摘要:叶片性状反映了植物对环境的适应能力及自我调控能力。以唐古特白刺天然种群为研究对象，沿300-40 mm年降水梯度，测定了7个样地的唐古特白刺叶片性状及叶片δ¹³C、δ¹⁵N。结果表明：（1）沿降水梯度变化，7个地区唐古特白刺叶宽、长宽比、叶厚、叶面积、比叶面积、叶氮含量、叶片δ¹³C和δ¹⁵N变异性显著（P < 0.05），而叶长差异不显著（P > 0.05）。唐古特白刺通过叶片各功能性状间的调节来适应环境的变化，并形成性状间的最佳功能组合。（2）唐古特白刺叶片δ¹³C与叶面积、比叶面积呈负相关关系，与叶氮含量呈正相关关系，但其相关性均未达到显著性水平（P > 0.05），仅与地下水埋深表现出了极显著的正相关关系（P < 0.01）。在降水量小于100 mm的区域，白刺主要利用地下水源，成为隐域植被，从而降低了对其他环境因子的响应。（3）叶片厚度和叶氮含量可以作为体现不同地区间唐古特白刺差异的叶功能性状。数据显示叶片厚度与年平均温度正相关（P < 0.05），尤其与年最高气温大于35℃日数关系更为密切（P < 0.01）；在高温环境下，叶片增厚的同时叶氮含量显著降低（P < 0.05），而这一过程中叶片δ¹⁵N值却有增加趋势（R²=0.62，P < 0.05），因此叶厚度和叶氮含量对叶片δ¹⁵N的相对影响在干旱与半干旱区之间发生转变，这为进一步探究干旱区荒漠植被的水分限制阈值提供了新思路。



Abstract:Leaf traits reflect the adaptability of plants to their surrounding environment and their self-regulatory capacity. In this study, the leaf traits, and leaf δ¹³C and δ¹⁵N content of Nitraria tangutorum natural populations were determined along the precipitation gradient (from 300 to 40 mm) in seven experimental plots. The results showed the following. (1) With changes in precipitation gradient, the leaf width (LW), length to width ratio (LWR), leaf thickness (LT), leaf area (LA), specific leaf area (SLA), leaf nitrogen content (LNC), and leaf δ¹³C and δ¹⁵N content of N. tangutorum in the seven plots were significantly different (P < 0.05), but the difference in leaf length (LL) was not significant (P > 0.05). N. tangutorum adapted to the changes in the environment by regulating various functional traits of its leaves and forming optimum functional combinations of the traits. (2) There was a negative correlation between leaf δ¹³C content and leaf area (LA), and SLA, and positive correlation between leaf δ¹³C content and LNC; however, these correlations were not significant (P > 0.05). Only groundwater depth and leaf δ¹³C content showed a very significant positive correlation (P < 0.01). In the areas with precipitation < 100 mm, N. tangutorum mainly used groundwater sources, thereby becoming a hidden vegetation, which reduced its response to other environmental factors. (3) The LT and LNC can be used as leaf functional traits that reflect the difference in N. tangutorum among different regions. The data showed that LT was positively correlated with the annual average temperature (P < 0.05), especially on days when the annual maximum temperature was > 35℃ (P < 0.01). In high-temperature environments, LNC decreased significantly (P < 0.05), but LT and leaf δ¹⁵N content increased during this process (R²=0.62, P < 0.05). Therefore, the relative influence of LT and LNC on leaf δ¹⁵N content changed between arid and semi-arid regions, providing new insights to further explore the water limit threshold of desert vegetation in arid regions.





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