N添加对白羊草种群特征及水土保持功能的影响

发布时间：2018-08-15 14:15

【摘要】：以黄土高原草地优势种和建群种白羊草(Bothriochloa ischaemum)为研究对象,以径流小区模拟人工降雨为基本研究方法,研究了0(CK),2.5(N2.5),5.0(N5)和10(N10)g N m-2 year-1不同N添加水平对白羊草种群的生理特征、土壤理化性质以及水土流失的影响。主要结论如下:N添加显著增加了白羊草种群的密度、株高和生物量,其中N5处理下种群生物量达到最大;N添加改变了白羊草生物量的分配策略,根冠比随N添加升高而减小,支持功能平衡假说;N添加有利于白羊草的生殖发育,提高了其繁殖竞争能力。N添加有效地促进白羊草单株分蘖,增加了单株从径。N2.5下单株分孽数和从径最大,而后随N添加量增加而减小。单株有性繁殖枝增加,养繁比随N添加量增加而减小,表明超过N2.5水平后,白羊草个体的生长发育增幅逐渐下降。适度N沉降或N添加(5 g N m-2 year-1)促进了白羊草种群的生长和发育,有利于白羊草种群水土保持等生态功能的发挥。N添加下,土壤pH值、有机质含量随N添加增加而降低,土壤全氮、有效氮均随N添加增加而增加,土壤全磷没有明显变化趋势。在本次N添加水平和处理时间下,土壤理化性质未发生显著变化。N添加有效减小了白羊草种群小区的产流量和产沙量,各N添加梯度之间减流减沙效益差异不显著,减流效益为54%-62%,减沙效益在83%-95%之间,减沙效益明显高于减流效益。N添加通过影响白羊草种群的生理生态特征,改变种群的地上株高、密度、生物量以及根长密度、根表面积密度等指标来影响其水土保持功能。
[Abstract]:The physiological characteristics of Aries chinensis population under different N addition levels of 0 (CK) 2.5 (N2.5) (N2.5) and 10 (N10) g N m ~ (-2) year-1) were studied on the basis of (Bothriochloa ischaemum), a dominant species of grassland and a new species in the Loess Plateau. The artificial rainfall in runoff plot was simulated as the basic research method, and the physiological characteristics of Aries chinensis population were studied at different N levels of 0 (CK) 2.5 (N2.5) and 10 (N10) g N m-2). Physical and chemical properties of soil and effects of soil erosion. The main conclusions were as follows: the density, plant height and biomass of Aegilops chinensis population were significantly increased with the addition of: n, and the biomass reached the maximum under N _ 5 treatment, which changed the allocation strategy of the biomass, and the ratio of root to shoot decreased with the increase of N addition. The supportant functional balance hypothesis that the addition of N was beneficial to the reproductive development of Aries chinensis, improved its reproductive competitive ability, promoted the tiller per plant effectively, and increased the number and the maximum number of subtillers per plant under the diameter of .N2.5 per plant. Then it decreases with the increase of N addition. The increase of sexual reproductive branch per plant and the ratio of feeding to propagation decreased with the increase of N addition, which indicated that the growth and development rate of individuals of Amur chinensis decreased gradually when N 2.5 level was higher than that of N 2. 5. Moderate N deposition or N addition (5 g N m ~ (-2) year-1) promoted the growth and development of Leymus chinensis population, which was beneficial to the soil and water conservation and other ecological functions of Aegilops chinensis population. The soil pH value and organic matter content decreased with the increase of N addition. Soil total nitrogen and available nitrogen increased with the increase of N addition, but there was no obvious change trend of soil total phosphorus. Under the N addition level and the treatment time, the physical and chemical properties of the soil did not change significantly. The N addition could effectively reduce the runoff and sediment yield in the population area of Amur chinensis, but there was no significant difference in the benefit of reducing the flow and sediment among the N addition gradients. The benefit of sediment reduction was between 83-95%. The benefit of sediment reduction was significantly higher than that of flow reduction. The addition of N changed the plant height, density, biomass and root length density of Amur chinensis population by affecting the physiological and ecological characteristics of the population. The soil and water conservation function is affected by the root surface area density.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157.4

【共引文献】