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在干旱、半干旱区甚至海岸带区,水分是影响植物群落结构和功能的主要生态因子。开展海岸带植物水分利用策略研究,对阐明海岸带生态水过程和预测全球变化背景下的植物群落演替趋势是非常重要的。以黄河三角洲贝壳堤岛优势灌木——柽柳(Tamarix chinensis)为研究对象,以稳定同位素技术为主要研究手段,分析土壤水分、土壤盐分及潜在水源和柽柳木质部d18O值的变化;利用Iso Source软件,计算潜在水源对柽柳木质部水分的贡献率,探讨柽柳在不同水分条件下的水分利用策略。研究结果表明,在降水量充足的2013年7月20~22日,在柽柳吸收利用的水分中,有78.2%来自土壤水,包括30.3%的浅层(0~60 cm深度)土壤水和47.9%的深层(60~100 cm深度)土壤水,有21.8%来自浅层地下水;而在降水量偏少的2014年6月21~23日,土壤含水量显著降低,柽柳的主要水源由土壤水转变为浅层地下水,其对浅层地下水和土壤水的利用比例分别为79.1%和20.9%。生长在黄河三角洲贝壳堤岛海岸带的柽柳可以通过转换水分的主要来源,以适应水分胁迫,这种水分利用策略有利于增强柽柳在植物群落中的种间竞争力,提高植物群落水资源的利用效率,为更好的阐述植物群落内的水分调节和分配机制提供理论基础。
In arid, semi-arid or even coastal zones, water is the main ecological factor that affects plant community structure and function. Carrying out the strategy of plant water use in coastal zone is very important for clarifying the ecological process of coastal zone and forecasting the trend of plant community success in the context of global change. Tamarix chinensis, a dominant shrubby bank in the Yellow River Delta, was selected as the research object. Stable isotope techniques were used as main research methods to analyze the changes of soil moisture, soil salinity, potential water sources and tamarisk wood d18O values. By using Iso Source software, The contribution rate of potential water sources to the xylem water fraction was calculated, and the strategy of water use under different water conditions was discussed. The results showed that 78.2% of the water absorbed by Tamarix chinensis came from soil water, including 30.3% of shallow (0-60 cm depth) soil water and 47.9 % Of deep (60 ~ 100 cm depth) soil water, 21.8% of them came from shallow groundwater; while on the 21 ~ 23 of June 2014 with a little rainfall, the soil water content decreased significantly. The main water source of Tamarix was composed of soil water Converted to shallow groundwater, its utilization of shallow groundwater and soil water were 79.1% and 20.9% respectively. Tamarix asphodelus grown on the coastal shores of the Yellow River Delta can adapt to water stress by converting the main sources of water use. This water use strategy is conducive to enhancing the interspecific competitiveness of Tamarix sibirica in plant communities and increasing the utilization of water resources in plant communities Efficiency, to provide a theoretical basis for better elucidation of mechanisms of water regulation and allocation within plant communities.