Characteristics of Water Physiological Integration and its Ecological Significance for Populus euphratica Young Ramets in an Extremely Drought Environment

Water physiological integration plays an important role and has profound effects on the population renewal and expansion of clonal plants. This work discussed the spatial distribution architecture, water sources, water physiological integration, and the ecological significance of Populus euphratica young ramets in an extremely drought environment based on field investigation, stable isotope technology, and eco‐physiological experiments. The spatial distribution architecture of P. euphratica young ramets assumes a guerrilla growth form that is adapted to significant heterogeneity and patches of habitat resources. There is obvious water integration that is characterized by an acropetally flow. The water integration process and daily flow showed the bimodal pattern following the physiological rhythm of parent trees and declined with increasing length of spacers connecting parent trees and their young daughter ramets. The young daughter ramets of P. euphratica can use the deeper soil water in a similar manner to the parent trees and obtain an average daily water acquisition of about 1.09 kg by water integration when the spacer length is about 2–3 m. It is about 5 times as much water as seedlings sucking by themselves. This lets young ramets maintain higher leaf water content and midday leaf water potential of 10.27% and 29.73%, respectively, than seedlings in same habitats. Therefore, P. euphratica young ramets can benefit from a higher survival advantage in extreme drought habitats compared to seedlings. This facilitates the establishment and growth of young ramets in those adverse habitats where P. euphratica seedlings are less likely to survive.