Determining soil N mineralization response to soil temperature and moisture changes is challenging in the field due to complicated effects from other factors. In the laboratory, N mineralization is highly dependent on...Determining soil N mineralization response to soil temperature and moisture changes is challenging in the field due to complicated effects from other factors. In the laboratory, N mineralization is highly dependent on temperature, moisture and sample size. In this study, a laboratory incubation experiment was carefully designed and conducted under controlled conditions to examine the effects of soil temperature and moisture on soil N mineralization using soil samples obtained from the Stipa krylovii grassland in Inner Mongolia, China. Five temperature（i.e. 9℃, 14℃, 22℃, 30℃ and 40℃） and five moisture levels（i.e. 20%, 40%, 60%, 80% and 100% WHC, where WHC is the soil water holding capacity） were included in a full-factorial design. During the 71-day incubation period, microbial biomass carbon（MBC）, ammonium nitrogen（NH4 ^＋-N） and nitrate nitrogen（NO3^--N） were measured approximately every 18 days; soil basal respiration for qCO2 index was measured once every 2 days（once a week near the end of the incubation period）. The results showed that the mineral N production and net N mineralization rates were positively correlated with temperature; the strongest correlation was observed for temperatures between 30℃ and 40℃. The relationships between moisture levels and both the mineral N production and net N mineralization rates were quadratic. The interaction between soil temperature and moisture was significant on N mineralization, i.e. increasing temperatures（moisture） enhanced the sensitivity of N mineralization to moisture（temperature）. Our results also showed a positive correlation between the net nitrification rate and temperature, while the correlation between the NH4 ^＋-N content and temperature was insignificant. The net nitrification rate was negatively correlated with high NH4 ^＋-N contents at 80%–100% WHC, suggesting an active denitrification in moist conditions. Moreover, qCO2 index was positively correlated with temperature, especially at 80% WHC. With a low net nitrification rate and high soil basal respiration rate, it was likely that the denitrification concealed the microbial gross mineralization activity; therefore, active soil N mineralization occurred in 60%–80% WHC conditions.展开更多
Disturbance can affect biomass allocation of plants,but can it influence plant reproductive behavior?To address this issue,we performed field plant community investigations and explored the reproductive behaviors of S...Disturbance can affect biomass allocation of plants,but can it influence plant reproductive behavior?To address this issue,we performed field plant community investigations and explored the reproductive behaviors of Stipa grandis and Stipa krylovii in response to grazing and mowing treatments at Maodeng pasture of Xilinguole League of Inner Mongolia,China during 2007–2009.The results showed that,with a similar niche width for the two plant species under mowing and grazing treatments,mowing significantly increased the ratio of ramet to genet number of S.krylovii and the carbon to nitrogen ratio of S.grandis,and grazing significantly decreased the ratio of vegetative to reproductive tiller biomass of S.grandis and increased the ratio of vegetative to reproductive tiller number of S.krylovii.Regression analysis showed that the significantly positive effect of root to shoot biomass ratio was stronger on the ratio of vegetative to reproductive tiller number of S.grandis than on that of S.krylovii.These results indicated that grazing and mowing influenced the reproductive manner and the process of sexual reproduction of S.grandis and S.krylovii.展开更多
本文在全球气候变化的背景下,利用开顶式生长室(OTC,open top chamber)于2011与2012年进行模拟增温,同时实施降水量增加的处理,研究增温与增水处理及其交互作用对内蒙古典型草原优势植物克氏针茅光合作用的影响。于2012年生长季使用Li-6...本文在全球气候变化的背景下,利用开顶式生长室(OTC,open top chamber)于2011与2012年进行模拟增温,同时实施降水量增加的处理,研究增温与增水处理及其交互作用对内蒙古典型草原优势植物克氏针茅光合作用的影响。于2012年生长季使用Li-6400对克氏针茅叶片的各光合作用特征参数进行测量。结果表明,增温明显降低克氏针茅的叶片光合速率(Pn)与气孔导度(Gs),并存在明显季节变化趋势。在7月与9月增温分别使Pn降低17%和27%,使Gs分别降低24%和32%。同时增温降低克氏针茅蒸腾速率(Tr)、叶绿素含量、核酮糖-1,5-二磷酸(RuBP)羧化的最大速率(Vcmax)、RuBP再生能力的最大速率(Jmax)、表观量子效率(AQE)与最大光合速率(Pnmax),但使水分利用效率(WUE)增加16.5%。降水增加对高温条件下的光合作用具有补偿效应。降水增加促进了克氏针茅的Pn、Gs、Tr、叶绿素含量、Vcmax、Jmax、AQE与Pnmax,但对WUE影响不明显。温度水分对克氏针茅光合作用与WUE的影响,是由气孔开合与非气孔因素共同引起的。增温与增水条件下克氏针茅气孔导度在光合速率与蒸腾速率间存在权衡。温度与降水增加显著影响克氏针茅叶片各光合特性参数,但二者交互作用对植物光合作用无显著影响。展开更多
基金funded by the National Natural Science Foundation of China (31270500, 31240002)the Strategic Priority Research Program of Chinese Academy of Sciences (XDA05 050602)+1 种基金the Open Research Fund of the Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Chinese Academy of Sciencesthe support of the Duolun Restoration Ecology Research Station, which is part of the Institute of Botany, Chinese Academy of Sciences, for providing access to the sampling site
文摘Determining soil N mineralization response to soil temperature and moisture changes is challenging in the field due to complicated effects from other factors. In the laboratory, N mineralization is highly dependent on temperature, moisture and sample size. In this study, a laboratory incubation experiment was carefully designed and conducted under controlled conditions to examine the effects of soil temperature and moisture on soil N mineralization using soil samples obtained from the Stipa krylovii grassland in Inner Mongolia, China. Five temperature（i.e. 9℃, 14℃, 22℃, 30℃ and 40℃） and five moisture levels（i.e. 20%, 40%, 60%, 80% and 100% WHC, where WHC is the soil water holding capacity） were included in a full-factorial design. During the 71-day incubation period, microbial biomass carbon（MBC）, ammonium nitrogen（NH4 ^＋-N） and nitrate nitrogen（NO3^--N） were measured approximately every 18 days; soil basal respiration for qCO2 index was measured once every 2 days（once a week near the end of the incubation period）. The results showed that the mineral N production and net N mineralization rates were positively correlated with temperature; the strongest correlation was observed for temperatures between 30℃ and 40℃. The relationships between moisture levels and both the mineral N production and net N mineralization rates were quadratic. The interaction between soil temperature and moisture was significant on N mineralization, i.e. increasing temperatures（moisture） enhanced the sensitivity of N mineralization to moisture（temperature）. Our results also showed a positive correlation between the net nitrification rate and temperature, while the correlation between the NH4 ^＋-N content and temperature was insignificant. The net nitrification rate was negatively correlated with high NH4 ^＋-N contents at 80%–100% WHC, suggesting an active denitrification in moist conditions. Moreover, qCO2 index was positively correlated with temperature, especially at 80% WHC. With a low net nitrification rate and high soil basal respiration rate, it was likely that the denitrification concealed the microbial gross mineralization activity; therefore, active soil N mineralization occurred in 60%–80% WHC conditions.
基金funded by the National Basic Research Program of China(2009CB421303,2007CB106802)
文摘Disturbance can affect biomass allocation of plants,but can it influence plant reproductive behavior?To address this issue,we performed field plant community investigations and explored the reproductive behaviors of Stipa grandis and Stipa krylovii in response to grazing and mowing treatments at Maodeng pasture of Xilinguole League of Inner Mongolia,China during 2007–2009.The results showed that,with a similar niche width for the two plant species under mowing and grazing treatments,mowing significantly increased the ratio of ramet to genet number of S.krylovii and the carbon to nitrogen ratio of S.grandis,and grazing significantly decreased the ratio of vegetative to reproductive tiller biomass of S.grandis and increased the ratio of vegetative to reproductive tiller number of S.krylovii.Regression analysis showed that the significantly positive effect of root to shoot biomass ratio was stronger on the ratio of vegetative to reproductive tiller number of S.grandis than on that of S.krylovii.These results indicated that grazing and mowing influenced the reproductive manner and the process of sexual reproduction of S.grandis and S.krylovii.
文摘本文在全球气候变化的背景下,利用开顶式生长室(OTC,open top chamber)于2011与2012年进行模拟增温,同时实施降水量增加的处理,研究增温与增水处理及其交互作用对内蒙古典型草原优势植物克氏针茅光合作用的影响。于2012年生长季使用Li-6400对克氏针茅叶片的各光合作用特征参数进行测量。结果表明,增温明显降低克氏针茅的叶片光合速率(Pn)与气孔导度(Gs),并存在明显季节变化趋势。在7月与9月增温分别使Pn降低17%和27%,使Gs分别降低24%和32%。同时增温降低克氏针茅蒸腾速率(Tr)、叶绿素含量、核酮糖-1,5-二磷酸(RuBP)羧化的最大速率(Vcmax)、RuBP再生能力的最大速率(Jmax)、表观量子效率(AQE)与最大光合速率(Pnmax),但使水分利用效率(WUE)增加16.5%。降水增加对高温条件下的光合作用具有补偿效应。降水增加促进了克氏针茅的Pn、Gs、Tr、叶绿素含量、Vcmax、Jmax、AQE与Pnmax,但对WUE影响不明显。温度水分对克氏针茅光合作用与WUE的影响,是由气孔开合与非气孔因素共同引起的。增温与增水条件下克氏针茅气孔导度在光合速率与蒸腾速率间存在权衡。温度与降水增加显著影响克氏针茅叶片各光合特性参数,但二者交互作用对植物光合作用无显著影响。
