Selected problems of sustainable management of rusty soils in forestry

Since the end of the 18th century Scots pine (Pinus sylvestris) monocultures have been artificially introduced in extensive areas of rusty soils in Central Europe. Such forest management practice has involved, however, several serious problems, like e.g. soil degradation implying the decrease in productivity of forest sites, and the clear increase in the risk of disturbances (pest gradations, fires, wind damages etc.) occurrence. Those troubles have involved the increasing discussion on rational forest management on sandy soils, which are predominant in lowland woodlands of Central Europe. Thus, in this paper we aimed to indicate selected problems of sustainable management of rusty soils in forestry with regard to lowland forests found in the region. The special focus was paid on controversies being related to conversion of pine stands overgrowing these soils, because of its especially high importance for forest management in Central Europe. We postulate that we should intensify the conversion of pure pine stands overgrowing rusty soils into mixed forests, which would reduce the risk of the assumed, and being involved with the ongoing climate changes, problems with the stability of pine forests in Central Europe. The study shows that the current methodology of forest site types diagnosis used in Poland may lead to underestimation of the types, and consequently it consolidates the focus of Polish forestry on breeding pine stands on rusty soils. Following the existing controversies regarding the diagnosis of a forest site type on rusty soils, we postulate that we should more broadly underplant pine stands overgrowing the soils with deciduous trees, regardless of the diagnosed forest site type in forest inventory works. In turn, in conversions executed in maturing conifer stands using a gap cutting, the emphasis should be put on plant diversity. Namely, we highlight in the paper that in the gaps, besides major deciduous species (usually oak and/or beech), the admixture of ameliorative trees should obligatory be introduced (e.g. European hornbeam, Carpinus betulus), which happens to be ignored in practice. We postulate also that logging residues removal, which is still executed in some forest districts in Poland, should be skipped. This practice is especially irrational when it is done in sites dedicated for stand conversion, because it highly increases the risk of mortality and/or of the distinct decrease in growth dynamics of young hardwoods introduced in post-pine sites.