Plant and Soil最新文献

Aims

Conversion of natural forests to plantations would change aboveground biodiversity and soil physiochemical properties. However, how forest conversion changes soil microbial community structure and assembly process has not been well addressed.

Methods

We characterized the abundances, diversity, assembly processes, and structures of bacterial and fungal communities from a broadleaf forest (BLF) and two plantations (Moso bamboo plantation, BP; Chinese fir plantation, CP) that converted from the BLF.

Results

Conversion of broadleaf forest to plantations significantly decreased soil organic carbon and total nitrogen concentrations (P < 0.05). Bacterial and fungal abundance and diversity in BP and BLF were significantly (P < 0.05) higher than those in CP. The dominant phyla (Acidobacteria and Proteobacteria) and predicted function (Amino acid metabolism and carbohydrate metabolism) of bacterial communities were weakly changed, whereas those of fungal communities were significantly altered by forest conversion. The habitat niche breadth of BP was significantly higher than that of CP and BLF (P < 0.05) due to the broader range of resource states (available P and K) in the BP soil. Forest conversion enhanced the deterministic process but weakened the stochastic assembly process of both bacterial and fungal community assembly. Random forest model demonstrated that both bacterial and fungal community assembly were the most important driving factors regulating their community structures by forest conversion.

Conclusion

Conversion of broadleaf forest to plantations markedly altered soil bacterial and fungal community structures and enhanced their deterministic community assembly processes, deepening the understanding of the impacts of ecological processes in forestry management.

Background and aims

Salt stress is one of the most important abiotic stresses that restrict crop growth. Plant root-related microorganisms are important in moderating abiotic stress in plants. In this study, changes in microbial community composition in the different ecological niches of maize roots were studied to evaluate whether earthworms and mycorrhizal fungi could improve the salt tolerance of maize.

Methods

This experiment was a 2 × 2 factorial design representing all the combinations of arbuscular mycorrhizal (AM) fungi (2.5 g/kg) with earthworms (10/pot) in saline soil. After culture, rhizosphere, rhizoplane and endosphere bacteria of maize were collected, and community assembly was analyzed and co-occurrence network was constructed.

Results

The regulating effect of earthworm-arbuscular mycorrhiza fungi (AMF) on bacterial community gradually decreased along the rhizosphere-rhizoplane-endosphere continuum. Earthworms and AMF are able to regulate key species in bacterial co-occurrence networks, thereby influencing the composition and function of the microbiome. Members of Rhizobiaceae and Gemmatimonadaceae, as key species, potentially regulate rhizosphere bacterial communities with earthworms and AMF. On the rhizoplane, AMF may specifically enriched bacterial communities with functions related to plant P absorption and maintenance of plant K-Na ratio, thereby maintaining plant nutrient homeostasis.

Conclusion

Soil nitrate nitrogen content, plant K-Na ratio and root abscisic acid content were correlated with a large number of microbial network modules, and had potential causal relationship with rhizosphere, rhizoplane and endosphere bacterial community changes, which played an important role in the biomass accumulation of maize seedlings in saline soil. These results will provide a theoretical basis for the study of soil root-microbe interactions.

Background and aims

Elemental stoichiometry is crucial for the functioning of biogeochemical cycles. However, it is unclear how the invasion of Moso bamboo (Phyllostachys edulis) into evergreen broadleaf forests influences soil C and N stoichiometry. In the present study, we aimed to investigate how bamboo invasion affects soil C and N content, C:N ratio, and their scaling relationship at a large scale.

Methods

We collected 1,098 soil samples from 90 invasive transects using pairwise sampling across three forest types (bamboo, mixed bamboo and broadleaf, and evergreen broadleaf forests) at 30 sites in China's major bamboo distribution areas.

Results

Bamboo invasion significantly decreased the topsoil C content and C:N ratio in the 0–20-cm layer but increased the subsoil C and N content at the 30–70-cm depth. Soil C content scaled approximately isometrically (scaling exponent ≈ 1) with N content in all soil layers across all invasion stages.

Conclusion

These findings highlight the general patterns of bamboo invasion-induced changes in soil stoichiometry and provide new insights into the events in forest ecosystems caused by bamboo invasion.

Background

Bromus japonicus Thunb. is a hazardous weed in wheat fields in China. One B. japonicus population, HB-1, which was collected in Hebei Province, survived field rate flucarbazone-sodium exposure.

Method

To investigate the mechanism of flucarbazone-sodium resistance in the HB-1 population, the herbicide target als gene was isolated, and the in vitro ALS activity was tested. HPLC‒MS/MS was applied to detect flucarbazone-sodium absorption and residue level. Furthermore, RNA-seq and qRT‒PCR were applied to detect genes related to flucarbazone-sodium metabolism or flucarbazone-sodium and its metabolite transport.

Result

The results indicated that in resistant population there were no mutations in the als gene sequences or differences in the IC₅₀ of ALS compared with the sensitive population. In addition, als gene relative copy number and expression also showed no difference. However, significantly increased herbicide metabolism was found in the HB-1 population. In the end, four cytochrome P450 genes (C71D55b, C71A1, C71D55, T5H), three glutathione S-transferase genes (GSTZ, GSTU6b, GSTFB), and three ABC transporter genes (ABCC3, ABCF1, ABCG11) were selected and identified as potentially playing a role in flucarbazone-sodium resistance.

Graphical Abstract

Aim

The objective of this research was to investigate the spatio-temporal variations in sedimentary nutrient levels and establish correlations with various hydro-geomorphic and ecological parameters, including the magnitude of tidal-inundation, distance from the river and sea-front, and litter production by different mangrove species within the study area.

Methods

Twelve transects were selected, each with atleast four sampling points spaced at intervals averaging 100 m, considering various hydro-geomorphic attributes for seasonal sediment sample collection. Eight major soil parameters were measured, including the nutrient parameters TN, TP, TK, OC, OM, NO₃^– and PO₄^3–, as well as CaCO₃. Mangrove litter collections were conducted using litter traps.

Results

The total-nitrogen (TN) exhibited distinct patterns: the lowest annual mean was 152.24 ± 7.05 kg/ha in the lower zone, peaking at 209.7 ± 11.8 kg/ha in the middle zone, and decreasing in the upper zone with increasing distance from the sea. Along the ‘mangrove dominated intertidal mudflat’ gradient, TN was lower near the riverfront and higher in the forest interior. Seasonally, TN was highest in postmonsoon and lowest during the monsoon. Other parameters showed similar patterns with varying magnitudes. Litter production varied among species, with Excoecaria agallocha showed highest rate at 41.60 ± 9.58 g/m²/month, followed by Bruguiera gymnorrhiza and Avicennia alba. Litter production was highest in postmonsoon, declining towards the monsoon. ANOVA results revealed intricate relationships between seasons, transects, and the eight dependent variables.

Conclusion

The analysis underscored the pronounced spatio-temporal variability in nutrient levels, influenced by a range of hydro-geomorphic factors, and highlights a good correlation with litter productivity of the region.

Background and aims

Nitrogen (N) addition affects plant biodiversity and community structure, subsequently altering the stability of above-ground net primary productivity (ANPP) in grassland ecosystems. However, the effect of adding different nitrogen compounds and their subsequent interactions with mowing on the stability of both below-ground net primary productivity (BNPP) and total net primary productivity (TNPP) are largely unknown.

Methods

This study compared the impact of adding two nitrogen compounds, NH₄NO₃ and urea, on the temporal stability of ANPP, BNPP, and TNPP in mowed and unmowed saline-alkaline grasslands.

Results

We found that the ANPP temporal stability in unmowed grasslands was not affected by NH₄NO₃ addition but increased with urea addition. Conversely, the ANPP temporal stability in mowed grasslands decreased with NH₄NO₃ addition and was not affected by urea addition. Mowing decoupled the ANPP and BNPP temporal stability responses to nitrogen addition. Without mowing, the BNPP temporal stability in response to adding different forms of nitrogen aligned with that of ANPP; however, with mowing, the BNPP temporal stability was not affected by adding NH₄NO₃ or urea, exhibiting an inconsistent trend of change in comparison to the ANPP temporal stability. The ANPP resistance indirectly regulates the response of the BNPP temporal stability to nitrogen addition in unmowed grasslands, whereas the BNPP temporal stability was not affected by plant above-ground indicators in mowed grasslands.

Conclusions

Overall, our study addresses the scarcity of research on ecosystem temporal stability in saline-alkaline grasslands and demonstrates that mowing management can regulate the effects of different forms of nitrogen addition on ecosystem stability.

Background and aims

Shallow water table (WT) forests (representing ~ 50% of Amazonian land areas) exhibit different characteristics and functioning compared to the more widely studied deep WT forests. However, less is understood about the determinants of biomass allocation to aerial and belowground components in shallow WT forests. Here we investigate how limitations imposed by soil physical properties influence the distribution of fine root biomass and the partitioning of biomass (BGB: AGB ratio) in shallow WT forests, and the relationships with their stand structure.

Methods

We used extensive ground-based data on soil properties, soil nutrients, WT monitoring, and direct biomass measurements along a 600 km transect of shallow WT forests in the central Amazon region.

Results

Soil water excess, due to a wetter climate or a persistently shallow WT, restricts fine-root distribution to the upper soil layers. This restriction, alone or combined with phosphorus limitation, leads to a higher biomass allocation belowground, associated with stand structures characterized by a higher density of smaller trees. Opposite patterns are found where the soil experiences no excess water or does so infrequently. Soil nutrient availability contributes to biomass partitioning, but with WT regimes strongly modulating its effects.

Conclusion

Finding that soil water regime have an overarching control on fine-root distribution and biomass partitioning in shallow WT forests challenges the dominant perspective of allocation being mostly affected by soil nutrients and climate. These findings improve our understanding of a large fraction of the Amazon rainforest, with important implications for modeling and predicting its functioning as a carbon store and the regulation of biogeochemical cycles.

Background and aims

The ‘home-field advantage’ (HFA) hypothesis posits that plant litters decompose faster in their native habitat than elsewhere. Uncovering the mechanisms of HFA effect during litter decomposition is crucial for understanding ecosystem nutrient cycling and carbon budgeting.

Methods

We investigated HFA effect in agricultural and forest ecosystems through a two-year reciprocal transplant field experiment in a temperate region, using post-harvest maize straw and mixed forest litter. We examined the temporal dynamics of HFA by analyzing the interplay influence of plant residue quality and soil microbial community composition.

Results

We observed that the presence and strength of HFA varied depending on the stage of litter decomposition, with the difference in initial chemistry between litters diminishing over time. Our findings indicate a variable HFA, ranging from neutral to positive, linked to the persistence of plant residue compounds (as inferred by Aromatic/Aliphatic ratio). In specific, we found a positive mean HFA effect for mixed litter and a negative effect for maize straw, highlighting that lower quality plant residues may enhance HFA. Moreover, we found that HFA was positively affected by dissimilarity in bacterial community between ‘home’ and ‘away’ soils in later stages of litter decomposition, which was indirectly impacted by bacterial regulation of N-related hydrolases activities, indicating a bacterial-driven rather than fungal-driven influence on HFA effect.

Conclusion

Our study underscores the importance of considering stage-dependence in HFA studies, emphasizing the influence of plant residue quality and highlighting the greater role of bacterial communities over fungi in affecting the dynamics of HFA effect.

Introduction

Crop mixtures can be an important part of the toolkit for maintaining crop production while addressing the climate and nature crises. However, uncertainties around some issues may prevent their uptake.

Research question

This study addressed several uncertainties, specifically the response of mixture yields to climate and management, and the impacts of mixed cropping on seed chemical composition, soil carbon and nutrients.

Materials and methods

We undertook 32 intercropping trials between 2020 and 2022 on both commercial and research farms. These varied in design, management and crop combinations, with mixture choice often determined by farmers. We assessed multiple responses including yield, weed cover, and seed and soil chemical composition.

Results and conclusions

When compared to monocultures, yield gains from growing a crop mixture were roughly 20% based on Crop Performance Ratio (CPR). We found limited impacts of mixture diversity and composition on seed chemical composition, influences of management on weed control, and enhanced crop mixture performance under cooler conditions with lower rainfall. We also found varying mixture performance depending on mixture composition. Importantly, irrespective of management, climate, and composition effects, crop mixtures always performed at least as well as expectations based on monocultures. Even without further refinement from, for example, targeted breeding, crop mixtures provide reliable crops without yield losses or (for parameters tested) substantial changes in seed chemistry. However, detected reductions in organic matter in upper soil layers indicate a priority for future research is understanding crop mixture impacts on soil carbon dynamics in both shallow and deep soils.

Aims

Opencast lignite mining causes significant disturbances to the natural environment. It isn’t only the plant cover that is destroyed, also the soil cover is damaged. Soils are replaced by dumps with material composition that properties differ significantly from natural soils. Reclamation of these areas is necessary.

Methods

This study presents the effect of forty-three years of agricultural reclamation involving alternating winter wheat and winter rapeseed in three fertilization treatments: 0- (without fertilization), I-NPK and II-NPK on the chemical properties of Technosols.

Results

The investigation demonstrated that the Ap-horizon emerged in the case of I-NPK and II-NPK treatments. There was an improvement in chemical properties for the Ap-horizon as compared to 1978: soil organic carbon (SOC), total nitrogen (TN), available phosphorus (P) and potassium (K) increased. The CaCO₃ decreased, and SOC/TN ratio declined, while pH and cation exchange capacity (CEC) remained unchanged. For the Technosols’ surface horizon of the 0-NPK, there were also temporal increases in TN and SOC with a decrease in the SOC/TN ratio, whereas P, K, pH, CEC and CaCO₃ values did not change significantly.

Conclusion

In the 43-year-old post-mining Technosols, under the effect of fertilization and cultivated plants, the Ap horizon has formed, while in the non-fertilized soil the AC and CA horizons. Soil that were fertilized had significantly higher SOC, TN, P and K values in the surface horizon than minesoils without fertilization. In the subsurface horizons, the properties of minesoils were similar regardless of fertilization.