Low impact of stump removal on mycorrhization and growth of replanted picea abies: Data from three types of hemiboreal forest

The objective was to investigate the impact of stump removal from clear-cuts on early mycorrhizal colonisation, seedling growth, and chemical properties of soil and needles of replanted Picea abies. The study included three forest types differing in soil conditions: Hylocomiosa (H), Myrtillo-sphagnosa (MS) and Myrtillosa-mel. (MM) forest types. Soil characteristic for H forest type is well-aerated dry podzol, while MS and MM comprise poorly-aerated gleyic, and respectively, wet and drained (dry) podzols. The clear-cuts were made in winter 2010-2011, stump removal accomplished during late spring – early autumn 2011, and the plantations established in April 2012. Prior to planting, each clear-cut was divided into discrete plots, subjected either to stump removal or, alternatively, to traditional soil preparation by disc trenching. After one growing season (in autumn 2012), seedling mycorrhization, shoot and root morphological parameters (length of the shoot, root collar diameter, mass of new roots), and chemical composition of needles and rhizosphere soil were determined. Seedling mycorrhization, chemical composition of needles and soil did not differ significantly between stump removal and trenching plots in any of the forest types. Also richness of mycorrhizal morphotypes and communities of root inhabiting fungi were similar. Fungi commonly detected in forest nurseries dominated fungal communities in roots, among which Thelephora terrestris was the most abundant composing 55.3 %. In each of the forest types, shoot length, root collar diameter and mass of new roots were either higher on stump removal plots or did not differ significantly. The only exception in this respect was the higher shoot height observed on trenching plots in H forest type. In conclusion, the study demonstrated that after one growing season stump removal has low or no impact on communities of mycorrhizal (and other soil) fungi, and performance of replanted P. abies seedlings on podzols with different mechanical composition, aeration and moisture.