摘要:降雨是荒漠生态系统过程和功能的最重要限制因子，荒漠植物幼苗对生长季降雨的变化极端敏感。为探讨荒漠植物对未来降雨格局变化的响应，选取乌兰布和沙漠两种典型荒漠植物幼苗（白刺和油蒿）为研究对象，根据生长季内（6-9月）每次降雨量，进行不同梯度的人工模拟增雨试验（CK：自然降雨、A：增雨25%、B：增雨50%、C：增雨75%、D：增雨100%），研究两种植物幼苗生长和根系形态特征对降雨量变化的响应。结果表明：（1）不同增雨处理对白刺和油蒿幼苗的地上部生长有显著影响（P<0.05），增雨处理的白刺和油蒿幼苗的株高、平均冠幅和基径显著高于CK，并随着增雨量的增大而增大（白刺基径除外）；（2）增雨处理之间、白刺和油蒿之间在总根长、总表面积、平均直径、总体积、根尖数和分叉数均有显著差异（P<0.05）。对白刺幼苗而言，B处理和C处理的根系参数均显著大于CK、A和D处理，且B和C处理之间没有显著差异（平均直径除外）；对油蒿幼苗而言，随着增雨量的增加，油蒿总根长、总表面积、总体积、根尖数和分叉数呈现逐渐增加的趋势，而平均直径呈现先增加后降低的趋势，且在B处理下达到最大值。（3）增雨处理显著降低了白刺幼苗的根冠比，而对油蒿幼苗的根冠比没有显著影响，并且白刺幼苗根冠比显著大于油蒿幼苗。（4）白刺和油蒿幼苗的根系主要分布在0-0.5 mm和0.5-1 mm内，<2 mm的细根比例分别在B和D处理下达到最大值。这表明白刺和油蒿幼苗能够通过调整地上部生长和根系形态来适应降雨的变化。



Abstract:Precipitation is the most important limiting factor for processes and functions of desert ecosystems and desert plant seedlings are extremely sensitive to precipitation changes during the growing season. In order to explore the response of desert plant seedlings to future precipitation pattern changes, two typical desert plant seedlings (Nitraria tangutorum and Artemisia ordosica) in Ulan Buh desert were selected as research objects. The artificial simulated precipitation addition experiment was conducted with five different gradients (CK: natural precipitation, A: +25% precipitation, B: +50% precipitation, C: +75% precipitation, D: +100% precipitation) based on the precipitation of growing season from June to September to study the growth of two plant seedlings and the response of root morphological characteristics to precipitation changes. The results showed that 1) different precipitation treatments had significant effects on the shoot growth of Nitraria tangutorum and Artemisia ordosica seedlings (P <0.05). The height, average crown, and base diameter of Nitraria tangutorum and Artemisia ordosica seedlings were significantly higher than the CK and increased with the amount of precipitation(except for the base diameter of Nitraria tangutorum).2) There were significant differences in total root length, total surface area, average diameter, total volume, number of root tips and number of branches between precipitation treatments(P <0.05). For the Nitraria tangutorum seedlings, the root parameters of B and C treatments were significantly greater than those of CK, A and D treatments, and there was no significant difference between B and C treatments (except for the average diameter); for the Artemisia ordosica seedlings, the total root length, total surface area, total volume, number of root tips and number of branches increased gradually with the increase of precipitation, while the average diameter increased first and then decreased, and reached the maximum under B treatment.3) Precipitation addition treatment significantly reduced the root-shoot ratio of Nitraria tangutorum seedlings, but had no effect on the seedlings of Artemisia ordosica, and the root-shoot ratio of Nitraria tangutorum seedlings was significant greater than the seedlings of Artemisia ordosica.4) The roots diameter of two seedlings were mainly distributed in 0-0.5mm and 0.5-1mm, and the ratio of fine root (<2mm) reached the maximum value under B and D treatment, respectively. It suggested that Nitraria tangutorum and Artemisia ordosica seedlings could adjust shoot growth and root morphology to adapt precipitation changes.





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