Abstract Understanding on relationships between seasonality of vegetation phenology and photosynthesis is lacking for desert ecosystems. We used digital camera (i.e., PhenoCam) to monitor the phenology of forest (i.e., 2 sites with one being closer to a lake) and grassland (i.e., 1 site) ecosystems in the Badain Jaran Desert, China. The vegetation phenology was quantified using vegetation indices calculated from the red, green, and blue digital numbers in images obtained by the PhenoCams. Additionally, various meteorological variables were continuously measured, and gross primary production (GPP) was obtained using the eddy covariance technique at the grassland site. The difference between the phenological periods extracted from the PhenoCam images and the artificial visual method was small (≤6 days), indicating that the digital camera can effectively obtain desert vegetation phenology. The key meteorological factors affecting changes in the vegetation indices were identified, with temperature being the most important factor (i.e., correlation coefficients = 0.4–0.8 and p ‐value < 0.001 for all three study sites). Although precipitation showed weak correlation with the vegetation index (correlation coefficient = 0.18–0.14, p ‐value < 0.01), rapid increases in the vegetation index were observed in response to precipitation events. Vegetation indices were strongly correlated with GPP variations at the grassland, and the strongest correlation was observed in the green‐up stage (correlation coefficient = 0.67 to 0.85, p ‐value < 0.001). The highest GPP lagged about 1 month behind the peak in the vegetation indices in summer (June–August). Our results can markedly improve the knowledge of desert ecosystem processes and aid in assessing the influence of future climate changes in drylands.
Soil organic carbon (SOC) and soil inorganic carbon (SIC) play essential roles in carbon cycling in terrestrial ecosystems; however, the effects of crop cultivation on them are still poorly understood, especially in alkali sodic soils widely distributed in semiarid regions. Alkali sodic soils from cornfields and paddies with cultivation years of 5, 15, and 25 were analyzed here to assess the response of soil properties and soil carbon pools to crop cultivation. Soil pH and exchangeable sodium percentages decrease in accordance with cultivation years, while enzyme activity (amylase, invertase, and catalase) shows a contrary trend. Soil pH and exchangeable sodium percentages are negatively correlated with SOC, but positively correlated with SIC. Redundancy analysis reveals an obvious relationship between SOC and invertase activity. The percentage of δ13CSOC found here is approximately –24.78‰ to –22.97‰ for cornfields and approximately –26.54‰ to –23.81‰ for paddies, suggesting that crop cultivation contributes to SOC sequestration and stocking, increasing with cultivation years. The percentage of δ13CSIC found here is approximately 1.90‰ to 3.73‰, proving that lithogenic inorganic carbon is the major SIC, where the stock decreases with increasing cultivation years. Significant total carbon stock loss is observed in cornfields, while it is preserved at 120 Mg ha−1 in paddies. We conclude here from the results that corn and rice cultivation reduce alkali sodic conditions in soil, thereby improving soil enzymes and favoring SOC stocking, but reducing SIC stocks.
The simultaneous desulfurization and denitrification technology has better economic and environmental values than conventional sulfate and nitrogen removal process.An anaerobic fluidized bed-microbial fuel cell (AFB-MFC) system was established to elucidate the effect of anodic different nitrate load on contaminant removal, electricity generation and anodic microbial community in a symbiotic ecosystem for sulfate reduction bacteria (SRB) and nitrate-reducing, sulphide-oxidizing bacteria (NR-SOB).Results showed that, when anodic load was 700 mg NO 3 --N/(m 3 d), 2.1 kg SO 4 2-/ (m 3 d) and 3.36 kg COD Cr /(m 3 d), the removal rate of NO 3 --N, SO 4 2-and COD Cr was 96.43%, 52.68% and 98.02%, theoretical sulfur yield was 0.92 kg/m 3 d, and output voltage and power density were 7.23 mW m -2 and 385.46 mV, respectively.It proved that the AFB-MFC had a good performance in treating organic wastewater containing nitrates and sulfates.Sulfur had also been observed in effluent.As the anodic NO 3 -load increased, the diversity of microbial community increased, hydrogen-producing bacteria, SRB and strains related to nitrate removal also increased significantly.The main functional bacteria were Sulfurovum, Desulfomicrobium, Thauera and Sulfurimonas.AFB-MFC system provides a new approach to cost-effective treatment of organic wastewater containing nitrate and sulfate.
Background Diet and exercise can affect the gut microbiota (GM); however, the effects of the same amount of exercise on gut microbiota changes in people on a low-fat diet (LFD) and high-fat diet (HFD) during pregnancy are unknown. Do different nutritional conditions respond equally to exercise intervention? This study aimed to investigate the effects of regular maternal exercise during pregnancy on the GM in mice fed different diets during pregnancy. Methods Six-week-old nulliparous female KunMing mice were fed either a HFD or LFD before and during pregnancy. Each group of mice were then randomly divided into two groups upon confirmation of pregnancy: sedentary (HFD or LFD; n = 4 and 5, respectively) and exercised (HFDex or LFDex, n = 5 and 6, respectively). Mice were sacrificed on day 19 of gestation and their colon contents were collected. We then performed 16S rDNA gene sequencing of the V3 and V4 regions of the GM. Results The pregnancy success rate was 60% for LFDex and 100% for HFDex. Both Chao1 and Simpson indices were not significantly different for either LFD vs. LFDex or HFD vs. HFDex. Desulfobacterota , Desulfovibrionia Desulfovibrionales , Desulfovibrionaceae , Desulfovibrio , Coriobacteriia , Coriobacteriales, and Eggerthellaceae were markedly decreased after exercise intervention in LFDex vs. LFD, whereas Actinobacteria , Bifidobacteriales , Bifidobacteriaceae , Bifidobacterium, and Bifidobacterium pseudolongum were significantly increased in LFDex vs. LFD. Furthermore, decreased Peptostreptococcales-Tissierellales and Peptostreptococcaceae and increased Bacteroides dorei were identified in the HFDex vs. HFD group. p_Desulfobacterota, c_Desulfovibrionia, o_Desulfovibrionales, f_Desulfovibrionaceae and g_Desulfovibrio were markedly decreased in the LFDex group vs. HFDex group. Conclusions Our data suggested that quantitative maternal exercise during pregnancy resulted in alterations in GM composition, but did not significantly change the diversity of the GM. These findings may have important implications when considering an individual’s overall diet when recommending exercise during pregnancy.
Abstract A high‐resolution study of bulk properties in a peat sequence from the Xinjiang Altai Mountains of northwestern China has allowed reconstruction of local variations in peat properties and peat C and N accumulation rates (CAR and NAR) during the Holocene. Analyses of peat bulk density, loss on ignition, and concentrations of total organic carbon (TOC) and total nitrogen (TN) and their elemental ratios and stable isotopic values suggest that changes in peat‐forming vegetation types during different parts of this epoch are the major factors responsible for the variations of peat properties in this sequence. The long‐term peat CAR has been 25.4 ± 7.7 (SD) g C/m 2 /yr, with lower values during the early Holocene and higher accumulations during the late Holocene, which is opposite to the Holocene variations in CAR in other northern peatlands. In contrast, the long‐term peat NAR is 1.5 ± 0.5 (SD) g N/m 2 /yr and is higher during the early and middle Holocene and lower during the late Holocene as in other northern peatlands. However, unlike other northern peatlands, long‐term peat NAR does not vary with the CAR, which is influenced by the peat density and accumulation rate. Variations in long‐term peat C and N accumulations in the Altai Mountains can be attributed to changes in primary productivity, in the dominant plant types and in peat decomposition caused by changes in both regional Holocene climate and local conditions.
Agricultural ecosystems are important contributors to atmospheric greenhouse gasses (GHGs); however, in situ winter emission data in saline-alkali fields are scarce. Gas samples were collected during different periods, from three rice (R1–R3) and three maize (M1–M3) fields with different soil pH levels and salinity conditions. Carbon dioxide (CO2) emissions in the rice and maize fields decreased with decreasing temperature during the freezing period and increased with the rising temperature during the thawing period, with the majority of winter CO2 emissions occurring during these two periods. Peaks in methane (CH4) emissions were observed during the freezing period in the rice fields and during the snow-melting period in the rice and maize fields. CH4 emissions in the rice fields and CH4 uptake rates in the maize fields were significantly (P < 0.05) related to surface soil temperature. Nitrous oxide (N2O) emissions remained relatively low, except for during the peaks observed during the snow-melting period in both the rice and maize fields, leading to the high GHG contribution of the snow-melting period throughout the winter. Higher pH and salinity conditions consistently resulted in lower CO2, CH4, and N2O emissions, CH4 uptake, and lower global warming potential (GWP). These results can contribute to the assessment of the GWP during winter in saline-alkali regions.
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