Sweet chestnut had better resistance to sulphur pollution than other forest species as measured by the adaptability indices (seedling survival and tree increment). Dendrometric parameters showed that chestnut had the best results in the experimental plantation situated on moderate soil texture. In the plantation settled on clay soil, its growth was moderate.
In 1999, the sulphur content of the leaves was high in both plantations for all the forest species, varying from 1329 ppm (Prunus serotina) to 7166 ppm (Betula pendula). The ratios between sulphur and nitrogen, phosphorus, potassium, and calcium, were unbalanced for Quercus rubra, Castanea sativa, Populus tremula, and Robinia pseudacacia. In older natural stands situated in regions without local pollution, the leaf sulphur content was significantly lower (<780 ppm for Fagus sylvatica and Quercus petraea).
The N/S ratio in chestnut leaves was significantly under the Zech toxicity level. The N/S ratio of chestnut was not significantly different from the N/S ratio of the pioneer species (aspen and birch), suggesting a comparable resistance to sulphur.