Effect of seedling production method on the growth of Pinus sylvestris L. on reclaimed post-industrial sites in Poland

Selection of tree species and proper technology of afforestation of post-industrial sites play a crucial role in new ecosystem stability and success of the restoration. There is still current discussion about the effectiveness of different methods in the production of seedlings for extreme site conditions. This study aimed to analyze the effect of the seedling production method on the growth of 6-year-old Scots pine (Pinus sylvestris L.) trees planted on reclaimed post-industrial sites in southern Poland. We compared four methods of seedling production: bare root system, containerized without and with inoculation of ectomycorrhizal fungi Laccaria bicolor (Maire) P.D. Orton, and Hebeloma crustuliniforme (Bull.) Quél. The experiment was carried out independently on two reclaimed sites: a post-sand-mining site in Bukowno, and a heavy metal polluted site in Miasteczko Śląskie. The effect of the seedling production method on tree growth expressed by height, root collar diameter, above- and belowground biomass of different tree components was analyzed on 240 sampled trees using analysis of variance and general linear model. In addition, the effect of the seedling production method on the root-to-shoot ratio was investigated. Scots pine tree growth was significantly affected by the seedling production method on heavy metal polluted site. The lowest tree growth parameters were observed in trees planted with bare roots, whereas the largest values were in the case of trees planted from containerized seedlings inoculated with H. crustuliniforme. In contrast, on the post-sand-mining site, the treatment effect turned out to be insignificant. The effect on biomass allocation was observed in the case of both sites. Trees prepared with the bare root method differed in greater biomass allocation to the belowground from other treatment groups. The use of containerized seedlings or additionally inoculated with ectomycorrhizal fungi in heavy metal contaminated sites improves the growth of trees and, although it is more costly and labor-intensive compared to the production of seedlings with a bare root system, should be preferred. In the post-sand-mining area, no effect of the seedling production method on tree growth was observed, and the use of bare root seedlings will be equally effective and additionally less time and cost-consuming.