UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.
UNASSIGNED: 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.

Lakes serve as heterogeneous ecosystems with rich microbiota. Although previous studies on bacterioplankton have advanced our understanding, there are gaps in our knowledge concerning variations in the taxonomic composition and community assembly processes of bacterioplankton across different environment conditions. This study explored the spatial dynamics, assembly processes, and co-occurrence relationships among bacterioplankton communities in 35 surface water samples collected from Hulun Lake (a grassland-type lake), Wuliangsuhai Lake (an irrigated agricultural recession type lake), and Daihai Lake (an inland lake with mixed farming and grazing) in the Inner Mongolia Plateau, China. The results indicated a significant geographical distance decay pattern, with biomarkers (Proteobacteria and Bacteroidota) exhibiting differences in the contributions of different bacteria branches to the lakes. The relative abundance of Proteobacteria (42.23%) were high in Hulun Lake and Wuliangsuhai Lake. Despite Actinobacteriota was most dominant, Firmicutes accounted for approximately 17.07% in Daihai Lake, suggested the potential detection of anthropogenic impacts on bacteria within the agro-pastoral inland lake. Lake heterogeneity caused bacterioplankton responses to phosphorus, chlorophyll a, and salinity in Hulun Lake, Wuliangsuhai Lake, and Daihai Lake. Although bacterioplankton community assembly processes in irrigated agricultural recession type lake were more affected by dispersal limitation than those in grassland-type lake and inland lake with mixed farming and grazing (approximately 52.7% in Hulun Lake), dispersal limitation and undominated processes were key modes of bacterioplankton community assembly in three lakes. This suggested stochastic processes exerted a greater impact on bacterioplankton community assembly in a typical Inner Mongolia Lake than deterministic processes. Overall, the bacterioplankton communities displayed the potential for collaboration, with lowest connectivity observed in irrigated agricultural recession type lake, which reflected the complex dynamic patterns of aquatic bacteria in typical Inner Mongolia Plateau lakes. These findings enhanced our understanding of the interspecific relationships and assembly processes among microorganisms in lakes with distinct habitats.

Species interactions such as facilitation and competition play a crucial role in driving species range shifts. However, density dependence as a key feature of these processes has received little attention in both empirical and modelling studies. Herein, we used a novel, individual-based treeline model informed by rich in situ observations to quantify the contribution of density-dependent species interactions to alpine treeline dynamics, an iconic biome boundary recognized as an indicator of global warming. We found that competition and facilitation dominate in dense versus sparse vegetation scenarios respectively. The optimal balance between these two effects was identified at an intermediate vegetation thickness where the treeline elevation was the highest. Furthermore, treeline shift rates decreased sharply with vegetation thickness and the associated transition from positive to negative species interactions. We thus postulate that vegetation density must be considered when modelling species range dynamics to avoid inadequate predictions of its responses to climate warming.

Reactive nitrogen (N) enrichment is a common environmental problem in estuarine ecosystems, while the microbial-mediated N removal process is complicated for other multi-environmental factors. Therefore, A systematic investigation is necessary to understand the multi-trophic microbiota-mediated N removal characteristics under various environmental factors in estuaries. Here, we studied how multiple factors affect the multi-trophic microbiota-mediated N removal potential (denitrification and anammox) and N2O emission along a river-estuary-bay continuum in southeastern China using the environmental DNA (eDNA) approach. Results suggested that hypoxia and salinity were the dominant environmental factors affecting multi-trophic microbiota-mediated N removal in the estuary. The synergistic effect of hypoxia and salinity contributed to the loss of taxonomic (MultiTaxa) and phylogenetic (MultiPhyl) diversity across multi-trophic microbiota and enhanced the interdependence among multi-trophic microbiota in the estuary. The N removal potential calculated as the activities of key N removal enzymes was also significantly constrained in the estuary (0.011), compared with the river (0.257) and bay (0.461). Structural equation modeling illustrated that metazoans were central to all sediment N removal potential regulatory pathways. The top-down forces (predation by metazoans) restrained the growth of heterotrophic bacteria, which may affect microbial N removal processes in the sediment. Furthermore, we found that the hypoxia and salinity exacerbated the N2O emission in the estuary. This study clarifies that hypoxia and salinity constrain estuarine multi-trophic microbiota-mediated N removal potential and highlights the important role of multi-trophic interactions in estuarine N removal, providing a new perspective on mitigating estuarine N accumulation.

Multiple species of Fusarium can contribute to the development of root rot in canola (Brassica napus), making disease management difficult. We conducted field and greenhouse experiments to investigate the impacts of Fusarium avenaceum and Fusarium proliferatum, and the interaction between Fusarium oxysporum and F. proliferatum on root rot severity and canola yields. Inoculation with any of the three Fusarium spp. resulted in significant disease severity and reduced seedling emergence compared with non-inoculated controls, leading to yield reductions of up to 35%. Notably, there was a strong correlation (r = 0.93) between root rot severity at the seedling stage and at maturity. Regression analysis indicated a linear decline in seedling emergence with increasing disease severity. Furthermore, disease severity at maturity adversely affected the pod number per plant and the seed weight per plant, with both parameters ultimately approaching zero at a severity of 4.0 on a 0-4 scale. Co-inoculation with F. oxysporum and F. proliferatum induced more severe root rot than inoculation with each species on its own, suggesting synergistic interactions between these fungi. Knowledge of these interactions and the relative virulence of Fusarium spp. will contribute to the improved management of root rot in canola.

Profound growth differences such as seedling length and biomass are often observed during the cultivation of Sargassum fusiforme despite the absence of detectable variance in abiotic factors that could have affected this process. This highlights the importance of biotic factors such as epiphytic microbiota in controlling seedling growth. Yet, how, and to what extent microbial activities can affect host growth in the presence of seawater flow and continuous erosion remains debatable. Particularly, the contribution of microbial network interactions to the growth of macroalgae remains poorly understood. This study aimed to compare the physicochemical properties of S. fusiforme seedlings via 16S rRNA gene Illumina sequencing-based profiling of the epiphytic microbial communities of seedlings with different lengths. Significantly different epiphytic bacterial communities were observed among S. fusiforme seedlings of different lengths. The result showed that community from longer seedlings maintained higher bacterial diversity with the taxa Gammaproteobacteria, Burkholderiales, Alteromonadales, Vibrionaceae, Ralstonia, Colwelliaceae, and Thalassotalea being selectively enriched. More importantly, microbial interspecific interactions, which were predominantly positive, were enhanced consistently in communities of the longer seedlings, indicative of reinforced prevalent and mutually cooperative relationships among the microorganisms associated with S. fusiforme seedlings of greater length. Furthermore, longer seedlings also displayed up-regulation of microbial functional potentials involved in N fixation and mineralization, P mineralization and transportation, and ion transportation compared with shorter ones. Lastly, stochastic processes dominated the community assembly of the epiphytic microorganisms. These findings could provide new insights into the relationship between microbial communities and growth in S. fusiforme seedlings and enable us to predict the community diversity and assembly of macroalgae-associated microbial communities. This could have important implications for linking microbial community diversity and network interactions to their host productivity.

Complex interspecific relationships between parasites and their insect hosts involve multiple factors and are affected by their ecological and evolutionary context. A parasitoid Sclerodermus guani (Hymenoptera: Bethylidae) and an entomopathogenic fungus Beauveria bassiana (Hypocreales: Cordycipitaceae) shared the same host in nature, Monochamus alternatus (Coleoptera: Cerambycidae). They often encountered the semi-enclosed microhabitat of the host larvae or pupae. We tested the survival and reproduction of the parasitoid\'s parent and its offspring fitness under different concentrations of B. bassiana suspension. The results show that S. guani parent females carrying higher concentrations of the pathogen shorten the pre-reproductive time and regulate their own fertility and their offspring\'s survival and development. This minimal model of the interspecific interactions contains three dimensionless parameters, vulnerability (θ), dilution ratio (δ), and PR, which were used to evaluate the mortality effect of the parasitoid S. guani on its host M. alternatus under the stress of the entomopathogenic fungus B. bassiana. We compared the infection and lethal effect of the fungus B. bassiana with different concentrations to the parasitoid S. guani and the host larvae M. alternatus. At higher concentrations of the pathogen, the parasitoid parent females shorten the pre-reproductive time and regulate their own fertility and their offspring\'s survival and development. At moderate concentrations of the pathogen, however, the ability of the parasitoid to exploit the host is more flexible and efficient, possibly reflecting the potential interspecific interactions between the two parasites which were able to coexist and communicate with their hosts in ecological contexts (with a high overlap in time and space) and cause interspecific competition and intraguild predation.

Long recognized as a threat to wildlife, particularly for large carnivores, livestock grazing in protected areas can potentially undermine conservation objectives. The interspecific interactions among livestock, snow leopards (Panthera uncia), and their wild prey in fragile Asian highland ecosystems have been a subject of debate. We strategically deployed 164 camera traps in the Wolong National Nature Reserve to systematically investigate the activities of snow leopards, their primary wild ungulate prey species, and free-ranging livestock. We found that snow leopard habitat use was influenced by both wild prey and livestock. Blue sheep served as the main wild prey that spatially attracted snow leopards and coexisted with yaks while free-ranging yaks significantly restricted snow leopard habitat use both temporally and spatially. This study challenges the conventional understanding that livestock indirectly impacts large carnivores by competing with and displacing wild prey. Our findings highlight that free-ranging yaks within the alpine canyon terrain could directly limit snow leopard habitat use, suggesting a potential risk of grazing in reducing apex predator distribution and jeopardizing their populations. Consequently, managing their coexistence in shared habitats requires a more nuanced approach. Furthermore, our research underscores the importance of further research efforts aimed at enhancing our comprehension of the complex interplay within animal communities and ecosystems. This knowledge will contribute to the development of informed, evidence-based conservation strategies and policies.

A reservoir is an important source of methane (CH4), which is consumed by aerobic methane-oxidizing bacteria (MOB), representing the main CH4 sink in water. The central urban area of Chongqing in the Three Gorges Reservoir (TGR) area was selected as the study area in 2021. High-throughput sequencing was used to analyze the community structure and abundance of MOBs. The results showed that Methylocystis (Type II) was the dominant MOB in water, whereas Methylococcus (Type I) and Methylocystis co-dominated the sediments. High water temperature in the study area largely accounted for the predominance of Type II MOBs in the two habitats. Moreover, the influence of environmental factors on MOB community and its interspecific relationship were significantly regulated by the operation of the TGR. In the low-water-level period, NO2--N and CO2 concentration significantly correlated with Methylocystis, whereas in the high-water-level period, the higher discharge and velocity weakened the influence of all environmental factors on Methylocystis. In addition, the scouring of sediments by increasing discharge in the high-water-level period caused a significant decrease in dissolved CH4 concentration. The decrease in substrate increased interspecific competition within the MOB community, especially between different types of MOBs, in the high-water-level period.

Understanding how non-trophic social systems respond to environmental gradients is still a challenge in animal ecology, particularly in comparing changes in species composition to changes in interspecific interactions. Here, we combined long-term monitoring of mixed-species bird flocks, data on participating species\' evolutionary history and traits, to test how elevation affected community assemblages and interspecific interactions in flock social networks. Elevation primarily affected flocks through reassembling interspecific associations rather than modifying community assemblages. Specifically, flock networks at higher elevations (compared to low elevations) had stronger interspecific associations (larger average weighted degree), network connectivity (enhanced network density) and fewer subnetworks. A phylogenetic and functional perspective revealed that associations between similar species weakened, whereas connections between dissimilar and/or random species were unchanged or strengthened with elevation. Likewise, network assortativity for the traits of vertical stratum and breeding period declined with elevation. The overall pattern is a change from modular networks in the lowlands, where species join flocks with other species that have matching traits, to a more open, random system at high elevations. Collectively, this rewiring of interspecific networks across elevational gradients imparts network stability and resiliency and makes mixed-species flocks less sensitive to local extinctions caused by harsh environments.