Agricultural intensification has had long-lasting negative legacies largely because of excessive inputs of agrochemicals (e.g., fertilizers) and simplification of cropping systems (e.g., continuous ...monocropping). Conventional agricultural management focuses on suppressing these negative legacies. However, there is now increasing attention for creating positive above- and belowground legacies through selecting crop species/genotypes, optimizing temporal and spatial crop combinations, improving nutrient inputs, developing intelligent fertilizers, and applying soil or microbiome inoculations. This can lead to enhanced yields and reduced pest and disease pressure in cropping systems, and can also mitigate greenhouse gas emissions and enhance carbon sequestration in soils. Strengthening positive legacies requires a deeper understanding of plant–soil–microbiome interactions and innovative crop, input, and soil management which can help to achieve agricultural sustainability.
Agricultural intensification leaves negative legacies that influence soil microbiomes, weakening their capacity to deliver multiple soil ecosystem functions.Innovative agricultural management can create positive above- and belowground legacies that improve agricultural sustainability.Deciphering the cascading effects of plant–soil–microbiome interactions will promote the innovation of soil, input, and crop management.In-season interspecific interactions in mixtures can create positive legacies for subsequent crops.
Interactions between species influence ecosystem functions and are sensitive to reintroductions. Our understanding of interactions between naturally co-occurring large herbivores, such as Eurasian ...beaver (Castor fiber) that are now re-establishing throughout their range, and well-established native ungulates, is limited, despite the potential implications for riparian woodlands. Observations in Scotland indicate that roe deer (Capreolus capreolus) readily exploit the regenerative secondary shoots produced after tree felling by beaver. Our study, based in eastern Scotland, investigates the role of beaver herbivory in riparian woodland regeneration and asks whether deer are attracted to this novel resource because it is either a) more readily available, b) nutritionally superior, or c) morphologically more appealing than accessible browse on unfelled (standing) trees. We firstly quantified the secondary shoots available to browsing deer at different heights on felled and standing birch (Betula spp.) trees in twenty riparian woodland plots across five well-established beaver territories (occupancy ten years). Shoots from birch and willow (Salix spp.) trees with contrasting levels and combinations of beaver and deer browsing were then analysed for nutritional content (nitrogen and carbon) and morphological characteristics (number of buds and lateral branches). We found that 62% of beaver-felled trees produced secondary shoots available to browsing deer. Compared to standing trees, regenerating beaver-felled trees had 18% more secondary shoots. These shoots were significantly higher in nitrogen content (+13%), but similar in carbon content and concentrated closer to the ground. Our results show that beaver herbivory can promote riparian woodland regeneration and heterogeneity by creating a mosaic of mature and multi-stemmed coppiced trees. The addition of a common, readily available, and nutritious resource through beaver browsing could, however, also enhance habitat quality for browsing deer, with the potential to affect deer distribution and feeding habits.
•Tree felling by beaver promotes riparian woodland regeneration.•Among beaver-felled trees 62 % produced secondary shoots accessible to deer.•Beaver-felled trees yielded more shoots (+18 %) that were richer in nitrogen (+13 %).•Tree felling by beaver could influence deer feeding and distribution.•Beaver-deer interactions have implications for riparian woodland conservation.
Microbial communities are complex multi-species assemblages that are characterized by a multitude of interspecies interactions, which can range from mutualism to competition. The overall sign and ...strength of interspecies interactions have important consequences for emergent community-level properties such as productivity and stability. It is not well understood how interspecies interactions change over evolutionary timescales. Here, we review the empirical evidence that evolution is an important driver of microbial community properties and dynamics on timescales that have traditionally been regarded as purely ecological. Next, we briefly discuss different modelling approaches to study evolution of communities, emphasizing the similarities and differences between evolutionary and ecological perspectives. We then propose a simple conceptual model for the evolution of interspecies interactions in communities. Specifically, we propose that to understand the evolution of interspecies interactions, it is important to distinguish between direct and indirect fitness effects of a mutation. We predict that in well-mixed environments, traits will be selected exclusively for their direct fitness effects, while in spatially structured environments, traits may also be selected for their indirect fitness effects. Selection of indirectly beneficial traits should result in an increase in interaction strength over time, while selection of directly beneficial traits should not have such a systematic effect. We tested our intuitions using a simple quantitative model and found support for our hypotheses. The next step will be to test these hypotheses experimentally and provide input for a more refined version of the model in turn, thus closing the scientific cycle of models and experiments. This article is part of the theme issue 'Conceptual challenges in microbial community ecology'.
Many notorious invasive plants are clonal, spreading mainly by vegetative propagules. Propagule pressure (the number of propagules) may affect the establishment, growth, and thus invasion success of ...these clonal plants, and such effects may also depend on habitat conditions. To understand how propagule pressure, habitat conditions and clonal integration affect the establishment and growth of the invasive clonal plants, an 8-week greenhouse with an invasive clonal plant, Alternanthera philoxeroides was conducted. High (five fragments) or low (one fragment) propagule pressure was established either in bare soil (open habitat) or dense native vegetation of Jussiaea repens (vegetative habitat), with the stolon connections either severed from or connected to the relatively older ramets. High propagule pressure greatly increased the establishment and growth of A. philoxeroides, especially when it grew in vegetative habitats. Surprisingly, high propagule pressure significantly reduced the growth of individual plants of A. philoxeroides in open habitats, whereas it did not affect the individual growth in vegetative habitats. A shift in the intraspecific interaction on A. philoxeroides from competition in open habitats to facilitation in vegetative habitats may be the main reason. Moreover, clonal integration significantly improved the growth of A. philoxeroides only in open habitats, especially with low propagule pressure, whereas it had no effects on the growth and competitive ability of A. philoxeroides in vegetative habitats, suggesting that clonal integration may be of most important for A. philoxeroides to explore new open space and spread. These findings suggest that propagule pressure may be crucial for the invasion success of A. philoxeroides, and such an effect also depends on habitat conditions.
•The common trees in boreal forest of Kanas are aggregated at small scale.•Competition occur in individuals among and between Picea and Pinus adults.•Facilitation mainly exists between individuals ...with different shade tolerances.•Competition are not as common as facilitation in boreal forest of Kanas.
Competition and facilitation are the primary mechanisms structuring communities and driving spatial distribution patterns of trees. However, we still know relatively little about the underlying effects of these two processes on natural forest ecosystems and this is particularly true in boreal forest ecosystems. Our lack of understanding regarding the factors regulating spatial patterns of boreal forest ecosystems is important given their role in carbon sequestration and timber products. Using data from a 12-ha boreal forest dynamic plot in the Kanas Nature Reserve of Northwest China, we assessed the population distribution and diameter at breast height (DBH) structure, as well as intra- and interspecific interactions, of the four most abundant tree species (Larix sibirica, Picea obovata, Pinus sibirica, and Betula pendula). Our results indicate that the spatial distribution patterns of these species were aggregated at small spatial scales because of dispersal limitation, and that the degree of aggregation decreased with increasing spatial scale. Aggregation was the highest for the less common species (i.e., B. pendula pendula). Saplings (1 cm ≤ DBH < 5 cm) and juveniles (5 cm ≤ DBH < 15 cm) were more aggregated than larger individuals (DBH ≥ 15 cm). Only P. obovata adults (DBH ≥ 15 cm) showed a regular (i.e., hyperdispersed) distribution because of the intense intraspecific competition at small scales (i.e., <5 m). Intraspecific interactions between individuals were either positive or not significant. In terms of interspecific competition, there were significant negative associations among large (DBH ≥ 15 cm) and small adults (5 cm ≤ DBH < 15 cm) for the two shade tolerant species (P. obovata and P. sibirica). In contrast, we observed positive interspecific interactions between individuals of different DBH classes and different shade tolerance species. Thus, most of the intra- and interspecific interactions showed positive or no significant correlations. Negative associations were generally less common than positive associations both within and between species. Our results show that competition and facilitation simultaneously influence the spatial patterns of plants in this community. Moreover, positive interactions between tree individuals in this temperate region are likely to be more common than competitions for survival and growth of tree stems.
Global food security is threatened by plant disease, and crop diversification often promotes productivity through reduced disease and facilitation for increased nutrient acquisition. However, whether ...such facilitation is a factor in disease resistance is unknown.
Investigate how crop diversity affects crop productivity and rust disease on maize, and whether competition or facilitation between crop species correspond with resistance.
Five irrigated intercropping experiments with different fertilization and crop combinations were conducted at two sites for four years. Productivity (542 data points) and disease severity (27150 data points) of maize monoculture, maize - legume and maize - non-legume intercropping were compared. A meta-analysis of literature was performed to confirm the broader applicability of results from these field experiments.
Legume-based intercropping increased the aboveground biomass of intercropped maize by 8% and grain yields by 10% in comparison to non-legume-based intercropping. Disease severity on maize intercropped with legumes was reduced by 45% and 48%, compared to monocultures of maize and maize intercropped with non-legumes, respectively. Moreover, as interactions among intercrops became more facilitative, the concentrations of zinc (Zn), copper (Cu) and iron (Fe) in maize increased, and these increases were highly correlated with decreasing disease severity. The global meta-analysis was consistent with our field experiments, as lower disease severity was associated with greater intensity of interspecific facilitation or with lower intensity of interspecific competition.
Lower disease severity was closely related to enhanced acquisition of nutrients that can enhance the resistance to crop diseases, driven by stronger interspecific facilitative effects in intercropping systems. Facilitative effects on maize was increased by the identity of leguminous companion crop species, and was increased by sufficient irrigation, but reduced by applications of nitrogen and phosphorus fertilizers.
Our findings identify a novel facilitative mechanism in general and advance the understanding of the facilitative mechanisms that underly disease control through crop diversification.
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•Maize intercropped with legumes has greater yields than maize without legumes.•Disease severity on maize was reduced by 45% by intercropping with legumes.•Intercropping increased concentrations of zinc, copper and iron in maize.•Decreased disease severity on maize is positively correlated with interspecific facilitation.
•Synchronous mast seeding of sympatric tree species can affect seed predation and dispersal.•We found both short-term mutualism and competition between C. mollissima and Q. aliena.•Synchronous mast ...seeding had various influences on the neighbor effects.•Such effects on seed dispersal shape forest regeneration and composition.
Knowledge is lacking on how masting regulates seed-seed interactions of sympatric tree species under the mediation of rodents. Here, we compared rodent-mediated seed dispersal between two sympatric tree species (Castanea mollissima and Quercus aliena) in both monospecific and mixed plots, across five successive years in the Qinling Mountains, China. We investigated: (a) whether the rodent-mediated seed dispersal success of each tree species was affected by the presence of the other, and (b) if any effects on dispersal were influenced by either the abundance of rodents present, or by (c) masting (i.e., seed abundance). We found both short-term mutualism and competition occurred between these two sympatric tree species. In non-mast years, the presence of Q. aliena seed reduced predation on C. mollissima seeds and promoted seed caching, which resulted in higher rates of C. mollissima seed dispersal. Synchronous masting enhanced this benefit to C. mollissima seeds, although we detected no clear neighbor or masting benefits for Q. aliena seed dispersal. This shows that inter-specific interactions differ between these masting neighbors, which may relate to either relative species-specific seed abundance or seed traits. We conclude that seed abundance mediates rodents’ seed forging and caching strategies, which may be important for forest regeneration and forest tree species composition.
Cities are expanding worldwide and urbanisation is considered a global threat to biodiversity. Urban ecology has provided important insights on how urban environmental changes might affect ...individuals, populations, and species; however, we know little about how the ecological impacts of urbanisation alter species interactions. Species interactions are the backbone of ecological communities and play a crucial role in population and community dynamics and in the generation, maintenance and structure of biodiversity. Here, I review urban ecological studies to identify key mechanistic pathways through which urban environmental processes could alter antagonistic and mutualistic interactions among species. More specifically, I focus on insect predation, parasitoidism and herbivory, competition, insect host–pathogen interactions, and pollination. I furthermore identify important knowledge gaps that require additional research attention and I suggest future research directions that may help to shed light on the mechanisms that affect species interactions and structure insect communities and will thus aid conservation management in cities.
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•Urban ecosystems are expanding worldwide with major effects on biodiversity.•All species are embedded in various antagonistic and mutualistic interactions.•Ecological interactions are the architecture of ecosystems.•A mechanistic framework is needed to identify the main urban ecological processes that affect ecological interactions.•Knowledge on how urbanisation affects species interactions is the key to understand how urbanisation alters biodiversity.
Intestinal microbiota plays crucial roles in nutrient uptake and contributes to obesity in aquatic animals, although the association between intestinal microbiota and obesity remains unclear. In this ...study, high-throughput sequencing was employed to determine the composition, interspecific interactions, and potential function of the microbial community in the intestine of rice field eel (Monopterus albus) fed with basal diet (Control group, 6.30% lipid) or high-fat diet (HF group, 12.11% lipid). The high-fat diet decreased species richness, accompanied by a significant reduction in the diversity of intestinal microbiota, and significantly increased the relative abundance of Fusobacteriia (classified as Cetobacterium), concurrent with a significant reduction in Clostridia (classified as Clostridium) in the eel. However, the eels in both groups shared the same dominant gut microbiota, comprising Clostridia, Fusobacteriia, and Gammaproteobacteria. Molecular ecological network analysis described the complex inter-species interactions within the intestinal bacterial community, which in both groups was predominated by positive interactions. The dominant intestinal microbiota was found to be the major component of the ecological network and could play vital roles, for instance, as connectors, which have a major contribution in maintaining the stability of the bacterial community. The high-fat diet disturbed the intestinal microbiota homeostasis through the deterioration of the ecological network by reducing the average connectivity, negative interactions, and the number of connectors. Analysis of predicted functions (PICRUSt) showed that the high-fat diet significantly increased some potential functions of intestinal microbiota involved in lipid, amino acid, carbohydrate, and energy metabolism, in accordance with metabolic changes observed in terms of low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, cholesterol, and glucose in the serum. These results suggested that the change in intestinal microbiota may contribute to the development of diet-induced fat deposition in eels.
•High-fat diet significantly increased the relative abundance of Cetobacterium in the gut of rice filed eel.•High-fat diet disturbed intestinal microbiota homeostasis through the deterioration of ecological network.•Long-term high-fat diet could induce dyslipidemia.
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