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20世纪50年代以来,樟子松(Pinus sylvestris var.mongolica)在中国北方干旱半干旱地区沙地广泛引种。近年来一些早期引种的樟子松人工林出现了早衰现象。分析生境水分条件变化、判断樟子松采取何种水分利用策略对于认识其早衰现象很有裨益。因此,本研究利用稳定同位素示踪技术,研究了科尔沁沙地东南缘固定沙丘丘间低地30年生樟子松人工林的水分来源及其利用的季节动态,分析了降水和土壤水分变化对樟子松水分利用的影响,阐明了樟子松与伴生植物(黄柳Salix gordeieril)在水分来源方面的异同。结果表明,樟子松及其主要伴生植物黄柳枝条水的稳定18O同位素组成(δ18O)存在明显的季节变化;樟子松的水分来源主要来自20～40cm或更深土层;樟子松和主要伴生植物黄柳之间存在明显的水分竞争,后者比樟子松先行利用最近较强降水(如降水量>10mm),从而影响樟子松水源的补给。本研究对于揭示沙地樟子松衰退与水分利用策略的关系具有重要意义。
Pinus sylvestris var. Mongolica has been widely introduced in sandy land of arid and semi-arid lands in northern China since the 1950s. In recent years some of the early introduction of Pinus sylvestris plantation appeared premature decline phenomenon. Analyzing the change of habitat water conditions and judging the water use strategy adopted by Pinus sylvestris var. Mongolica is very helpful for understanding the phenomenon of premature aging. Therefore, the stable isotope tracing technique was used in this study to study the seasonal dynamics of the water sources and their utilization in the 30-year-old Pinus sylvestris var. Mongolica plantation in the fixed dune hills in the southeast margin of Horqin Sandy Land. The effects of precipitation and soil moisture on Pinus sylvestris The effects of pine water use, elucidating the similarities and differences between the water sources of Pinus sylvestris and companion plants (Salix gordeieril). The results showed that the stable 18O isotopic composition (δ18O) of Pinus sylvestris var. Mongolica and its main companion plant Huangliu had obvious seasonal changes. The water sources of Pinus sylvestris mainly came from the soil layers of 20-40cm or deeper. The Pinus sylvestris var. Significant water competition exists between the associated plants, Huangliu, which uses the most recent precipitation (eg,> 10mm) earlier than Pinus sylvestris var. Mongolica and thus affects the supply of Pinus sylvestris var. Mongolica. This study is of great significance for revealing the relationship between recession and water use strategy of Pinus sylvestris var. Mongolica in sandy land.