Arbuscular mycorrhizal fungal phylogeny-related interactions with a non-host

Arbuscular mycorrhizal fungi (AMF) form symbiotic relationships with most vascular plants including some gymnosperm species. Although species in the gymnosperm family Pinaceae normally develop ectomycorrhizal associations, AMF hyphae and vesicles, typical of members of the Suborder Glomineae, have been reported in the roots of some Pinaceae species. However, it is not known whether AMF belonging to various species and suborders are able to colonize roots of Pinaceae species and to what extent this influences the performance of Pinaceae seedlings. We tested in each of the Glomaceae, Acaulosporaceae and Gigasporineae AMF families two species for their ability to colonize and affect the growth of Pinus strobus (eastern white pine) in the presence or absence of an AMF host plant (Trifolium pretense—red clover). Glomus intraradices was the only AMF that colonized pine roots, predominantly in the presence of clover, forming intracellular hyphae and vesicles but not arbuscules. Colonization, however, did not relate to increased pine biomass and the overall presence of AMF, regardless of colonization abilities, resulted in a biomass reduction. This effect on pine seedling biomass was explained by the AMF family to which the AMF belonged, indicating that the effects of AMF on the non-host pine may be related to phylogeny. Acaulosporaceae species reduced pine biomass the most whereas, Gigasporineae species had the smallest effect on biomass. These preliminary results suggest that AMF may affect the soil microflora differently among AMF families in previously unsuspected ways with potential consequences for non-AMF host growt

Dschungel unter den Füßen Unterirdisches Leben bestimmt das Funktionieren von Agrarökosystemen

This work demonstrates that soil biodiversity plays an important role in agroecosystems. The presence of an enriched soil community in large outdoor lysimeters enhanced plant yield and reduced nutrient leaching losses. Moreover, soil biodiversity loss and simplification of soil communities reduced ecosystem multifunctionality. Further analysis revealed that promotion of soil biodiversity and soil ecological engineering can help to reduce the reliance on external inputs and is especially suitable for a transition to organic agriculture. This work points to the need to support soil life for a sustainable agriculture

Bedeutung von Mykorrhiza-Pilzen für Rotklee-Gras-Mischungen

Grass-clover pastures form an essential part of organic farming systems. It is well known that nitrogen fixing bacteria play a key role in determining productivity of grass-clover pastures. Yet, the impact of other plant symbionts, such as arbuscular mycorrhizal (AM) fungi, on grass-clover is still poorly understood. Here we demonstrate that AM fungi enhanced red clover biomass and enabled red clover to coexist with grass. Moreover, the diversity of AM fungi in the soil promoted productivity of grass-clover mixtures. Inoculation experiments in a range of field soils with native AM fungi showed that addition of AM fungi promoted clover biomass in several (but not all) soils. This study shows that AM fungi can be important for clover establishment in pastures

Pitfall trap sampling bias depends on body mass, temperature, and trap number: insights from an individual-based model

The diversity and community composition of ground arthropods is routinely analyzed by pitfall trap sampling, which is a cost- and time-effective method to gather large numbers of replicates but also known to generate data that are biased by species-specific differences in locomotory activity. Previous studies have looked at factors that influence the sampling bias. These studies, however, were limited to one or few species and did rarely quantify how the species-specific sampling bias shapes community-level diversity metrics. In this study, we systematically quantify the species-specific and community-level sampling bias with an allometric individual-based model that simulates movement and pitfall sampling of 10 generic ground arthropod species differing in body mass. We perform multiple simulation experiments covering different scenarios of pitfall trap number, spatial trap arrangement, temperature, and population density. We show that the sampling bias decreased strongly with increasing body mass, temperature, and pitfall trap number, while population density had no effect and trap arrangement only had little effect. The average movement speed of a species in the field integrates body mass and temperature effects and could be used to derive reliable estimates of absolute species abundance. We demonstrate how unbiased relative species abundance can be derived using correction factors that need only information on species body mass. We find that community-level diversity metrics are sensitive to the particular community structure, namely the relation between body mass and relative abundance across species. Generally, pitfall trap sampling flattens the rank-abundance distribution and leads to overestimations of ground arthropod Shannon diversity. We conclude that the correction of the species-specific pitfall trap sampling bias is necessary for the reliability of conclusions drawn from ground arthropod field studies. We propose bias correction is a manageable task using either body mass to derive unbiased relative abundance or the average speed to derive reliable estimates of absolute abundance from pitfall trap sampling

Within-species trade-offs in plant-stimulated soil enzyme activity and growth, flowering, and seed size

Soil microbial communities affect species demographic rates of plants. In turn, plants influence the composition and function of the soil microbiome, potentially resulting in beneficial feedbacks that alter their fitness and establishment. For example, differences in the ability to stimulate soil enzyme activity among plant lineages may affect plant growth and reproduction. We used a common garden study to test differences in plant-stimulated soil enzyme activity between lineages of the same species across developmental stages. Lineages employed different strategies whereby growth, days to flowering and seed size traded-off with plant-stimulated soil enzyme activity. Specifically, the smaller seeded lineage stimulated more enzyme activity at the early stage of development and flowered earlier while the larger seeded lineage sustained lower but consistent enzyme activity through development. We suggest that these lineages, which are both successful invaders, employ distinct strategies (a colonizer and a competitor) and differ in their influence on soil microbial activity. Synthesis. The ability to influence the soil microbial community by plants may be an important trait that trades off with growth, flowering, and seed size for promoting plant establishment, reproduction, and invasion

Drought-exposure history increases complementarity between plant species in response to a subsequent drought

Growing threats from extreme climatic events and biodiversity loss have raised concerns about their interactive consequences for ecosystem functioning. Evidence suggests biodiversity can buffer ecosystem functioning during such climatic events. However, whether exposure to extreme climatic events will strengthen the biodiversity-dependent buffering effects for future generations remains elusive. We assess such transgenerational effects by exposing experimental grassland communities to eight recurrent summer droughts versus ambient conditions in the field. Seed offspring of 12 species are then subjected to a subsequent drought event in the glasshouse, grown individually, in monocultures or in 2-species mixtures. Comparing productivity between mixtures and monocultures, drought-selected plants show greater between-species complementarity than ambient-selected plants when recovering from the subsequent drought, causing stronger biodiversity effects on productivity and better recovery of drought-selected mixtures after the drought. These findings suggest exposure to recurrent climatic events can improve ecosystem responses to future events through transgenerational reinforcement of species complementarity

Linking diversity, synchrony and stability in soil microbial communities

1. It is becoming well established that plant diversity is instrumental in stabilizing the temporal functioning of ecosystems through population dynamics and the so-called insurance or portfolio effect. However, it is unclear whether diversity-stability relationships and the role of population dynamics in soil microbial communities parallel those in plant communities. 2. Our study took place in a long-term land management experiment with and without perturbation to the soil ecosystem by tilling. We assessed the impacts of the soil perturbation on the diversity, synchrony and stability relationships in soil fungal and bacterial communities. 3. We found that the perturbation to the soil ecosystem not only reduced the abundance and richness of the fungal community, but it also reduced the temporal stability in both bacterial and fungal abundance. The fungal community abundance was destabilized by soil tilling due to reduced richness and increased temporal variation of individual taxa. In contrast, soil tilling destabilized the bacterial community abundance by reducing the temporal variation of individual taxa. Both bacterial and fungal community abundances were more temporally variable when taxa fluctuated more synchronously through time. 4. Our results show that land management practices, such as tilling, can destabilize soil microbial abundance by reducing the richness and disrupting the temporal dynamics belowground. However, the differences in the mechanisms that underlie the temporal variations in fungal and bacterial net abundances suggests that the mechanisms that drive the stability can differ among guilds of organisms within the same system. The different temporal responses between the fungal and bacterial communities are likely linked to changes in edaphic properties resulting from the physical alteration of the soil structure

Synergism between production and soil health through crop diversification, organic amendments and crop protection in wheat-based systems

One of the critical challenges in agriculture is enhancing yield without compromising its foundation, a healthy environment and, particularly, soils. Hence, there is an urgent need to identify management practices that simultaneously support soil health and production and help achieve environmentally sound production systems.To investigate how management influences production and soil health under realistic agronomic conditions, we conducted an on-farm study involving 60 wheat fields managed conventionally, under no-till or organically. We assessed 68 variables defining management, production and soil health properties. We examined how management systems and individual practices describing crop diversification, fertiliser inputs, agrochemical use and soil disturbance influenced production-quantity and quality-and soil health focusing on aspects ranging from soil organic matter over soil structure to microbial abundance and diversity.Our on-farm comparison showed marked differences between soil health and production in the current system: organic management resulted in the best overall soil health (+47%) but the most significant yield gap (-34%) compared to conventional management. No-till systems were generally intermediate, exhibiting a smaller yield gap (-17%) and only a marginally improved level of soil health (+5%) compared to conventional management. Yet, the overlap between management systems in production and soil health properties was considerably large.Our results further highlight the importance of soil health for productivity by revealing positive associations between crop yield and soil health properties, particularly under conventional management, whereas factors such as weed pressure were more dominant in organic systems.None of the three systems showed advantages in supporting production-soil health-based multifunctionality. In contrast, a cross-system analysis suggests that multifunctional agroecosystems could be achieved through a combination of crop diversification and organic amendments with effective crop protection.Synthesis and applications: Our on-farm study implies that current trade-offs in managing production and soil health could be overcome through more balanced systems incorporating conventional and alternative approaches. Such multifunctionality supporting systems could unlock synergies between vital ecosystem services and help achieve productive yet environmentally sound agriculture supported by healthy soils

Synergism between production and soil health through crop diversification, organic amendments and crop protection in wheat‐based systems

One of the critical challenges in agriculture is enhancing yield without compromising its foundation, a healthy environment and, particularly, soils. Hence, there is an urgent need to identify management practices that simultaneously support soil health and production and help achieve environmentally sound production systems. To investigate how management influences production and soil health under realistic agronomic conditions, we conducted an on‐farm study involving 60 wheat fields managed conventionally, under no‐till or organically. We assessed 68 variables defining management, production and soil health properties. We examined how management systems and individual practices describing crop diversification, fertiliser inputs, agrochemical use and soil disturbance influenced production—quantity and quality—and soil health focusing on aspects ranging from soil organic matter over soil structure to microbial abundance and diversity. Our on‐farm comparison showed marked differences between soil health and production in the current system: organic management resulted in the best overall soil health (+47%) but the most significant yield gap (−34%) compared to conventional management. No‐till systems were generally intermediate, exhibiting a smaller yield gap (−17%) and only a marginally improved level of soil health (+5%) compared to conventional management. Yet, the overlap between management systems in production and soil health properties was considerably large. Our results further highlight the importance of soil health for productivity by revealing positive associations between crop yield and soil health properties, particularly under conventional management, whereas factors such as weed pressure were more dominant in organic systems. None of the three systems showed advantages in supporting production‐soil health‐based multifunctionality. In contrast, a cross‐system analysis suggests that multifunctional agroecosystems could be achieved through a combination of crop diversification and organic amendments with effective crop protection. Synthesis and applications: Our on‐farm study implies that current trade‐offs in managing production and soil health could be overcome through more balanced systems incorporating conventional and alternative approaches. Such multifunctionality supporting systems could unlock synergies between vital ecosystem services and help achieve productive yet environmentally sound agriculture supported by healthy soils