Ding Ya Li, Chen Hong Song, Nie Yun Peng, Wang Sheng, Zhang Hui Ling, Wang Ke Lin
Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang 547100, Guangxi, China.
Ying Yong Sheng Tai Xue Bao. 2016 Sep;27(9):2729-2736. doi: 10.13287/j.1001-9332.201609.029.
Using stable isotope techniques, water sources and water use efficiencies of Eucalyptus urophylla ×E. grandis (exotic tree species) and Liquidambar formosana (native tree species, as a reference) were studied in a typical karst artificial forest, and the risk of drought stress of the plantation was discussed. The results showed that the isotope value of shallow soil water (0-50 cm) had obvious gradient features and was similar to the recent rain, while that of deep water was more stable and different from the shallow soil water. The soil water content in wet season (May and September) was higher than in dry season (October), and was higher in upslope than in downslope segment. The main water source of L. formosana was shallow soil water, which corresponded to high water use efficiency in different seasons. The main water sources for E. urophylla ×E. grandis on the upper slope and downslope segments were both shallow soil water in wet season, however, the sum of average water using the proportion of deep soil water increased for the downslope segment in the end of wet season. In dry season, E. urophylla ×E. grandis on the downslope segment mainly used shallow soil water, while it used deeper soil water on the upslope segment when soil water was relatively low. Meanwhile, the water use efficiency of E. urophylla ×E. grandis was lower compared with L. formosana, which revealed E. urophylla ×E. grandis did not get enough water supply under drought stress. The above results indicated that E. urophylla ×E. grandis would encounter high risk of water stress if extreme drought events happened in karst regions in the coming future.
利用稳定同位素技术，在典型喀斯特人工林中研究了尾叶桉×巨桉（外来树种）和枫香（本地树种，作为参照）的水源利用及水分利用效率，并探讨了人工林干旱胁迫风险。结果表明，浅层土壤水（0 - 50厘米）的同位素值具有明显的梯度特征，与近期降雨相似，而深层水的同位素值更稳定，与浅层土壤水不同。雨季（5月和9月）土壤含水量高于旱季（10月），上坡段高于下坡段。枫香的主要水源是浅层土壤水，其在不同季节的水分利用效率较高。上坡段和下坡段尾叶桉×巨桉在雨季的主要水源均为浅层土壤水，但在雨季末期下坡段深层土壤水利用比例的平均用水总量增加。旱季，下坡段尾叶桉×巨桉主要利用浅层土壤水，而上坡段在土壤水分相对较低时利用更深层的土壤水。同时，尾叶桉×巨桉的水分利用效率低于枫香，这表明尾叶桉×巨桉在干旱胁迫下没有获得足够的水分供应。上述结果表明，如果未来喀斯特地区发生极端干旱事件，尾叶桉×巨桉将面临较高的水分胁迫风险。
