the atmospheric S input in both beech stands accumulated in the vegetation. The S input–output balance in the acidic beech forest indicated a slight tendency towards S accumulation in the soil in the form of AlOHSO4. The S budget in the calcareous beech forest stand was more or less balanced.

Sulphate, Nitrogen and Base Cation Budgets at 21 Forested Catchments in Canada, the United States and Europe

“…In general, net SO 4 export is greatest at sites that currently receive the highest SO 4 deposition and undoubtedly dry deposition accounts for a portion of the apparent excess export. Several studies have shown that dry deposition can account for up to 50% of total SO 4 input to forested catchments (Sah and Meiwes, 1993), and the contribution of dry deposition is generally highest close to emission sources (e.g., Edwards et al, 1999).…”