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Forest soils play an important role in controlling global warming by reducing atmospheric methane (CH4) concentrations. However, little attention has been paid to how nitrogen (N) deposition may alter microorganism communities that are related to the CH4 cycle or CH4 oxidation in subtropical forest soils. We investigated the effects of N addition (0, 30, 60, or 90 kg N ha−1 yr−1) on soil CH4 flux and methanotroph and methanogen abundance, diversity, and community structure in a Moso bamboo (Phyllostachys edulis) forest in subtropical China. N addition significantly increased methanogen abundance but reduced both methanotroph and methanogen diversity. Methanotroph and methanogen community structures under the N deposition treatments were significantly different from those of the control. In N deposition treatments, the relative abundance of Methanoculleus was significantly lower than that in the control. Soil pH was the key factor regulating the changes in methanotroph and methanogen diversity and community structure. The CH4 emission rate increased with N addition and was negatively correlated with both methanotroph and methanogen diversity but positively correlated with methanogen abundance. Overall, our results suggested that N deposition can suppress CH4 uptake by altering methanotroph and methanogen abundance, diversity, and community structure in subtropical Moso bamboo forest soils.

Background It is still not clear whether the effects of N deposition on soil greenhouse gas (GHG) emissions are influenced by plantation management schemes. A field experiment was conducted to investigate the effects of conventional management (CM) versus intensive management (IM), in combination with simulated N deposition levels of control (ambient N deposition), 30 kg N·ha− 1·year− 1 (N30, ambient + 30 kg N·ha− 1·year− 1), 60 kg N·ha− 1·year− 1 (N60, ambient + 60 kg N·ha− 1·year− 1), or 90 kg N·ha− 1·year− 1 (N90, ambient + 90 kg N·ha− 1·year− 1) on soil CO2, CH4, and N2O fluxes. For this, 24 plots were set up in a Moso bamboo (Phyllostachys edulis) plantation from January 2013 to December 2015. Gas samples were collected monthly from January 2015 to December 2015. Results Compared with CM, IM significantly increased soil CO2 emissions and their temperature sensitivity (Q10) but had no significant effects on soil CH4 uptake or N2O emissions. In the CM plots, N30 and N60 significantly increased soil CO2 emissions, while N60 and N90 significantly increased soil N2O emissions. In the IM plots, N30 and N60 significantly increased soil CO2 and N2O emissions, while N60 and N90 significantly decreased soil CH4 uptake. Overall, in both CM and IM plots, N30 and N60 significantly increased global warming potentials, whereas N90 did not significantly affect global warming potential. However, N addition significantly decreased the Q10 value of soil CO2 emissions under IM but not under CM. Soil microbial biomass carbon was significantly and positively correlated with soil CO2 and N2O emissions but significantly and negatively correlated with soil CH4 uptake. Conclusion Our results indicate that management scheme effects should be considered when assessing the effect of atmospheric N deposition on GHG emissions in bamboo plantations.

The aim of this study was to investigate the mechanisms by which nitrogen (N) and phosphorous (P) additions affect plant C:N:P stoichiometry via changes in AMF communities in a Chinese fir plantation. Experimental plots in a 10-year-old Chinese fir plantation were treated with N addition (LN, 30 kg•ha−1•yr−1, and HN, 60 kg•ha−1•yr−1) and P addition (LP, 20 mg•kg−1, and HP, 40 mg•kg−1) for 2 years starting from 2017. Soil properties, leaf C:N:P stoichiometry, and changes in AMF community composition and diversity were measured. N or P addition increased soil N availability, decreased P availability, and increased N:P in the leaves and soil. Changes in soil pH induced by N and P additions affected the colonization rate and spore density of AMF. AMF colonization rate was increased by N or P addition, and AMF diversity was increased by LN addition. N and P additions altered AMF species composition, and the dominant genus of the AMF in the soil was Glomus in all treatments. The interaction of N and P treatments had no significant effect on AMF diversity. AMF colonization rate and diversity, rather than its composition, affected leaf C:N:P stoichiometry. N and P additions affected colonization rate and diversity of AMF though changes in soil pH, which drove leaf C:N:P stoichiometry, and potentially affected forest productivity via the fungi-soil-plant system.

Secondary forest restoration can alter terrestrial ecosystem processes and potentially impact subsurface carbon dynamics. However, the effects of long-term forest restoration on the soil microbial metabolic activity remain unclear. So, the aim of this study was to explore the response of soil microbial metabolism to forest restoration. Among them, the soil basal respiration (BR), microbial quotient ( qMB), and metabolic quotient ( qCO ) were studied. This study investigated a natural vegetation restoration sequence approximately ~160 years after farmland abandonment on the central Loess Plateau, China, corresponding to five vegetation restoration stages including farmland, grassland, shrubland, pioneer forests, and climax forests. The results showed that BR and qCO were increased following forest restoration, whereas qMB showed the opposite trend. Forest restoration also increased the activities of β-1,4-glucosidase and β-D-cellobiosidase. Restoration age, litter traits such as nitrogen, cellulose and lignin decomposition rates, dissolved organic carbon contents, fungi and bacteria composition were also important indicators affecting microbial metabolic activities. Long-term forest restoration can change soil microbial community structure, reduce carbon mineralization efficiency, improve soil microbial carbon utilization efficiency, and promote soil organic carbon accumulation.

Nitrogen (N) deposition is a key factor that affects terrestrial biogeochemical cycles with a growing trend, especially in the southeast region of China, where shortage of available phosphorus (P) is particularly acute and P has become a major factor limiting plant growth and productivity. Arbuscular mycorrhizal fungi (AMF) establish a mutualistic symbiosis with plants, and play an important role in enhancing plant stress resistance. However, the response of AMF to the combined effects of N deposition and P additions is poorly understood. Thus, in this study, a field experiment was conducted in 10-year Chinese fir forests to estimate the effects of simulated nitrogen (N) deposition (low-N, 30 kg ha−1 year−1 and high-N, 60 kg ha−1 year−1) and phosphorus (P) addition treatments (low-P, 20 mg kg−1 and high-P, 40 mg kg−1) on AMF since April 2017, which was reflected in AMF root colonization rates and spore density of rhizosphere soil. Our results showed that N deposition significantly decreased AMF root colonization rates and spore density. In N-free plots, P addition significantly decreased AMF root colonization rates, but did not significantly alter spore density. In low-N plots, colonization rates significantly decreased under low P addition, but significantly increased under high P addition, and spore density exhibited a significant decline under high P additions. In high-N plots, colonization rates and spore density significantly increased under P additions. Interactive effects of simulated N deposition and P addition on both colonization rates and spore density were significant. Moderate N deposition or P addition can weaken the symbiotic relationship between plants and AMF, significantly reducing AMF colonization rates and inhibiting spore production. However, a moderate addition of P greatly enhances spore yield. In the case of interactive effects, the AMF colonization rates and spore density are affected by the relative content of N and P in the soil.

The effects of nitrogen (N) deposition on soil organic carbon (C) and greenhouse gas (GHG) emissions in terrestrial ecosystems are the main drivers affecting GHG budgets under global climate change. Although many studies have been conducted on this topic, we still have little understanding of how N deposition affects soil C pools and GHG budgets at the global scale. We synthesized a comprehensive dataset of 275 sites from multiple terrestrial ecosystems around the world and quantified the responses of the global soil C pool and GHG fluxes induced by N enrichment. The results showed that the soil organic C concentration and the soil CO2 , CH4 and N2 O emissions increased by an average of 3.7%, 0.3%, 24.3% and 91.3% under N enrichment, respectively, and that the soil CH4 uptake decreased by 6.0%. Furthermore, the percentage increase in N2 O emissions (91.3%) was two times lower than that (215%) reported by Liu and Greaver (Ecology Letters, 2009, 12:1103-1117). There was also greater stimulation of soil C pools (15.70 kg C ha-1 year-1 per kg N ha-1 year-1 ) than previously reported under N deposition globally. The global N deposition results showed that croplands were the largest GHG sources (calculated as CO2 equivalents), followed by wetlands. However, forests and grasslands were two important GHG sinks. Globally, N deposition increased the terrestrial soil C sink by 6.34 Pg CO2 /year. It also increased net soil GHG emissions by 10.20 Pg CO2 -Geq (CO2 equivalents)/year. Therefore, N deposition not only increased the size of the soil C pool but also increased global GHG emissions, as calculated by the global warming potential approach.

In forest ecosystems, the majority of methane (CH4) research focuses on soils, whereas tree stem CH4 flux and driving factors remain poorly understood. We measured the in situ stem CH4 flux using the static chamber–gas chromatography method at different heights in two poplar (Populus spp.) forests with separate soil textures. We evaluated the relationship between stem CH4 fluxes and environmental factors with linear mixed models and estimated the tree CH4 emission rate at the stand level. Our results showed that poplar stems were a net source of atmospheric CH4. The mean stem CH4 emission rates were 97.51 ± 6.21 μg·m−2·h−1 in Sihong and 67.04 ± 5.64 μg·m−2·h−1 in Dongtai. The stem CH4 emission rate in Sihong with clay loam soils was significantly higher (P

Soil enzymes are the metabolic motors for soil organisms. However, how soil enzymes respond to biochar amendment in plantations under increasing chronic atmospheric nitrogen (N) deposition is poorly understood. In this study, we analyzed the effects of N deposition (30, 60, and 90 kg N ha−1 yr−1 for treatments N30, N60 and N90, respectively) and biochar amendment (20 and 40 t ha−1 for treatments BC20 and BC40, respectively) on six soil enzyme activities (β-fructofuranosidase, cellulase, nitrate reductase, nitrite reductase, urease, and acid phosphatase) in a Moso bamboo (Phyllostachys edulis (Carrière) J. Houz) plantation. We found that N deposition significantly decreased the β-fructofuranosidase activity in the N30 and N90 treatments (P P P β-fructofuranosidase activity from N to carbon (C). The adsorption capability of biochar to soil N nutrient elements could decrease urease activity to limit the utilization of N; meanwhile, biochar addition could aggravate phosphorus (P) limitation to repress acid phosphatase activity. However, biochar addition could increase soil pH to promote urease activity. These findings provide new insights into the effects of biochar amendment on soil enzyme activities in plantations that suffer from the effects of N deposition.

Increased availability of soil phosphorus (P) has recently been recognised as an underlying driving factor for the positive relationship between plant diversity and ecosystem function. The effects of plant diversity on the bioavailable forms of P involved in biologically mediated rhizospheric processes and how the link between plant and soil microbial diversity facilitates soil P bioavailability, however, remain poorly understood. This study quantified four forms of bioavailable P (CaCl₂‐P, citric‐P, enzyme‐P and HCl‐P) in mature subtropical forests using a novel biologically based approach, which emulates how rhizospheric processes influence the release and supply of available P. Soil microbial diversity was measured by Illumina high‐throughput sequencing. Our results suggest that tree species richness significantly affects soil microbial diversity (p

Nitrogen (N) deposition plays an important role in regulating forest productivity and microbial biomass and activities, ultimately influencing soil respiration (Rs). However, the effects of increasing atmospheric N depositions on Rs in subtropical Moso bamboo forests remain poorly understood. Here, we conducted a 4-year field experiment in a subtropical Moso bamboo forest to quantify the effect of simulated N depositions at four rates (0, 30, 60 and 90 kg N ha−1 yr-1) on Rs. The mean Rs rate of the control was 353.17 ± 53.23 mg CO2 m-2 h-1 or 30.75 ± 2.38 t CO2 ha-1 yr-1. Soil respiration showed significantly higher sensitivity (Q10) to soil temperature than to air temperature, and the Rs rate was significantly positively related to soil microbial biomass carbon, soil temperature, and NO3-. In response to N addition treatments of 30, 60, and 90 kg N ha-1 yr-1, the mean annual Rs increased by approximately 45.7%, 37.7%, and 13.0%, respectively, compared with the control. Nitrogen depositions decreased the temperature sensitivity of Rs, leading to predictions that they may be able to mitigate the priming effects of future climate warmings on Rs in Moso bamboo forests in the coming decades. Combined models based on the significant relationships between Rs rates, daily mean air temperatures, and hourly soil temperatures at a depth of 5 cm may reliably and feasibly estimate annual soil CO2 efflux. On average, soil emitted 470 kg CO2 ha-1 yr-1 per 1 kg N ha-1 yr-1 added, which declined when N addition surpassed the N saturation threshold of 60 kg N ha-1 yr-1. Our findings provide a method for estimating annual soil CO2 efflux and new insights into the effects of N deposition rates on soil CO2 efflux in Moso bamboo forests.

Moso bamboo forests have greater net carbon uptake benefits with increasing nitrogen deposition in the coming decades., Atmospheric nitrogen (N) deposition affects the greenhouse gas (GHG) balance of ecosystems through the net atmospheric CO2 exchange and the emission of non-CO2 GHGs (CH4 and N2O). We quantified the effects of N deposition on biomass increment, soil organic carbon (SOC), and N2O and CH4 fluxes and, ultimately, the net GHG budget at ecosystem level of a Moso bamboo forest in China. Nitrogen addition significantly increased woody biomass increment and SOC decomposition, increased N2O emission, and reduced soil CH4 uptake. Despite higher N2O and CH4 fluxes, the ecosystem remained a net GHG sink of 26.8 to 29.4 megagrams of CO2 equivalent hectare−1 year−1 after 4 years of N addition against 22.7 hectare−1 year−1 without N addition. The total net carbon benefits induced by atmospheric N deposition at current rates of 30 kilograms of N hectare−1 year−1 over Moso bamboo forests across China were estimated to be of 23.8 teragrams of CO2 equivalent year−1.

Increased reactive N deposition has widespread effects on terrestrial ecosystems, such as biodiversity loss, soil acidification, as well as stimulated plant growth. Empirical studies show that biochar often affects soil quality, crop productivity, soil microbial community composition and enzyme activities. However, the effect of biochar addition on forest soil bacterial community along with enzyme activities under nitrogen (N) deposition and its related mechanisms have not been well studied yet. Therefore, a 2-year field study was conducted to investigate the effects of biochar amendment (0, 20, 40 kg biochar ha−1 yr−1) on soil nutrients, enzyme activities, and bacterial community in a Torreya grandis orchard under different levels of N deposition (0, 30, 60 kg N ha−1 yr−1). N deposition significantly increased soil nutrients availability, such as N, phosphorus (P) and potassium (K), while biochar amendment led to significant increase in soil pH, organic carbon (SOC), total N (TN), total P (TP), available P (AP) and available K (AK). Both N deposition and biochar amendment significantly decreased the soil microbial biomass carbon (MBC), altered soil microbial community and enzyme activities significantly. Biochar addition increased the relative abundance of phylum Proteobacteria under different levels of N deposition, but had variable effect on Acidobacteria groups. Non-metric multidimensional scaling (NMDS) indicated that biochar amendment can mitigate the effect of N deposition on soil bacterial community composition and enzyme activities. Soil pH and SOC played an important role in shaping soil bacterial community composition, while available AP and AK contents significantly related to the variation of soil enzyme activities. Structure equation modeling (SEM) revealed that N deposition had negative effect on soil enzyme activities while biochar amendment can mitigate this negative effect through increasing AP content. Our result suggests that biochar amendment can mitigate the alteration of soil bacterial community and enzyme activities induced by N deposition, and this mitigation effect was linked to the alteration of soil physicochemical properties, especially the increased AP content. Thus, biochar amendment could be a promising way to develop sustainable forest management under increasing N deposition.

Despite fresh and pyrogenic organic matter have been widely used as amendments to improve soil organic carbon (SOC) storage, mineralization that links to C quality and soil temperature, microbial community composition and enzyme activity remain poorly understood. This study aims to explore the effects of amendments (bamboo leaves and its biochar) and incubation temperature on mineralization, and disentangle the relationships of SOC mineralization with chemical composition of SOC, labile organic C, microbial community composition, and activities of enzymes in a subtropical bamboo forest soil. Results showed that cumulative soil CO2 emissions ranked as bamboo leaf (Leaf) > bamboo leaf biochar (Biochar) > Control, regardless of the incubation temperature. Compared to the control, the Leaf treatment markedly increased, whereas the Biochar treatment decreased, the temperature sensitivity of SOC mineralization (P < 0.05). The cumulative soil CO2 emission was positively correlated (P < 0.05) with water-soluble organic C (WSOC), microbial biomass C (MBC), O-alkyl C and alkyl C contents, and activities of β-glucosidase and dehydrogenase, but negatively correlated (P < 0.01) with aromatic C content, regardless of the incubation temperature. This indicated that the lower SOC mineralization rate and lower temperature sensitivity in the Biochar (cf. Leaf) treatment were intimately associated with the lower WSOC, MBC, O-alkyl C content, and β-glucosidase and dehydrogenase activities, and higher aromatic C content in the Biochar. The high relative abundance of bacteria relating SOC mineralization included Rhizobiales, Sphingobacteriales and JG30-KF-AS9, whereas that of fungi included Eurotiales, Sordariales, Agaricales and Helotiales. Our results revealed that the application of pyrogenic organic matter, as compared to the application of fresh organic matter, can reduce SOC mineralization and its temperature sensitivity in a subtropical forest soil by limiting the availability of C and microbial activity, and thus has a great potential for maintaining soil carbon stock in subtropical forest ecosystems.

Fertilization is a common practice to increase forest productivity; however, the responses of soil respiration (RS) components to the application of inorganic and organic fertilizers and the associated mechanisms are not clear in subtropical forest ecosystems. In this field trial conducted within an intensively-managed Moso bamboo (Phyllostachys edulis) forest, we aimed to compare the effects of inorganic and organic fertilizers, and their combination on seasonal variations in RS components, i.e., heterotrophic (RH) and autotrophic (RA) respiration, and to establish the relations of RS components with soil properties. Fertilizer additions increased RH (P

Moso bamboo ( Phyllostachys edulis ) is widely distributed in subtropical regions, especially in China. However, the capacity of Moso bamboo forests to sequester carbon remains poorly quantified at the ecosystem level. To our knowledge, this study reports the first use of the eddy covariance technique to measure and quantify the net ecosystem production (NEP) of Moso bamboo forests from 2011 to 2015. The mean annual NEP was 602.7 ± 59.7 g C m −2 , which is far higher than that of the other forest types in subtropical China. The total NEP of China’s Moso bamboo forests was roughly estimated at 0.027 Pg C yr −1 , which accounts for 15–36% of the NEP of all forests of China. In Moso bamboo, the explosive growth pattern, high photosynthetic rate, and sufficient and synchronous water and heat availability, coupled with high atmospheric deposition of nitrogen and phosphorus contribute to the regulation of NEP dynamics and its carbon sequestration efficiency. An extreme drought that occurred in the July and August of 2013 significantly reduced the NEP of Moso bamboo forest by 60–78%. Our findings suggest that the carbon uptake of Moso bamboo forests is much higher than previously thought and that the large potential of these forests in mitigating climate change should not be ignored.

Methane (CH4) is one of the three most important greenhouse gases. To date, observations of ecosystem-scale methane (CH4) fluxes in forests are currently lacking in the global CH4 budget. The environmental factors controlling CH4 flux dynamics remain poorly understood at the ecosystem scale. In this study, we used a state-of-the-art eddy covariance technique to continuously measure the CH4 flux from 2016 to 2018 in a subtropical forest of Zhejiang Province in China, quantify the annual CH4 budget and investigate its control factors. We found that the total annual CH4 budget was 1.15 ± 0.28~4.79 ± 0.49 g CH4 m−2 year−1 for 2017–2018. The daily CH4 flux reached an emission peak of 0.145 g m−2 d−1 during winter and an uptake peak of −0.142 g m−2 d−1 in summer. During the whole study period, the studied forest region acted as a CH4 source (78.65%) during winter and a sink (21.35%) in summer. Soil temperature had a negative relationship (p &lt, 0.01, R2 = 0.344) with CH4 flux but had a positive relationship with soil moisture (p &lt, R2 = 0.348). Our results showed that soil temperature and moisture were the most important factors controlling the ecosystem-scale CH4 flux dynamics of subtropical forests in the Tianmu Mountain Nature Reserve in Zhejiang Province, China. Subtropical forest ecosystems in China acted as a net source of methane emissions from 2016 to 2018, providing positive feedback to global climate warming.

While there is a sound understanding of the range of mechanisms by which biochar can contribute to the mitigation of soil N2O emissions, a paucity of information remains on the efficacy and mechanisms associated with biochar-based fertilizer (BF). The present 12-month field trial aimed to: (1) investigate the responses of the seasonal variations in soil N2O emissions and environmental factors, including soil temperature and moisture content, concentrations of NH4+-N, NO3−-N, water-soluble organic N (WSON), microbial biomass N (MBN), water-soluble organic C (WSOC) and microbial biomass C (MBC), and urease and protease activities, to application of BF, chemical fertilizer (CF) and a mixture of BF and CF (BCF) within a Moso bamboo plantation, and (2) reveal contributions of variation in soil properties to change in soil N2O emissions. The fertilized treatments matched doses of N, P and K among BF, CF and BCF, with an unfertilized treatment as a control. Compared to the control, BF treatment decreased soil N2O emissions (P

Biome-specific soil respiration (Rs) has important yet different roles in both the carbon cycle and climate change from regional to global scales. To date, no comparable studies related to global biome-specific Rs have been conducted applying comprehensive global Rs databases. The goal of this study was to develop artificial neural network (ANN) models capable of spatially estimating global Rs and to evaluate the effects of interannual climate variations on 10 major biomes. We used 1,976 annual Rs field records extracted from global Rs literature to train and test the ANN models. We determined that the best ANN model for predicting biome-specific global annual Rs was the one that applied mean annual temperature (MAT), mean annual precipitation (MAP) and biome type as inputs (r2 = 0.60). The ANN models reported an average global Rs of 93.3 ± 6.1 Pg C year−1 from 1960 to 2012 and an increasing trend in average global annual Rs of 0.04 Pg C year−1. Estimated annual Rs increased with increases in MAT and MAP in cropland, boreal forest, grassland, shrubland and wetland biomes. Additionally, estimated annual Rs decreased with increases in MAT and increased with increases in MAP in desert and tundra biomes, and only significantly decreased with increases in MAT (r2 = 0.87) in the savannah biome. The developed biome-specific global Rs database for global land and soil carbon models will aid in understanding the mechanisms underlying variations in soil carbon dynamics and in quantifying uncertainty in the global soil carbon cycle.

The effects of nitrogen (N) deposition and management practices on leaf litterfall and N and P return in Moso bamboo forest are not yet known. In this study, we investigated the effects of four levels of simulated N deposition, including low-N (N30, 30 kg ha−1 year−1), medium-N (N60, 60 kg ha−1 year−1), and high-N (N90, 90 kg ha−1 year−1), and a control with no N (N-free addition). The experiment was performed in a Moso bamboo forest under conventional management (CM) and intensive management (IM). The results showed that leaf litterfall and N and P return occurred mainly from March to June and accounted for 78.2–82.2, 78.5–82.1, and 85.6–94.6% of annual leaf litterfall, N return, and P return, respectively. Unlike CM, IM significantly increased leaf litterfall and N and P return. The positive effects were further amplified by low- and medium-N deposition, but not high-N deposition. The combination of low- and medium-N deposition and IM significantly increased N and P return, but not litterfall. Our results indicated that the interaction of anthropogenic management practices and N deposition need to be considered when estimating the effects of N deposition on the biogeochemical cycle of a forest ecosystem.

Torreya grandis , an economically important nut tree in Southeast China, is being subjected to increasing atmospheric nitrogen (N) deposition, and thus far its impact on nut quality remains unknown. Also, studies evaluating nut quality response to biochar application (commonly used as soil amendment) to soils under N deposition conditions are rare. Here, we investigated changes of nut physical characteristics (i.e., nut weight, length and width and kernel weight) and nut nutritional components (i.e., lipid, protein, starch and total soluble sugars) under a factorial combination of biochar application (0, 20 t ha −1 ) and simulated additional nitrogen deposition (0, 30 and 60 kg N ha −1 yr −1 ) treatments in a growing season (approximately 7 months). Results showed that N addition had a direct fertilizing effect, with a significant increase of nut weight, nut size, kernel weight, and nut nutritional components in terms of lipid, protein, starch and total soluble sugars. However, soil chemical properties were negatively affected by N addition with significant decreases in soil pH and available N, P and K. Biochar application showed a liming effect, with a significant increase of soil pH which was significantly correlated with nut weight and the main nut nutritional components. Additionally, biochar strongly interacted with additional N deposition by increasing the availability of N, P and K in soil. Our study suggested, for the first time, that the ‘win-win’ can be achieved, both nut quality of T. grandis and soil fertility can be improved by biochar application to soils suffering from N deposition. Results are relevant for the successful improvement of nut crop quality and development of sustainable agriculture under accelerated N deposition worldwide.

Global lakes have been identified as an important component of natural methane (CH4) sources. Given that lake CH4 emissions involve multiple, complex processes influenced by various environmental factors, estimates of global lake CH4 emissions are largely uncertain. In this study, we compiled global CH4 emission data on 744 lakes from published studies, and found a significantly negative correlation (R2 = 0.50, p

Understanding the composition and diversity of soil microorganisms that typically mediate the soil biogeochemical cycle is crucial for estimating greenhouse gas flux and mitigating global changes in plantation forests. Therefore, the objectives of this study were to investigate changes in diversity and relative abundance of bacteria and archaea with soil profiles and the potential factors influencing the vertical differentiation of microbial communities in a poplar plantation. We investigated soil bacterial and archaeal community compositions and diversities by 16S rRNA gene Illumina MiSeq sequencing at different depths of a poplar plantation forest in Chenwei forest farm, Sihong County, Jiangsu, China. More than 882,422 quality-filtered 16S rRNA gene sequences were obtained from 15 samples, corresponding to 34 classified phyla and 68 known classes. Ten major bacterial phyla and two archaeal phyla were found. The diversity of bacterial and archaeal communities decreased with depth of the plantation soil. Analysis of variance (ANOVA) of relative abundance of microbial communities exhibited that Nitrospirae, Verrucomicrobia, Latescibacteria, GAL15, SBR1093, and Euryarchaeota had significant differences at different depths. The transition zone of the community composition between the surface and subsurface occurred at 10&ndash, 20 cm. Overall, our findings highlighted the importance of depth with regard to the complexity and diversity of microbial community composition in plantation forest soils.

The effects of nitrogen (N) deposition on soil organic carbon (C) and greenhouse gas (GHG) emissions in terrestrial ecosystems are the main drivers affecting GHG budgets under global climate change. Although many studies have been conducted on this topic, we still have little understanding of how N deposition affects soil C pools and GHG budgets at the global scale. We synthesized a comprehensive dataset of 275 sites from multiple terrestrial ecosystems around the world and quantified the responses of the global soil C pool and GHG fluxes induced by N enrichment. The results showed that the soil organic C concentration and the soil CO

Ecosystem-level effects of increasing atmospheric nitrogen (N) deposition on the phosphorus (P) cycle and P use strategy are poorly understood. Here, we conducted a seven year N-addition experiment to comprehensively evaluate the effects of N deposition on P limitation, cycling, and use strategy in a subtropical Moso bamboo forest. N addition significantly increased foliar litterfall by 4.7%–21.7% and subsequent P return to the soil by 49.0%–70.1%. It also increased soil acidity, acid phosphatase activity, and soil microbial biomass P, which substantially contributed to a significantly increased soil P availability and largely alleviated the P limitation. This resulted in a significant decrease in the foliar P-resorption efficiency and the abundance and colonization of arbuscular mycorrhizal fungi. Our results indicate that N deposition can reduce plant internal cycling while enhancing ecosystem-scale cycling of P in Moso bamboo forests. This suggests a shift in P use from a ‘conservative consumption’ strategy to a ‘resource spending’ strategy. Our findings shed new light on N deposition effects on P cycle processes and P use strategy at the ecosystem scale under increasing atmospheric N deposition.

Aims The combined effects of nitrogen (N) deposition and management practices on fine root decomposition remain unknown. The objective of this study was to investigate the effects of the two factors on fine root decay in Moso bamboo plantations.