Plant and Soil最新文献

Background and aims

Wetlands play an important role in biogeochemical cycle processes and are pivotal in sustaining ecosystem functions and mitigating climate change. This study investigated the intertwined ecological stoichiometry of carbon (C), nitrogen (N), and phosphorus (P) within the soil–plant system of the Hanzhong Crested Ibis National Nature Reserve, Shaanxi, under varying levels of ecological disturbance.

Methods

We conducted field investigations and nutrient analyses of both plants and soil during the peak growing season in July and August 2022.

Results

Comprehensive statistical analysis was performed to evaluate variations in soil and plant stoichiometric traits across different disturbance levels within the study area. One-way Analysis of Variance (ANOVA) revealed significant differences in soil and plant stoichiometric traits under varying disturbance intensities (p < 0.05). Regression analysis demonstrated that disturbance intensity is a significant predictor of nutrient variability, particularly affecting soil N and P content. Effect sizes indicated that disturbance has a considerable impact on plant P levels, while Principal Component Analysis (PCA) highlighted distinct clustering of sites based on nutrient stoichiometric ratios, explaining 68% of the variance. The findings underscore the critical role of disturbance intensity in shaping the ecological stoichiometry of wetland ecosystems.

Conclusion

The findings of this study indicate the significant impacts of disturbance intensity on the stoichiometric traits of soil and plants, particularly highlighted by the elevated C and N levels in PJW under high disturbance conditions. These variations suggest that disturbance regimes could play a critical role in shaping ecological stoichiometry, although further experimental studies are required to delineate the causative mechanisms behind these patterns.

Graphical abstract

Background and aims

Plants retain and reabsorb nutrients as a resource conservation strategy. However, studies demonstrating the patterns of nutrient resorption for a single species across a broad spatial scale in grassland ecosystems are still scarce, and our understanding of how environmental changes modify these patterns remains limited.

Methods

We established a 1200-km transect in Inner Mongolia, China, and selected the local dominant species of Leymus chinensis to explore the spatial patterns and predictors of nutrient resorption.

Results

Nitrogen (NRE) and phosphorus resorption efficiency (PRE) decreased with increasing latitude, while they increased with elevation across our transect. The average values of NRE and PRE were 63.7% and 70.2%, respectively. The NRE of L. chinensis was lower than its PRE, suggesting that the L. chinensis in Inner Mongolian generally suffers from P deficiency. Soil pH and the Standardized Precipitation Evapotranspiration Index of current growing season (SPEIgs) emerged as the primary predictors influencing spatial variations in nutrient resorption. NRE and PRE increased with soil pH and decreased with SPEIgs, emphasizing that nutrient resorption is particularly sensitive to changes in nutrient and water availability. Moreover, soil contributed significantly more than climatic factors in driving large-scale changes in nutrient resorption.

Conclusion

Soil pH and SPEIgs co-regulated the spatial patterns of nutrient resorption. L. chinensis was at phosphorus limitation in the study area. Soil characteristics can better explain the variation of nutrient resorption than climate factors, highlighting that the soil is a critical aspect when predicting the relative vulnerability of natural communities to environmental changes.

Background and aims

Root nodule microsymbionts of native Prosopis cineraria and three exotic species of Neltuma (formerly Prosopis), N. juliflora, N. alba and N. pallida, were trapped from soils of different agro-climatic regions of India to analyze preferences of host plants towards their microsymbionts.

Methods

Ability of Prosopis/Neltuma species to nodulate in alkaline to acidic soils was determined through trap experiments. Nodule anatomy was examined using light and transmission electron microscopy. Symbionts were genetically characterized using multi locus gene sequence-based phylogenies of core and symbiotic genes. Host range was confirmed through cross-inoculation experiments.

Results

Nodules of Prosopis and Neltuma species are of the mimosoid type with genetically diverse strains of Ensifer/Sinorhizobium, Mesorhizobium, Bradyrhizobium and Rhizobium as their microsymbionts. Only P. cineraria nodulated in acidic soils of Meghalaya wherein it adopted Bradyrhizobium as symbionts. In addition to large variability based on core genes, substantial diversity was observed in the nodA genes harbored by Sinorhizobium with clear incidences of horizontal gene transfer; several Sinorhizobium strains harbored dominant and typical “Indian mimosoid clade” nodA genes. Sinorhizobium is the dominant symbiont of Prosopis/Neltuma species and cross nodulates related Indian native mimosoids such as Mimosa himalayana and species of Vachellia.

Conclusion

Overlaps were seen in symbionts isolated from the native and exotic species suggesting that these hosts are open and inclusive towards a wide range of symbionts irrespective of their origin. Most tree rhizobia were incompatible with herbaceous papilionoid legumes. Invasive mesquites are assisted in their invasiveness by their ability to nodulate with native rhizobia.

Methods and aims

This study continuously monitored the greenhouse gas (GHG) emissions from different stand ages apple orchards, estimated the carbon footprint (CF) based on the life cycle assessment (LCA) method, and evaluated the net ecosystem carbon budget (NECB) and net ecosystem economic benefit (NEEB).

Results

The CO₂ emissions from soil respiration increased with the stand ages. The N₂O emission in 15-year fertilized orchard (N15) was higher than that in 5-year fertilized orchard (N5) and 25-year fertilized orchard (N25) by 119.5% and 53.7%, respectively. Compared to non-fertilized plots, fertilization significantly increased the soil CO₂ emissions, N₂O emissions, soil organic carbon (SOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) contents and soil organic carbon sequestration rate (SOCSR). Meanwhile, SOC, MBC, SOCSR increased with the stand ages. The total CF in different stand ages apple orchards ranged from –786.8 to 8768.1 kg CO₂-eq ha^–1yr^–1, and the CF was positively correlated with fertilizer application rates and N₂O emissions. For the fertilized plots, fertilizer (38.6%-49.1%) and N₂O emissions (12.0%-14.9%) were the top two contributors to total CF. N₂O emissions and pesticides were essential contributors to total CF for the non-fertilized plots. The NECB was negatively correlated with yield and CO₂ emissions, and the NEEB was positively correlated with yield, excessive fertilizer input decreased the NEEB.

Conclusions

The optimizing fertilizer management and increasing apple yield should be the efficiency strategies employed to increase economic benefit and decrease environmental effects, which would be beneficial to the sustainable development of apple orchards in Loess Plateau, China.

Background and aims

Mangrove forests have the potential to colonize and grow in both muddy and sandy coastal areas, but the effects of mangrove presence or absence on nitrate (NO_x⁻) reduction processes in these two types of coastal sediments have not been well studied.

Method

The dynamics of NO_x⁻ reduction processes were studied in surface sediments (0–5 cm) of mangrove and the adjacent bare flat in muddy and sandy coasts of China using stable isotope (¹⁵N) pairing and quantitative PCR.

Result

Sediment NO_x⁻ reduction rates (denitrification, anammox and DNRA) and their relative contributions (DEN%, ANA% and DNRA%) exhibited significant spatial and temporal variations, while the function-related genes (nirS, ANA 16S rRNA and nrfA) only exhibited significant differences in space. Sediment grain size, organic matter, nutrients, Fe²⁺/Fe³⁺, sulfide and temperature were critical factors controlling spatial and temporal variability in NO_x⁻ reduction rates. Mangrove grown in muddy coasts only had a significant impact on DNRA rates (p < 0.05), while the impact on denitrification and anammox rates were both not significant (p > 0.05). The N retention index (NIRI) variation indicated that the presence of mangrove had a more significant positive role of N retention in sandy coasts than in muddy coasts.

Conclusion

Mangrove grown in sandy coast is more effective at promoting both sediment N-loss and N retention activities compared to those in muddy coast. And our results highlight the impact of mangroves on NO_x⁻ reduction processes in muddy and sandy sediments, which is crucial for effective management and conservation efforts in nearshore ecosystems.

Background and aims

Soil warming influences decomposition not only through direct changes in the soil environment, but also by modifying litter quality. We tested the indirect effects by examining whether warming-induced changes in soil nitrogen (N) mineralization rates affect litter quality and decomposition.

Methods

Soil warming experiments were conducted in three forests characterized by differing snow depths. Soil N dynamics and leaf litter quality were measured after 5–8 years of warming. Following this warming treatment, a 2-year litter-bag experiment was performed.

Results

Soil warming affected soil N dynamics and the litter carbon-to-nitrogen (C: N) ratio, with varying effects across forests. The parameters of N dynamics during the growing season correlated with the C: N ratio of litter across the three forests; in the shallow snow forest, winter N dynamics were also related. Unlike the other two forests where the snowpack prevents soil freezing, freezing occurs in the shallow snow forest. When warming prevents freezing, ammonia production is suppressed in winer, associated with a higher C: N ratio in the litter. Additionally, in our study, soil warming decreased phenol concentrations in the shallow snow forest. Multiple regression analysis indicated that phenol concentration and C: N ratio in the litter were critical to decomposition, particularly during the early phase. Among litter traits, phenol concentration emerged as the strongest predictor of decomposition.

Conclusion

Soil warming changes litter quality, linked to changes in soil N dynamics, potentially affecting decomposition rates. This reveals indirect effects of soil warming and underscore the impacts on ecosystem processes through plant-soil interactions.

Background and aims

Despite increasing evidence of strong relationships between plants and soil microbial communities, most studies on this topic have been controlled experimental studies at small spatial and temporal scales.

Methods

In this study, we examined the relationships between tree communities and soil microbial communities by examining 1,287 soil samples collected from a 20-ha subtropical forest plot using high-throughput sequencing.

Results

We found a negative association between above- and belowground biodiversity, primarily driven by the interactions between tree communities and six specific soil microbial genera (Bryobacter, ADurb.Bin063-1, Russula, Archaeorhizomyces, Tolypocladium, and Trichoderma). These interactions were mediated by abiotic factors, particularly metal elements, which were positively correlated with the relative abundance of these specific microbial groups but negatively correlated with tree richness. Random forest analysis revealed that Archaeorhizomyces was most strongly correlated to the total basal area of evergreen and deciduous trees. Additionally, structural equation modeling indicated that the indirect impact of abiotic factors on Archaeorhizomyces was mediated by the total basal area of trees.

Conclusion

Overall, our results provide robust observational evidence for the intricate relationship between tree diversity and soil microbial communities at a large scale, revealing that specific microbial genera and abiotic factors, particularly metal elements, play crucial roles in regulating this relationship. Effective management of these interactions is essential for maintaining ecosystem function and resilience in subtropical forests.

Background and aims

The environment on Mars dramatically differs from that on the Earth, including light, radiation, magnetic field and regolith, however, the effects of Martian regolith on plant growth, environmental fitness, circadian rhythm, and rhizosphere microbiota remains unclear.

Methods

We grew Arabidopsis thaliana in simulated Martian regolith (SMR) and the changes in plant growth and development were observed. The changes in circadian rhythms of CCA1:LUC activity were monitored and transcriptomic expression was assessed by RNA sequencing (RNA-seq). 16S rRNA sequencing was carried out to analyze the rhizosphere microbiota.

Results

Arabidopsis grown in SMR displayed significantly repressed growth and rosette leaf development, and the seedlings died after 50 days with only one pair of euphylla. The plants grown in SMR showed an overall dramatically disrupted circadian rhythm. Growth in SMR led to changes in the rhythmicity of a subset of genes that regulate multiple pathways, including the circadian rhythm, porphyrin and chlorophyll metabolism. Furthermore, we identified genes associated with the circadian clock and metal metabolism. SMR contains lower absorbable contents of some basic elements, and supplementation with iron (Fe) partially restored the disturbed circadian phenotypes. Moreover, among the rhizosphere microbiota in SMR, the decreased abundance of Actinobacteria were observed, which may be associated with Fe metabolism.

Conclusion

SMR may have deleterious effects on plant growth, uptake and metabolism of elements, and circadian clock. The low absorbable level of Fe in SMR may be one of the factors causing disruption of the plant’s circadian clock and the altered abundance of microorganisms.

Aims

Ectomycorrhizal fungi are pivotal drivers in storing carbon (C) in soil. Yet, whether and how ectomycorrhizal hyphae turnover controls soil organic carbon (SOC) accumulation under nitrogen (N) deposition remains unknown.

Methods

We quantified the responses of SOC and its physical fractions (particulate organic carbon, POC and mineral-associated organic carbon, MAOC) regulated by ectomycorrhizal hyphae decomposition to chronic N addition (25 kg N ha⁻¹ yr⁻¹, 50 kg N ha⁻¹ yr⁻¹). We also explored the microbial necromass C (i.e. amino sugar) contributions SOC accumulation mediated by ectomycorrhizal hyphae decomposition under N addition.

Results

Our results showed that the ectomycorrhizal hyphae decomposition promoted the SOC sequestration dominated by MAOC accrual, and this positive effect was enhanced under N addition. Furthermore, the effects of N addition on stable SOC fraction accumulation during ectomycorrhizal hyphae decomposition was mainly attributed to the increase of microbial necromass C and the enhancement of mineral protection for SOC.

Conclusions

Our results highlight the importance of ectomycorrhizal hyphae decomposition in regulating stable SOC accumulation under N deposition. Collectively, our findings provide direct evidence for the significant role of ectomycorrhizal hyphae turnover on soil C dynamics, and contribute valuable insights into ectomycorrhizal hyphae turnover and associated soil C feedback under atmospheric N deposition.

Aims

Soil fertility depletion caused by intensive farming is a major constraint on crop production in tropical regions. However, the ability of winter fallow or green manure cultivation to improve soil quality and ecosystem multifunctionality remains largely unknown, particularly in tropics.

Methods

Here, a 4-year field study was conducted to evaluate soil quality, and ecosystem multifunctionality under four cropping systems, including pepper-double rice, cowpea-double rice, fallow-double rice, and green manure-double rice.

Results

Fallow-double rice has a limited impact on soil quality compared to vegetable cultivation, while incorporation of green manure increases soil quality by 23.0–41.2% in 0–40 cm depth (p < 0.05). Similarly, green manure-double rice increased C- and N-cycling enzyme activities by 54.2–62.3% and 80.1–106.9% in 0–40 cm depth compared to vegetable cultivation (p < 0.05), respectively. However, the cropping system has no significant effect on soil P-cycling enzyme activity. Fallow-double rice can slightly increase soil nutrients, but it does not affect soil quality and ecosystem multifunctionality. Pearson’s index showed that total soil C and NO₃⁻-N were positively correlated with soil ecosystem multifunctionality in the topsoil (0–20 cm) (p < 0.05).

Conclusion

winter green manure improves soil quality and ecosystem multifunctionality by increasing soil available nutrients and extracellular enzyme activities under the paddy system, which could be recognized as a promising strategy for soil restoration.

Graphical abstract