Search

Phosphorus (P) fertilizer is commonly used in subtropical plantations to augment nutrients including carbon (C), nitrogen (N), and P to maintain plants engaged in metabolism. Stoichiometric homeostasis reflects the adaptation of plants to various environments (including P fertilizer supply rates). It is thus of great significance to understand C:N:P stoichiometry in the plant–litter–soil system under P addition and the stoichiometric homeostasis of plant tissues for the P fertilization management of slash pine (Pinus elliottii Engelm) plantations. In subtropical China, we measured the C, N, and P contents in root, branch, needle, litter, and soil in slash pine plantations fertilized with four treatments, P1 (25 kg P ha1 yr1), P2 (50 kg P ha1 yr1), P3 (100 kg P ha1 yr1), and a control (CK), and calculated the stoichiometric homeostasis of plant tissues. The results show that P3 treatment increased the C, N, and P contents of the needle. P2 and P3 treatments increased the P content of the litter and the N:P ratio of the root while decreasing the C:N ratio of the root. P addition treatments increased C and P element accumulation in soil but had no effect on soil stoichiometry. The nutrient contents of needle and branch were higher than those of root and litter, indicating that slash pine was more inclined to allocate nutrients to the aboveground tissues. The stoichiometric homeostasis of C, N, and P among plant tissues was graded as follows: root > branch > needle. The needle's nutritional homeostasis was C > N > P, with 1/H values of 0.08, 0.34, and 0.74, respectively. These findings demonstrate that during P addition, the C, N, and P stoichiometric homeostasis varied among plant tissues and element types. In conclusion, P application altered nutrient distribution in the plant–litter–soil system, alleviating P restriction in slash pine forests in southern China. P addition levels should be finely adjusted in the future for longer-term observation trials, and the trade-off between P addition rates and economic and ecological advantages should be properly examined. [ABSTRACT FROM AUTHOR]

Purpose: Nitrogen (N) and phosphorus (P) amendments considerably influence fungal diversity and community composition in various ecosystems. Nevertheless, how N and P additions would change arbuscular mycorrhizal (AM) fungal community and functional guilds in forest soil remains largely unclear. Materials and methods: A 5-year N and P addition experiment was conducted in a subtropical forest of southeastern China. Soil AM fungal communities were detected by the high throughput sequencing of 18S rRNA gene-fragments. We investigated the six-seasonal responses of AM fungal diversity, community assembly pattern and functional guild composition to N and/or P amendments. Results and discussion: The AM fungal Shannon index changed from a positive (3–4 years) to a nonsignificant (4–5 years) effect under P and NP additions as the duration of fertilization increased. P addition, but not N addition, changed the AM fungal community assembly pattern from stochastic- to deterministic-dominant processes. In contrast, P and NP additions significantly influenced AM fungal functional guild components, and the relative abundances of ancestral and edaphophilic guilds increased with increasing years of fertilization. Additionally, the AM fungal guild structure was significantly affected by soil P-related parameters. Conclusions: Our results emphasize the substantial impacts of P amendment on soil AM community assembly pattern and functional guild composition. This study contributes to a better understanding of the temporal dynamics and potential ecological functioning of AM fungi under global environmental changes. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is considered to be one of the most limiting elements in terrestrial ecosystems, especially in the subtropical forests in China. However, little is known about how rhizosphere soil bacterial communities and functions, especially at the level of functional genes abundance, respond to P inputs. Herein we conducted a P addition experiment and treatments included 80 g m−2 yr−1 (P1), 160 g m−2 yr−1 (P2), 240 g P m−2 yr−1 (P3), 320 g P m−2 yr−1 (P4) and the control without any fertilizer application (CK) in the Phoebe bournei young plantations. This study used the quantitative microbial element cycling (QMEC) smart chip technology and 16S rRNA gene sequencing to investigate changes in the relative abundance of C-, N-, and P-cycle genes and rhizosphere soil bacterial community that received various inputs of P nutrients. Soil bacterial diversity showed a progressively decreased trend with increasing of P fertilizer, accompanied by significant differences in bacterial community structure between CK and P4 treatment. The relative abundance of N- and P-cycle genes were increased by P addition, and the highest relative abundance was observed in P3 treatment among the five P addition treatments. The relative abundance of C-cycle genes was significantly enhanced by P4 treatment, promoting C fixation, degradation, and methane metabolism. Random forest model indicated that invertase activity was the most important predictor for the relative abundance of C-, N-, and P-cycle genes. Partial least squares path modeling analysis revealed that the predominant effect of P fertilizer in driving the relative abundance of functional genes was maintained when accounting for multiple abiotic factors (total P, available P, available potassium, soil organic carbon and soil pH) drivers and there was a strong relationship between the relative abundance of functional genes and catalase, invertase and urease activities. Overall, our findings confirm that high P addition significantly altered rhizosphere soil bacterial community composition in the Phoebe bournei young plantations, and significantly enhanced the relative abundance of C-, N- and P-cycle genes. These results suggest that sufficient P fertilizer benefits to improve the nutrients cycle processes mediating by soil bacteria in Phoebe bournei young plantations. [Display omitted] • Soil bacterial diversity showed a progressively decreased trend with increasing of P fertilizer. • High P addition increased the relative abundance of functional genes involving in C-, N- and P-cycle genes. • TP, AP, AK, SOC and pH had significant effects on the relative abundance of functional genes. • Enzyme activities were significantly correlated with the relative abundance of functional genes. • Invertase activity was the most important predictor for the relative abundance of functional genes. [ABSTRACT FROM AUTHOR]

Rice-fish coculture (RFC), as a traditional agricultural strategy in China, can optimally utilize the scarce resource, especially in subtropical regions where phosphorus (P) deficiency limits agricultural production. However, ammonia-oxidizing archaea (AOA) and bacteria (AOB) are involved in the ammonia oxidation, but it remains uncertain whether their community compositions are related to the RFC combined with and without P addition that improves soil nitrogen (N) use efficiency. Here, a microcosm experiment was conducted to assess the impacts of RFC combined with and without inorganic P (0 and 50 mg P kg -1 as KH 2 PO 4 ) addition on AOA and AOB community diversities, enzyme activities and N availability. The results showed that RFC significantly increased available N content without P addition compared with P addition. Moreover, RFC significantly increased urease activity and AOA shannon diversity, and reduced NAG activity and AOB shannon diversity without P addition, respectively. Higher diversity of AOA compared with that of AOB causes greater competition for resources and energy within their habitats, thereby resulting in lower network complexity. Our findings indicated that the abundances of AOA and AOB are influenced through the introduction of fish and/or P availability, of which AOB is linked to N availability. Overall, RFC could improve paddy soil N availability without P addition in subtropical region, which provides a scientific reference for promoting the practices that reduce N fertilizer application in RFC., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interest/personal relationships that could have appeared to influence the work reported in this paper, and that this study complies with local and national guidelines., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Aims: Soil microorganisms play an important role in biogeochemical cycles in terrestrial ecosystems. Increasing nitrogen (N) and phosphorus (P) deposition are likely to regulate microbial growth by altering soil nutrient availability in tropical forests, yet their impacts on microbial community structure and function between primary forests and secondary forests are not well understood. Methods: To investigate how nutrient availability affects microbial community structure and function in tropical forests, we measured soil phospholipid fatty acids and enzyme activities in a seven-year N and P fertilization experiment in two tropical montane rainforests, China. Results: In N addition plots, fungal biomass, arbuscular mycorrhizal fungal biomass and fungi to bacteria ratio (F/B) decreased in the secondary forest, but had moderate changes in the primary forest. In P and N plus P addition plots, microbial biomass showed minor changes, but the F/B increased significantly in both forests. However, hydrolytic enzyme activities did not show a significant change in the secondary forest, while they decreased significantly in the primary forest. Microbial P limitation in the primary forest decreased under P addition and N plus P addition. Conclusions: Our findings suggest inconsistent responses of microbial community structure and enzyme activity to N and P additions in tropical soils depending on forest type. [ABSTRACT FROM AUTHOR]

Nutrient resorption, one of the most important strategies for plant nutrient conservation, is significantly affected by soil fertility. However, the effects of experimentally altered soil fertility on plant N and P resorption are poorly understood.The potential nutrient resorption response mechanisms of the dominant species Leymus chinensis to six N addition levels (0, 2.5, 5, 10, 20 and 40 g·N·m−2·year−1), two P addition levels (0 and 10 g P·m−2·year−1) and their interactions were studied after 3 years of treatments in a temperate meadow steppe.In both green leaves and culms, N and P addition significantly increased N and P concentrations, respectively. Nitrogen addition led to a decrease in the N resorption efficiency (NRE) of both leaves and culms. Within each N treatment, P addition decreased the P resorption efficiency (PRE) of both leaves and culms and the NRE of leaves, except in the N2.5 treatment. Both NRE and PRE in leaves were higher than those in culms under N and P addition conditions. The nutrient concentrations and resorption efficiency were significantly correlated with the soil nutrient availability.Our results suggest that plants rely more on nutrient absorption from the soil, reducing the proportion of elements obtained through nutrient resorption in nutrient‐rich environments. [ABSTRACT FROM AUTHOR]

Background and aims: Human activities have significantly increased nitrogen (N) and phosphorous (P) inputs to terrestrial ecosystems. However, the impact of N and P enrichment on soil microbial community structure and functioning in temperate and alpine grassland ecosystems remains unclear. Methods: In this study, we investigated the responses of soil microbial communities to nutrient (N and P) additions in two temperate and one alpine grassland ecosystems in China. We measured soil chemical properties, microbial community composition (indicated by the phospholipid fatty acids, PLFA) and potential enzyme activities related to carbon (C), N, and P cycling in the peak growing season after 4 years of nutrient addition. Results: We found that N addition reduced soil pH and increased soil total N content at two meadow sites, P addition increased soil total P content at all three sites, but both N and P additions had minimal effects on soil organic C content. Bacteria and total microbial abundances did not change after N and P additions, while fungi and arbuscular mycorrhizal fungi (AMF) abundances were suppressed by N addition. Moreover, the activity of soil extracellular enzymes involved in C, N and P cycling and their stoichiometric ratios were not responsive to N and P additions, except for inhibition of acid phosphatase by P addition at the temperate meadow site. Conclusions: Despite significant changes in soil chemistry (e.g., pH and available nutrients), soil microbial biomass (except fungi and AMF abundances), community structure, and enzyme activities (except phosphatase) were generally resistant to 4 years of N and P addition in the three temperate and alpine grassland ecosystems in China. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) addition, either individually or in combination, has been demonstrated to enhance plant productivity in grassland ecosystems. Soil bacterial community, which is the driver of litter decomposition and nutrient cycling, is assumed to control responses of terrestrial ecosystem structure and function to N and P addition. Using a high-throughput Illumina MiSeq sequencing platform, we conducted a 9-year field experiment of N (0, 5, 10, and 20 g N m -2 yr -1 ) and P (0 and 10 g P m -2 yr -1 ) additions in the Inner Mongolian steppes to elucidate long-term effects of N and P addition on soil bacterial richness, diversity and composition. We found that N addition reduced the relative abundance of Acidobacteria, Chloroflexi, and Nitrospirae, while increased that of Bacteroides. The results showed that the bacterial biomarker was enriched in P addition treatments, either individually or combined with N addition. Both N and P addition altered the bacterial community structure, while only N addition greatly decreased bacterial richness and diversity. More importantly, we showed that all of these effects were most significant in N3P treatment (20 g N m -2 yr -1 and 10 g P m -2 yr -1 ), implying that P coupled with a high-level N addition exerted a great influence on soil bacterial community. Structural equation models revealed that N and P addition had a great direct effect on soil bacterial community and an indirect effect on it mainly by changing the litter biomass. Our findings highlighted that severe niche differentiation was induced by P along with a high-level N, further emphasizing the importance of simultaneously evaluating response of soil bacterial community to N and P addition, especially in the context of increasing anthropogenic nutrient additions., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Abstract Increased nitrogen (N) deposition endangers the biodiversity and stability of forest ecosystems, and much of the original phosphorus (P) parent material continues to decrease in most lowland tropical forests. It remains poorly understood as to how soil microbial diversity at a molecular level responds to the addition of excess N and mitigation of soil P limitation, as well as their influencing factors, in the N-rich tropical forest ecosystems. To reach a better understanding, we conducted a six-year N and P-addition experiment consisting of three treatments: N-addition (150 kg N ha−1 yr−1), P-addition (150 kg P ha−1 yr−1), and NP-addition (150 kg N ha−1 yr−1 plus 150 kg P ha−1 yr−1), besides a control treatment in an old-growth tropical forest in southern China. We examined the snapshot responses of soil bacterial richness and community composition to the elevated N and P levels after six years using a 16S rRNA gene MiSeq sequencing method. The soil bacterial α-diversity, which is represented by Chao1 index in terms of bacterial richness, was 783 ± 87 (mean ± SD) across all samples in this study. The N addition caused a decline in soil bacterial richness, most likely through its negative effect on soil pH. The decrease in soil pH resulted from the direct N input and indirect NO 3 − increase. However, the P treatment had no effect on soil bacterial richness. The NP treatment also reduced the soil bacterial richness as the N addition. These results suggested that the P input could not alleviate the loss of soil bacterial richness induced by excess N deposition in the old-growth N-rich tropical forest. The Acidobacteria, which comprised 31.1% of the soil bacterial community, were the most dominant bacteria across all samples. The addition of P shifted the soil bacterial community composition. The elevated P availability with P-addition and the decreased understory plant coverage in the N-input treatment altered the soil bacterial β-diversity. Our results highlight the different roles of N and P depositions in shaping the soil bacterial richness and community composition, thereby causing concomitant changes in understory plant and underground microbial communities in this ecosystem. Highlights • A decrease in soil pH resulted from the direct N input and indirect NO 3 − increase. • N addition caused a decline in bacterial richness, possibly through its effect on pH. • Phosphorus addition shifted the soil bacterial community composition. • Elevated P availability and lower understory coverage altered bacterial community. • N and P additions play different roles in shaping bacterial richness and community. [ABSTRACT FROM AUTHOR]

Pine resin is a widely used forestry by-product, and its yield can be determined using the resin flow rate (RFR). The application of phosphorus (P) fertiliser is prevalent in plantation forests; however, its effects on the RFR are currently unclear. Here, a P fertiliser addition experiment was conducted in a slash pine (Pinus elliottii Engelm) plantation in subtropical China with four treatments - P1 (25 kg P ha−1 yr−1), P2 (50 kg P ha−1 yr−1), P3 (100 kg P ha−1 yr−1), and a control. Tree growth represented by diameter at breast height (DBH), height (H) and timber volume (V) increments, the RFR over 9 months, nine needle parameters, and non-structural carbohydrates (NSC) in the organs of the slash pine were measured. The RFR was highest from June to August. The P addition, especially after the P2 and P3 treatments, enhanced the RFR overall, except during March, April, and November. Compared with other treatments, the P3 treatment improved the increments in DBH and V. Meanwhile, the P addition regulated the synthesis of soluble sugars (SS), starch (S) and other NSC, which varied among organs. P addition increased needle morphogenesis and chlorophyll content while reduced the dry matter content and the ratio of dry to fresh weight. RFR was positively correlated with tree growth and needle length, area, chlorophyll and NSC but negatively correlated with the dry matter content and the dry:fresh weight ratio of the needle. The structural equation model showed that P addition not only had a direct positive effect on the RFR but also indirectly altered it through tree growth and organ NSC. These results indicate that P fertiliser application can effectively promote resin yield by altering tree morphology and physiology in subtropical slash pine plantations. The trade-off between the P fertiliser application rate and economic and ecological benefits should be considered in the future research. [Display omitted] • Phosphorus (P) addition promoted resin yield represented by the resin flow rate (RFR). • P addition increased the needle chlorophyll while decreased dry matter content. • P addition regulated the synthesis of NSC, which varied among tree organs. • The enhanced RFR influenced by tree morphology and organs NSC after P addition. [ABSTRACT FROM AUTHOR]

In China, phosphorus (P) is recognized as a "key limiting nutrient" for crop production, and its overuse results in underground leaching, ecosystem alterations and risks to humans, such as degraded surface water quality. The coupling of nitrogen (N) and P implies that soil N dynamics are largely affected by P availability. However, how the addition of P affects soil N transformations remains less understood. To determine the optimal P-input level, we performed an incubation experiment on an upland soil from Jinxian in China after long-term mineral fertilizer application and P addition. The two treatments without N addition T1 (no fertilizer) and T2 (inorganic potassium fertilizer) and the two treatments with N addition T3 (inorganic nitrogen fertilizer) and T4 (inorganic nitrogen and potassium fertilizer) were selected from the long-term experiment that involved scientific management at five P-input levels (0, 25, 50, 75, and 100 kg P 2 O 5 ha−1) with three replications. The results showed that soil organic matter (SOM) increased in the T3 and T4 treatments compared with the T1 and T2 treatments. The T4 treatment resulted in the maximum N concentration of 1.28 g kg−1, followed by that in the T3 treatment (1.25 g kg−1), T2 (0.16 g kg−1) and that in the T1 treatment (0.10 g kg−1), in the soil. Among the different treatments, soil microbial biomass carbon (SMBC) and nitrogen (SMBN) were significantly higher (492.69 mg kg−1 and 73.36 mg kg−1, respectively) in the T3 treatment than in the other treatments, while soil microbial biomass phosphorus (SMBP) was higher in the T4 treatment (17.55 mg kg−1). With the addition of P, the gross N mineralization rate was substantially enhanced when N and K were applied. After the 90-day incubation period, with higher concentrations of NO 3 --N and NH 4 +-N in the T4 treatment than in the other treatments, the concentrations were significantly increased by P addition, specifically T4P4 by 11.27% and 37.37%, T4P3 by 12.64% and 30.29%, T4P2 by 22.94% and 64.53%, and T4P1 by 3.93% and 11.09%, compared with those of T4P0, respectively; these results indicated a maximum N mineralization potential (N o) and mineralization rate constant, k (NMR). As a result of the increased gross nitrogen mineralization rates and associated NH 4 + substrate availability, the gross nitrification rate was also increased by P addition. Based on the polynomial regression analysis, the inclusion of P at the rate of 60 kg P 2 O 5 ha−1 can be used effectively to obtain maximum gross N mineralization rates in soil. Additionally, to fully understand why P addition is more effective under specific soil and environmental conditions, more research is necessary to determine the underlying mechanisms. • We determined the effects of P with different addition levels on soil N dynamics in soil with different N status. • Gross N mineralization increased with N fertilization at the optimum level of P addition. • P application at the rate of 60 kg ha−1 yr−1 appeared to be optimal for a sustained gross N mineralization rate. [ABSTRACT FROM AUTHOR]

Imbalanced nitrogen (N) and phosphorus (P) depositions are profoundly shifting terrestrial ecosystem biogeochemical processes. However, how P addition and its interaction with N addition influence the release of litter carbon (C), N, P, and especially metal nutrients in subtropical forests remains unclear. Herein, a two-year field litterbag experiment was conducted in a natural subtropical evergreen broadleaved forest of southwestern China using a factorial design with three levels of N addition (0, 10, and 20 g N m -2 y -1 ) and P addition (0, 5, 15 g P m -2 y -1 ). During two years of decomposition, N- and P-only addition treatments decreased the accumulated mass loss and release rates of litter C, N, P, K, Na, and Mn (p < 0.05); N and P coaddition treatments increased the accumulated mass loss and release rates of litter C, N, K, Na, Mn, and Cu (p < 0.05) and decreased the accumulated release rates of litter P and Mg (p < 0.05); the C/P and N/P ratios of the residual litter increased under the N-only addition treatments (p < 0.05) and decreased under the P-only addition and N and P coaddition treatments (p < 0.05). Overall, the results suggest that combined N and P supply can increase biological activities and thus accelerate the release of litter C, N, and most metal nutrients, as expected within the framework of ecological stoichiometry and growth rate hypothesis. Our study also highlights that the effect of N addition on litter C and nutrients release depends on P availability., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Anthropogenic activities have increased ecosystem phosphorus (P) inputs and have affected terrestrial ecosystem carbon (C) cycles. However, the fate of soil organic C (SOC) under P addition remains elusive, and the potential mechanisms underlying plant-microbial linkages mediated SOC formation and decomposition are poorly understood. Here, we conducted a field P fertilization experiment to explore the effects on SOC dynamics in a typical temperate grassland in northern China. P addition increased soil P availability and pH, thereby stimulating plant nutrient uptake and growth, leading to higher C inputs to soils via plant biomass (shoots, litter and roots). However, P addition exacerbated microbial N limitation, altered microbial community composition (with a lower fungal to bacterial ratio), shifted microbial life-history strategies, which transitioned from the K -strategy (Acidobacteria, Chloroflexi, and Verrucomicrobia dominant) to the r - strategy (Proteobacteria, Bacteroidetes, and Firmicutes dominant), and modulated their functional characteristics. All of these factors regulated microbial substrate preferences and changed the C components that undergo decomposition. These changes ultimately accelerated the utilization of active C, hampered passive C decomposition, and helped to create a longer-term stable C sink in the grassland. • P addition decreased active C and increased passive C and this resulted in a net increase of SOC. • Increased plant productivity and litter quality improved plant C inputs to the soil. • Altered microbial characteristics regulated their substrate preference, thus stimulating active C loss. • Decreased soil metallic elements may partially weaken the stability of SOC. • Accumulated passive C would be beneficial in creating a longer-term stable C sink. [ABSTRACT FROM AUTHOR]

Elevated nitrogen (N) deposition has dramatically altered soil phosphorus (P) and carbon (C) cycles in forests and altered extracellular enzyme activity. However, the effects of N addition and the interactive effects of combined N and P additions on soil enzyme (e.g. phosphatase and glucosidase) activity in different types of forests (young vs. old-growth) remain unclear. To better understand this, a long-term N–P fertilization experiment was initiated in January 2007 in two subtropical forests (an old-growth monsoon evergreen broadleaf forest (MEBF) and a young Masson pine forest (MPF)) in southern China. Four treatments were established, including control (no nutrient addition), N addition (150 kg N ha −1 yr −1 ), P addition (150 kg P ha −1 yr −1 ) and NP addition (150 kg N ha −1 yr −1 plus 150 kg P ha −1 yr −1 ). Soil physicochemical properties, acid phosphatase (APA-s) and β-glucosidase (BGA-s) activity per soil were measured in July 2012 and July 2013. Both APA-s and BGA-s were higher in MEBF than in MPF. N addition significantly stimulated APA-s in MEBF and BGA-s in MPF. P addition significantly suppressed APA-s in both forests and BGA-s in MEBF. Moreover, P addition decreased the stimulating effect of N addition on APA-s in MEBF and on BGA-s in MPF. Our results suggest that (1) N addition may exacerbate soil P limitation in old-growth forests and result in the deficiency of easily available C in young forests and (2) P addition may mitigate these negative effects of N addition in both forest types. Our findings suggest that P fertilization may be an effective practice to improve soil P availability in old-growth forests and soil C availability in young forests under N deposition condition. [ABSTRACT FROM AUTHOR]

• Hydrologic changes enhanced CH 4 emission, but inhibited CO 2 and N 2 O fluxes. • N and N + P addition increased N 2 O fluxes, which is contrary to p addition. • No interactive effects of hydrologic changes and nutrient additions on GHGs fluxes. • Global warming potential was reduced by continuous flooding and enhanced by N + P. Changes in global rainfall patterns and construction of artificial dams have led to widespread alteration of hydrological processes in riparian ecosystems. At the same time, many riparian ecosystems, such as those associated with the Yangtze, are being subjected to enhanced inputs of nitrogen (N) and phosphorus (P) due to intensified agricultural activity in surrounding uplands. Together, these environmental changes may alter the magnitude and direction of greenhouse gasses (GHGs) fluxes from riparian soils. We conducted an in situ experiment combined with quantitative PCR approach (qPCR) to elucidate the effects of hydrological alterations (continuous flooding (CF), periodic flooding (PF), and no flooding (NF)) and nutrient addition (N addition (urea, 100 kg N ha−1 y−1), P addition (P 2 O 5 , 20 kg ha−1y−1), N + P addition, and control (CK)) on three major GHGs including carbon dioxide (CO 2), methane (CH 4) and nitrous oxide (N 2 O) fluxes as well as the underlying mechanisms. Our results showed that hydrological alterations greatly affected GHGs emissions, possibly by altering soil moisture, soil organic C, and C:N ratios. The CF, with higher soil moisture and lower C:N ratio, increased CH 4 emissions 13-fold and reduced CO 2 and N 2 O emissions by 37.3% and 72.2% averaged over the growing seasons compared with no flooding. PF enhanced CH 4 emissions 5.7-fold and decreased N 2 O emissions by 69.0% in comparison with no flooding. Nutrient additions had no significant effect on CO 2 or CH 4 flux, but P addition significantly lowered N 2 O flux. Interactions between hydrological alterations and nutrient additions were not detected for any GHGs. As a result, hydrological alterations and nutrient additions affected the global warming potential (GWP) of growing season GHG budgets on a 100-year time horizon, mainly by changing the CO 2 emissions. CF reduced GWP from 597 to 439 g CO 2 -eq m−2, and N + P addition enhanced GWP from 489 to 625 g CO 2 -eq m−2. The qPCR analysis revealed that decreased CH 4 oxidation potential may lead to the enrichment of CH 4 emissions under the hydrological alterations, and reduced nitrification and denitrification potential contributed to the reduction of N 2 O fluxes under all the treatments. Our study indicates that continuous flooding could curb the contribution of riparian GHGs fluxes to global warming but that the combination of N and P additions may increase the greenhouse effect mainly by regulating the CO 2 emissions of growing season in riparian ecosystem. [Display omitted] [ABSTRACT FROM AUTHOR]