Assessing the atmospheric deposition of inorganic nitrogen and phosphorus over the Yellow Sea

Low retention of added nitrogen at realistic levels of simulated nitrogen deposition in the Northern Chihuahuan Desert

The adaptation of Machilus pauhoi cuttings to nitrogen deposition and seasonal drought stress is superior to seedlings

Forms of nitrogen deposition shift soil microbial resource limitation and carbon use efficiency in temperate forest

Carbon sequestration patterns in the Yellow River Basin of China are governed by the vegetation structural dynamics.

Low-protein (LP) diets have been proposed as a strategy for animal production to conserve protein resources and reduce environmental nitrogen pollution. The aim of this study was to investigate the effect of a LP diet during gestation on the reproductive performance, serum amino acid concentrations and nitrogen excretion in sows. A total of 24 healthy Landrace × Yorkshire sows (4 to 5 parities) with similar body weight and back fat were fed with normal gestational diet (control group, crude protein = 13.65%, n = 12) or a LP gestational diet (LP group, crude protein = 11.30%, n = 12) from day 30 of gestation to the day before parturition. All sows received same diet during lactation. Results showed that LP diet during mid-to-late gestation reduced the gain of backfat thickness during days 30 to 60 of gestation (P < 0.05) compared with the control group, without changing the reproductive performance of the sows. The gene expression levels of amino acid transporters in the placenta, and the organ indices of neonatal and weaned piglets, were all unchanged by the LP diet. The digestion and metabolism experiment revealed that the LP diet decreased nitrogen excretion and net nitrogen deposition during late gestation (P < 0.05). Additionally, the LP diet reduced serum concentrations of valine, arginine, lysine, and methionine on day 110 of gestation, and arginine, lysine and methionine on day 21 of lactation, while it tended to decrease serum concentration of the total essential amino acids and the level of threonine in the milk throughout lactation (P < 0.05). Gestational LP diet also significantly reduced concentrations of serine and the total non-essential amino acids in the serum of neonatal piglets (P < 0.05) and serum threonine in weaned piglets, but increased leucine (P < 0.05) in the serum of weaned piglets. In conclusion, an appropriate reduction of dietary protein during mid-to-late gestation in sows (11.30% vs. 13.65%) could reduce their nitrogen excretion while maintaining reproductive performance, and it is recommended to supplement arginine and valine in the LP diets in addition to lysine, methionine, tryptophan and threonine. This study highlights the significance of low-protein diets in protein feed saving and environmental protection.

With continuous increases in nitrogen (N) deposition in the future, its impacts on terrestrial ecosystems are attracting growing concern. Arbuscular mycorrhiza (AM) fungi play a crucial role in shaping both soil microbial and plant communities. AM fungi play a crucial role in shaping the soil microbial and plant communities, yet their patterns of influence under increased N deposition scenarios remain unclear, particularly in desert ecosystems. Therefore, we conducted a field experiment simulating increased N deposition and AM fungal suppression to assess the effects of increased N deposition and AM fungi on soil microbial communities, employing phospholipid fatty acid (PLFA) biomarker technology in the Gurbantunggut Desert of Xinjiang. We found that increased N deposition promoted soil microbial biomass, including AM fungi, fungi, Actinomycetes (Act), Gram-positive bacteria (G+), Gram-negative bacteria (G−), and Dark Septate Endophyte (DSE). AM fungal suppression significantly increased the content of soil Act and G+. There were clearly and significantly interactive effects of increased N deposition and AM fungi on soil microbial contents. Both increased N deposition and AM fungi caused significant changes in soil microbial community structure. Random forest analysis revealed that soil nitrate N (NO3−-N), Soil Organic Carbon (SOC), and pH were main factors influencing soil microorganisms; soil AM fungi, G+, and Act significantly affected plant Shannon diversity; soil G−, Act, and fungi posed significant effects on plant community biomass. Finally, the structure equation model results indicated that soil fungi, especially AM fungi, were the main soil microorganisms altering the plant community diversity and biomass under increased N deposition. This study reveals the crucial role of AM fungi in regulating soil microbial responses to increased N deposition, providing experimental evidence for understanding how N deposition affects plant communities through soil microorganisms.

Abstract Interspecific variation in intra‐annual growth dynamics is an important determinant of species coexistence in plant communities. Species are expected to have contrasting growth responses to global changes, especially in the forest understorey where diverse phenological strategies have evolved as a result of tree canopy shading. Accordingly, impacts of climate warming, canopy disturbances, atmospheric nitrogen deposition and legacy effects from former land‐use will likely have implications for competitive interactions and may in turn alter community composition and functioning. Yet, intra‐annual growth dynamics in forest understorey species, which are crucial for forest biodiversity and functioning, have seldom been studied, certainly in response to global change. Our study provides the first comprehensive characterization of growth curves in temperate forest understorey species in response global changes. We performed a mesocosm experiment and carried out high‐resolution plant height and cover measurements to assess species‐specific growth curves and study growth phenology responses to warming, illumination (simulating canopy opening), nitrogen deposition and soil land‐use history (comparing ancient and post‐agricultural forest soil). Furthermore, we investigated how plant height and cover responses to global change treatments varied throughout the year. We identified four distinct growth patterns among the nine studied species, demonstrating the diversity of growth strategies in the understorey. Interspecific variation in growth phenology responses to global change was very large, but all species exhibited advances in response to experimental warming. Light and nitrogen addition delayed growth phenophases in most cases, but only had an effect on late‐spring and summer‐growing species and evergreens. Soils with an agricultural land‐use legacy produced advances for some species and delays for others. Furthermore, our findings revealed that traditional snapshot data collections can only uncover a limited number of effects from global change treatments. Synthesis . This study provides new insights into the growth dynamics of forest understorey species and their responses to global change drivers. Our findings suggest that global changes, such as climate warming, canopy disturbances, atmospheric nitrogen deposition and land‐use legacy effects will continue to shift growth phenologies, therewith disrupting competitive balances in plant communities. These insights can help to support adaptive forest management in a changing world.

Abstract Global nitrogen (N) deposition and changes in precipitation patterns profoundly influence leaf photosynthesis and carbon sequestration in terrestrial ecosystems. Foliar fungi, a critical microbial community on leaf surfaces, could simultaneously impact several leaf functions. However, the regulated effects of foliar fungi on leaf photosynthesis in response to nitrogen and water additions remain unclear. Here, using a long‐term field and a complementary pot fungicide experiment in an alpine meadow, we quantified the effects of nitrogen and water addition on leaf photosynthesis and foliar fungal communities in two dominant species. We found that, under the combined effects of nitrogen and water addition, the light‐saturated CO 2 assimilation capacity ( A sat ) of two dominant species ( Carex alatauensis and Leymus secalinus ) increased significantly. Moreover, nitrogen and water additions significantly increased leaf N content, which in turn reduced foliar fungal diversity, enhanced stomatal conductance, and ultimately improved A sat . Importantly, the fungicide experiment demonstrated that foliar fungi removal could improve A sat , highlighting the negative effects of higher foliar fungal Shannon diversity on leaf photosynthesis. Synthesis . Our findings found that foliar fungi mediate photosynthetic responses to resource enrichment. These findings extend the mechanistic understanding of how foliar fungi mediate leaf photosynthesis and plant growth under global change, offering insights into microbial regulation of photosynthesis in response to varied resource availability.

Tropical N-poor soils have strong acidity buffering capacity for short-term increased and decreased nitrogen deposition

We face increasing concerns about how the local diversity of native plant communities responds to various drivers of global change, yet often lack comprehensive studies that integrate several components of diversity and the effects of both local and regional drivers of change. We analyzed changes in taxonomic, functional, and phylogenetic diversity across 2681 (semi-)permanent temperate forest understory plots surveyed and resurveyed for all vascular plants over intervals of 15-78 yr, spanning 72 regions distributed across Europe. We quantified temporal changes in these diversity indices and assessed their responses to changes in both local drivers (plot-level overstory cover, indicator values for soil nutrients) and regional shifts in macroclimate and nitrogen deposition. Overall, local changes in taxonomic, functional, and phylogenetic diversity were centered around zero, reflecting - on average - little net change in forest diversity. Observed diversity changes mostly reflected local conditions such as overstory cover change and baseline soil nutrients rather than regional drivers of large-scale change. Changes in phylogenetic diversity correlated positively with changes in taxonomic diversity but negatively with changes in functional diversity. Our findings underscore the importance of local habitat management and multifaceted diversity monitoring for effective biodiversity conservation in temperate forests.

Nitrogen deposition and water addition affect microbial carbon and nitrogen cycling: Insights from a 10-year experiment in a semi-arid steppe

Nitrogen enhancement amplifies the precipitation-driven productivity allocation pattern in temperate and alpine grasslands.

Effects of simulated nitrogen deposition on N fate in a temperate steppe: Evidence from multi-year 15N isotope study.

Data fusion of modelled and measured deposition in the US and Canada, Part II: Dry deposition of sulfur, nitrogen and ozone.

Transformation of organic matter input to sediments of a typical alpine lake over the past approximately 240 years and its link to atmospheric nitrogen deposition and climate warming

Atmospheric nitrogen deposition in the northwestern Pacific and its responses to changes of anthropogenic emissions in East Asia

Atmospheric nitrogen deposition to cropland in Fujian province, China

Abstract Background The decline in soil organic carbon accumulation caused by intensified nitrogen deposition is concerning. Although phosphorus input may alleviate the negative impacts, there is still a research gap regarding the mechanisms, particularly those involving the soil biota, that drive the stability of soil organic carbon. Methods We conducted a 2-year nitrogen (0, 30 and 90 kg N ha – 1 yr – 1 ) and phosphorus (0, 30 kg P ha – 1 yr – 1 ) addition experiment with six treatments in a 25-year-old Pinus massoniana plantation in subtropical China. Results The addition of external nutrients improved soil nutrient availability but led to a decrease in pH. Low nitrogen input promoted the particulate organic carbon (POC) and total organic carbon, whereas high nitrogen input had the opposite effect. Phosphorus addition alleviated these negative impacts to some extent. Nitrogen and phosphorus addition significantly affected the dissimilarity of soil biological communities. Nitrogen treatments generally reduced the alpha diversity index of soil bacteria, while the trend for fungi was the opposite. Arthropods showed a rise followed by a decline, with phosphorus addition weakening these effects. Soil respiration decreased with increasing nitrogen addition, and phosphorus addition didn’t alter this trend. The POC was primarily influenced by the soil environment-microorganism-respiration and environment-microorganism pathways, whereas the mineral-associated organic carbon (MAOC) was mainly influenced by the soil environment-arthropod pathway. POC (Path coefficient, pc = 0.524) and MAOC (pc = 0.237) directly determine the accumulation of organic carbon. This conceptual model explained 59.4% of the variation in total organic carbon (Goodness-of-fit, GOF = 0.594), thereby delineating the integrated mechanisms underlying SOC accumulation. Conclusions Excessive nitrogen input was unfavorable for organic carbon accumulation, while phosphorus addition partially mitigated the negative effects of nitrogen excess. Under this context, active organic carbon was significantly influenced by soil microorganisms and soil respiration, whereas stable organic carbon was primarily affected by soil arthropods. Graphical Abstract

The Response of Forest C: N:P Stoichiometry to Nitrogen Deposition and Underlying Mechanisms: a Review