Zhu Li-Wei, Li Yan-Qiong, Lu Long-Wei, Wang Jing-Yi, Du Jie, Zhao Ping
South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Tianhe District, Guangzhou, 510650, China.
South China National Botanical Garden, Tianyuan Road 1190, Tianhe District, Guangzhou, 510650, China.
Tree Physiol. 2024 Dec 25;44(13):246-259. doi: 10.1093/treephys/tpae016.
Stomata are pivotal in modulating water and carbon processes within plants. However, our understanding of the temporal dynamics of water- and carbon-related traits, as influenced by stomatal behavior, remains limited. Here, we explore how stomatal regulation behavior and water- and carbon-related traits vary with changing environments by examining the seasonal variations in these traits of the native tree species Schima superba Gardn. et Champ. in low subtropical China. In February, April and July of 2022, a series of water- and carbon-related traits were measured in the leaves and stems. The results showed that S. superba exhibited isohydric behavior in February when the soil dried out and vapor pressure deficit (VPD) was lower but anisohydric behavior in April and July when the soil was wetter and VPD was higher. In February, nonstructural carbohydrates (NSC) and their components increased, and a relatively large contribution of soluble sugars to the change in NSC was observed. In the branches and phloem, NSC and their components displayed a relatively high monthly variability, suggesting their role in maintaining carbon balance within the trees. Conversely, the NSC in the leaves demonstrated minimal monthly variability. The specific leaf area, as well as the concentration of nitrogen (N) and phosphorus (P) per unit mass in leaves and the cumulative stem water release, exhibited a decrease with a reduction in soil water potential. Interestingly, the hydraulic conductivity remained consistent throughout this process. Furthermore, the relatively low monthly growth rate observed in February could suggest a carbon sink limitation. In conclusion, the increased NSC and decreased water status of S. superba under relatively stressed soil conditions indicated a trade-off between water and carbon storage. Our findings enhance our comprehension of the dynamics and regulation of water and carbon status in forests, thereby advancing the development of plant carbon and water process models under climate change scenarios.
气孔在调节植物体内的水分和碳过程中起着关键作用。然而，我们对受气孔行为影响的与水和碳相关性状的时间动态的理解仍然有限。在这里，我们通过研究中国低亚热带地区乡土树种木荷（Schima superba Gardn. et Champ.）这些性状的季节变化，来探讨气孔调节行为以及与水和碳相关的性状如何随环境变化而变化。在2022年2月、4月和7月，对叶片和茎干中的一系列与水和碳相关的性状进行了测量。结果表明，2月土壤干燥且水汽压亏缺（VPD）较低时，木荷表现出等水行为，但在4月和7月土壤较湿润且VPD较高时，表现出非等水行为。2月，非结构性碳水化合物（NSC）及其组分增加，且观察到可溶性糖对NSC变化的贡献相对较大。在树枝和韧皮部中，NSC及其组分表现出相对较高的月度变异性，表明它们在维持树木碳平衡中的作用。相反，叶片中的NSC月度变异性最小。比叶面积以及叶片中单位质量的氮（N）和磷（P）浓度以及茎干累计水分释放量，都随着土壤水势的降低而减少。有趣的是，在此过程中水力传导率保持一致。此外，2月观察到的相对较低的月度生长速率可能表明存在碳汇限制。总之，在相对胁迫的土壤条件下，木荷的NSC增加而水分状况下降，表明在水分和碳储存之间存在权衡。我们的研究结果增强了我们对森林中水分和碳状况动态及调节机制 的理解，从而推动了气候变化情景下植物碳和水分过程模型的发展。
