关键词: 有序加权平均, 情景分析, 生态适宜性, 雨洪淹没, 城市增长边界

Abstract: Planting multi purpose and salt-tolerant tree species is one of the most effective ways for ecological restoration of salt-affected soil, with great ecological and economic benefits.Elaeagnus angustifolia L. is a representative tree species as a pioneer species for ecological restoration of salt-affected soil in China. E. angustifolia can significantly improve nutrient concentrations in salt-affected soil, with the mechanism underlying nutrient transport being still unclear. Based on the analysis of geographical distribution and climatic adaptability, we summarized the degree and ways of improving nutrient status in salt-affected soil by E. angustifolia from the aspects of soil nutrient increase, biological N-fixation, leaf litter and fine root decomposition. We quantitatively elaborated the key processes of nutrient transport and the effect of soil salinity, giving a straightforward understanding of the positive effects of E. angustifolia on salt-affected soil.E. angustifolia was distributed in most salt-affected areas of China, with great geographical and climatic adaptability. E. angustifolia had high salt tolerance, and could significantly increase nutrient content, especially N content, in moderate and severe saline-alkali soils. The prominent fertilization effect of E. angustifolia attributed to its efficient biological N-fixation and rapid litter and fine root decomposition, which release a large amount of N into soil in a short time, thus rapidly improving soil fertility. The processes of biological N-fixation and nutrient release were affected by soil salinity. Further studies of nutrient transport mechanism of E. angustifolia in salt-affected soil should focus on the long-term positioning monitoring with nitrogen cycle as the kernel, and the combination of qualitative and quantitative research for salt types and E. angustifolia provenances. Precise understanding of the mechanism, pathway and function of E. angustifolia on improving salt-affected soil nutrients is helpful to establish the mechanism model of soil improvement by tree species represented by E. angustifolia from the perspective of nutrient management, which provides scientific support for precise ecological restoration and vegetation construction for salt-affected soils.

Key words: ecological suitability, urban growth boundary, ordered weighted averaging, rain flooding, scenario analysis.