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Seasonal dynamics of Zooplankton functional groups in relation to environmental variables in Xiquanyan Reservoir, Northeast China
No full textIn this study, the concept of functional feeding groups was used to classify and model the seasonal variation of zooplankton functional groups in relation to environmental variables. A total of 48 zooplankton species were observed in the reservoir and grouped into 8 functional groups. Both environmental variable and the biomass of zooplankton functional groups vary spatially and seasonally. Water temperature, water transparency, total nitrogen and nitrates were significantly higher in summer, while chlorophyll-a and ammonium were higher in autumn and spring, respectively. Biomass of zooplankton was significantly higher in summer (245.81 μg/L), followed by autumn (196.54 μg/L) and spring (54.25 μg/L). Group RF (rotifer filter feeders) dominated in spring, accounting for 80% of the total biomass. In summer and autumn, group RC (rotifer carnivore) and SCF (small copepods and cladocerans filter feeders) were the dominant, respectively. Total nitrogen, total phosphorus, ammonium, chlorophyll-a and water transparency were the major factor influencing zooplankton community. Group RF was positively influenced by ammonium and total phosphorus, while RC, SCF and MCF (middle copepods and cladocerans filter feeders) were positively correlated with chlorophyll-a. Top-down control of phytoplankton by groups RC, SCF and MCF in Xiquanyan reservoir is not strong enough to produce negative effect. Increase in predator size biomass did not strengthen top-down control on prey. It is quite clear that the zooplankton function groups of Xiquanyan reservoir followed a predictable seasonal pattern. This therefore highlights the significance of environmental variables in structuring plankton composition in the reservoir.The concept of functional feeding groups was used to classify and model the seasonal variation of zooplankton functional groups in relation to environmental variables.
Zooplankton species were grouped into 8 functional groups that vary spatially and followed a predictable seasonal pattern.
Total nitrogen, total phosphorus, ammonium, chlorophyll-a and water transparency were the major factor influencing zooplankton community.
Top-down control of phytoplankton by zooplankton in Xiquanyan reservoir is not strong enough to produce negative effect
Laboratory study on nitrate removal and nitrous oxide emission in intact soil columns collected from nitrogenous loaded riparian wetland, Northeast China - Fig 1
No full textBottom at the right corner is the location of Northeast China (A) and shaded grey and yellow dot is Sanjiang Plain and Qixing River Wetland National Nature Reserve, respectively. The enlarged map at the top (B) is Qixing River Wetland National Nature Reserve and 1, 2, 3 are the sampling sites.</p
Soil characteristics of the three studied wetland vegetation sites (<i>C</i>. <i>epigeios</i>, <i>P</i>. <i>australis</i> and <i>C</i>. <i>schnimdtii</i>) in Qixing River National Nature Reserve wetland.
No full textResults are in mean ± SE.</p
Trend and Abrupt Regime Shift of Temperature Extreme in Northeast China, 1957–2015
No full textTrend and an abrupt regime shift of temperature extremes were investigated based on diurnal data at 116 meteorological stations in the Northeast China region during 1957–2015. A total of 10 temperature indices divided into two categories: extremely cold and warm indices, were used in this study. The Mann–Kendall (MK) test was employed to evaluate the trend in temperature while changepoint, an R package for changepoint analysis, was used to detect changes in the mean levels of temperature extreme data series. The results of this study reveal that occurrence frequencies of the extreme cold night (TN10p) and extreme warm night (TN90p) have decreased and increased by −1.67 and 1.79 days/decade, respectively. Moreover, variations in temperature extremes have not been uniform with warming trends in minimum temperature being rapidly compared to maximum temperature extremes. The diurnal temperature range (DTR) depicted a remarkable decrease as a result of rapid warming in the minimum temperature. Warming in the region led to a reduction in the number of frost days (FD) and icing days (ID) and an increase in the number of growing season length (GSL) and tropical nights (Tr). Seasonally, TN10p largely decreased in winter and spring, while TNn and TN90p largely increased in winter and summer, respectively. Spatially, most of the stations with a significant warming trend in minimum temperatures were located in the Changbai Mountain, Greater Khingan Range, and Lesser Khingan Range. This implies that the mountainous regions are more sensitive and vulnerable to warming than the plain regions. On the contrary, most stations located in the Songnen Plain, Sanjiang Plain, and Liao River Plain displayed significant positive trend GSL and Tr. These climate extreme trends show that the region is experiencing warming which may have an impact on the hydrological process, ecological process, and agricultural production capacity
Hourly fluxes of surface water at different soil depths in laboratory setup incubated for 30 days.
No full text(a) Soil from site dominated by C. epigeios, (b) soil from site dominated by P. australis, (c) soil from site dominated by C. schnimdtii. Error bars represent standard error of the mean.</p
Hourly fluxes of surface water at different soil depths in laboratory setup incubated for 30 days.
No full text(a) Soil from site dominated by C. epigeios, (b) soil from site dominated by P. australis, (c) soil from site dominated by C. schnimdtii. Error bars represent standard error of the mean.</p
Nitrate concentrations at different soil depths in the soil columns from three sites dominated by different vegetation types in Qixing River Wetland National Nature Reserve.
No full textNitrate concentrations at different soil depths in the soil columns from three sites dominated by different vegetation types in Qixing River Wetland National Nature Reserve.</p
Temporal variation of concentration at different soil depth in the soil columns from site dominated <i>C</i>. <i>epigeios</i>.
No full textTemporal variation of concentration at different soil depth in the soil columns from site dominated C. epigeios.</p
Correlation coefficients between pH, TOC, TN, C/N, concentration and concentration.
No full textCorrelation coefficients between pH, TOC, TN, C/N, concentration and concentration.</p
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