Hydrological niche regulation induced by different resistance strategies facilitates coexistence of P. longipes and L. communis under drought stress

Abstract

Under global warming, the availability of water resources is one of the most important factors affecting trait evolution and plant species distribution across terrestrial ecosystems, and the relationships between drought resistance strategies and the hydrological niche characteristics of plants are worth studying. We continuously monitored physiological drought response parameters such as gs, Tr, proline, soluble sugar, gene expression and activities of SOD, POD, and CAT to assess drought resistance strategies of Platycarya longipes and Lindera communis; determined plant soil hydrological niche separation by stable H and O isotope analysis; and analysed the effects of interspecific water competition by comparing the differences in morphological and physiological parameters between solo and mixed planting. Under drought stress, L. communis exhibited a drought avoidance strategy, and P. longipes exhibited a drought tolerance strategy. L. communis utilized the water within the shallow soil layer, while P. longipes mainly utilized the water in the deeper soil layer; there were fewer parameters with significant differences between the solo planting and the mixed planting of L. communis compared to P. longipes. Overall, P. longipes benefited from coexistence with L. communis under drought stress, which may be because L. communis employs a drought avoidance strategy, reducing soil water consumption in the drought environment. These results suggested that differences in functional traits or resistance strategies among species benefit species' coexistence in a community under drought stress.

Isotope Distribution Analysis in H₂18O Pulse‐Labeled Trees Frozen with Liquid Nitrogen

“…The water in individual mature trees and the surrounding deep soil layers shares the same isotope ratio (Dawson and Ehleringer 1991). Consequently, stable isotopes of hydrogen and oxygen have been utilized to analyze various plant components, including soil around plants (Yao et al 2023), roots (Plamboeck et al 1999, Von Freyberg et al 2020), stems (Álvarez‐Cansino et al 2010, Zhao et al 2016, Treydte et al 2021), and leaves (Barbour et al 2017, Bögelein et al 2017). Some studies have emphasized isotopic variations in water across different locations within a tree (Zhao et al 2016, Barbeta et al 2022); on this issue, previous research used different stable isotopes as tracers, which were separately introduced into the leaves and roots of Japanese cedar saplings.…”