Ecological stoichiometry and biomass responses of Agropyron michnoi under simulated N deposition in a sandy grassland, C
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Ecological stoichiometry and biomass responses of Agropyron michnoi under simulated N deposition in a sandy grassland, China JIN Xiaoming1*, YANG Xiaogang1, ZHOU Zhen1, ZHANG Yingqi2, YU Liangbin3, ZHANG Jinghua1, LIANG Runfang3 1
Department of Life Science, Hulunbuir University, Hulunbuir 021008, China; College of Environmental Science, Northeast Normal University, Changchun 130024, China; 3 Grassland Research Institute, Chinese Academy of Agricultural Sciences, Hohhot 010010, China 2
Abstract: Sandy grassland in northern China is a fragile ecosystem with poor soil fertility. Exploring how plant species regulate growth and nutrient absorption under the background of nitrogen (N) deposition is crucial for the management of the sandy grassland ecosystem. We carried out a field experiment with six N levels in the Hulunbuir Sandy Land of China from 2014 to 2016 and explored the Agropyron michnoi Roshev. responses of both aboveground and belowground biomasses and carbon (C), N and phosphorus (P) concentrations in the plant tissues and soil. With increasing N addition, both aboveground and belowground biomasses and C, N and P concentrations in the plant tissues increased and exhibited a single-peak curve. C:N and C:P ratios of the plant tissues first decreased but then increased, while the trend for the N:P ratio was opposite. The peak values of aboveground biomass, belowground biomass and C concentration in the plant tissues occurred at the level of 20 g N/(m2•a), while those of the N and P concentrations in the plant tissues occurred at the level of 15 g N/(m2•a). The maximum growth percentages of aboveground and belowground biomasses were 324.2% and 75.9%, respectively, and the root to shoot ratio (RSR) decreased with the addition of N. N and P concentrations in the plant tissues were ranked in the order of leaves>roots>stems, while C concentration was ranked as roots>leaves>stems. The increase in N concentration in the plant tissues was the largest (from 34% to 162%), followed by the increase in P (from 10% to 33%) and C (from 8% to 24%) concentrations. The aboveground biomass was positively and linearly correlated with leaf C, N and P, and soil C and N concentrations, while the belowground biomass was positively and linearly correlated with leaf N and soil C concentrations. These results showed that the accumulation of N and P in the leaves caused the increase in the aboveground biomass, while the accumulation of leaf N resulted in the increase in the belowground biomass. N deposition can alter the allocation of C, N and P stoichiometry in the plant tissues and has a high potential for increasing plant biomass, which is conducive to the restoration of sandy grassland. Keywords: biomass; nitrogen deposition; plant tissue; C, N and P stoichiometry; sandy grassland Citation: JIN Xiaoming, YANG Xiaogang, ZHOU Zhen, ZHANG Yingqi, YU Liangbin, ZHANG Jinghua, LIANG Runfang. 2020. Ecological stoichiometry and biomass responses of Agropyron michnoi under simulated N deposition in a sandy grassland, China.
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