Soil Feedback Research Articles

Key Soil Abiotic Factors Driving Soil Sickness in Lycium barbarum L. Under Long-Term Monocropping

Sustainable cultivation of Lycium barbarum L. (L. barbarum) in northwest China faces challenges due to soil sickness. While previous studies have explored variations in L. barbarum’s root-associated microbiota, the impact of soil properties on its growth performance and plant–soil feedback remains unclear. This study investigated changes in soil properties across topsoil (0–20 cm) and subsoil (20–40 cm) in primary L. barbarum cultivation regions of northwest China, evaluating seedling growth and plant–soil feedback through pot experiments. Results revealed significantly higher fresh shoot weights in seedlings cultivated in topsoil compared to subsoil, with plant–soil feedback showing an inverse trend. Redundancy analysis indicated positive correlations between both fresh weight and plant–soil feedback with electrical conductivity and dissolved nitrogen content, while negative correlations were observed with soil pH at both depths. Notably, dissolved organic carbon content negatively correlated with fresh weight and plant–soil feedback in topsoil, suggesting a potential relationship between continuous single-species plant litter input and soil sickness under monocropping conditions. These findings indicate that long-term input of a single plant litter type, rather than chemical fertilization, may primarily contribute to L. barbarum soil sickness in northwest China, providing valuable insights for developing sustainable cultivation practices for growing L. barbarum.

Zooming in on the temporal dimensions of plant–soil feedback: Plant sensitivity and microbial dynamics

Abstract The magnitude of plant–soil feedback (PSF) can depend on the time of conditioning as well as the length of feedback. Understanding the temporal variation in PSF requires insight in the response of both soil characteristics and the plant. We examined how conspecific PSF varies with the length of conditioning and the size of the response plant using Jacobaea vulgaris, a species known to experience negative conspecific PSF. Together with reanalysis of an existing microbial sequence dataset, we tested whether the temporal variation in PSF is due to size‐dependent plant sensitivity to conditioned soil or due to compositional changes in microbial communities of conditioned soil. Further, by reanalysing another existing dataset, we examined temporal dynamics of the relative growth rates (RGR) of J. vulgaris during the feedback phase. Testing varying conditioning lengths, uncovered that J. vulgaris exhibited the strongest negative PSF at 5 weeks of conditioning, after which PSF gradually attenuated. Plant sensitivity to conditioned soil decreased with increasing plant age/size of the response plant. In the feedback phase, the RGR of J. vulgaris was first higher, then lower and at the end similar in ‘away’ soil compared to ‘home’ soil. The dissimilarity in bacterial and fungal communities in ‘home’ and ‘away’ soil significantly decreased during the feedback phase. When J. vulgaris grew in ‘away’ soil, the relative abundance of 10 (out of 80) bacterial OTUs that positively correlated with plant growth decreased over time, while 5 (out of 86) OTUs that negatively correlated with plant growth the relative abundance increased over time. Additionally, only one (out of 10) fungal OTU that negatively associated with plant growth increased over time in ‘away’ soil. Synthesis. Our findings illustrate that PSF varies with the duration of soil conditioning and of the feedback phase. During the feedback phase, changes in PSF can be attributed to both the size‐dependent plant sensitivity to conditioned soil and temporal changes in the microbial community of conditioned soil. This highlights the importance of considering the reconditioning of soil microbial communities by the test plants during the feedback phase for understanding temporal variation in PSF.

Soil metabolic disturbance drives replant disease (intraspecific negative plant–soil feedback): Insights from an experiment examining soil impacts up to 20 years after a ginseng crop

Replant diseases (RDs), intraspecificnegativeplant–soilfeedback, often stem from nutrient deficiency, allelopathy, or pathogen accumulation. However, the RDs of certain crops are long-lasting and their causes remain unknown. We examined Panax quinquefolius RD in a space-for-time soil sequence representing crop rotation restoration over 1, 10, and 20 years using multiomics and bioassays. Compared with the soils with no ginseng cultivation history, we found 110 significant potential factors related to RD, surprisingly, 53 of which remained unrestored after 20 years. Soil pH and the levels of organic nutrients (amino acids, carbohydrates, and alditols), allelopathic-promoting metabolites (phenolic acids, amines, pyridines, etc.), and beneficial bacteria (Sphingomonas, Burkholderia-Caballeronia-Paraburkholderia, and Terrabacter) and fungi (Acremonium, Penicillium, and Naganishia) decreased, while the levels of allelochemicals (pyruvic and fatty acids) increased. The expression of all metabolic pathways was significantly down-regulated, with the exception of the up-regulated fatty acid-related metabolic pathways. We confirmed that decreased organic nutrient levels and increased levels of allelochemicals impaired P. quinquefolius growth. Soil metabolic factors rather than microbial factors were dominant by network analysis. In conclusion, we found that the overall changes in nutrient levels and metabolic and microbial factors contributed to short-term RD (1–10 year) persistence, whereas long-term RD (after 20 years) primarily resulted from disordered soil metabolite levels and pathways. This research will help deepen our understanding of the relationship between RD and potential changes in the factors influencing RD that are caused by soil legacy effects of valuable plants and provide theoretical guidance for effective soil quality improvement.

Elevated O3 has stronger effects than CO2 on soil nematode abundances but jointly inhibits their diversity in paddy soils

Anthropogenic activities have resulted in rising atmospheric concentrations of carbon dioxide (CO2) and ozone (O3), exerting substantial direct and indirect impacts on soil biodiversity within agroecosystems. Despite the considerable attention given to the individual impacts of elevated CO2 and O3 levels, the combined effects on soil nematode communities have not been extensively explored. In this study, we investigated the interactive effects of elevated CO2 (+200 ppm, eCO2) and O3 (+40 ppb, eO3) levels on the abundance, diversity, and trophic composition of soil nematode communities associated with two rice cultivars (Nanjing 5055, NJ5055 and Wuyujing 3, WYJ3). Our findings revealed that soil nematodes had greater abundances under eO3, whereas eCO2 had no significant impacts. Conversely, both eCO2 and eO3, and their combination led to significant reductions in nematode generic richness, accompanied by a decline in the diversity particularly associated with the WYJ3 cultivar. Moreover, eCO2 and eO3 influenced nematode community composition and environmental factors, particularly for the WYJ3 cultivar. Both eCO2 and eO3 significantly increased soil nitrate levels. The changes in nematode community composition were related to soil nitrate levels, as well as nitrogen and carbon concentrations in rice plant roots. Furthermore, interactions between eCO2 and eO3 significantly impacted soil nematode abundance and trophic composition, revealing intricate consequences for soil nematode communities that transcend predictions based on single-factor experiments. This study unveils the potential impacts posed by eCO2 and eO3 on soil biodiversity mediated by rice cultivars, plant functional characteristics and soil feedback mechanisms, thereby underscoring the complex and interactive outcomes arising from concurrent drivers of climate change within the soil food web.

Setting the stage for plant–soil feedback: Mycorrhizal influences over conspecific recruitment, plant and fungal communities, and coevolution

Abstract Plant–soil feedback (PSF) plays a central role in determining plant community dynamics, yet our understanding of how different combinations of plants and microbes influence PSF remains limited. Plants of different mycorrhizal types often exhibit contrasting PSF outcomes, influencing plant recruitment and spatial structure. Generalizing across plant species based on mycorrhizal type creates the potential to examine broader effects on ecological communities. We review mechanisms contributing to different PSF outcomes between arbuscular mycorrhizal and ectomycorrhizal trees. We focus on how plant and fungal traits that differ between mycorrhizal types interact with pathogenic and saprotrophic microorganisms and nutrient and carbon cycling. Synthesis. Building on this framework, we propose several new research directions. First, mycorrhizal‐induced changes in soils can operate beyond the conspecific level, spilling over from abundant plant species onto less abundant ones. This community‐level ‘mycorrhizal spillover’ is hypothesized to affect PSF in ways that are additive and interactive with conspecific density dependence. Second, we describe how mycorrhizal effects on PSF could structure the way plant communities respond to global change. Third, we discuss how they may influence plant evolution by altering the balance of selection pressures on traits and genes related to pathogen defence and mutualism formation.

Asymmetric sharing of generalist pathogens between exotic and native plants correlates with exotic impact in communities

Abstract As exotic plants invade into a new range, they can escape from specialist enemies. However, they may support generalist enemies, including both native and introduced fungal pathogens, which creates the potential for spillover and apparent competition from exotic to native plants in communities. To assess the potential for spillover of putatively pathogenic, root‐associated fungi (hereafter, ‘pathogens’) in communities invaded by exotic plants, we conducted a two‐phase plant–soil feedback experiment: a monoculture experiment with native and exotic plants grown alone and a multi‐species, community‐level experiment that ranged in the extent of exotic dominance. We used next‐generation sequencing to characterise sharing of pathogens between native and exotic plants in communities. Exotic plants outperformed natives in communities, despite harbouring higher relative abundance of generalist pathogens. The higher generalism of pathogens supported by exotic plants made them more prone to be shared with natives. The proportion of pathogens shared between exotic and native plants in communities correlated with reduced competitive ability of native compared with exotic plants. Synthesis: These data suggest that exotic plants host more generalist pathogens that are shared with native plants, which may confer an indirect benefit to exotic over native plants through apparent competition.

Parasitism by Cuscuta gronovii mediated soil legacy effects and the competitive ability of invasive and native plant species by changing soil abiotic and biotic properties

Parasitic plants can mediate soil conditioning by invasive and native host plant species, but how this may affect the competitive ability of these plants when they later grow in the conditioned soil has never been tested. This study tested whether soil conditioned by three invasive and three native plant species, either parasitized by a holoparasitic plant Cuscuta gronovii or non-parasitized, would differentially affect the competitive ability of those species. In the first phase, field soil was conditioned using individuals of the six host plant species, either parasitized or non-parasitized. The second phase tested the competitive ability of individuals of those invasive and native plants by growing them alone or in competition with Trifolium repens in either live or sterilized conditioned soil. In the soil conditioning phase, parasitism significantly increased soil NH4+-N concentration by 17 %, decreased soil organic carbon by 18 %, and marginally decreased microbial biomass carbon concentration by 21 %. In the soil feedback phase, native plant species generally had higher competitive ability in soil that was conditioned by parasitized plants than in soil that was conditioned by non-parasitized plants. In contrast, soil conditioned by parasitized plants had only a marginal effect on the competitve ability of invasive plants, compared to growth in soil conditioned by non-parasitized plants. Native plants had greater competitive ability in soil with lower soil organic carbon, while invasive plants had greater competitive ability in soil with higher microbial biomass carbon and lower NH4+-N. These findings demonstrate that parasitism by C. gronovii mediated different soil legacy effects of invasive and native plant species through changes in soil organic carbon, soil NH4+-N, and microbial biomass carbon levels. Broadly, these results suggest that parasitic plants may limit invasions by alien plant species and promote the co-existence of the invaders with native plant species through soil-mediated legacy effects.

Root traits and soil legacies drive species competition outcomes

Abstract Plant competition can be affected by plant functional traits but also by differences in fitness mediated by soil microbes. Climatic conditions such as drought further influence plant competition. Yet little is known about how soil microbes and drought interact with plant species that have distinct root traits and how this influences plant competition outcomes. We grew three plant species that co‐occur in temperate grasslands in China (Stipa krylovii, Artemisia frigida, Agropyron cristatum) in monocultures and mixtures and subjected the plant combinations to five soil inocula (root‐associated soil of S. krylovii, A. frigida, A. cristatum, an equal mixture of the three root zone soils and sterilized soil) as well as to a drought treatment. The relative change in plant biomass was used to determine plant competition outcomes. The three species exhibited clear differences in competitive abilities with A. cristatum > S. krylovii > A. frigida, and soil inocula or the drought treatment did not change the order. The relative yield (RY) of plants was affected by soil inocula, drought and plant arrangement. The strongest competitor, A. cristatum, with high total root length, root surface area and root volume experienced more negative biotic feedback, and drought enhanced the magnitude of these negative effects. On the contrary, the most inferior competitor, A. frigida, with high specific root length tended to have neutral or positive biotic feedback, and drought had no effect. Furthermore, the RY and fitness difference (reflected as the competitive ability in the mixture) of the three species were differentially influenced by root traits and plant–soil feedback. RY of A. cristatum could be predicted by the feedback effect in the mixture, and the fitness difference was mainly related to root traits. Both RY and fitness differences of A. frigida (the weakest competitor) could be predicted by root trait differences and feedback effects. Differences in root traits were the best predictors of the intermediate competitor S. krylovii. Our study shows that competition outcomes of co‐existing species depend on root traits and species‐specific PSF effects in mixture. Future work should examine the mechanisms that explain how plant competition and soil microbial heterogeneity act in conjunction with climate change in influencing plant coexistence. Read the free Plain Language Summary for this article on the Journal blog.

Soil Legacies of Tree Species Composition in Mature Forest Affect Tree Seedlings’ Performance

AbstractTrees affect the biotic and abiotic properties of the soil in which they grow. Tree species-specific effects can persist for a long time, even after the trees have been removed. We investigated to what extent such soil legacies of different tree species may impact tree seedlings in their emergence and growth. We performed a plant–soil feedback experiment, using soil that was conditioned in plots that vary in tree species composition in Białowieża Forest, Poland. Soil was taken from plots varying in proportion of birch, hornbeam, pine, and oak. In each soil, seeds of the same four target species were sown in pots. Seedling emergence and growth were monitored for one growing season. To further explore biotic implications of soil legacies, ectomycorrhizal root tip colonization of oak, a keystone forest species, was determined. We found no effect of soil legacies of tree species on the emergence measures. We, however, found a clear negative effect of pine legacies on the total biomass of all four seedling species. In addition, we found relationships between the presence of pine and soil fertility and between soil fertility and root tip colonization. Root tip colonization was positively correlated with the biomass of oak seedlings. We conclude that tree species can leave legacies that persist after that species has been removed. These legacies influence the growth of the next generation of trees likely via abiotic and biotic pathways. Thus, the choice of species in today’s forest may also matter for the structure and composition of future forests.

Restoration of degraded alpine meadows from the perspective of plant–soil feedbacks

Restoration of degraded alpine meadows from the perspective of plant–soil feedbacks

Intraspecific variation in Janzen-Connell effect is mediated by stress and plant-soil feedbacks.

Janzen-Connell (JC) effects, hypothesized to be partially driven by negative plant-soil feedbacks (PSFs), are considered to be a key mechanism that regulates tropical forest plant diversity and coexistence. However, intraspecific variation in JC effects may weaken this mechanism, with the strength of PSFs being a potentially key variable process. We conducted a manipulated experiment with seedlings from two populations of Pometia pinnata (Sapindaceae), a tropical tree species in southwest China. We aimed to measure the intraspecific difference in PSF magnitude caused by inoculating the soil from different P. pinnata source populations and growing seedlings under differing light intensity and water availability treatments, and at varying plant densities. We found negative PSFs for both populations with the inoculum soil originating from the same sites, but PSFs differed significantly with the inoculum soil from different sites. PSF strength responded differently to biotic and abiotic drivers; PSF strength was weaker in low moisture and high light treatments than in high moisture and low light treatments. Our study documents intraspecific variation in JC effects: specifically, P. pinnata have less defenses to their natively-sourced soil, but are more defensive to the soil feedbacks from soil sourced from other populations. Our results imply that drought and light intensity tended to weaken JC effects, which may result in loss of species diversity with climate change.

Effects of plant-soil feedbacks on the invasion and competitiveness of Aegilops tauschii

The interaction between plants and soil is an important aspect that affects the invasive ability of foreign plants and the invasiveness of ecosystems. The study on plant soil feedback of A. tauschii can provide reference for its invasion mechanism. Firstly, the effects of A. tauschii on the nutrients and enzyme activities of invaded soil were investigated; Secondly, in conjunction with soil sterilization, pot experiments were conducted using the De Wit substitution method to investigate the impact of different degree invasive soils on the development of A. tauschii and its interaction with wheat. The results showed that the invasion of A. tauschii significantly increased soil organic matter, soluble phosphorus and soluble potassium, while also causing a significant decrease in the concentration of nitrate nitrogen. And according to the changes of morphological and biomass indicators of A. tauschii, the results of two-way ANOVAs showed that the invaded soil and its microbiota have a positive feedback effect on the growth of A. tauschii. Finally, it can be seen from the value of the competition balance index, the competition ability of A. tauschii in different invasion degree soil is greater than that of wheat whether the soil invaded by A. tauschii had undergone sterilization treatment or not. In conclusion, the invasion potential of A. tauschii is not only derived from its strong competitiveness, but also may be related to the soil conditions.

Self‐help or self‐sabotage? A common invader's soil legacy does not impede, and may facilitate, potential competitors

AbstractIntroduced plants create lasting abiotic and biotic changes to soil that are increasingly implicated as major drivers of invasion success, yet models for investigating patterns in the impacts of these soil legacies are lacking. Here, we used Bohemian knotweed (Reynoutria × bohemica) to present a novel approach for testing whether accounting for diverse evolutionary drivers can clarify how an invader's soil legacy mediates its success. For most tested species, R. × bohemica's soil legacy did not influence seedling performance irrespective of its evolutionary history or the evolutionary novelty of species that share its soil. However, we found the relative importance of legacy effects versus other mechanisms of invader dominance depends on the life stage of the plants growing in soil conditioned by the invader. While the effects of R. × bohemica's soil legacy on seedling performance were context dependent, emergence was, on average, higher in R. × bohemica‐conditioned soils than in unconditioned soils. Thus, contrary to theory, R. × bohemica's soil legacy not only fails to impede potential competitors but may also facilitate them. Our results are particularly powerful: we detected novel insights in the face of biological complexity, even for R. × bohemica, which likely does not depend on heterospecific plant–soil feedbacks for its competitive dominance in its introduced range. Designing rigorous investigations that explore how plant species' evolutionary histories mediate an invader's soil legacy across diverse abiotic environments, as shown here, is key for producing insights in other systems.

Plant functional traits modulate the effects of soil acidification on above- and belowground biomass

Abstract. Atmospheric sulfur (S) deposition has been increasingly recognized as a major driver of soil acidification. However, little is known about how soil acidification influences above- and belowground biomass by altering leaf and root traits. We conducted a 3-year S-addition experiment to simulate soil acidification in a meadow. Grass (Leymus chinensis (Trin.) Tzvelev) and sedge (Carex duriuscula C.A.Mey) species were chosen to evaluate the linkage between plant traits and biomass. Sulfur addition led to soil acidification and nutrient imbalances. Soil acidification decreased specific leaf area (SLA) but increased leaf dry-matter content (LDMC) in L. chinensis, showing a conservative strategy and thus suppressing aboveground instead of belowground biomass. However, in C. duriuscula, soil acidification increased plant height and root nutrients (N, P, S, and Mn), favoring competition for natural resources through enhanced above- and belowground biomass, i.e., adoption of an acquisitive strategy. Increased soil acidity resulted in an overall reduction in aboveground community biomass by 3 %–33 %, but it led to an increase in community root biomass by 11 %–22 % due to upregulation as a result of higher soil nutrient availability. Our results demonstrate that both above- and belowground plant biomass is affected by S-induced acidification. Understanding the linkage between plant biomass and functional traits contributes to a better understanding of plant–soil feedback in grassland ecosystems.

Shift in the effects of invasive soil legacy on subsequent native and invasive trees driven by nitrogen deposition

Invasive plants can interact with soil microbes to enhance their own performance. Such interactive effects may persist and later affect plant performance and their population dynamics. Such ‘invasive soil legacy’ is the specific plant–soil feedback that can affect future invasions, while it is not clear how nitrogen deposition and interspecific competition influence invasive soil legacy. Thus, we collected field soil and conducted a greenhouse experiment to investigate the effects of soil legacy of the invasive tree Rhus typhina on the performance, functional traits and soil microbial communities of R. typhina and the native tree Ailanthus altissima under three nitrogen levels with and without interspecific competition. The experiment revealed that the outcomes of invasive soil legacies were context-specific and depended on local soil nutrient levels and species competition. Specifically, nitrogen addition changed the negative conspecific soil legacy on subsequent R. typhina to a positive effect, while it became negative in A. altissima. The invasive soil legacy promoted the transpirational rate of R. typhina and A. altissima in monoculture, but inhibited it in a mixture under nitrogen deposition. Nitrogen deposition reduced bacteria and fungi biomass of A. altissima in monocultures and mixtures. In contrast, nitrogen deposition decreased bacterial and fungal biomass of R. typhina in monocultures, but enhanced them in mixtures. Therefore, changes in plant growth, transpiration rate and soil microbial biomass might contribute to the different responses of invasive and native plants to invasive soil legacies. Nitrogen deposition and interspecific competition promote the viability of invasive plants from plant–soil feedback and indicate that ranges of subsequent plants might further expand through below-ground process under nitrogen deposition in the future.

Grazing increases the positive feedback of legumes while decreasing the negative feedback of grass

AbstractHerbivore grazing affects plant growth and community structure in grasslands. This effect could be directly through foraging and dung/urine return or indirectly through plant–soil feedbacks (PSFs). Addressing the grazing effect on the feedback of plants can explicate the causes of community changes in the grazing system. However, how grazing and PSF interact to affect plant growth remains unclear. Here, we conducted a classic PSF experiment. In the conditioning stage, two native plant species (a grass Bromus inermis and a legume Medicago sativa) were planted in the field with four simulated grazing treatments (ambient, mowing, dung/urine addition, and mowing + dung/urine addition) in a meadow grassland of northern China. In the feedback stage, B. inermis and M. sativa were planted in the soils (both unsterilized and sterilized) from each treatment in the field experiment. Plant biomass of M. sativa showed positive feedback while B. inermis showed negative feedback across all the simulated grazing treatments. Simulated grazing (mowing and dung/urine addition) increased the positive feedback of M. sativa, while decreasing the negative feedback of B. inermis. The addition of dung/urine to the soil was found to have a significantly stronger impact on plant growth feedback compared to the effect of mowing. Dung/urine addition enriches the soil with higher levels of available nitrogen and phosphorus. Our results suggested that legume plants should have positive PSFs while grass should have negative feedback, which might be amplified by grazing because of the dung/urine fertilization effect. Our study improves the understanding of PSF effects on plant growth and community change in grazed grassland.

Nontarget effects of pre‐emergent herbicides and a bioherbicide on soil resources, processes, and communities

Community‐type conversions, such as replacement of perennials by exotic annual grasses in semiarid desert communities, are occurring due to plant invasions that often create positive plant–soil feedbacks, which favor invaders and make restoration of native perennials difficult. Exotic annual grass control measures, such as pre‐emergent herbicides, can also alter soil ecosystems directly or indirectly (i.e. via the plant community), yet there are few studies on the topic in natural, non‐cropped landscapes. We asked how spray treatments applied to soil post‐fire with the intention of inhibiting invasive annual grasses (such as Bromus tectorum L.) and releasing existing native perennial grasses affected soil resources, a microbial process, and invertebrates in three climatically varied sagebrush steppe sites. Spray treatments included chemical herbicides (imazapic and rimsulfuron) that strongly affected plant communities and a bioherbicide (Pseudomonas fluorescens strain D7) that did not. Chemical herbicides increased soil mineral nitrogen in proportion to their negative effects on plant cover for 2 years after treatments in all sites and increased soil water and net N mineralization (measured at one site) but did not affect total carbon, nitrogen, or organic matter. Invertebrate responses to herbicides varied by site, and invertebrates increased with chemical herbicides at the highest, wettest site. We show that herbicide treatments can exacerbate pulses of mineral nutrients, which previous studies have shown can weaken ecosystem resistance to invasion. Thus, restoration strategies that increase the likelihood that desired plants can capture mineralized nutrients after herbicide application will likely be more successful.

Mechanism of plant–soil feedback in a degraded alpine grassland on the Tibetan Plateau

Abstract Although biotic and abiotic factors have been confirmed to be critical factors that affect community dynamics, their interactive effects have yet to be fully considered in grassland degradation. Herein, we tested how soil nutrients and microbes regulated plant–soil feedback (PSF) in a degraded alpine grassland. Our results indicated that soil total carbon (STC; from 17.66 to 12.55 g/kg) and total nitrogen (STN; from 3.16 to 2.74 g/kg) exhibited significant (P < 0.05) decrease from non-degraded (ND) to severely degraded (SD). Despite higher nutrients in ND soil generating significantly (P < 0.05) positive PSF (0.52) on monocots growth when the soil was sterilized, a high proportion of pathogens (36%) in ND non-sterilized soil resulted in a strong negative PSF on monocots. In contrast, the higher phenotypic plasticity of dicots coupled with a higher abundance of mutualists and saprophytes (70%) strongly promoted their survival and growth in SD with infertile soil. Our findings identified a novel mechanism that there was a functional group shift from monocots with higher vulnerability to soil pathogens in the ND fertile soil to dicots with higher dependence on nutritional mutualists in the degraded infertile soil. The emerging irreversible eco-evolutionary in PSF after degradation might cause a predicament for the restoration of degraded grassland.

Plant-soil interactions during the native and exotic range expansion of an annual plant.

Range expansions, whether they are biological invasions or climate change-mediated range shifts, may have profound ecological and evolutionary consequences for plant-soil interactions. Range-expanding plants encounter soil biota with which they have a limited coevolutionary history, especially when introduced to a new continent. Past studies have found mixed results on whether plants experience positive or negative soil feedback interactions in their novel range, and these effects often change over time. One important theoretical explanation is that plants locally adapt to the soil pathogens and mutualists in their novel range. We tested this hypothesis in Dittrichia graveolens, an annual plant that is both expanding its European native range, initially coinciding with climate warming, and rapidly invading in California after human introduction. In parallel greenhouse experiments on both continents, we used plant genotypes and soils from five locations at the core and edge of each range to compare plant growth in soil inhabited by D. graveolens and nearby control microsites as a measure of plant-soil feedback. Plant-soil interactions were highly idiosyncratic across each range. On average, plant-soil feedbacks were more positive in the native range than in the exotic range. In line with the strongly heterogeneous pattern of soil responses along our biogeographic gradients, we found no evidence for evolutionary differentiation between plant genotypes from the core to edge of either range. Our results suggest that the evolution of plant-soil interactions during range expansion may be more strongly driven by local evolutionary dynamics varying across the range than by large-scale biogeographic shifts.

Improving rotational partners: Intraspecies variation for pea cover cropping traits

AbstractTo improve cover crops such as peas (Pisum sativum), as rotational partners, intraspecific variation for cover cropping traits such as nutrient mobilization, carbon deposition, and beneficial microbial recruitment must be identified. The majority of research on cover crops has focused on interspecies comparisons for cover cropping variation with minimal research investigating intraspecies variation. To address if variation of cover cropping traits is present within a cover cropping species, we grew 15 diverse accessions (four modern cultivars, three landraces, and eight wild accessions) of pea in a certified organic setting. We measured various cover cropping traits, such as nutrient mobilization, soil organic matter deposition, and microbial recruitment, and quantified the effect of pea accession on the growth and yield of a subsequently planted crop of corn (Zea mays). We discovered that the domestication history of pea has a significant impact on soil properties. Specifically, domesticated peas (modern cultivars and landraces) had higher average plant–soil feedback values for amounts of nitrogen, carbon, and manganese compared to wild peas. Additionally, no variation for prokaryotic recruitment (α‐ and β‐diversity) was observed within pea; however, we did observe significant variation for fungal recruitment (α‐ and β‐diversity) due to domestication and accession. Our results demonstrate that there is variation present in peas, and likely all crops, that can be selected to improve them as rotational partners to ultimately boost crop yields in sustainable agroecosystems.