Profiling functions of ectomycorrhizal diversity and root structuring in seedlings of Norway spruce (Picea abies) with fast‐ and slow‐growing phenotypes

Abstract

SummaryWe studied the role of taxonomical and functional ectomycorrhizal (ECM) fungal diversity in root formation and nutrient uptake by Norway spruce (Picea abies) seedlings with fast-and slow-growing phenotypes.Seedlings were grown with an increasing ECM fungal diversity gradient from one to four species and sampled before aboveground growth differences between the two phenotypes were apparent. ECM fungal colonization patterns were determined and functional diversity was assayed via measurements of potential enzyme activities of eight exoenzymes probably involved in nutrient mobilization.Phenotypes did not vary in their receptiveness to different ECM fungal species. However, seedlings of slow-growing phenotypes had higher fine-root density and thus more condensed root systems than fast-growing seedlings, but the potential enzyme activities of ectomycorrhizas did not differ qualitatively or quantitatively. ECM species richness increased host nutrient acquisition potential by diversifying the exoenzyme palette. Needle nitrogen content correlated positively with high chitinase activity of ectomycorrhizas.Rather than fast-and slow-growing phenotypes exhibiting differing receptiveness to ECM fungi, our results suggest that distinctions in fine-root structuring and in the belowground growth strategy already apparent at early stages of seedling development may explain later growth differences between fast-and slow-growing families.

Fertility-dependent effects of ectomycorrhizal fungal communities on white spruce seedling nutrition

“…These studies found that both EcMF diversity and sampling/species effects can affect host nutrition and growth, possibly mediated by variation in extracellular enzyme activity (Velmala et al 2014). Studies examining seedling nutritional effects of naturally occurring communities have found effects of location of origin (e.g., Kranabetter 2004), diversity (e.g., Karst et al 2011), and community composition (e.g., Poznanovic et al 2014).…”

“…and T. terrestris abundance on foliar N under low N conditions requires further investigation. T. terrestris has been associated with increased seedling N content, but not concentration in experimental communities (Velmala et al 2014). Its sister taxon, Tomentella sublilacina, was similarly correlated with higher foliar N concentrations in eastern hemlock and yellow birch seedlings growing on coarse woody debris (Poznanovic et al 2014).…”

“…Previous studies of EcMF community effects on seedlings have mostly involved artificially constructed communities used to explore effects of diversity on host function (e.g., Jonsson et al 2001;Baxter and Dighton 2001;Velmala et al 2014). These studies found that both EcMF diversity and sampling/species effects can affect host nutrition and growth, possibly mediated by variation in extracellular enzyme activity (Velmala et al 2014).…”

Short-term impacts of energy wood harvesting on ectomycorrhizal fungal communities of Norway spruce saplings

“…In the reference forests with intact organic layer, EMF communities of sapling roots were significantly more diverse and even, consisting of typical coniferous forest symbiont species, such as Piloderma, Cortinarius and Russula (Hansen and Knudsen, 1992), which are suggested to mobilize organically bound nutrients from soil humus (Buée et al, 2007;Bö deker et al, 2014;Velmala et al, 2014). In the intact forest soil, trees and saplings are typically connected by a shared EMF mycelial network (Simard et al, 2012).…”

“…Thus, maintaining high EMF diversity in roots has been shown to have an impact on the host tree productivity in the field (Korkama et al, 2006;Saravesi et al, 2011). In more controlled laboratory conditions, tree seedling growth increased with higher number of EMF associated with their roots, but the effect was dependent on tree species and nutrient status in the soil (Jonsson et al, 2001), as well as on functional complementarity of the EMF community (Velmala et al, 2014).…”