Nutrient Cycling Research Articles

Deciphering the environmental adaptation and functional trait of core and noncore bacterial communities in impacted coral reef seawater

Microorganisms play pivotal roles in different biogeochemical cycles within coral reef waters. Nevertheless, our comprehension of the microbially mediated processes following environmental perturbation is still limited. To gain a deeper insight into the environmental adaptation and nutrient cycling, particularly within core and noncore bacterial communities, it is crucial to understand reef ecosystem functioning. In this study, we delved into the microbial community structure and function of seawater in a coral reef under different degrees of anthropogenic disturbance. To achieve this, we harnessed the power of 16S rRNA gene high-throughput sequencing and metagenomics techniques. The results showed that a continuous temporal succession but little spatial heterogeneity in the bacterial communities of core and noncore taxa and functional profiles involved in nitrogen (N) and phosphorus (P) cycling. Eutrophication state (i.e., nutrient concentration and turbidity) and temperature played pivotal roles in shaping both the microbial community composition and functional traits of coral reef seawater. Within this context, the core subcommunity exhibited a remarkably broader habitat niche breadth, stronger phylogenetic signals and lower environmental sensitivity when compared to the noncore taxa. Null model analysis further revealed that the core subcommunity was governed primarily by stochastic processes, while deterministic processes played a more significant role in shaping the noncore subcommunity. Furthermore, our observations indicated that changes in function related to N cycling were correlated to the variations in noncore taxa, while core taxa played a more substantial role in critical processes such as P cycling. Collectively, these findings facilitated our knowledge about environmental adaptability of core and noncore bacterial taxa and shed light on their respective roles in maintaining diverse nutrient cycling within coral reef ecosystems.

Marine Fungal Diversity and Dynamics in the Gulf of Trieste (Northern Adriatic Sea)

Fungi contribute to different important ecological processes, including decomposition of organic matter and nutrient cycling, but in the marine environment the main factors influencing their diversity and dynamics at the spatial and temporal levels are still largely unclear. In this study, we performed DNA metabarcoding on seawater sampled monthly over a year and a half in the Gulf of Trieste (northern Adriatic Sea), targeting the internal transcribed spacer (ITS) and the 18S rRNA gene regions. The fungal communities were diverse, very dynamic, and belonged predominantly to marine taxa. Samples could be clustered in two groups, mainly based on the high (> 30%) or low relative proportion of the ascomycetes Parengyodontium album, which emerged as a key taxon in this area. Dissolved and particulate organic C:N ratio played important roles in shaping the mycoplankton assemblages, suggesting that differently bioavailable organic matter pools may be utilized by different consortia. The proportion of fungal over total reads was 31% for ITS and 0.7% for 18S. ITS had the highest taxonomic resolution but low power to detect early divergent fungal lineages. Our results on composition, distribution, and environmental drivers extended our knowledge of the structure and function of the mycobiome of coastal waters.

Dissecting the role of soybean rhizosphere-enriched bacterial taxa in modulating nitrogen-cycling functions

Crop roots selectively recruit certain microbial taxa that are essential for supporting their growth. Within the recruited microbes, some taxa are consistently enriched in the rhizosphere across various locations and crop genotypes, while others are unique to specific planting sites or genotypes. Whether these differentially enriched taxa are different in community composition and how they interact with nutrient cycling need further investigation. Here, we sampled bulk soil and the rhizosphere soil of five soybean varieties grown in Shijiazhuang and Xuzhou, categorized the rhizosphere-enriched microbes into shared, site-specific, and variety-specific taxa, and analyzed their correlation with the diazotrophic communities and microbial genes involved in nitrogen (N) cycling. The shared taxa were dominated by Actinobacteria and Thaumarchaeota, the site-specific taxa were dominated by Actinobacteria in Shijiazhuang and by Nitrospirae in Xuzhou, while the variety-specific taxa were more evenly distributed in several phyla and contained many rare operational taxonomic units (OTUs). The rhizosphere-enriched taxa correlated with most diazotroph orders negatively but with eight orders including Rhizobiales positively. Each group within the shared, site-specific, and variety-specific taxa negatively correlated with bacterial amoA and narG in Shijiazhuang and positively correlated with archaeal amoA in Xuzhou. These results revealed that the shared, site-specific, and variety-specific taxa are distinct in community compositions but similar in associations with rhizosphere N-cycling functions. They exhibited potential in regulating the soybean roots’ selection for high-efficiency diazotrophs and the ammonia-oxidizing and denitrification processes. This study provides new insights into soybean rhizosphere-enriched microbes and their association with N cycling.Key points• Soybean rhizosphere affected diazotroph community and enriched nifH, amoA, and nosZ.• Shared and site- and variety-specific taxa were dominated by different phyla.• Rhizosphere-enriched taxa were similarly associated with N-cycle functions.

Low levels of Al stimulate the aboveground growth of Davidia involucrata saplings

Davidia involucrata is a woody perennial and the only living species in the Genus Davidia. It is native to southern China where it holds cultural and scientific importance. However, D. involucrata is now an endangered species and its natural range includes low pH soils which are increasingly impacted by acid rain, nitrogen deposition and imbalanced nutrient cycling. The combination of these stresses also poses the additional risk of aluminum (Al) toxicity. Since the responses of D. involucrata to low pH and aluminum toxicity have not been investigated previously, a hydroponic experiment was conducted to examine the growth of one year old D. involucrata saplings after 50 d growth in a range of pH and Al conditions. Plant biomass, morphology, antioxidant enzyme activity, mineral concentrations and plant ecological strategy were compared at pH 5.8 and pH 4.0 without added Al (AlCl3) and in 0.1, 0.2 and 0.5 mM Al at pH 4.0. Our results showed that compared with pH 5.8, pH 4.0 (without added Al) not only inhibited root and shoot growth but also limited accumulation of nitrogen (N) and phosphorus (P) in leaves of D. involucrate. However, low Al concentrations (0.1 and 0.2 mM Al) at pH 4.0 partially restored the aboveground growth and leaf N concentrations, suggesting an alleviation of H+ toxicity by low Al concentrations. Compared with low Al concentrations, 0.5 mM Al treatment decreased plant growth and concentrations of N, P, and magnesium (Mg) in the leaves, which demonstrated the toxicity of high Al concentration. The results based on plant ecological strategy showed that D. involucrate decreased the competitiveness and favored its stress tolerance as pH changed from 5.8 to 4.0. Meanwhile, the competitiveness and stress tolerance of D. involucrata increased and decreased at low Al concentrations, respectively, and decreased and increased at high Al concentration, respectively. These trade-offs in ecological strategy were consistent with the responses of growth and antioxidant enzyme activity, reflecting a sensitive adaptation of D. involucrata to acid and Al stresses, which may aid in sustaining population dynamics. These findings are meaningful for understanding the population dynamics of D. involucrata in response to aluminum toxicity in acid soils.

Forest degradation hinders soil fauna's contribution to litter decomposition and community dynamics in Andean temperate Nothofagus forests

Biodiversity losses driven by human disturbance hinder chief ecosystem functions like litter decomposition, among the most critical processes regulating forest ecosystems' carbon and nutrient cycles. Historical logging, wildfire, and ongoing livestock grazing pressure have degraded most southern temperate Nothofagus forests. Yet, the effect of forest degradation on soil fauna composition and, in turn, litter decomposition and nutrient cycling still need to be determined. This study aims to i) quantify the contribution of soil fauna to litter decomposition and mineralization of C, N, and P in Nothofagus sp. forest displaying different levels of degradation (mature, secondary, and degraded forests and a newly reforested site) and ii) assess the effect of forest degradation on the temporal composition of soil invertebrates' communities. Decomposition bags with 0.1 and 2 mm mesh were installed in long-term research plots across forest conditions. Litter decomposition and C, N, and P mineralization were estimated monthly for one year. Likewise, meso- and macrofauna's richness, abundance, and diversity were assessed bimonthly during the same period. We found that the contribution of mesofauna to decomposition was the lowest in the newly reforested site and 20 % higher in the degraded forest than in mature and secondary forests. Soil fauna substantially increased C, N, and P mineralization, particularly in the degraded forest. Differences in fauna's contribution to litter decomposition were likely related to changes in the community composition, primarily composed of detritivores in the three forested conditions and phytophagous and predators in the newly reforested site. We concluded that forest degradation modified the invertebrate community composition, and soil fauna enhances litter decomposition and nutrient mineralization in the degraded forests. In addition, our data suggest that forest degradation leads to a loss of invertebrate meso- and macrofauna orders, which alter litter decomposition processes.

The impact of Ethiopian Green Legacy Initiative (GLI) on landscape functionality and plant species diversity in Lake Hawassa watershed, Ethiopia

AbstractAs one of the responses to the global commitments against climate change, the Ethiopian Government launched a nationwide Green Legacy Initiative (GLI) in 2019, which largely focused on forest tree plantations with some inclusion of fruit trees. Despite its tremendous efforts and investments, its effectiveness and impacts have not been studied. This paper attempted to address this necessity by conducting a cross‐sectional quasi‐experiment in three randomly selected woredas/districts of Lake Hawassa Watershed from August 20 to September 2, 2023. The research hypothesized the likely impacts of GLI on four dependent variables (hydrological regulation, soil stability, nutrient cycling and plant species diversity). To achieve this, the research considered the two variants of GLI practices (plantation with and without soil and water conservation measures) and the corresponding control sites. Having three sites and three treatments with five replications, the study involved a total of forty‐five quadrats of the same size (20 m × 20 m). The first three parameters were analysed using the landscape functionality analysis method, while the fourth employed Shannon's diversity index. Results of ANOVA showed that, on average 87% of randomly selected quadrats were found to significantly improve the local hydrology (runoff potential) (≈ 83.3% with Av. p = 0.012), soil stability (≈100% with Av. p = 0.002), nutrient cycling (≈83.3% with Av. p = 0.017) and plant species diversity (≈83.3% with Av. p = 0.012). The research revealed positive results from the Ethiopian Green Legacy Initiative. The small number of samples is acknowledged as a limitation of the research.

Evaluation of Algal Control Measures in Eutrophic Reservoirs Based on Aquatic Ecosystem Models

The frequency of freshwater cyanobacterial blooms is increasing globally due to climate change and eutrophication, particularly in reservoirs. Reservoir ecosystems exhibit unique characteristics, and there is a complex relationship between factors such as light, temperature, nutrient salts, hydrology, and algal growth. The impact of the other factors on algal growth varies significantly among different reservoirs. Thus, it is crucial to assess the effectiveness of various algal control measures implemented in different reservoirs. This study conducted a comprehensive assessment by establishing a eutrophication model for the Shanzi Reservoir in Fuzhou City. The model incorporated meteorology, hydrology, carbon dynamics, nutrient cycling, and biological communities. The effectiveness of diverse management measures was systematically evaluated. The findings demonstrate that increasing the water level, reducing nutrient salts in sediments, and implementing ecological fish stocking effectively suppressed algal growth to varying degrees and improved nitrogen and phosphorus levels. Lower water levels and ecological fish stocking had a significant impact on algal reproduction, while sediment reduction had a minimal effect. Conversely, lower water levels and ecological fish stocking did not significantly improve nitrogen and phosphorus concentrations in the reservoir, whereas sediment reduction had a noticeable effect. Consequently, the management strategies for the Shanzi Reservoir should prioritize external control measures and the implementation of ecological fish stocking.

Variation in insect community structure between natural and constructed tidal marshes

Abstract Insects perform important ecological roles that influence ecosystem functions, including primary production and nutrient cycling. Likewise, wetland ecosystems perform important functions and provide numerous services, yet they are highly vulnerable to loss. Wetland restoration and construction can provide habitat for insects and other organisms and recover ecosystem functions. While the community structure of plants and non‐insect macroinvertebrates in restored and constructed wetlands often fails to recover to comparable levels of reference wetlands, less is known about the recovery of insect communities in restored wetlands. We aimed to determine if differences in biological structure (i.e., plant biomass and soil organic matter) between one reference and two constructed Juncus roemerianus‐dominated tidal marshes extend to their respective insect communities. We classified insect communities into taxonomic families and functional feeding groups in one reference marsh and two constructed marshes in Alabama, USA. Sampling methods included replicated pan trapping, line‐transect netting, floral observations and floral clippings. We also conducted light trapping at one site per marsh. All insect taxa and functional groups were identified monthly from April to October 2021 and analysed for taxon richness, abundance and H′ diversity. Floral density and herbivory scars on J. roemerianus shoots were also measured during flowering and peak growing seasons, respectively. While insect abundance and taxon richness were similar among sites, the reference marsh generally supported a more diverse insect community than the constructed marshes, although nocturnal flying insects were less diverse. Additionally, temporal shifts in community composition, based on relative abundances of insect taxa and functional feeding groups, differed among marshes, likely reflecting differences in habitats in the surrounding landscapes of each site. By comparing structural differences (i.e., taxonomic and functional) of insect communities in reference and constructed marshes, we can further understand the community composition of an understudied group of organisms, thereby informing restoration strategies to recover habitat and support the health of tidal marshes.

Sedimentology of a delta formed by agricultural river discharge into a flood‐control reservoir, Iowa

AbstractRiver deltas are ecologically critical landscape components and are responsible as habitats for millions of people, wildlife, and plant communities. Deltas store vast quantities of eroded nutrient‐rich sediment and play a significant role in water quality management through nutrient cycling and storage. Many studies have been conducted in marine and tidal delta environments that characterize the sedimentology and geomorphic characteristics of these relatively young landscapes. However, little work has been completed in even younger inland reservoir deltas. This study characterized the sediments and geomorphology of the growing delta forming at the outlet of the Des Moines River into Red Rock Reservoir in south‐central Iowa and discussed the implications of the lower delta sediment and topographic characteristics in terms of sediment and nutrient storage, and the potential impact of the delta on other hydroecological factors. We found that the ca. 30‐year‐old lower delta is storing up to 60% of the contributing watershed's eroded sediment and total carbon, with total sediment depths of ca. 9 m across the 755‐ha area. Further, we identified two major geomorphic landscape positions within the lower delta that were categorized as distributary channels and delta plains. Sedimentological differences in these microscale landscape positions were identified. Sand content was greater at lowest distributary channel elevations and at the highest plain elevations whereas silt dominated the elevation range between these two extremes. The zone of silt accumulation corresponds to the range in elevation associated with normal lake level management. The silt‐dominated area is regularly inundated and covered with a variety of emergent vegetation and is the zone of critical importance for waterbird habitat and nutrient‐processing capacity.

Stoichiometry of litter decomposition under the effects of climate change and nutrient enrichment: A meta-analysis

Abstract Aims The cycling of nutrients from plant litter has key implications for the functioning of terrestrial ecosystems by controlling nutrient availability and net primary production. Despite extensive research on the effects of global change on ecosystem functioning, the direct implications of global change on stoichiometry and nutrient dynamics during litter decomposition remain poorly understood. To address this gap, we conducted a meta-analysis. Methods We analysed 178 experiments that simulated (i) warming, (ii) drought, (iii) increased water availability, (iv) N enrichment, (v) P enrichment, and (vi) combined N and P (N + P) enrichment. We compared earlier (approximately six months) and later (approximately one year) stages of decomposition and analysed the specific effects taking into account climate and plant type. Results The C:N and C:P ratios decreased in most warming and nutrient enrichment scenarios, leading to losses of litter C content, while the N:P ratio remained more resilient and affected by water availability. Furthermore, the abundance of resources (water and N + P) fosters the decomposition of litter. The nutrient mobilisation increases for both P and N under non-limited nutrient enrichment and it is faster for N than for P when water increases its availability. Nutrient enrichment was relevant in later stages of decomposition. Conclusions Our study provides insights into the fate of litter decomposition and its stoichiometric dynamics in response to drivers of global change. Concerning scenarios of C release and N and P immobilisation were identified. However, further experimentation and analysis are necessary to consider all interacting drivers.

Developing stable, simplified, functional consortia from Brachypodium rhizosphere for microbial application in sustainable agriculture

The rhizosphere microbiome plays a crucial role in supporting plant productivity and ecosystem functioning by regulating nutrient cycling, soil integrity, and carbon storage. However, deciphering the intricate interplay between microbial relationships within the rhizosphere is challenging due to the overwhelming taxonomic and functional diversity. Here we present our systematic design framework built on microbial colocalization and microbial interaction, toward successful assembly of multiple rhizosphere-derived Reduced Complexity Consortia (RCC). We enriched co-localized microbes from Brachypodium roots grown in field soil with carbon substrates mimicking Brachypodium root exudates, generating 768 enrichments. By transferring the enrichments every 3 or 7 days for 10 generations, we developed both fast and slow-growing reduced complexity microbial communities. Most carbon substrates led to highly stable RCC just after a few transfers. 16S rRNA gene amplicon analysis revealed distinct community compositions based on inoculum and carbon source, with complex carbon enriching slow growing yet functionally important soil taxa like Acidobacteria and Verrucomicrobia. Network analysis showed that microbial consortia, whether differentiated by growth rate (fast vs. slow) or by succession (across generations), had significantly different network centralities. Besides, the keystone taxa identified within these networks belong to genera with plant growth-promoting traits, underscoring their critical function in shaping rhizospheric microbiome networks. Furthermore, tested consortia demonstrated high stability and reproducibility, assuring successful revival from glycerol stocks for long-term viability and use. Our study represents a significant step toward developing a framework for assembling rhizosphere consortia based on microbial colocalization and interaction, with future implications for sustainable agriculture and environmental management.

Effects of Simulated Warming on Bacterial Community Structure in Litters of Chinese Fir Based on Displacement Test

Bacterial communities are vital factors for regulating litter decomposition in forests. With the gradual increase in global climate change, the effects of global warming on the decomposition of forest litter have become a cause for concern. In this study, we used a displacement test to simulate the effects of warming (+2.5, +4.6, and +6.5 °C) on the composition and diversity of bacterial communities in Chinese fir litters based on the natural differences in temperature between the elevation of Wuyi Mountain. Warming significantly increased the abundance and diversity of bacterial communities and altered the functional abundance of bacterial communities. Warming significantly increased the relative abundance of Acidothermus and decreased that of Bacteroidetes and Mucilaginibacter. Structural variations in the bacterial communities were closely related to the chemical properties of the litter. The relative abundance of Planctomycetes exhibited a positive association with nitrogen content and a negative association with cellulose content, whereas phosphorus content was the main driving factor of Acidothermus abundance. Warming increased the complexity of the bacterial community structure, which promoted the decomposition of Chinese fir litter and accelerated nutrient cycling in the Chinese fir plantation ecosystem.

Feedbacks between phytoplankton and nutrient cycles in a warming ocean

Feedbacks between phytoplankton and nutrient cycles in a warming ocean

Autophagy-related ncRNAs: Regulatory Roles and Potential Therapeutic Effects in Digestive System Neoplasms.

Among all cancers in the world, the incidence rate of digestive system neoplasms accounts for about 25%, while the mortality rate accounts for about 35%. Difficulty in detecting early digestive system cancers and its poor prognosis are the two main reasons for the high mortality rate. Understanding of the basic cellular processes is of significance and autophagy is one of these processes. Considering the importance of autophagy in pathological state functions, the mechanism of autophagy was initially carried out. In this paper, we will review the molecular mechanisms and biological functions of autophagy-associated ncRNAs in different types of digestive system cancers. Autophagy is a process that supports nutrient cycling and metabolic adaptation accomplished through multi-step lysosomal degradation. It has been suggested that autophagy has a dual role in cancer, which limits tumorigenesis in some stages but promotes tumor progression in others. NcRNAs are also shown to modulate cellular autophagy and thus affect the development of digestive system neoplasms. More and more evidence suggests that the regulation of autophagy by ncRNAs plays a complex role in cancer initiation, progression, metastasis, recurrence, and treatment resistance, which might make ncRNAs therapeutic targets for digestive system neoplasms. While miRNAs participate mainly in post-transcriptional regulation, lncRNAs, and circRNAs usually serve as molecular sponges that have more diverse regulatory functions.

The first mitogenomic phylogenetic framework of Dorcus sensu lato (Coleoptera: Lucanidae), with an emphasis on generic taxonomy in Eastern Asia

BackgroundDorcus stag beetles in broad sense are one of the most diverse group in Lucanidae and important saproxylic insects playing a crucial role in nutrient recycling and forest biomonitoring. However, the dazzling morphological differentiations have caused numerous systematic confusion within the big genus, especially the puzzlingly generic taxonomy. So far, there is lack of molecular phylogenetic study to address the chaotic situation. In this study, we undertook mitochondrial genome sequencing of 42 representative species including 18 newly-sequenced ones from Eastern Asia and reconstructed the phylogenetic framework of stag beetles in Dorcus sensu lato for the first time.ResultsThe mitogenome datasets of Dorcus species have indicated the variable mitogenomic lengths ranged from 15,785 to 19,813 bp. Each mitogenome contained 13 PCGs, 2 rRNAs, 22 tRNAs, and a control region, and all PCGs were under strong purifying selection (Ka/Ks < 1). Notably, we have identified the presence of a substantial intergenic spacer (IGS) between the trnAser (UCN) and NAD1 genes, with varying lengths ranging from 129 bp (in D. hansi) to 158 bp (in D. tityus). The mitogenomic phylogenetic analysis of 42 species showed that Eastern Asia Dorcus was monophyletic, and divided into eight clades with significant genetic distance. Four of them, Clade VIII, VII, VI and I are clustered by the representative species of Serrognathus Motschulsky, Kirchnerius Schenk, Falcicornis Séguy and Dorcus s.s. respectively, which supported their fully generic positions as the previous morphological study presented. The topology also showed the remaining clades were distinctly separated from the species of Dorcus sensu lato, which implied that each of them might demonstrate independent generic status. The Linnaeus nomenclatures were suggested as Eurydorcus Didier stat. res., Eurytrachellelus Didier stat. res., Hemisodorcus Thomson stat. res. and Velutinodorcus Maes stat. res. For Clade V, IV, III and II respectively.ConclusionThis study recognized the monophyly of Dorcus stag beetles and provided a framework for the molecular phylogeny of this group for the first time. The newly generated mitogenomic data serves as a valuable resource for future investigations on lucanid beetles. The generic relationship would facilitate the systematics of Dorcus stag beetles and thus be useful for exploring their evolutionary, ecological, and conservation aspects.

Microbial central carbon metabolism in a tidal freshwater marsh and an upland mixed conifer soil under oxic and anoxic conditions.

The central carbon (C) metabolic network is responsible for most of the production of energy and biosynthesis in microorganisms and is therefore key to a mechanistic understanding of microbial life in soil communities. Many upland soil communities have shown a relatively high C flux through the pentose phosphate (PP) or the Entner-Doudoroff (ED) pathway, thought to be related to oxidative damage control. We tested the hypothesis that the metabolic organization of the central C metabolic network differed between two ecosystems, an anoxic marsh soil and oxic upland soil, and would be affected by altering oxygen concentrations. We expected there to be high PP/ED pathway activity under high oxygen concentrations and in oxic soils and low PP/ED activity in reduced oxygen concentrations and in marsh soil. Although we found high PP/ED activity in the upland soil and low activity in the marsh soil, lowering the oxygen concentration for the upland soil did not reduce the relative PP/ED pathway activity as hypothesized, nor did increasing the oxygen concentration in the marsh soil increase the PP/ED pathway activity. We speculate that the high PP/ED activity in the upland soil, even when exposed to low oxygen concentrations, was related to a high demand for NADPH for biosynthesis, thus reflecting higher microbial growth rates in C-rich soils than in C-poor sediments. Further studies are needed to explain the observed metabolic diversity among soil ecosystems and determine whether it is related to microbial growth rates.IMPORTANCEWe observed that the organization of the central carbon (C) metabolic processes differed between oxic and anoxic soil. However, we also found that the pentose phosphate pathway/Entner-Doudoroff (PP/ED) pathway activity remained high after reducing the oxygen concentration for the upland soil and did not increase in response to an increase in oxygen concentration in the marsh soil. These observations contradicted the hypothesis that oxidative stress is a main driver for high PP/ED activity in soil communities. We suggest that the high PP/ED activity and NADPH production reflect higher anabolic activities and growth rates in the upland soil compared to the anaerobic marsh soil. A greater understanding of the molecular and biochemical processes in soil communities is needed to develop a mechanistic perspective on microbial activities and their relationship to soil C and nutrient cycling. Such an increased mechanistic perspective is ecologically relevant, given that the central carbon metabolic network is intimately tied to the energy metabolism of microbes, the efficiency of new microbial biomass production, and soil organic matter formation.

Fungal and Prokaryotic Communities in Soil Samples of the Aral Sea Dry Bottom in Uzbekistan

Due to the falling water level in the Aral Sea and Muynak Lake, the content of salts dissolved in the water has gradually increased, and toxic elements have been deposited at the lake’s bottom and subsequently washed into the Aral region by the river. Bacteria, archaea and fungi are crucial for the cycling of several important inorganic nutrients in soils. From 15 genera and 31 species of recovered microscopic filamentous fungi, a big group was melanized, of which most of them were also phytopathogenic. The second group consisted of keratinophilic species. Isolated bacteria mainly included members of the genera Arthrobacter, Bacillus, Massilia, Rhodococcus and Nocardiopsis. High-throughput sequencing analysis permitted a better view of the mycobiome and prokaryotic communities (comprising archaea). The cultivation and sequencing approaches were shown to be complementary. The aim of the work was to identify soil microorganisms, including the order Halobacteriales, and to discover the differences in species diversity depending on soil salinity and the presence of PTEs in soil.

Profiling sediment bacterial communities and the response to pattern-driven variations of total nitrogen and phosphorus in long-term polyculture ponds

Sediment bacterial communities are decisive drivers of nutrient cycling processes in aquaculture ecosystems and are readily affected by surrounding environmental factors. However, the knowledge of sediment nutrient accumulations and bacterial community structure is limited in the emerging polyculture systems. Herein, we investigated the profiles of sediment properties and bacterial communities in six typical polyculture ponds and primarily explored the influence of total nitrogen and phosphorus on the bacterial species and diversity. In almost all sediment samples, Proteobacteria, Chloroflexi, and Bacteroides were the dominant species at the phylum level, and the five most abundant bacterial genera were Sulfurovum, Woeseia, Ilumatobacter, Robiginitalea, and Cyanobium_PCC-6307. A clear different bacterial community was observed with the most dominant bacterial phylum Firmicutes and the lowest bacterial diversity in TZ1 pond sediment; meanwhile, the TZ1 pond also showed the highest TN and TP concentrations. Notably, sediments from WZ1 and WZ2 ponds in low-latitude regions exhibited higher bacterial richness and diversity. Based on Pearson’s correlation analysis, bacterial α-diversity indices showed significant negative correlation with sediment TP content, and TN content contributed the most to the abundance of sediment dominant bacterial genus, indicating that the bacterial community is highly associated with sediment nutrient concentrations. Moreover, co-occurrence network analysis further revealed some keystone taxa that exhibited high correlations with other bacterial species, especially the high-abundance genus Robiginitalea bridging a large number of connections. Compared to traditional mono-mariculture pattern, our study provided direct evidence of lower nutrient loadings and different bacterial communities in the polyculture ponds. This could assist polyculture practitioners in developing effective strategies for detailed nutritional management.

Towards a Greener Future: Scaling Up Agroforestry for Global Sustainability

The current world faces several challenges, including climate change, an exponentially increasing population, the loss of biodiversity and environmental concerns which necessities the adoption of the sustainable nature-based solutions such as agroforestry. Agroforestry is the intricate integration of trees, crops, and livestock on the same piece of land management unit that helps to restore the ecosystem, improve soil health, thus combating the environmental degradation. Moreover, agroforestry has also emerged as a potential tool that bridges the ecological preservation, while increasing or at least maintaining the productivity of the whole agroecosystem. Agroforestry is a contemporary food system that relies primarily on natural inputs, leading to the creation of more sustainable and resilient landscapes. Simultaneously, agroforestry systems reduce the soil erosion, and increases the accumulation of organic matter, hence established a closed nutrient cycling which sustain the agricultural production for longer duration. Simultaneously, agroforestry systems are effective in enhancing food security, diversifying farm income and strengthening the resilience of community to climate change thus empower the farmers and provide an opportunity to combat poverty. However, there are numerous constraints including clear land tenure rights, market infrastructure and linkage, and lack of the traditional knowledge which influenced the adoption of agroforestry systems at global level. This immediately need to be addressed by implementing flexible legislation (such as National Agroforestry Policy 2014 adopted by India), capacity building and community involvement, value chain development and payment for ecosystem services. Overall, it is crucial to adopt low-carbon perennial agroecological practices like agroforestry in order to increase the CO2 abatement rate, improve the food, nutritional and livelihood security of smallholder farmers and contribute to a more environmental friendly and sustainable future.

Sensitivity of root production to long‐term aridity under environmental perturbations in Chihuahuan Desert ecosystems

Abstract Root production influences carbon and nutrient cycles and subsidizes soil biodiversity. However, the long‐term dynamics and drivers of belowground production are poorly understood for most ecosystems. In drylands, fire, eutrophication, and precipitation regimes could affect not only root production but also how roots track interannual variability in climate. We manipulated the intra‐annual precipitation regime, soil nitrogen, and fire in four common Chihuahuan Desert ecosystem types (three grasslands and one shrubland) in New Mexico, USA, where the 100‐year record indicates both long‐term drying and increasing interannual variability in aridity. First, we evaluated how root production tracked aridity over 10–17 years using climate sensitivity functions, which quantify long‐term, nonlinear relationships between biological processes and climate. Next, we determined the degree to which perturbations by fire, nitrogen addition or intra‐annual rainfall altered the sensitivity of root production to both mean and interannual variability in aridity. All ecosystems had nonlinear climate sensitivities that predicted declines in production with increases in the interannual variance of aridity. However, root production was the most sensitive to aridity in Chihuahuan Desert shrubland, with reduced production under drier and more variable aridity. Among the perturbations, only fire altered the sensitivity of root production to aridity. Root production was more than twice as sensitive to declines with aridity following prescribed fire than in unburned conditions. Neither the intra‐annual seasonal rainfall regime nor chronic nitrogen fertilization altered the sensitivity of roots to aridity. Synthesis. Our results yield new insight into how dryland plant roots respond to climate change. Our comparison of dryland ecosystems of the northern Chihuahuan Desert predicted that root production in shrublands would be more sensitive to future climates that are drier and more variable than root production in dry grasslands. Field manipulations revealed that fire could amplify the climate sensitivity of dry grassland root production, but in contrast, the climate sensitivity of root production was largely resistant to changes in the seasonal rainfall regime or increased soil fertilization.