Mycelium Of Mycorrhizal Fungi Research Articles

Mycorrhiza-feeding soil invertebrates in two coniferous forests traced with 13C labelling.

Mycorrhizal fungi represent a potentially abundant carbon resource for soil animals, but their role in soil food webs remains poorly understood. To detect taxa that are trophically linked to the extraradical mycelium of mycorrhizal fungi, we used stable isotope (13C) labelling of whole trees in combination with the in-growth mesh bag technique in two coniferous forests. This allowed us to detect the flux of carbon in the mycelium of mycorrhizal fungi, and consequently in the tissues of soil invertebrates. The mycorrhizal fungal genera constituted 93.5% of reads in mycelium samples from the in-growth mesh bags. All mycelium from in-growth mesh bags and about 32% of the invertebrates sampled (in total 11 taxa) received the 13C label after 45days of exposure. The extent of feeding of soil invertebrates on the mycelium of mycorrhizal fungi depended on the taxonomic affinity of the animals. The strongest trophic link to the mycorrhiza-derived carbon was detected in Isotomidae (Collembola) and Oppiidae (Oribatida). The label was also observed in the generalist predators, indicating the propagation of mycorrhiza-derived carbon into the higher trophic levels of the soil food web. Higher 13C labelling in the tissues of euedaphic Collembola and Oribatida compared to atmobiotic and hemiedaphic families indicates the importance of mycorrhizal fungi as a food resource for invertebrates in deeper soil horizons.

Mycorrhizal fungal mycelium as a global carbon pool

Mycorrhizal fungal mycelium as a global carbon pool

The Contrasting Responses of Mycorrhizal Fungal Mycelium Associated with Woody Plants to Multiple Environmental Factors

Research Highlights: Extraradical mycorrhizal fungal mycelium (MFM) plays critical roles in nutrient absorption and carbon cycling in forest ecosystems. However, it is often ignored or treated as a root uptake apparatus in existing biogeochemical models. Methods: We conducted a meta-analysis to reveal how MFM responds to various, coinciding environmental factors and their interactions. Results: Nitrogen (N) addition and N-phosphorus (P)-potassium (K) combination significantly decreased MFM. However, elevated CO2, organic matter addition, P addition, and CO2-N combination significantly increased MFM. In contrast, warming, K addition, N-P combination, and P-K combination did not affect MFM. Mycorrhizal fungal levels (individual vs. community), mycorrhizal type (ectomycorrhizal fungi vs. arbuscular mycorrhizal fungi), treatment time (<1 year vs. >1 year), and mycelium estimation/sampling method (biomarker vs. non-biomarker; ingrowth mesh bag vs. soil core) significantly affected the responses of MFM to elevated CO2 and N addition. The effect sizes of N addition significantly increased with mean annual precipitation, but decreased with soil pH and host tree age. The effect sizes of P addition significantly increased with N concentration in host plant leaves. Conclusions: The differential responses revealed emphasize the importance of incorporating MFM in existing biogeochemical models to precisely assess and predict the impacts of global changes on forest ecosystem functions.

Carbon use efficiency of mycorrhizal fungal mycelium increases during the growing season but decreases with forest age across a Pinus sylvestris chronosequence

Abstract In boreal forest soils, mycelium of mycorrhizal fungi is pivotal for regulating soil carbon (C) cycling and storage. The carbon use efficiency (CUE), a key parameter in C cycling models, can inform on the partitioning of C between microbial biomass, and potential soil storage, and respiration. Here, we test the dependency of mycorrhizal mycelial CUE on stand age and seasonality in managed boreal forest stands. Based on mycelial production and respiration estimates, derived from sequentially incubated ingrowth mesh bags, we estimated CUE on an ecosystem scale during a seasonal cycle and across a chronosequence of eight, 12‐ to 158‐year‐old, managed Pinus sylvestris forest stands characterized by decreasing pH and nitrogen (N) availability with increasing age. Mycelial respiration was related to total soil respiration, and by using eddy covariance flux measurements, primary production (GPP) was estimated in the 12‐ and 100‐year‐old forests, and related to mycelial respiration and CUE. As hypothesized, mycelial CUE decreased significantly with increasing forest age by c. 65%, supposedly related to a shift in mycorrhizal community composition and a metabolic adjustment reducing their own biomass N demand with declining soil N availability. Furthermore, mycelial CUE increased by a factor of five over the growing season; from 0.03 in May to 0.15 in November, and we propose that the seasonal change in CUE is regulated by a decrease in photosynthate production and temperature. The respiratory contribution of mycorrhizal mycelium ranged from 14% to 26% of total soil respiration, and was on average 17% across all sites and occasions. Synthesis. Carbon is retained more efficiently in mycorrhizal mycelium late in the growing season, when fungi have access to a more balanced C and nutrient supplies. Earlier in the growing season, at maximum host plant photosynthesis, when below‐ground C availability is high in relation to N, the fungi respire excess C resulting in lower mycelial carbon use efficiency (CUE). Additionally, C is retained less efficiently in mycorrhizal fungal biomass in older forest stands characterized by more nutrient depleted soils than younger forest stands.

Lifespan and functionality of mycorrhizal fungal mycelium are uncoupled from host plant lifespan

Arbuscular mycorrhizal fungi (AMF) are obligate symbionts, living in associations with the roots of most land plants. AMF produce wide networks of extraradical mycelium (ERM) of indeterminate length, spreading from host roots into the surrounding soil and establishing belowground interconnections among plants belonging to the same or to different taxa. Whether their lifespan and functionality are limited by host plant viability or can be extended beyond this limit is unknown. To address this issue, we performed time-course studies to investigate viability and functionality of ERM produced in an in vivo whole-plant system by Funneliformis mosseae and Rhizoglomus irregulare, after shoot detachment. Our data revealed that viability and functionality of F. mosseae and R. irregulare extraradical hyphae were uncoupled from host plant lifespan. Indeed, ERM spreading from roots of intact or shootless plants showed comparable levels of viability, similar structural traits and ability to establish mycorrhizal symbioses with new plants, as long as five months after shoot removal. Our findings expand the current knowledge on AMF biology and life cycle, providing data on ERM long-term survival in the soil of two Glomeracean species, functional to the prompt establishment of mycorrhizal symbioses and to the maintenance of soil biological fertility.

Soil biota effects on soil structure: Interactions between arbuscular mycorrhizal fungal mycelium and collembola

Soil aggregation is an important ecosystem process mediated by soil organisms. Collembola and arbuscular mycorrhizal (AM) fungi are major soil biota representing different functional groups, and are known as two key promoters of soil aggregation. Although several studies have experimentally demonstrated that AM fungi and, more recently, collembola affect soil structure, there is no study investigating how both soil organisms affect soil aggregation excluding the influence of plant roots, another important driver of soil aggregation. Considering the importance of AM fungi and collembola in terrestrial ecosystems, here we asked if both organisms have any influence on soil aggregation when roots are not present.In order to examine this question we conducted a completely factorial greenhouse study manipulating the presence of both collembola and AM fungi and excluded the roots of Plantago lanceolata using a 38 μm nylon screen compartment. We quantified soil aggregation as water stable soil aggregates in four size classes in the hyphal compartment and monitored a number of other explanatory variables, including AM (and non-AM) fungal soil hyphal length.The soil in the hyphal compartment showed greater soil aggregation with larger mean weight diameter when collembola were present, and a similar result was found in the presence of AM fungi, compared to control treatments. Moreover, combined presence of both AM fungi and collembola resulted in a non-additive increase of soil aggregation.Our study clearly indicated that collembola can enhance soil aggregation, that they can partially complement effects of AM fungi, and that these effects are independent of roots.