Independent variations of plant and soil mixtures reveal soil feedback effects on plant community overyielding

Abstract

Summary 1.Recent studies have shown that the positive relationship between plant diversity and plant biomass ('overyielding') can be explained by soil pathogens depressing productivity more in low than in high diverse plant communities. However, tests of such soil effects in field studies were constrained by experimental limitations to manipulate soil community composition independent of plant community composition. Here, we report of an experiment where feedback effects to plants were tested for both plant and soil monocultures and mixtures.2. Our results demonstrate that overyielding is the result of plant species in mixture being more growth-limited by 'own' soil biota than by soil biota of other plant species. This effect disappeared when the soils had been sterilized by gamma-irradiation. Mixing plants themselves did not result in overyielding except when grown in the soil of one of the species (Leucanthemum vulgare), where growth of one species disproportionally increased in mixture compared to monoculture.3. Soil nutrient availability could not explain differences in growth between the non-sterilized soils. Therefore, our results suggest that plant species-specific soil biota rather than the plants have contributed to the plant community overyielding.4. Species biomass ranking in mixtures highly differed between non-sterilized soils of different histories of soil conditioning, whilst the ranking was more consistent in sterilized soil. Sterilized soils of different origin differed significantly in nutrient availability. These results suggest that shifts in competitive hierarchies depend on plant species-specific interactions influenced by soil biota and cannot be induced by mineral nitrogen. Synthesis.Our results show that overyielding in four plant species mixtures can be due to species-specific interactions between plants and their specific soil biota. Neither mixing the plant species alone nor the differential responses of species to mineral nitrogen influenced community productivity, but mixing soil biota did.

Linking ecology and plant pathology to unravel the importance of soil-borne fungal pathogens in species-rich grasslands

“…These patterns of host specificity are consistent with results of plant-soil feedback studies that have shown reduced plant growth on soil with a history of plants of the same species or functional group compared to the average community soil (e.g. Cortois et al 2016;Hendriks et al 2013;Mangan et al 2010;Petermann et al 2008). It is, however, crucial to reveal the (fungal) actors and their functional role in grassland plant communities, if we want to increase our understanding of the myriad of plantfungal interactions belowground.…”

Inhibitory effects of soil biota are ameliorated by high plant diversity

“…These results indicate that high plant species diversity ameliorated the inhibitory effects of soil biota that were expressed at low diversity and provide a direct test of the negative effects of soil biota on plants growing at reasonably natural, but low richness levels. Since our low-diversity plots had between 2 and 5 species, our results are quite conservative relative to other tests comparing feedback effects in high-diversity soil to soil collected from monocultures of species (e.g., Petermann et al 2008;Hendriks et al 2013). Our results suggest that local patches of plants that contain only a few species (which are likely to be more common in nature than the monocultures that are more commonly experimented with in this context) can accumulate inhibitory soil biota to a greater extent than higher diversity patches.…”

“…Concomitantly, plant productivity increased nearly 500 % at high versus low diversity, primarily because of the strong suppressive effects of density-dependent disease on plant productivity at low diversity (see also Knops et al 1999). Hendriks et al (2013) found that soil feedbacks in soil in which species in monoculture were grown were substantially more negative than feedbacks in soil containing diverse mixture of the same species grown in monocultures. Taken together, these results suggest that the accumulation of inhibitory soil biota at low plant species diversity may help to explain the common pattern of low species diversity corresponding with low ecosystem productivity (Cardinale et al 2007;Eisenhauer et al 2012).…”

“…Both components are based on the notion that resource availability and utilization drive the positive asymptotic diversity-productivity relationship. Recently, however, the role of soil biota has emerged as an important driver of the positive relationship between plant species diversity and ecosystem function (Maron et al 2011;Schnitzer et al 2011;Hendriks et al 2013). Maron et al (2011) found a strong positive relationship between the number of intermountain grassland plant species in plots and total aboveground biomass.…”

Soil biochar amendment in a nature restoration area: effects on plant productivity and community composition

“…On the other hand, the observed alterations in plant community composition will also affect soil community composition, as each plant species creates its own soil biotic community (Bezemer et al 2010). Via biotic plant-soil interactions, these species-specific soil communities can differentially affect the growth of subsequent plant species growing in that soil, which could then alter the succession of the community as a whole (van de Voorde et al 2011, Hendriks et al 2013. Even when the direct effects of biochar addition disappear rapidly in the following growing seasons, for example, due to leaching or utilization of mobile ions such as K, the effect of biochar addition will remain visible in the plant community and in the ecosystem via altered mechanisms like seed production, competition, and plant-soil interactions over a much longer period.…”