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.
● The 4C approach considers intercropping performances as the result of joint 4C effects. ● Partial land equivalent ratios indicate which effect(s) are the major one(s). ● A major effect of ...complementarity is related to a better capture of abiotic resources.
Modern agriculture needs to develop transition pathways toward agroecological, resilient and sustainable farming systems. One key pathway for such agroecological intensification is the diversification of cropping systems using intercropping and notably cereal-grain legume mixtures. Such mixtures or intercrops have the potential to increase and stabilize yields and improve cereal grain protein concentration in comparison to sole crops. Species mixtures are complex and the 4C approach is both a pedagogical and scientific way to represent the combination of four joint effects of Competition, Complementarity, Cooperation, and Compensation as processes or effects occurring simultaneously and dynamically between species over the whole cropping cycle. Competition is when plants have fairly similar requirements for abiotic resources in space and time, the result of all processes that occur when one species has a greater ability to use limiting resources (e.g., nutrients, water, space, light) than others. Complementarity is when plants grown together have different requirements for abiotic resources in space, time or form. Cooperation is when the modification of the environment by one species is beneficial to the other(s). Compensation is when the failure of one species is compensated by the other(s) because they differ in their sensitivity to abiotic stress. The 4C approach allows to assess the performance of arable intercropping versus classical sole cropping through understanding the use of abiotic resources.
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'.
* Intercropping is a useful practice when agricultural sustainability is emphasized.
* We integrate biodiversity-ecosystem functioning and intercropping.
* Intercropping optimizes ecosystem services ...such as stabilizing yield and reducing use of chemicals.
* Intercropping benefits are attributed partly to complementarity and selection effects.
* Application of ecological principles is key to sustainable agricultural development.
Intercropping is a traditional farming system that increases crop diversity to strengthen agroecosystem functions while decreasing chemical inputs and minimizing negative environmental effects of crop production. Intercropping is currently considerable interest because of its importance in sustainable agriculture. Here, we synthesize the factors that make intercropping a sustainable means of food production by integrating biodiversity of natural ecosystems and crop diversity. In addition to well-known yield increases, intercropping can also increase yield stability over the long term and increase systemic resistance to plant diseases, pests and other unfavorable factors (e.g. nutrient deficiencies). The efficient use of resources can save mineral fertilizer inputs, reduce environmental pollution risks and greenhouse gas emissions caused by agriculture, thus mitigating global climate change. Intercropping potentially increases above- and below-ground biodiversity of various taxa at field scale, consequently it enhances ecosystem services. Complementarity and selection effects allow a better understanding the mechanisms behind enhanced ecosystem functioning. The development of mechanization is essential for large-scale application of intercropping. Agroecosystem multifunctionality and soil health should be priority topics in future research on intercropping.
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.
Introduction Maize/soybean intercropping is a common cropping practice in Chinese agriculture, known to boost crop yield and enhance soil fertility. However, the role of below-ground interactions, ...particularly root exudates, in maintaining intercropping advantages in soybean/maize intercropping systems remains unclear. Methods This study aimed to investigate the differences in root exudates between intercropping and monocropping systems through two pot experiments using metabolomics methods. Multiple omics analyses were conducted to explore correlations between differential metabolites and the community of Arbuscular Mycorrhizal Fungi (AMF), shedding light on the mechanisms underlying the dominance of intercropping from the perspective of root exudates-soil microorganism interactions. Results and discussion The study revealed that intercropping significantly increased the types and contents of root exudates, lowered soil pH, increased the availability of nutrients like available nitrogen (AN) and available phosphorus (AP), and enhanced AMF colonization, resulting in improving the community composition of AMF. Besides, root exudates in intercropping systems differed significantly from those in monocropping, with 41 and 39 differential metabolites identified in the root exudates of soybean/maize, predominantly amino acids and organic acids. The total amount of amino acids in the root exudates of soybean intercropping was 3.61 times higher than in monocropping. Additionally, the addition of root exudates significantly improved the growth of soybean/maize and AMF colonization, with the mycorrhizal colonization rate in intercropping increased by 105.99% and 111.18% compared to monocropping, respectively. The identified metabolic pathways associated with root exudates were closely linked to plant growth, soil fertility improvement, and the formation of AMF. Correlation analysis revealed a significant relationship (P < 0.05) between certain metabolites such as tartaric acid, oxalic acid, malic acid, aspartic acid, alanine, and the AMF community. Notably, the photosynthetic carbon fixation pathway involving aspartic acid showed a strong association with the function of Glomus_f_Glomerace, the dominant genus of AMF. A combined analysis of metabolomics and high throughput sequencing revealed that the root exudates of soybean/maize intercropping have direct or indirect connections with AMF and soil nutrients. Conclusion This suggests that the increased root exudates of the soybean/maize intercropping system mediate an improvement in AMF community composition, thereby influencing soil fertility and maintaining the advantage of intercropping.
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.
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