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沙地樟子松是三北防护林工程中最重要的常绿针叶造林树种。然而,自20世纪90年代初起,最早引种的沙地樟子松人工林在林龄30~35 a后出现枝梢枯黄、长势衰弱、病虫害发生、继而全株死亡且不能天然更新的衰退现象。以科尔沁沙地的樟子松疏林草地和呼伦贝尔沙地的樟子松天然林为参照,以热扩散、稳定同位素和遥感监测等技术开展的系列研究,基本明确了樟子松人工林衰退机制。本文对以往相关研究结果进行了系统总结:确定了沙地樟子松人工林严重水分胁迫的土壤含水量阈值(20%田间持水量),阐明了沙地樟子松人工林水分利用策略(9~21年生樟子松人工林仅利用土壤水,而31~41年生既利用土壤水也利用地下水),明确了沙地樟子松人工林水量平衡特征(水量失衡,吸收至少39mm地下水方能维持水量平衡),量化了樟子松人工林耗水对区域水资源消耗的贡献(消耗12.3%水资源),揭示了樟子松人工林衰退过程,找出了樟子松人工林发展存在的问题及产生的原因。在此基础上,提出了解决衰退对策与营林方案,为防止现存沙地樟子松人工林衰退、合理经营,未来该林种合理布局提供参考。
Pinus sylvestris var. Mongolica is the most important evergreen coniferous tree species in the Three North Shelterbelt project. However, since the early 1990s, the earliest introduced Pinus sylvestris var. Mongolica plantations in the sand stands aged 30-35 years after the emergence of branches yellow, growing weak, pests and diseases, and then the whole plant died and can not be naturally updated recession . Based on a series of researches on thermal diffusivities, stable isotopes and remote sensing monitoring, taking the Pinus sylvestris var.mongolica forest in Horqin sandy land and the natural forest of Pinus sylvestris var. Mongolica in Hulunbeier sandy land as reference, the decay mechanism of Pinus sylvestris var. Mongolica plantation was basically clarified . This paper summarizes the results of previous studies: The threshold of soil moisture (20% of field capacity) for severe water stress in Pinus sylvestris var. Mongolica plantations was determined, and the water use strategy of Pinus sylvestris var. Mongolica on sandy land The 21-year-old Pinus sylvestris var. Mongolica plantation only uses soil water, while the 31-41 year-old uses both soil water and groundwater) to clarify the water balance characteristics of the Pinus sylvestris var. Mongolica plantation (imbalance of water volume, absorption of at least 39 mm groundwater Water balance) to quantify the contribution of water consumption of Pinus sylvestris var. Mongolica plantation to regional water consumption (consumption of 12.3% water), revealing the decay process of Pinus sylvestris plantation and finding out the problems in the development of Pinus sylvestris plantation And the reason that causes. On this basis, proposed to solve the recession measures and forest management programs, in order to prevent the existing sand Pinus sylvestris plantation recession, rational management, the rational distribution of the forest species in the future to provide a reference.