Switchgrass is an introduced C_(4)grass in the semi-arid Loess Plateau of China,but there is a lack of information to assess its ecological invasive risk.In this study,Old World bluestems(native C_(4)grass)and switchg...Switchgrass is an introduced C_(4)grass in the semi-arid Loess Plateau of China,but there is a lack of information to assess its ecological invasive risk.In this study,Old World bluestems(native C_(4)grass)and switchgrass were sowed at five mixture ratios(8:0,6:2,4:4,2:6 and 0:8)under two soil water levels(80%field capacity(FC)and 40%FC)and two nitrogen(N)treatments(0 and 100 mg N/kg dry soil,termed N0-unfertilized and N1-fertilized treatments,respectively)in a pot experiment in 2012.Biomass,root morphological traits and relative competitive abilities of these two species were analyzed.Results showed that biomass of both species was significantly greater under 80%FC or N fertilization,and switchgrass had a relatively larger root:shoot ratio(RSR).Total root length(TRL)and root surface area(RSA)of switchgrass were significantly higher under 80%FC irrespective of N treatment,while those of Old World bluestems were only significantly higher under N fertilization.N had no significant effect on TRL and RSA of switchgrass,while RSA of Old World bluestems significantly increased under 80%FC and N fertilization.Under 40%FC and N0-unfertilized treatment,the aggressivity of Old World bluestems was larger than zero at 2:6 and 4:4 mixture ratios of two species,whereas it was close to zero at 6:2 mixture ratio.Root competitive ability of switchgrass significantly increased under 80%FC or N fertilization.The aggressivity of Old World bluestems was negative at 6:2 mixture ratio under 80%FC and N fertilization,while it was positive at 2:6 mixture ratio.Switchgrass may become more aggressive when N deposition or rainfall increases,while a proper mixture ratio with appropriate water and N management could help with grassland management in the semi-arid Loess Plateau.展开更多
Soil respiration（SR） in crop field is affected by environmental factors, agronomic practices and crop types. To clarify how planting density affects the SR dynamics in switchgrass（Panicum virgatum L.） field on the...Soil respiration（SR） in crop field is affected by environmental factors, agronomic practices and crop types. To clarify how planting density affects the SR dynamics in switchgrass（Panicum virgatum L.） field on the semi-arid Loess Plateau, this research investigated diurnal and seasonal changes of soil respiration rate（RS） under three different row-spacing treatments（20, 40 and 60 cm） in the fourth growing year of switchgrass. Results showed that RS presented a pronounced seasonality under all row-spacing treatments. The highest daily average RS values appeared in August, while the lowest（P〉 0.05） among the row-spacing treatments, and similar results were found for soil temperature in 0–15 cm soil depth. Soil respiration temperature sensitivity（Q_（10）） values were 1.0–3.7 during the growing months, which were strongly correlated with air temperature in May and June and the soil temperature at 15 cm depth in August. Higher aboveground biomass production and lower RS in most growth months indicated that 20 cm row-spacing treatment was beneficial for increasing the carbon fixation in switchgrass field. Results also implied that it is necessary to take into account the influence of phenology and root growth of switchgrass on soil respiration for accurately evaluating the carbon cycle in the region.展开更多
基金The study was supported by the National Natural Science Foundation of China(41371509,41771553)the Intergovernmental International Cooperation on Science and Technology Innovation under the Ministry of Science and Technology of People's Republic of China(2018YFE0112400).
文摘Switchgrass is an introduced C_(4)grass in the semi-arid Loess Plateau of China,but there is a lack of information to assess its ecological invasive risk.In this study,Old World bluestems(native C_(4)grass)and switchgrass were sowed at five mixture ratios(8:0,6:2,4:4,2:6 and 0:8)under two soil water levels(80%field capacity(FC)and 40%FC)and two nitrogen(N)treatments(0 and 100 mg N/kg dry soil,termed N0-unfertilized and N1-fertilized treatments,respectively)in a pot experiment in 2012.Biomass,root morphological traits and relative competitive abilities of these two species were analyzed.Results showed that biomass of both species was significantly greater under 80%FC or N fertilization,and switchgrass had a relatively larger root:shoot ratio(RSR).Total root length(TRL)and root surface area(RSA)of switchgrass were significantly higher under 80%FC irrespective of N treatment,while those of Old World bluestems were only significantly higher under N fertilization.N had no significant effect on TRL and RSA of switchgrass,while RSA of Old World bluestems significantly increased under 80%FC and N fertilization.Under 40%FC and N0-unfertilized treatment,the aggressivity of Old World bluestems was larger than zero at 2:6 and 4:4 mixture ratios of two species,whereas it was close to zero at 6:2 mixture ratio.Root competitive ability of switchgrass significantly increased under 80%FC or N fertilization.The aggressivity of Old World bluestems was negative at 6:2 mixture ratio under 80%FC and N fertilization,while it was positive at 2:6 mixture ratio.Switchgrass may become more aggressive when N deposition or rainfall increases,while a proper mixture ratio with appropriate water and N management could help with grassland management in the semi-arid Loess Plateau.
基金financially supported by the Program for New Century Excellent Talents in University (NCET-110444)the Fundamental Research Funds for the Central Universities (ZD2013020)
文摘Soil respiration（SR） in crop field is affected by environmental factors, agronomic practices and crop types. To clarify how planting density affects the SR dynamics in switchgrass（Panicum virgatum L.） field on the semi-arid Loess Plateau, this research investigated diurnal and seasonal changes of soil respiration rate（RS） under three different row-spacing treatments（20, 40 and 60 cm） in the fourth growing year of switchgrass. Results showed that RS presented a pronounced seasonality under all row-spacing treatments. The highest daily average RS values appeared in August, while the lowest（P〉 0.05） among the row-spacing treatments, and similar results were found for soil temperature in 0–15 cm soil depth. Soil respiration temperature sensitivity（Q_（10）） values were 1.0–3.7 during the growing months, which were strongly correlated with air temperature in May and June and the soil temperature at 15 cm depth in August. Higher aboveground biomass production and lower RS in most growth months indicated that 20 cm row-spacing treatment was beneficial for increasing the carbon fixation in switchgrass field. Results also implied that it is necessary to take into account the influence of phenology and root growth of switchgrass on soil respiration for accurately evaluating the carbon cycle in the region.
