为了解大气氮沉降对荒漠草原植物物种多样性和生产力的影响,在黄土高原荒漠草原区进行了氮素添加试验,研究了氮素添加量对草本植物物种多样性和植物生产力的短期影响.结果表明:随氮素添加量的增加,群落Margalef物种丰富度指数和Shannon-Wiener多样性指数显著减小,中,高水平氮素添加处理下,群落Margalef物种丰富度指数和Shannon-Wiener 多样性指数分别比对照下降了39.14%、47.07% 和25.57%、31.52%.随氮素添加量的增加,主要优势植物种相对重要值增大;处于弱势的伴生植物种在氮素添加后从群落中消失.氮素添加后,群落生产力显著提高,尤其是低水平氮添加时生产力增加量最大.氮素增加在短期内即可以提高黄土高原荒漠草原草本植物群落生产力,促进优势种群的生长,抑制不占主要地位的伴生种的生长,改变物种组成并降低物种多样性.
In order to deeply understand effects of atmospheric nitrogen deposition on herbaceous plant diversity and productivity in desert grassland. A nitrogen addition experiment was carried out in desert grassland of the Loess Plateau. The short-term response of species diversity and productivity of herbaceous plants to different levels of nitrogen additions were studied. The results showed that the Margalef species richness index and Shannon-Wiener diversity index decreased significantly with nitrogen addition increased. Compared to control, in middle and high nitrogen addition level the Margalef species richness index and Shannon-Wiener diversity index were decreased by 39.14%, 47.07% and 25.57%, 31.52% respectively. As the nitrogen addition increasing, the relative importance value of the main dominant species increased, relative importance value of the main companion species increased at low levels of nitrogen addition but showed decreasing change trend in high nitrogen addition level, and some companion species in week position disappeared from plant communities. With nitrogen addition increasing, community productivity increased especially at low level of nitrogen addition. Nitrogen addition can promote growth of dominant species, but restrain growth of companion species in week position. Nitrogen addition can improve the community productivity and induce changes in community composition and species diversity of herbaceous plants in desert grassland of Loess Plateau.
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