scholarly journals Nitrogen addition turns a temperate peatland from a near-zero source into a strong sink of nitrous oxide

2022 ◽  
Vol 68 (No. 1) ◽  
pp. 49-58
Author(s):  
Boli Yi ◽  
Fan Lu ◽  
Zhao-Jun Bu
Keyword(s):  
Nitrous Oxide ◽  
Pearson Correlation ◽  
Growing Season ◽  
Nitrogen Addition ◽  
Changbai Mountains ◽  
High Dose ◽  
N Addition ◽  
Flux Dynamics ◽  
Factors Affecting ◽  
Hani Peatland

Peatlands, as important global nitrogen (N) pools, are potential sources of nitrous oxide (N<sub>2</sub>O) emissions. We measured N<sub>2</sub>O flux dynamics in Hani peatland in a growing season with simulating warming and N addition for 12 years in the Changbai Mountains, Northeastern China, by using static chamber-gas chromatography. We hypothesised that warming and N addition would accelerate N<sub>2</sub>O emissions from the peatland. In a growing season, the peatland under natural conditions showed near-zero N<sub>2</sub>O fluxes and warming increased N<sub>2</sub>O emissions but N addition greatly increased N<sub>2</sub>O absorption compared with control. There was no interaction between warming and N addition on N<sub>2</sub>O fluxes. Pearson correlation analysis showed that water table depth was one of the main environmental factors affecting N<sub>2</sub>O fluxes and a positive relationship between them was observed. Our study suggests that the N<sub>2</sub>O source function in natural temperate peatlands maybe not be so significant as we expected before; warming can increase N<sub>2</sub>O emissions, but a high dose of N input may turn temperate peatlands to be strong sinks of N<sub>2</sub>O, and global change including warming and nitrogen deposition can alter N<sub>2</sub>O fluxes via its indirect effect on hydrology and vegetation in peatlands.  

scholarly journals Effects of rainfall manipulation and nitrogen addition on plant biomass allocation in a semiarid sandy grassland

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jing Zhang ◽  
Xiaoan Zuo ◽  
Xueyong Zhao ◽  
Jianxia Ma ◽  
Eduardo Medina-Roldán
Keyword(s):  
Biomass Allocation ◽  
Plant Biomass ◽  
Extreme Rainfall ◽  
Growing Season ◽  
Nitrogen Addition ◽  
Extreme Drought ◽  
N Addition ◽  
Rainfall Distribution ◽  
Grassland Plants ◽  
Sandy Grassland

Abstract Extreme climate events and nitrogen (N) deposition are increasingly affecting the structure and function of terrestrial ecosystems. However, the response of plant biomass to variations to these global change drivers is still unclear in semi-arid regions, especially in degraded sandy grasslands. In this study, a manipulative field experiment run over two years (from 2017 to 2018) was conducted to examine the effect of rainfall alteration and nitrogen addition on biomass allocation of annuals and perennial plants in Horqin sandy grassland, Northern China. Our experiment simulated extreme rainfall and extreme drought (a 60% reduction or increment in the growing season rainfall with respect to a control background) and N addition (20 g/m2) during the growing seasons. We found that the sufficient rainfall during late July and August compensates for biomass losses caused by insufficient water in May and June. When rainfall distribution is relatively uniform during the growing season, extreme rainfall increased aboveground biomass (AGB) and belowground biomass (BGB) of annuals, while extreme drought reduced AGB and BGB of perennials. Rainfall alteration had no significant impacts on the root-shoot ratio (R/S) of sandy grassland plants, while N addition reduced R/S of grassland species when there was sufficient rainfall in the early growing season. The biomass of annuals was more sensitive to rainfall alteration and nitrogen addition than the biomass of perennials. Our findings emphasize the importance of monthly rainfall distribution patterns during the growing season, which not only directly affect the growth and development of grassland plants, but also affect the nitrogen availability of grassland plants.

scholarly journals Short Legacy Effects of Growing Season Nitrogen Addition and Reduced Precipitation alter Soil Respiration during Nongrowing Season

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 358
Author(s):  
Guoyong Yan ◽  
Yajuan Xing ◽  
Qinggui Wang ◽  
Changcheng Mu
Keyword(s):  
Soil Respiration ◽  
Temperate Forest ◽  
Growing Season ◽  
Nitrogen Addition ◽  
Late Winter ◽  
N Addition ◽  
Legacy Effects ◽  
Manipulative Experiment ◽  
Soil C ◽  
C Cycle

The short legacy effects of growing season nitrogen (N) addition and reduced precipitation on nongrowing season soil respiration (Rs), autotrophic respiration (Ra), and heterotrophic respiration (Rh) are still unclear. Therefore, a field manipulative experiment to determine the responses of nongrowing season Rs and its components to growing season N addition and reduced precipitation was conducted in a temperate forest. The results show that growing season N addition and reduced precipitation significantly increased nongrowing season Rs by regulating the response of Ra and Rh. The combination of N addition and reduced precipitation also showed a much stronger effect on Rs and its components, but the magnitude and direction largely depended on the snowpack thickness. The effects of growing season N addition and reduced precipitation on nongrowing season Rs and its components were mediated by different sampling periods. N addition significantly decreased Rs by decreasing Rh in early winter and significantly increased Rs by increasing Ra in deep winter and late winter. All treatments decreased temperature sensitivity (Q10) of Rs and Rh. Our findings contribute to a better understanding of how nongrowing season Rs and its components will change under growing season N addition and reduced precipitation and could improve predictions of the future states of the soil C cycle in response to climate change.

scholarly journals Impacts of long-term nitrogen addition on nitrous oxide in a temperate grassland

2021 ◽  
Vol 293 ◽  
pp. 01001
Author(s):  
Si Chen ◽  
Tianpeng Gao ◽  
Tianxiang Hao ◽  
Kaihui Li ◽  
Xuejun Liu
Keyword(s):  
Nitrous Oxide ◽  
Structural Equation ◽  
Industrial Revolution ◽  
Nitrogen Addition ◽  
N Deposition ◽  
Temperate Grassland ◽  
Equation Modeling ◽  
Limiting Factor ◽  
N Addition

Atmospheric nitrogen (N) deposition has increased dramatically due to increased human activities since the industrial revolution. However, it is still unclear what the responses of soil nitrous oxide (N2O) is to long-term elevated N deposition in a temperate grassland. Here, we conducted an in situ field experiment to investigate these responses to long-term high N addition on a temperate steppe in Inner Mongolia, China, from April 2017 to October 2018. Soil N2O emissions significantly increased by long-term N addition, use of structural equation modeling (SEM) showed that topsoil (0-5 cm) NH4+-N content was the most important limiting factor for N2O emission. Our results indicate that long-term high N addition showed a significantly increase in N2O emission in this temperate grassland.

scholarly journals The role of serum β-trophin and endostatin in patients with polycystic ovary syndrome: Are they correlated?

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Gong ◽  
Aikmu Bilixzi ◽  
Xinmei Wang ◽  
Yanli Lu ◽  
Li Wan ◽  
...  
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Influencing Factors ◽  
Polycystic Ovary ◽  
Pearson Correlation ◽  
Healthy Controls ◽  
Newly Diagnosed ◽  
Ovary Syndrome ◽  
Factors Affecting ◽  
Main Factors

Abstract Background It’s necessary to investigate the serum β-trophin and endostatin (ES) level and its influencing factors in patients with newly diagnosed polycystic ovary syndrome (PCOS). Methods Newly diagnosed PCOS patients treated in our hospital were selected, and healthy women who took physical examination during the same period as healthy controls. We detected and compared the related serum indicators between two groups, Pearson correlation were conducted to identify the factors associated with β-trophin and ES, and the influencing factors of β-trophin and ES were analyzed by logistic regression. Results A total of 62 PCOS patients and 65 healthy controls were included. The BMI, WHI, LH, FSH, TT, FAI, FBG, FINS, HOMA-IR, TC, TG, LDL, ES in PCOS patients were significantly higher than that of healthy controls, while the SHBG and HDL in PCOS patients were significantly lower than that of healthy controls (all p < 0.05). β-trophin was closely associated with BMI (r = 0.427), WHR (r = 0.504), FBG (r = 0.385), TG (r = 0.405) and LDL (r = 0.302, all p < 0.05), and ES was closely associated with BMI (r = 0.358), WHR (r = 0.421), FBG (r = 0.343), TC (r = 0.319), TG (r = 0.404, all p < 0.05). TG, BMI, WHR and FBG were the main factors affecting the serum β-trophin levels (all p < 0.05). FBG, TC and BMI were the main factors affecting the serum ES levels (all p < 0.05). The TG, β-trophin, ES level in PCOS patients with insulin resistance (IR) were significantly higher than that of those without IR (all p < 0.05). Conclusion Increased β-trophin is closely associated with increased ES in patients with PCOS, which may be the useful indicators for the management of PCOS.

Nitrogen addition amplifies the nonlinear drought response of grassland productivity to extended growing‐season droughts

Ecology ◽  
2021 ◽  
Author(s):  
Bo Meng ◽  
Junqin Li ◽  
Gregory E. Maurer ◽  
Shangzhi Zhong ◽  
Yuan Yao ◽  
...  
Keyword(s):  
Growing Season ◽  
Nitrogen Addition ◽  
Drought Response ◽  
Grassland Productivity

scholarly journals The features of the coastal fronts in the Eastern Guangdong coastal waters during the downwelling-favorable wind period

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chaoyu Yang ◽  
Haibin Ye
Keyword(s):  
Coastal Waters ◽  
Meteorological Data ◽  
Pearson Correlation ◽  
Ocean Model ◽  
Ekman Pumping ◽  
Zonal Distribution ◽  
Factors Affecting ◽  
China Sea ◽  
Hybrid Coordinate Ocean Model ◽  
The Mean

AbstractA coastal front was detected in the eastern Guangdong (EGD) coastal waters during a downwelling-favorable wind period by using the diffuse attenuation coefficient at 490 nm (Kd(490)). Long-term satellite data, meteorological data and hydrographic data collected from 2003 to 2017 were jointly utilized to analyze the environmental factors affecting coastal fronts. The intensities of the coastal fronts were found to be associated with the downwelling intensity. The monthly mean Kd(490) anomalies in shallow coastal waters less than 25 m deep along the EGD coast and the monthly mean Ekman pumping velocities retrieved by the ERA5 dataset were negatively correlated, with a Pearson correlation of − 0.71. The fronts started in October, became weaker and gradually disappeared after January, extending southwestward from the southeastern coast of Guangdong Province to the Wanshan Archipelago in the South China Sea (SCS). The cross-frontal differences in the mean Kd(490) values could reach 3.7 m−1. Noticeable peaks were found in the meridional distribution of the mean Kd(490) values at 22.5°N and 22.2°N and in the zonal distribution of the mean Kd(490) values at 114.7°E and 114.4°E. The peaks tended to narrow as the latitude increased. The average coastal surface currents obtained from the global Hybrid Coordinate Ocean Model (HYCOM) showed that waters with high nutrient and sediment contents in the Fujian and Zhejiang coastal areas in the southern part of the East China Sea could flow into the SCS. The directions and lengths of the fronts were found to be associated with the flow advection.

scholarly journals Effects of nitrogen and phosphorus additions on nitrous oxide emission in a nitrogen-rich and two nitrogen-limited tropical forests

2016 ◽  
Vol 13 (11) ◽  
pp. 3503-3517 ◽  
Author(s):  
Mianhai Zheng ◽  
Tao Zhang ◽  
Lei Liu ◽  
Weixing Zhu ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Tropical Forests ◽  
N2o Emission ◽  
N Deposition ◽  
Soil N ◽  
N Addition ◽  
Old Growth ◽  
Old Growth Forest ◽  
P Addition ◽  
Stimulation Of

Abstract. Nitrogen (N) deposition is generally considered to increase soil nitrous oxide (N2O) emission in N-rich forests. In many tropical forests, however, elevated N deposition has caused soil N enrichment and further phosphorus (P) deficiency, and the interaction of N and P to control soil N2O emission remains poorly understood, particularly in forests with different soil N status. In this study, we examined the effects of N and P additions on soil N2O emission in an N-rich old-growth forest and two N-limited younger forests (a mixed and a pine forest) in southern China to test the following hypotheses: (1) soil N2O emission is the highest in old-growth forest due to the N-rich soil; (2) N addition increases N2O emission more in the old-growth forest than in the two younger forests; (3) P addition decreases N2O emission more in the old-growth forest than in the two younger forests; and (4) P addition alleviates the stimulation of N2O emission by N addition. The following four treatments were established in each forest: Control, 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). From February 2007 to October 2009, monthly quantification of soil N2O emission was performed using static chamber and gas chromatography techniques. Mean N2O emission was shown to be significantly higher in the old-growth forest (13.9 ± 0.7 µg N2O-N m−2 h−1) than in the mixed (9.9 ± 0.4 µg N2O-N m−2 h−1) or pine (10.8 ± 0.5 µg N2O-N m−2 h−1) forests, with no significant difference between the latter two. N addition significantly increased N2O emission in the old-growth forest but not in the two younger forests. However, both P and NP addition had no significant effect on N2O emission in all three forests, suggesting that P addition alleviated the stimulation of N2O emission by N addition in the old-growth forest. Although P fertilization may alleviate the stimulated effects of atmospheric N deposition on N2O emission in N-rich forests, this effect may only occur under high N deposition and/or long-term P addition, and we suggest future investigations to definitively assess this management strategy and the importance of P in regulating N cycles from regional to global scales.

scholarly journals Analysis of Drought Characteristics in Xilingol Grassland of Northern China Based on SPEI and Its Impact on Vegetation

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Siqin Tong ◽  
Yuhai Bao ◽  
Rigele Te ◽  
Qiyun Ma ◽  
Si Ha ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Pearson Correlation ◽  
Growing Season ◽  
Vegetation Coverage ◽  
Semiarid Region ◽  
Linear Regression Method ◽  
Upward Trend ◽  
Drought Effect ◽  
Positive Correlation

This research is based on the standardized precipitation evapotranspiration index (SPEI) and normalized difference vegetation index (NDVI) which represent the drought and vegetation condition on land. Take the linear regression method and Pearson correlation analysis to study the spatial and temporal evolution of SPEI and NDVI and the drought effect on vegetation. The results show that (1) during 1961–2015, SPEI values at different time scales showed a downward trend; SPEI-12 has a mutation in 1997 and the SPEI value significantly decreased after this year. (2) During 2000–2015, the annual growing season SPEI has an obvious upward trend in time and the apparent wetting spatially. (3) In the recent 16 years, the growing season NDVI showed an upward trend and more than 80% of the total area’s vegetation increased in Xilingol. (4) Vegetation coverage in Xilingol grew better in humid years and opposite in arid years. SPEI and NDVI had a significant positive correlation; 98% of the region showed positive correlation, indicating that meteorological drought affects vegetation growth more in arid and semiarid region. (5) The effect of drought on vegetation has lag effect, and the responses of different grassland types to different scales of drought were different.

scholarly journals The effects of maternal and infant vitamin A supplementation on vitamin A status: a randomised trial in Kenya

2007 ◽  
Vol 98 (2) ◽  
pp. 422-430 ◽  
Author(s):  
R. A. Ayah ◽  
D. L. Mwaniki ◽  
P. Magnussen ◽  
A. E. Tedstone ◽  
T. Marshall ◽  
...  
Keyword(s):  
Vitamin A ◽  
Controlled Trial ◽  
Randomised Trial ◽  
Maternal Serum ◽  
High Dose ◽  
Serum Retinol ◽  
Double Blind ◽  
Vitamin A Supplementation ◽  
Factors Affecting ◽  
Vitamin A Status

Postpartum vitamin A supplementation of mothers and infants is recommended, but the efficacy has been questioned. In this double-blind, placebo-controlled trial, Kenyan mother–infant pairs were randomised to maternal vitamin A (400 000 IU) or placebo < 24 h postpartum, and infant vitamin A (100 000 IU) or placebo at 14 weeks. Milk retinol was determined at weeks 4, 14 and 26, and maternal and infant serum retinol at weeks 14 and 26. Infant retinol stores were assessed at week 26, using a modified relative dose response (MRDR) test. Among 564 women, serum retinol at 36 weeks gestation was 0·81 (sd 0·21) μmol/l, and 33·3 % were < 0·7 μmol/l. Maternal serum retinol was not different between groups, but milk retinol was higher in the vitamin A group: (0·67 v. 0·60 μmol/l; 0·52 v. 0·44 μmol/l; 0·50 v. 0·44 μmol/l at 4, 14 and 26 weeks, respectively). When expressed per gram fat, milk retinol was higher in the vitamin A group only at 4 weeks. Infant serum retinol was not different between groups. However, although most infants had deficient vitamin A stores (MRDR>0·06 %) at 26 weeks, vitamin A to infants, but not mothers, resulted in a lower proportion of infants with deficient vitamin A stores (69 v. 78 %). High-dose postpartum vitamin A supplementation failed to increase serum retinol and infant stores, despite modest effects on milk retinol. Infant supplementation, however, increased stores. There is a need for a better understanding of factors affecting absorption and metabolism of vitamin A.

scholarly journals Lack of Association between Pulse Steroid Therapy and Bone Mineral Density in Patients with Multiple Sclerosis

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Serap Zengin Karahan ◽  
Cavit Boz ◽  
Sevgi Kilic ◽  
Nuray Can Usta ◽  
Mehmet Ozmenoglu ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Bone Mineral Density ◽  
Lumbar Spine ◽  
Femoral Neck ◽  
Bone Mineral ◽  
Steroid Therapy ◽  
Negative Relationship ◽  
High Dose ◽  
Mineral Density ◽  
Factors Affecting

Multiple sclerosis (MS) has been associated with reduced bone mineral density (BMD). The purpose of this study was to determine the possible factors affecting BMD in patients with MS. We included consecutive 155 patients with MS and 90 age- and sex-matched control subjects. Patients with MS exhibited significantly lowerT-scores andZ-scores in the femoral neck and trochanter compared to the controls. Ninety-four (61%) patients had reduced bone mass in either the lumbar spine or the femoral neck; of these, 64 (41.3%) had osteopenia and 30 (19.4%) had osteoporosis. The main factors affecting BMD were disability, duration of MS, and smoking. There was a negative relationship between femoral BMD and EDSS and disease duration. No association with lumbar BMD was determined. There were no correlations between BMD at any anatomic region and cumulative corticosteroid dose. BMD is significantly lower in patients with MS than in healthy controls. Reduced BMD in MS is mainly associated with disability and duration of the disease. Short courses of high dose steroid therapy did not result in an obvious negative impact on BMD in the lumbar spine and femoral neck in patients with MS.

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