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Background: Biodiversity loss may impact essential ecological functions. How litter diversity affects soil carbon and nitrogen cycles in temperate forests remains unknown. Methods: We collected fresh leaf litter from eight tree species in Northeast China and incubated it with native soil for one year. We assessed the effect of tree species richness and arbuscular mycorrhizal (AM) tree fraction of leaf litter on soil aggregate formation and soil C and N retention. The soil aggregate size class distribution and the concentrations of glomalin-related soil protein (GRSP), soil organic carbon (SOC), and total nitrogen (TN) in the aggregate size classes were measured. Results: Tree species richness and AM tree fraction of leaf litter promoted SOC and TN accrual in the macroaggregates. They also increased the proportion of macroaggregates and decreased that of the silt and clay fraction. The SOC and TN accrual were accompanied by an increase of easily extractable GRSP (EEG) and total GRSP (TG) in the macroaggregate and a decrease in the silt and clay fraction. Structural equation modeling revealed that aggregate stability was directly increased by EEG (0.476) and TG (0.276). Tree species richness of leaf litter (0.182), AM tree fraction of leaf litter (0.321), and TG (0.430) directly promoted SOC accumulation, while tree species richness of leaf litter (0.338), TG (0.331), and EEG (0.203) increased the TN concentration in bulk soil. Conclusion: This study demonstrates that macroaggregates and GRSP are vital in improving SOC and TN accrual through tree species richness and AM tree fraction of leaf litter. [ABSTRACT FROM AUTHOR]

Aim: Phosphorus (P) is vital for ecosystem functioning, but how boreal forest succession affects soil P is not yet well defined. Method: We collected 134 soil samples from ten plant succession stages of climax vegetation of larch forests in the Greater Khingan Mts., northeast China, and measured soil total P (TP) and nine fraction-Ps, together with detailed records of trees, shrubs, herbs diversity, and geo-topographical conditions. Results: Our results showed that TP and nine fraction-Ps declined non-linearly in the chronosequence in concentration, and three organic fractions (NaHCO3-Po, NaOH-Po, and conc.HCl-Po) showed a similar non-linear decrease. The stoichiometric percent of Pi, conc.HCl-Pi and NaOH-Pi linearly increased (R2 = 0.81–0.92), and Po, NaOH-Po, and Re-P decreased linearly (R2 = 0.59–0.61). Partial ordination excluding geo-climatic impacts (30.8%) could identify the exact association between plant succession and P changes. The negative relations between tree diversity, biomass and organic fraction-Ps showed that P storage in tree biomass was responsible for soil P declines during plant succession, and tree diversity accelerated these P changes. In contrast, the significantly higher soil P in the grass stage was due to P's grass-upload function to surface soils. Conclusion: Our data highlighted that soil P was depleted, with a higher Pi proportion during plant succession in high-latitude boreal forests, favoring precise soil P management and evaluation of these forests. [ABSTRACT FROM AUTHOR]

Aims: Biological nitrification inhibitors (BNIs) can play an important role in inhibiting nitrification and enhancing nitrogen use efficiency (NUE) in agriculture. However, most current BNI studies have been conducted under hydroponics. Genotypic differences in the inhibition of nitrification in soil are still largely unknown. Our main aim was to investigate the regulation of N transformation processes by different rice genotypes with different BNI release potentials on NUE and N loss. Methods: Two rice genotypes, i.e. Wuyujing 3 (WYJ3) and Wuyunjing 7 (WYJ7), reported to have weak and strong BNI capacity, respectively, under hydroponic conditions, and four soils with different pH (i.e. JX (pH 5.09), FJ (pH 6.00), SC1 (pH 7.96) and SC2 (pH 7.94)) were selected for this study. Plant N uptake rates (esp. NH4+ uptake, UNH4) and soil N transformation rates were quantified by 15 N tracing to assess the effects of rice genotypes on nitrification inhibition activity. NUE and N loss were quantified in a separate 15 N-urea labeling experiment. Results: The results showed that the rice genotype with high BNI exudation (i.e. WYJ7) had lower autotrophic nitrification rate (ONH4) and higher UNH4 compared to WYJ3. ONH4 in WYJ7 decreased by 0.05, 0.42, 1.14, and 0.48 mg N kg−1 d−1 compared to WYJ3 for JX, FJ, SC1 and SC2, respectively. The abundance of AOB in soils planted with WYJ7 was lower than in soils planted with WYJ3, which was the most important factor to explain the variation of ONH4. WYJ7 tends to have a relatively higher NUE than WYJ3 in JX, SC1 and SC2. NUE was negatively correlated with ONH4. Conclusion: Our results indicate that some rice genotypes can optimize their N acquisition by regulating soil N transformations (especially nitrification). The development of rice genotypes with strong BNI exudation capacity could be a suitable management practice to increase NUE and yield. [ABSTRACT FROM AUTHOR]

Aims: Soil nitrogen (N) mineralization-immobilization turnover (MIT) regulates the inorganic N supply in terrestrial ecosystems. Much research has been done to understand the factors that control the MIT in soils, but how plants-soil-microbe interactions influence the MIT remains to be further explored.A series of 15N tracing experiments, including with and without maize (Zea mays L.) planting, maize shading, and maize root endophytes inoculation, were conducted to investigate the drivers of the change in MIT by the presence of plant.Soil gross N mineralization (M), especially the mineralization of recalcitrant organic-N to NH4+ (MNrec, 0.51 mg N kg−1 d−1) was significantly improved by maize compared with the control treatment (without maize) (0.07 mg N kg−1 d−1). MNrec significantly decreased after removing maize or covering maize with a black box (preventing photosynthesis). Soil dissolved organic carbon (DOC) concentration significantly decreased after preventing photosynthesis, and showed a significant positive relationship with MNrec, confirming that photosynthetic substrate supply was the dominating factor in stimulating MNrec. Simultaneously, the release of absorbed NH4+ on the cation exchange sites increased with decreasing MNrec when photosynthesis was prevented. Microbial N immobilization (I), especially NO3− immobilization rate (INO3), was significantly stimulated in all maize treatments compared to the control. The INO3 of unsterilized soil applied with unsterilized plant endophytes was significantly higher than unsterilized soil applied with sterilized endophytes, indicating a close relationship between endophytes and microorganisms on INO3.MNrec was stimulated by the photosynthetic substrate supply, and the increasing microbial N immobilization induced by plant significantly increased the ratio of I to M in the presence of maize, which was beneficial to soil N retention and reduced N loss. Our results provide new insights of the MIT for better understanding the productivity of agricultural systems and its driving factors.Methods: Soil nitrogen (N) mineralization-immobilization turnover (MIT) regulates the inorganic N supply in terrestrial ecosystems. Much research has been done to understand the factors that control the MIT in soils, but how plants-soil-microbe interactions influence the MIT remains to be further explored.A series of 15N tracing experiments, including with and without maize (Zea mays L.) planting, maize shading, and maize root endophytes inoculation, were conducted to investigate the drivers of the change in MIT by the presence of plant.Soil gross N mineralization (M), especially the mineralization of recalcitrant organic-N to NH4+ (MNrec, 0.51 mg N kg−1 d−1) was significantly improved by maize compared with the control treatment (without maize) (0.07 mg N kg−1 d−1). MNrec significantly decreased after removing maize or covering maize with a black box (preventing photosynthesis). Soil dissolved organic carbon (DOC) concentration significantly decreased after preventing photosynthesis, and showed a significant positive relationship with MNrec, confirming that photosynthetic substrate supply was the dominating factor in stimulating MNrec. Simultaneously, the release of absorbed NH4+ on the cation exchange sites increased with decreasing MNrec when photosynthesis was prevented. Microbial N immobilization (I), especially NO3− immobilization rate (INO3), was significantly stimulated in all maize treatments compared to the control. The INO3 of unsterilized soil applied with unsterilized plant endophytes was significantly higher than unsterilized soil applied with sterilized endophytes, indicating a close relationship between endophytes and microorganisms on INO3.MNrec was stimulated by the photosynthetic substrate supply, and the increasing microbial N immobilization induced by plant significantly increased the ratio of I to M in the presence of maize, which was beneficial to soil N retention and reduced N loss. Our results provide new insights of the MIT for better understanding the productivity of agricultural systems and its driving factors.Results: Soil nitrogen (N) mineralization-immobilization turnover (MIT) regulates the inorganic N supply in terrestrial ecosystems. Much research has been done to understand the factors that control the MIT in soils, but how plants-soil-microbe interactions influence the MIT remains to be further explored.A series of 15N tracing experiments, including with and without maize (Zea mays L.) planting, maize shading, and maize root endophytes inoculation, were conducted to investigate the drivers of the change in MIT by the presence of plant.Soil gross N mineralization (M), especially the mineralization of recalcitrant organic-N to NH4+ (MNrec, 0.51 mg N kg−1 d−1) was significantly improved by maize compared with the control treatment (without maize) (0.07 mg N kg−1 d−1). MNrec significantly decreased after removing maize or covering maize with a black box (preventing photosynthesis). Soil dissolved organic carbon (DOC) concentration significantly decreased after preventing photosynthesis, and showed a significant positive relationship with MNrec, confirming that photosynthetic substrate supply was the dominating factor in stimulating MNrec. Simultaneously, the release of absorbed NH4+ on the cation exchange sites increased with decreasing MNrec when photosynthesis was prevented. Microbial N immobilization (I), especially NO3− immobilization rate (INO3), was significantly stimulated in all maize treatments compared to the control. The INO3 of unsterilized soil applied with unsterilized plant endophytes was significantly higher than unsterilized soil applied with sterilized endophytes, indicating a close relationship between endophytes and microorganisms on INO3.MNrec was stimulated by the photosynthetic substrate supply, and the increasing microbial N immobilization induced by plant significantly increased the ratio of I to M in the presence of maize, which was beneficial to soil N retention and reduced N loss. Our results provide new insights of the MIT for better understanding the productivity of agricultural systems and its driving factors.Conclusions: Soil nitrogen (N) mineralization-immobilization turnover (MIT) regulates the inorganic N supply in terrestrial ecosystems. Much research has been done to understand the factors that control the MIT in soils, but how plants-soil-microbe interactions influence the MIT remains to be further explored.A series of 15N tracing experiments, including with and without maize (Zea mays L.) planting, maize shading, and maize root endophytes inoculation, were conducted to investigate the drivers of the change in MIT by the presence of plant.Soil gross N mineralization (M), especially the mineralization of recalcitrant organic-N to NH4+ (MNrec, 0.51 mg N kg−1 d−1) was significantly improved by maize compared with the control treatment (without maize) (0.07 mg N kg−1 d−1). MNrec significantly decreased after removing maize or covering maize with a black box (preventing photosynthesis). Soil dissolved organic carbon (DOC) concentration significantly decreased after preventing photosynthesis, and showed a significant positive relationship with MNrec, confirming that photosynthetic substrate supply was the dominating factor in stimulating MNrec. Simultaneously, the release of absorbed NH4+ on the cation exchange sites increased with decreasing MNrec when photosynthesis was prevented. Microbial N immobilization (I), especially NO3− immobilization rate (INO3), was significantly stimulated in all maize treatments compared to the control. The INO3 of unsterilized soil applied with unsterilized plant endophytes was significantly higher than unsterilized soil applied with sterilized endophytes, indicating a close relationship between endophytes and microorganisms on INO3.MNrec was stimulated by the photosynthetic substrate supply, and the increasing microbial N immobilization induced by plant significantly increased the ratio of I to M in the presence of maize, which was beneficial to soil N retention and reduced N loss. Our results provide new insights of the MIT for better understanding the productivity of agricultural systems and its driving factors. [ABSTRACT FROM AUTHOR]

Background and aims: Litter decomposition is the main source of forest soil carbon (C) and nitrogen (N), which is critical for maintaining ecosystem function and stability. Exploring the impact of litter diversity on soil C and N will provide the basis for afforestation tree species selection and forest management. However, the influences of leaf litter diversity, functional identity, and chemical properties on soil properties are less known. This study investigated their effects on soil C and N in boreal forest soil in Northeast China.Fresh leaf litter from 8 dominant tree species in Northeast China was collected. The soil was mixed with litter from single species and all combinations of 2, 4, and 8 species (321 treatments). The soil C and N parameters were measured.Tree species richness and AM tree fraction of leaf litter promoted soil organic carbon (SOC) stability by decreasing soil respiration rate (Rs) and temperature sensitivity (Q10). The concentrations of SOC, total nitrogen (TN), microbial mass C and N (MBC and MBN) increased with the increase in tree species richness and AM tree fraction of leaf litter. Variance partitioning analysis showed that AM tree fraction of leaf litter explained 3.86 times more variation of soil C and N than tree species richness of leaf litter, which directly or indirectly influenced them via litter chemical properties.This study provides the basis for understanding the importance of litter diversity, and chemical properties for soil C and N and highlights the importance of AM tree fraction of leaf litter for soil properties.Methods: Litter decomposition is the main source of forest soil carbon (C) and nitrogen (N), which is critical for maintaining ecosystem function and stability. Exploring the impact of litter diversity on soil C and N will provide the basis for afforestation tree species selection and forest management. However, the influences of leaf litter diversity, functional identity, and chemical properties on soil properties are less known. This study investigated their effects on soil C and N in boreal forest soil in Northeast China.Fresh leaf litter from 8 dominant tree species in Northeast China was collected. The soil was mixed with litter from single species and all combinations of 2, 4, and 8 species (321 treatments). The soil C and N parameters were measured.Tree species richness and AM tree fraction of leaf litter promoted soil organic carbon (SOC) stability by decreasing soil respiration rate (Rs) and temperature sensitivity (Q10). The concentrations of SOC, total nitrogen (TN), microbial mass C and N (MBC and MBN) increased with the increase in tree species richness and AM tree fraction of leaf litter. Variance partitioning analysis showed that AM tree fraction of leaf litter explained 3.86 times more variation of soil C and N than tree species richness of leaf litter, which directly or indirectly influenced them via litter chemical properties.This study provides the basis for understanding the importance of litter diversity, and chemical properties for soil C and N and highlights the importance of AM tree fraction of leaf litter for soil properties.Results: Litter decomposition is the main source of forest soil carbon (C) and nitrogen (N), which is critical for maintaining ecosystem function and stability. Exploring the impact of litter diversity on soil C and N will provide the basis for afforestation tree species selection and forest management. However, the influences of leaf litter diversity, functional identity, and chemical properties on soil properties are less known. This study investigated their effects on soil C and N in boreal forest soil in Northeast China.Fresh leaf litter from 8 dominant tree species in Northeast China was collected. The soil was mixed with litter from single species and all combinations of 2, 4, and 8 species (321 treatments). The soil C and N parameters were measured.Tree species richness and AM tree fraction of leaf litter promoted soil organic carbon (SOC) stability by decreasing soil respiration rate (Rs) and temperature sensitivity (Q10). The concentrations of SOC, total nitrogen (TN), microbial mass C and N (MBC and MBN) increased with the increase in tree species richness and AM tree fraction of leaf litter. Variance partitioning analysis showed that AM tree fraction of leaf litter explained 3.86 times more variation of soil C and N than tree species richness of leaf litter, which directly or indirectly influenced them via litter chemical properties.This study provides the basis for understanding the importance of litter diversity, and chemical properties for soil C and N and highlights the importance of AM tree fraction of leaf litter for soil properties.Conclusions: Litter decomposition is the main source of forest soil carbon (C) and nitrogen (N), which is critical for maintaining ecosystem function and stability. Exploring the impact of litter diversity on soil C and N will provide the basis for afforestation tree species selection and forest management. However, the influences of leaf litter diversity, functional identity, and chemical properties on soil properties are less known. This study investigated their effects on soil C and N in boreal forest soil in Northeast China.Fresh leaf litter from 8 dominant tree species in Northeast China was collected. The soil was mixed with litter from single species and all combinations of 2, 4, and 8 species (321 treatments). The soil C and N parameters were measured.Tree species richness and AM tree fraction of leaf litter promoted soil organic carbon (SOC) stability by decreasing soil respiration rate (Rs) and temperature sensitivity (Q10). The concentrations of SOC, total nitrogen (TN), microbial mass C and N (MBC and MBN) increased with the increase in tree species richness and AM tree fraction of leaf litter. Variance partitioning analysis showed that AM tree fraction of leaf litter explained 3.86 times more variation of soil C and N than tree species richness of leaf litter, which directly or indirectly influenced them via litter chemical properties.This study provides the basis for understanding the importance of litter diversity, and chemical properties for soil C and N and highlights the importance of AM tree fraction of leaf litter for soil properties. [ABSTRACT FROM AUTHOR]