Biomass Ratio Research Articles

Latitudinal patterns and drivers of plant lignin and microbial necromass accumulation in forest soils: Disentangling microbial and abiotic controls

Plant- and microbial-derived compounds are the two primary sources of the soil organic carbon (SOC) pool. However, whether and how biotic and abiotic factors regulate the means through which microbes and plants contribute to SOC accumulation at a regional scale remains unclear. This study investigated the distribution patterns of plant lignin components and microbial necromass in soils, as indicated by lignin phenols and amino sugars across five latitudinal forests in eastern China. The contents of plant lignin and microbial necromass in the soil increased with increasing latitude. However, their contributions to SOC followed quadratic patterns with increasing latitude. Given its positive relationship with SOC content in all examined forests, microbial necromass seemed to play a more critical role in SOC accumulation than lignin phenols. Moreover, plant lignin and microbial necromass accumulation and their contributions to SOC were mainly influenced by the joint effects of climatic variables, microbial traits, and soil properties, but their importance was divergent. Specifically, the mean annual temperature (MAT) and soil phosphorus content were central to plant lignin accumulation, whereas MAT and the microbial richness: biomass ratio mainly controlled microbial necromass accumulation. These findings demonstrate that microbial necromass plays a more critical role than plant lignin in forest SOC accumulation and further highlight the importance of microbial traits in microbial necromass accumulation.

Soil microbes deal with the nitrogen deposition enhanced phosphorus limitation by shifting community structure in an old-growth subtropical forest

Elevated atmospheric nitrogen (N) deposition potentially enhances the degree of phosphorus (P) limitation in tropical and subtropical forests. However, it remains elusive that how soil microorganisms deal with the N deposition-enhanced P limitation. We collected soils experienced 9 years of manipulative N input at various rates (0, 40, and 80 kg N ha−1 y−1) in an old-growth subtropical natural forest. We measured soil total and available carbon (C), N and P, microbial biomass C, N and P, enzyme activities involved in C, N and P acquisition, microbial community structure, as well as net N and P mineralization. Additionally, we calculated element use efficiency and evaluated microbial homeostasis index. Our findings revealed that N input increased microbial biomass C:P (MBC:P) and N:P (MBN:P) ratios. The homeostasis indexes of MBC:P and MBN:P were 0.68 and 0.75, respectively, indicating stoichiometric flexibility. Interestingly, MBC:P and MBN:P correlated significantly with the fungi:bacteria ratio (F:B), not with N and P use efficiencies, net N and P mineralization, and enzyme C:P (EEAC:P) and N:P (EEAN:P) ratios. Furthermore, EEAC:P and EEAN:P correlated positively with F:B but did not negatively correlate with the C:P and N:P ratios of available resources and microbial biomass. The effects of N deposition on MBC:P, MBN:P and EEAN:P became insignificant when including F:B as a covariate. These findings suggest that microbes flexibly adapted to the N deposition enhanced P limitation by changing microbial community structure, which not only alter microbial biomass C:N:P stoichiometry, but also the enzyme production strategy. In summary, our research advances our understanding of how soil microorganisms deal with the N deposition-enhanced soil P limitation in subtropical forests.

Sandy soil reclamation technologies to improve crop productivity and soil health: a review

Sandy soils are characterized by low soil moisture content and nutrient retention due to high permeability, limiting crop productivity and threatening food security in arid and semi-arid regions worldwide. Various reclamation technologies have been developed to address these challenges, but their effectiveness has not been comprehensively evaluated. This systematic review evaluated the performance of 42 sandy soil reclamation technologies reported in 144 studies from 27 countries that met specified selection criteria. Performance was evaluated based on response ratio (RR) of aboveground biomass and grain yield, as indicators of productivity, and soil moisture content and soil organic carbon (SOC), as indicators of soil health. The 42 technologies employed four main soil amendments: biochar, organic amendments, organic amendments combined with biochar, and soft rock. Overall, all technologies increased productivity and improved soil health. Biochar application was found to be the most effective technology, increasing grain yield by 51.6%, aboveground biomass by 67.4%, soil moisture content by 17.3%, and SOC by 74.2%. Soft rock application increased grain yield by 20.3%, aboveground biomass by 27.6%, soil moisture content by 54.5%, and SOC by 12.8%. Organic amendments increased grain yield by 48.7%, aboveground biomass by 45.6%, soil moisture content by 20.8%, and SOC by 36.7%. However, the combination of biochar and organic amendments showed lower improvements, with increases of 25.4%, 15.6%, 1.3%, and 25.4% for grain yield, aboveground biomass, soil moisture content, and SOC, respectively. Our conclusion is that the findings provide strong evidence that sandy soil reclamation technologies can significantly improve crop productivity and food security. Considering the variability in technologies responses across continents, there is need for further research to determine the optimal technology for specific locations, crops, and management practices.

Light Intensity: A Key Ecological Factor in Determining the Growth of Pseudolarix amabilis Seedlings

The notable absence of juvenile Pseudolarix amabilis trees in forest understories suggests their vulnerability to ecological niche competition, leading to limited survival prospects. This study examines the key factors limiting the growth of P. amabilis seedlings by investigating the effects of five ecological factors: light intensity, rainfall, groundwater level, soil type, and type of fertilization, on the growth of one-year-old P. amabilis seedlings. Our results demonstrate that increasing the light intensity promotes plant growth by augmenting the leaf count, leaf biomass, plant height, stem biomass, root biomass, and total biomass. Further analysis reveals that increased light intensity influences biomass allocation, reducing the specific leaf area and leaf–stem biomass ratio, and favoring root and stem growth over leaf investment. Rainfall, groundwater level, fertilization type, and rhizosphere soil type primarily influence root growth by impacting the soil’s physicochemical properties. Specifically, rising groundwater levels lower the soil temperature and increase the soil moisture, total potassium content, and soil pH, leading to reductions in root biomass, plant height, net height increment, leaf number, and total biomass. When groundwater levels reach 21 cm and 28 cm, submerging the surface soil layer, root biomass decreases by 1.6 g/plant (−51.6%) and 2.3 g/plant (−74.2%), respectively. Further analysis reveals a gradual decrease in the root–shoot ratio above the 14 cm groundwater level, while the specific leaf area and leaf–stem biomass ratio remains unaffected, indicating stronger belowground root stress compared to aboveground stem and leaf components. The results highlight light intensity as the key ecological factor determining the growth of P. amabilis seedlings. These findings underscore the importance of considering light intensity in the management of natural stands, the cultivation of artificial forests, and the nursery cultivation of endangered P. amabilis.

The effects of litter input and increased precipitation on soil microbial communities in a temperate grassland.

Global warming has contributed to shifts in precipitation patterns and increased plant productivity, resulting in a significant increase in litter input into the soils. The enhanced litter input, combined with higher levels of precipitation, may potentially affect soil microbial communities. This study aims to investigate the effects of litter input and increased precipitation on soil microbial biomass, community structure, and diversity in a temperate meadow steppe in northeastern China. Different levels of litter input (0%, +30%, +60%) and increased precipitation (0%, +15%, +30%) were applied over a three-year period (2015-2017). The results showed that litter input significantly increased the biomass of bacteria and fungi without altering their diversity, as well as the ratio of bacterial to fungal biomass. Increased precipitation did not have a notable effect on the biomass and diversity of bacteria and fungi, but it did increase the fungal-to-bacterial biomass ratio. However, when litter input and increased precipitation interacted, bacterial diversity significantly increased while the fungal-to-bacterial biomass ratio remained unchanged. These findings indicate that the projected increases in litter and precipitation would have a substantial impact on soil microbial communities. In energy-and water-limited temperate grasslands, the additional litter inputs and increased precipitation contribute to enhanced nutrient and water availability, which in turn promotes microbial growth and leads to shifts in community structure and diversity.

Box-Behnken design for the synthesis optimization of mesoporous sulfur-doped carbon-based materials from birch waste: Promising candidates for environmental and energy storage application

The development of biomass-based carbon materials has accelerated the research interest in environmental (e.g., adsorbents for wastewater decontamination) and energy applications (e.g., batteries). In this paper, we developed a series of carbon materials (CMs) using a sulfur doping strategy to improve the physicochemical, adsorptive and energy storage properties of the aforementioned CMs. CMs were prepared and optimized using an experimental design denoted as the Box-Behnken design approach with three independent factors (i.e., the temperature of pyrolysis, zinc chloride: biomass ratio and sulfur: biomass ratio), and the responses were evaluated, namely the Specific Surface Area (SBET), mesopore area (AMeso) and micropore area (AMicro) with the help of Nitrogen Physisorption. According to the statistical analysis, under the studied conditions, the responses were mainly influenced by the pyrolysis temperature and ZnCl2 ratio, while the sulfur content did not give rise to any remarkable differences in the selected responses. The physicochemical characterization of the CMs suggested that very high Specific Surface Areas ranging from 1069 to 1925 m2 g−1 were obtained. The sulfur doping resulted in up to 7.33 wt% of sulfur in the CM structure, which yielded CMs with more defects and hydrophilic surfaces. When tested as adsorbents, CMs exhibited a very high adsorption capacity (190 – 356 mg g−1), and as anodes, they demonstrated a competitive Lithium Ion Battery (LIB) storage capacity, at least during the first five cycles (306 mAhg−1 at 1 C for CM9). However, further studies on long-term cyclability are required to prove the CM materials suitability in LIBs. This work extends our understanding of how pyrolysis and sulfur doping of biomass feedstock affects carbon materials' usability, final characteristics and potential to use in wastewater decontamination by adsorption and as anodes in LIBs.

Belowground exploration by trees and shrubs

Unlike trees, shrubs (i.e., multiple-stemmed woody plants) do not need evenly spaced large diameter structural roots and therefore should be more responsive to heterogeneous distributions of soil resources and spread further per unit belowground biomass. We therefore hypothesized that compared to trees, shrubs respond more to asymmetric distributions of nutrients, reach nutrient-rich patches of soil faster, and do so with less below-ground biomass. To test these three hypotheses, we planted individual seedlings of shrubs (Cornus racemosa, Rhus glabra, and Viburnum dentatum) and trees (Acer rubrum, Betula populifolia, and Fraxinus americana) in the centers of sand-filled rectangular boxes. In one direction we created a stepwise gradient of increasing nutrients with slow-release fertilizer; in the other direction, no fertilizer was added. Seedlings were harvested when their first root reached the plexiglass-covered fertilized end of their box; time taken, above-ground biomass, and below-ground biomass per nutrient segment were determined. Shrubs and trees did not consistently differ in precision of root foraging (i.e., the ratio of biomass in the fertilized and unfertilized soil) or in rates (g/day) and efficiencies (cm/day) of lateral root growth. Interspecific variation appeared more related to species’ habitats than to growth form. The fastest and most efficient roots were produced by the shrub (R. glabra) and the tree (B. populifolia), both characteristic of poor and heterogeneous soils. Root foraging by R. glabra was also facilitated by rapid rhizomatous expansion.

Development of yield prediction model for wheat by using AquaCrop model with different nitrogen dose applications in Central Anatolia Region (semi arid) conditions

In this study, yield prediction was made for Tosunbey and Bayraktar bread wheat varieties under rainfall conditions and 4 different fertilizer ratios with AquaCrop model, one of the plant growth models. In this experiment conducted at Haymana Ikizce Research Farm, actual field observations and model predicted grain yield, biomass, and green area coverage ratio were evaluated. Mean deviation (α), standard error (RMSE), and model efficiency coefficient (E) tests were used to determine the performance of the model. The AquaCrop model was calibrated in the first year and validated based on observational data collected in the first and second years of the experiment, respectively. Based on the results obtained, it was observed that the AquaCrop model simulated grain yield at different levels of nitrogen fertilizer applications with higher precision for Bayraktar variety. For Bayraktar variety, grain yield E = 0.93 in the first year and 0.99 in the second year for grain yield, and E = 0.83 in the first year and 0.98 in the second year for biomass, indicating excellent agreement between model and observation was found. In Tosunbey variety, first-year grain yield E=0.66 and 2nd year grain yield 0.76 were found. The 2nd year RMSE value for grain yield of Bayraktar variety was 0.266, and the 2nd year RMSE value for the grain yield of Tosunbey variety was 0.664 and found to be statistically compatible. Grain yield, biomass, and percent cover (CC) values obtained from the model were found to be highly consistent with field observations.

Spatio-temporal dynamics in microalgal communities in Arctic land-fast sea ice

Sea ice microalgae are an important source of energy for the polar marine food web, representing the primary carbon source prior to pelagic phytoplankton blooms. Here we investigate community dynamics of sea ice microalgal communities in land-fast sea ice across six different fjords in high-Arctic Svalbard, Norway, during Spring (April – May). We found that light (0.1 – 23% incoming PAR / 0.1 – 193 μmol photons m-2s-1) played a central role in determining community composition, with more diverse assemblages observed in sites with more light transmitted to the bottom ice community. In April, microalgal assemblages were similar when under-ice light transmittance was similar, independent of geographical location, however this light-derived separation of community structure was not evident in May. At all sites, assemblages were dominated by pennate diatoms, with the most abundant taxon being Nitzschia frigida. However, with increasing under-ice light transmittance, we saw an increase in the relative abundance of Dinophyceae, Navicula spp. and Thalassiosira spp.. A positive relationship between light and δ13C enrichment and C:N ratios in the ice algal biomass demonstrated the effect of light on the biochemical composition of ice algae. Light did not correlate with cell abundance or chlorophyll a concentration. With anticipated changes to Arctic sea ice extent and snow cover as a result of climate change, we will see shifts in the light transmitted to the bottom ice community. These shifts, whether caused by reduced light transmittance from increased snow cover or increased light transmittance from thinning ice, snow depth or increased rainfall, will likely alter sea ice microalgal community composition, which in turn, may influence the success of secondary production and biogeochemical cycling in polar waters.

Influence of reaction parameters on biofuels derived from solvothermal liquefaction of Citrus limetta fruit wastes

Citrus limetta or sweet lime is a widely consumed fruit worldwide. The wastes generated from their processing are enormous and are discarded without any value-addition. Biomass liquefaction in hydrogen-donor solvent is an effective thermochemical conversion technique to produce value added products such as biocrude and biochar from wet biomasses directly. Thus, liquefaction studies of Citrus limetta peel and pulp were conducted using solvent methanol at temperatures of 240 °C–280 °C, 30 min residence time as well as 1:2, 1:3 and 1:4 ratios of biomass to solvent. The impact of temperature as well as biomass to solvent ratio on yield of biocrude and biochar were investigated herein. Biocrude produced from Citrus limetta peel at 240 °C and 1:3 ratio of biomass to solvent is maximum (12.5 wt. %). At reaction parameters of 280 °C and 1:4 ratio of biomass to solvent, biocrude from Citrus limetta pulp showed higher heating value of 27.18 MJ kg−1 which was the maximum obtained in this study. The gas-chromatography mass-spectrometry (GC-MS) indicated presence of alcohols, phenols, alkanes, ketones, ethers, esters and fatty acid methyl esters as major compounds. The characteristics and energy content of biochar demonstrated their potentiality for bioenergy applications.

Dynamic carbon allocation trade‐off: A robust approach to model tree biomass allometry

Abstract Forest above‐ground biomass (AGB) is often estimated by converting the observed tree size using allometric scaling between the dry weight and size of an organism. However, the variations in biomass allocation and scaling between tree crowns and stems due to survival competition during a tree's lifecycle remain unclear. This knowledge gap can improve the understanding of modelling tree biomass allometry because traditional allometries ignore the dynamics of allocation. Herein, we characterised allometric scaling using the dynamic ratio (r) of the stem biomass (SB) to AGB and a dynamic exponent. The allometric models were biologically parameterised by the r values for initial, intermediate and final ages rather than only a regression result. The scaling was tested using field measurements of 421 species and 2213 different‐sized trees in pantropical regions worldwide. We found that the scaling fluctuated with tree size, and this fluctuation was driven by the trade‐off relationship of biomass allocation between the tree crown and stem depending on the dynamic crown trait. The allometric scaling between SB and AGB varied from 0.8 to 1.0 for a tree during its entire lifecycle. The fluctuations presented a general law for the allometric scaling of the pantropical tree biomass and size. Our model quantified the trade‐off and explained 94.1% of the allometric relationship between the SB and AGB (93.8% of which between D2H and AGB) for pantropical forests, which resulted in a better fit than that of the traditional model. Considering the effects of the trade‐off on modelling, the actual biomass of large trees could be substantially greater than conventional estimates. These results highlight the importance of coupling growth mechanisms in modelling allometry and provide a theoretical foundation for better describing and predicting forest carbon accumulation.

Decoupled response of microbial taxa and functions to nutrients: The role of stoichiometry in plantations

The resource quantity and elemental stoichiometry play pivotal roles in shaping belowground biodiversity. However, a significant knowledge gap remains regarding the influence of different plant communities established through monoculture plantations on soil fungi and bacteria's taxonomic and functional dynamics. This study aimed to elucidate the mechanisms underlying the regulation and adaptation of microbial communities at the taxonomic and functional levels in response to communities formed over 34 years through monoculture plantations of coniferous species (Japanese larch, Armand pine, and Chinese pine), deciduous forest species (Katsura), and natural shrubland species (Asian hazel and Liaotung oak) in the temperate climate. The taxonomic and functional classifications of fungi and bacteria were examined for the mineral topsoil (0–10 cm) using MiSeq-sequencing and annotation tools of microorganisms (FAPROTAX and Funguild). Soil bacterial (6.52 ± 0.15) and fungal (4.46 ± 0.12) OTUs' diversity and richness (5.83*103±100 and 1.12*103±46.4, respectively) were higher in the Katsura plantation compared to Armand pine and Chinese pine. This difference was attributed to low soil DOC/OP (24) and DON/OP (11) ratios in the Katsura, indicating that phosphorus availability increased microbial community diversity. The Chinese pine plantation exhibited low functional diversity (3.34 ± 0.04) and richness (45.2 ± 0.41) in bacterial and fungal communities (diversity 3.16 ± 0.15 and richness 56.8 ± 3.13), which could be attributed to the high C/N ratio (25) of litter. These findings suggested that ecological stoichiometry, such as of enzyme, litter C/N, soil DOC/DOP, and DON/DOP ratios, was a sign of the decoupling of soil microorganisms at the genetic and functional levels to land restoration by plantations. It was found that the stoichiometric ratios of plant biomass served as indicators of microbial functions, whereas the stoichiometric ratios of available nutrients in soil regulated microbial genetic diversity. Therefore, nutrient stoichiometry could serve as a strong predictor of microbial diversity and composition during forest restoration.

Effect of Ludwigia octovalvis biomass ratio on hydrocarbon phytotoxicity

Phytoremediation, an environmentally friendly approach that uses plants to break down and remove contaminants from the environment, as a viable treatment for the removal of hydrocarbons. It has the potential to be more efficient, less expensive, and more ecologically friendly than the conventional treatment. This study aimed to determine the phytoremediation capability of native plant, Ludwigia octovalvis, by varying the biomass of plants to 100 % petroleum sludge with 33,368 mg/kg total petroleum hydrocarbon (TPH). After 30 days of treatment, a different biomass of L. octovalvis (0.106 g of plants/g of TPH, 0.159 g of plants/g of TPH and 0.212 g of plants/g of TPH) was exposed to 30 kg petroleum sludge. Two treatments with and without plants were tested to investigate if there is an effect of plant number on the removal of TPH in sludge. Results revealed that exposure to real petroleum sludge had removal efficiencies of 45.2 % (106.2 g biomass of plants), 30.1 % (159.3 g biomass of plants) and 40.0 % (212.4 g biomass of plants). Relative growth rate (RGR) analysis showed that as the biomass of plants increased, the concentration of pollutant decreased. Scanning electron microscopic analysis showed that plant root had increasing C percentage in the root part compared to stem. The plant biomass of 106.2 g had the highest TPH removal efficiency in 30 kg petroleum sludge, and the ratio of plant biomass to TPH mass was 0.106 g/g. The results could be used as a basis for other research on scaling up phytoremediation.

Under-canopy afforestation after 10 years: assessing the potential of converting monoculture plantations into mixed stands.

Under-canopy afforestation using different tree species is a key approach in close-to-nature management to improve the structural and functional stability of plantation forests. However, current research on understory afforestation mainly focuses on the seedling stage, with limited attention to saplings or young trees. In this study, we evaluated the growth characteristics and leaf traits of 14-year-old Pinus sylvestris var. Mongolica trees under four different upper forest density (UFD) treatments: 0 trees/hm2 (canopy openness 100%, CK), 150 trees/hm2 (canopy openness 51.9%, T1), 225 trees/hm2 (canopy openness 43.2%, T2), and 300 trees/hm2 (canopy openness 28.4%, T3). We found that the survival rate of P. sylvestris in the T3 was significantly lower than in the other treatments, with a decrease of 30.2%, 18.3%, and 19.5% compared to CK, T1, and T2, respectively. The growth of P. sylvestris in the T1 treatment exhibited superior performance. Specifically, T1 showed a significant increase of 18.8%, 5.5%, and 24.1% in tree height, diameter at breast height, and crown width, respectively, compared to the CK. The mean trunk biomass ratio in the understory was significantly higher than that in full light by 15.4%, whereas the mean leaf biomass ratio was significantly lower by 12.3%. Understory P. sylvestris trees tended to allocate more biomass to the trunk at the expense of decreasing leaf biomass, which would facilitate height growth to escape the shading environment, although the promotion was relatively limited. Leaf length, leaf width, leaf area, leaf thickness, mesophyll tissue thickness, epidermis thickness, and leaf carbon content were the highest in the CK and tended to decrease with increasing UFD, indicating that a high-light environment favored leaf growth and enhanced carbon accumulation. In summary, young P. sylvestris trees adapted to moderate shading conditions created by the upper canopy, and the T1 treatment was optimal for the growth of understory P. sylvestris. This study provides insights into different adaptive strategies of young P. sylvestris trees to changes in light environment, providing practical evidence for under-canopy afforestation using light-demanding trees during pure plantation transformation.

Exogenous Organic Matter Improves Potato Yield by Regulating the Microbiological Fertility Index

The nutrient availability of carbon (C), nitrogen (N), and phosphorus (P) has been decreasing due to a decline in the biological function of yellow soil, limiting potato yield (PY). Increasing biochar or organic fertilizer input is an effective way to improve soil microbiological fertility. However, indexes to regulate soil microbiological fertility using biochar and organic fertilizer individually or in combination and these indexes’ associations with PY remain unclear. In this study, four fertilization strategies were developed using the nutrient balance method: CK (recommended NPK fertilization), BC (NPK + biochar), OF (NPK + organic fertilizer), and BF (NPK + 1/2 biochar + 1/2 organic fertilizer). Using different fertilization strategies, the eco-stoichiometry characteristics of the soil microbial biomass and enzyme activity; the bioavailability of C, N, and P; and the differences in PY were investigated, and the direct and indirect effects of these factors on PY were determined over a two-year period. The results showed that exogenous organic matter input could considerably affect the stoichiometric ratios of soil microbial biomass; C; N; P; the stoichiometric ratios of C-converting, N-converting, and P-converting enzyme activities (expressed as BG+CBH, NAG+LAP, and AP, respectively); and the integrated enzyme index (IEI). The IEI was the highest in BF, followed by OF, BC, and CK. A significant positive correlation was found between the microbial biomass C, N, and P and their corresponding converting enzyme activities (p < 0.05). The ln(BG+CBH):ln(NAG+LAP), ln(BG+CBH):lnAP, and ln(NAG+LAP):lnAP ratios were all higher than 1:1, but they approached 1:1 in the order of CK-BC-OF-BF. Compared to soil C and N, P-converting enzyme activity was the primary limiting factor for soil nutrient conversion in the study area. BF was less restricted by P and more balanced in its nutrient ratio. The microbial biomass C:N:P could affect PY in eight ways. (1) Microbial biomass C:N directly decreased PY, and microbial biomass C:P indirectly increased PY. (2) It could decrease C-converting enzyme activity, (3) decrease N availability to increase C-converting enzyme activity, (4) decrease P availability, or (5) decrease P availability to decrease the soil C:P-converting enzyme activity ratio. Microbial biomass N:P indirectly increased PY (6) by increasing the soil C:P-converting enzyme activity ratio, (7) by increasing C-converting enzyme activity, or (8) by increasing N availability to increase C-converting enzyme activity. Thus, BF is an effective strategy for regulating the soil microbiological fertility index; enhancing C, N, and P nutrient conversion; and increasing PY. The input of exogenous organic matter can alter the stoichiometric ratios of soil microbial biomass C, N, and P; the stoichiometric ratios of C-converting, N-converting, and P-converting enzyme activities; and nutrient availability, thus regulating PY. Microbial biomass N:P and soil C:P-converting enzyme activity ratios influence PY the most.

Plant ammonium sensitivity is associated with external pH adaptation, repertoire of nitrogen transporters, and nitrogen requirement.

Modern crops exhibit diverse sensitivities to ammonium as the primary nitrogen source, influenced by environmental factors such as external pH and nutrient availability. Despite its significance, there is currently no systematic classification of plant species based on their ammonium sensitivity. We conducted a meta-analysis of 50 plant species and present a new classification method based on the comparison of fresh biomass obtained under ammonium and nitrate nutrition. The classification uses the natural logarithm of the biomass ratio as the size effect indicator of ammonium sensitivity. This numerical parameter is associated with critical factors for nitrogen demand and form preference, such as Ellenberg indicators and the repertoire of nitrogen transporters for ammonium and nitrate uptake. Finally, a comparative analysis of the developmental and metabolic responses, including hormonal balance, is conducted in two species with divergent ammonium sensitivity values in the classification. Results indicate that nitrate has a key role in counteracting ammonium toxicity in species with a higher abundance of genes encoding NRT2-type proteins and fewer of those encoding the AMT2-type proteins. Additionally, the study demonstrates the reliability of the phytohormone balance and methylglyoxal content as indicators for anticipating ammonium toxicity.

Context‐dependent impact of changes in precipitation on the stability of grassland biomass

Abstract Community stability plays a crucial role in ensuring the consistent provision of ecosystem services despite environmental changes, including alterations in precipitation patterns. Over the past decades, significant progress has been made in understanding the responses of the stability of grassland plant communities and underlying mechanisms, defined as the ratio of the temporal mean biomass to the standard deviation. However, a crucial knowledge gap remains regarding whether the impacts of precipitation on the stability of grassland biomass are contingent upon specific contextual factors. Here, we examined the stability of above‐ and below‐ground biomass in adjacent grass‐ and shrub‐dominated communities through a 7‐year manipulation experiment involving seven precipitation levels: 20%, 40% and 60% decrease, as well as 20%, 40% and 60% increase in natural rainfall, in addition to ambient precipitation. We found that the stability of community biomass was influenced by three contextual factors including the magnitude and directionality of precipitation, above‐ and below‐ground biomass and the type of vegetation. In particular, higher and more intense precipitation resulted in higher stability of above‐ground biomass in both grass‐ and shrub‐dominated communities. Conversely, higher precipitation intensity led to decreased below‐ground biomass stability in grass‐dominated communities but increased below‐ground biomass stability in shrub‐dominated communities. Species stability and species asynchrony consistently played a positive role in explaining the stability of above‐ground biomass in both grass‐ and shrub‐dominated communities. However, species asynchrony negatively influenced below‐ground biomass stability in grass‐dominated communities without a comparable effect in shrub‐dominated communities. The preeminent contribution to the total community biomass was identified in the stability of below‐ground biomass, evident in both grass‐dominated and shrub‐dominated communities. Synthesis. This study highlights that while the specific effects of changes in precipitation may vary depending on the context, the fundamental processes governing biomass stability are consistent. These findings elucidate the desert steppe ecosystems' adaptive response to precipitation variations and emphasize their pivotal role in maintaining ecosystem functions under climatic perturbations. Read the free Plain Language Summary for this article on the Journal blog.

Differences in dry matter production and grain yield of maize (Zea mays L.) cultivars with contrasting nitrogen efficiency

ABSTRACT We aimed to investigate the differences in dry matter accumulation (DMA), distribution, remobilisation, and yield of maize cultivars with contrasting nitrogen efficiency responses to nitrogen application rates. Nitrogen fertiliser increased DMA, crop growth rate (CGR), redistribution of pre-silking dry matter, and accumulation of post-silking dry matter while reducing the root/shoot biomass ratio to substantially increase biomass yield and final maize grain yield. Higher final theoretical biomass yield, maximum increasing rate (MIR), and average increasing rate, later days to MIR, longer duration of rapid growth period, higher ratio of vegetative organs, and rational dry matter distribution aboveground and belowground contribute to higher DMA and CGR in the later growth stage, and higher assimilated dry matter into grain and biomass yield to finally obtain higher grain yield for N-efficient maize cultivar. The N-efficient cultivar had obvious advantages on grain yield compared with N-inefficient cultivar caused by higher dry matter average increasing rate and biomass and kernels per ear, while the advantages increased first, then decreased with higher N rates, and the highest value was observed at 247.5 kg N ha−1. Therefore, selecting N-efficient maize improves maize yield per unit area while reducing N fertiliser supply, especially at low N application rates.

Clonal integration reduced sexual reproduction of Leymus chinensis clones in heterogeneous environments regardless of stress/disturbance intensities

Clonal integration can benefit the performance and fitness of clonal plants in heterogeneous environments. Although trade-offs of sexual and asexual reproduction are key life-history strategies to assess the plant fitness and adaptive abilities, the effects of clonal integration on these is less studied. In this study, a pot experiment was conducted to test how reproductive strategies were affected by clonal integration of clonal plant species Leymus chinensis growing in heterogeneous saline-alkali soils. The results showed that clonal integration had no significant effect on total biomass of whole clone of L. chinensis. The total biomass of younger ramets was higher (+32.8%, P < 0.001) under integration condition, while at the cost of the older ramets (-21.7%, P < 0.001). Moreover, the ratio of ear biomass to clonal growth organs (CGO) biomass was slightly reduced by 31.7% (P = 0.09). For younger ramets, clonal integration enhances biomass allocation towards CGO, while reducing allocation towards ear growth, and the ratio of ear/CGO biomass was significantly reduced by 39.1% (P < 0.01). Results indicated that clonal integration reduced the ratio of ear to clonal growth organ biomass of whole clone, and more biomass was allocated to younger ramets for spatial expansion. Clonal integration influenced reproductive strategies of L. chinensis, while its impact is not depended on nutrient levels or defoliation interference. The study emphasized the significance of clonal integration in promoting the growth of offspring ramets and, consequently, enhancing their abilities to expand rapidly. It could enhance the spatial expansion of L. chinensis on a site scale and provide high potential for restoration of patchy degraded grassland where it is dominant.

Impact of Biomass Fuel Feeding Ratio in Co-firing Circulating Fluidized Bed Boiler: A Computational Fluid Dynamics Study

Nowadays, our global population is on a notable rise, coupled with an annual surge in energy consumption. The prevailing reliance on fossil fuels, especially in electricity generation, has significantly contributed to environmental pollution and exacerbated global warming. The circulating fluidized bed, distinguished for its continuous operation and effective heat transfer in the combustion chamber, emerges as a prominent boiler type. Furthermore, the use of biomass fuel, recognized for its renewable and environmentally friendly characteristics, presents an attractive option. Hence, exploring a co-firing system incorporating both coal and biomass as fuel feeds for the boiler holds promise, necessitating optimization for efficient energy production and reduced gas emissions. This study employs computational fluid dynamics to simulate the intricate interactions of solid fuel and flue gas reactions within the boiler, utilizing the two-fluid method for multiphase flow simulation. The circulating fluidized bed boiler in focus employs subbituminous coal, woodchips as biomass sources, and sand as the bed material. Model validation against operational data, including bed temperature, flue gas velocity outlet, and carbon dioxide mass fraction, indicates minimal deviation. Examination of the biomass ratio's impact on fuel feed reveals a reduction in sulfur dioxide emissions with an increasing biomass ratio, attributed to the lower sulfur content in woodchips compared to coal. However, a heightened woodchip blending ratio results in diminished boiler efficiency due to the altered heating value of the mixed solid fuel. The optimized biomass-to-coal ratio in fuel feeding is determined as 59.15%, achieving a maximized boiler efficiency of 82.84% and minimized pollution gas emissions of sulfur oxide and nitrogen oxide in accordance with industrial standards.