Critical deposition levels for nitrogen and sulphur on dutch forest ecosystems

Abstract

Critical loads for N and S on Dutch forest ecosystems have been derived in relation to effects induced by eutrophication and acidification, such as changes in forest vegetation, nutrient imbalances, increased susceptibility to diseases, nitrate leaching, and Al toxicity. The criteria that have been used are N contents in needles, nitrate concentrations in groundwater (drinking water), and NH4/K ratios, Ca/Al ratios, and Al concentrations in the soil solution. Assuming an equal contribution of N and S, all effects seem to be prevented at a total deposition level below 600 molc ha-1 yr-1 due to N uptake by stemwood and acid neutralization by base cation weathering. The most serious effects will probably be prevented at total deposition levels between 1500 and 2000 molc ha-1 yr-1. The current average deposition in the Netherlands is 4900 molc ha-1 yr-1. © 1988 Kluwer Academic Publishers.