Regional-Scale Soil Mycobiome woodlands and parks and thinning of forests, but especially for forests the results depended on fungal group and time since partial harvesting. We conclude that the positive effects of tree diversity on overall fungal richness represent a combined niche effect of soil properties and intimate associations.

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Fast-growing tree species will be an important tool in the future production of renewables and in substituting non-renewable fossil energy sources. Sweden, like other countries around the Baltic Sea, has large areas of abandoned farmland usable for biomass production, but knowledge of growth performance of tree species candidates is insufficient. An experiment was initiated where six potentially high-producing tree species were compared. The best available plant material for each species was used on five sites over latitudes 56–64°N in Sweden. Results from the first 8–9 years are reported. Short rotation coppice willow (Salix schwerinii Wolf × S. viminalis L., clone ‘Tora’) had the fastest initial growth and production in southern Sweden. Hybrid aspen (Populus tremula L. × P. tremuloides Michx.) and poplar (Populus spp., section Tacamahaca), grown as short rotation forest, grew well over all sites and showed the highest productivity at the two northern sites. Hybrid larch (Larix ×eurolepis Henry) displayed a high potential at the two most southerly sites, whilst silver birch (Betula pendula Roth) was a medium-producing species at all sites. Norway spruce (Picea abies (L.) Karst.) started slowly, and Siberian larch (L. sukaczewii Dylis) produced poorly at the two northern sites in the initial stage. All tree species followed existing height development curves for the respective species on a high site quality level. Currently, well-growing clones of Populus spp. indicated that a wider selection of tree species can be used at high latitudes under climate change. The study showed a high growth potential for most species on former agricultural lands. However, measures to reduce climate and biological damage must be included in future efforts.

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plantations in Nordic and Baltic countries is estimated to cover ca 9000 ha (Tullus et al. 2015) and most of the plantations are established on the abandoned agricultural lands (Soo et al. 2009a). Studies about the nutritional status of soil in first generation hybrid aspen plantations on former agricultural fields revealed the decrease of soil reaction (pH) but did not show significant depletion of primary macronutrients (N, P, K) and soil organic carbon (Lutter et al. 2016). Forest plantations, especially single-species plantations, have earned a reputation of

Ecosystem biomass, soil conditions and the diversity of different taxa are often interrelated. These relationships could originate from biogeographic affinity (varying species pools) or from direct ecological effects within local communities. Disentangling regional and local causes is challenging as the former might mask the latter in natural ecosystems with varying habitat conditions. However, when the species pool contribution is considered in statistics, local ecological effects might be detected. In this study we disentangle the indirect effects of the species pool and direct ecological effects on the complex relationships among wood volume, soil conditions and diversities of different plant and fungal groups in 100 old‐growth forest sites (10 × 10 m) at the border of boreal and nemoral zones in northern Europe. We recorded all species for different vegetation groups: woody and herbaceous vascular plants, terricolous and epiphytic bryophytes and lichens. Fungal communities were detected by DNA‐based analyses from soil samples. Above‐ground wood volume was used as a proxy of biomass. We measured soil pH and nutrient content and obtained modelled climate parameters for each site. Species pool effect was considered by dividing sites into boreal and nemoral groups based on community composition. In order to disentangle direct and indirect effects, we applied variation partitioning, and raw and partial correlations. We found many significant positive relationships among studied variables. Many of these relationships were associated to boreal and nemoral species pools, thus indicating that biogeographic affinity of interacting plants and fungi largely defines forest diversity and functioning. At the same time, several relationships were significant also after considering biogeography: woody plant and ectomycorrhizal fungi diversities with wood volume, many plant and fungal groups with each other, or with soil conditions. These direct ecological interactions could be considered in forestry practices to achieve both economic gain and maintenance of biodiversity.

Background: Increasing demand for renewable energy resources and the need to mitigate climate change have raised interest in short-rotation forestry with fast-growing deciduous trees like hybrid aspen (Populus tremula L. × P. tremuloides Michx.) in northern Europe. Given that climate warming has already considerably extended the growing season in this region, northward transfer of genotypes could improve forest plantation productivity and enable more efficient mitigation of climate change. We studied the spring and autumn phenology of hybrid aspen genotypes of different geographic origin (European P. tremula parent from 51°to 60°N and North American P. tremuloides parent from 45°to 54°N) 3 and 6 years after planting in a progeny trial established in Estonia at 58°N. Findings: The effect of geographic origin on spring and autumn phenology of hybrid aspen was evident at the age of 3 and 6 years. Geographic origin did not affect spring phenology. However, hybrids with P. tremula parents of northern origin, with bud-burst occurring some days later, were able to unfold and develop full-sized leaves faster than genotypes with early bud-burst. The main differences between different geographic origins appeared in the autumn of year 6, when genotypes of northern origin (60°N) started autumn defoliation significantly earlier than those of southern origin (51°to 57°N). The genotypes of southern origin (55°53′ to 57°31′ N) had a period from bud-burst to defoliation 27 days longer than that of genotypes of northern origin (60°22′ N). The interval between spring and autumn phenological processes showed significant positive correlation with current annual height growth for both study years. Conclusions: Hybrid aspen genotypes from 55°to 57°N responded well to northward transfer, having a longer leafy period and greater height increment than southward transferred genotypes. Northward-transferred genotypes were apparently better adapted to climate-change-induced extension of the growing season at higher latitudes.