Liu Wenna, Behzad Hamid M, Luo Zidong, Huang Li, Nie Yunpeng, Chen Hongsong
Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.
Guangxi Key Laboratory of Karst Ecological Processes and Services, Huanjiang Observation and Research Station for Karst Ecosystems, Chinese Academy of Sciences, Huanjiang, Guangxi, China.
Plant Cell Environ. 2025 Jan;48(1):199-212. doi: 10.1111/pce.15139. Epub 2024 Sep 10.
The driving forces of transpiration are not only atmospheric evaporation but also root zone water supply and stomatal regulation among species. However, the biophysiological drivers of transpiration remain incompletely understood in heterogeneous karst habitats. This study investigated the commonly coexisting tree species Mallotus philippensis and Celtis biondii in two typical karst habitats: rock-dominated (RD) habitat and control soil-dominated (SD) habitat. Over 2 years, soil moisture, transpiration, root distribution, and leaf water potential were measured. The results showed that soil moisture in the RD habitat was significantly lower than in the SD habitat. Transpiration patterns also differed between habitats, with species-specific distinctions driven by biophysiological traits. M. philippensis showed small hydroscape areas and its root system mainly distributed in the soil zone in both habitats. The isohydric behaviour and lower root density in the RD habitat drove M. philippensis to reduce transpiration in response to soil water deficiency. Conversely, C. biondii had large hydroscape areas and roots capable of penetrating bedrock. It transpired higher relying on ample accessible water through anisohydric behaviour and having a more robust root system both in soil and bedrock zones in the RD habitat. Our study highlights the critical role of root water accessibility and leaf iso/anisohydric tendencies in driving transpiration.
蒸腾作用的驱动力不仅包括大气蒸发，还包括根区供水以及物种间的气孔调节。然而，在异质喀斯特生境中，蒸腾作用的生物生理驱动因素仍未被完全理解。本研究调查了两种典型喀斯特生境中常见的共存树种——粗糠柴和铜钱树：以岩石为主的（RD）生境和对照土壤为主的（SD）生境。在两年多的时间里，测量了土壤湿度、蒸腾作用、根系分布和叶水势。结果表明，RD生境中的土壤湿度显著低于SD生境。不同生境的蒸腾模式也有所不同，由生物生理特征驱动的物种特异性差异显著。在两个生境中，粗糠柴的水分景观面积较小，其根系主要分布在土壤层。RD生境中粗糠柴的等水行为和较低的根密度促使其在土壤水分不足时减少蒸腾作用。相反，铜钱树的水分景观面积较大，根系能够穿透基岩。在RD生境中，它通过非等水行为和在土壤层及基岩层拥有更强大的根系，依靠充足的可利用水分进行较高的蒸腾作用。我们的研究强调了根系水分可利用性和叶片等水/非等水趋势在驱动蒸腾作用中的关键作用。
