极端干旱生境下胡杨克隆水分整合特征及其生态意义

克隆水分整合是克隆植物有效利用异质性生境资源的重要对策，也是在恶劣生境下得以定植、存活的重要生存策略。本研究以塔里木河下游的胡杨（Populus euphratica Oliv.）为对象，结合野外调查、稳定同位素技术、生理生态监测实验，调查胡杨的克隆水分整合特征并分析其生态意义。结果显示，胡杨母株与其克隆幼株间存在显著水分生理整合，水分整合以顶向传输为主，水分整合过程与整合水量受到母株生理节律及母株到幼株间隔子长度的影响；克隆幼株因水分整合而能够获取与母株相似的深层土壤水分，比同一区域实生幼株拥有更好的水分获取能力，并使胡杨克隆幼株比实生幼株保持相对更高的水力导度、叶片水分含量及叶水势；在极端干旱生境下的这种水分获取及利用策略使胡杨克隆幼株比实生幼株具有更高的光化学效率与光合性能，有助于克隆幼株在不利生境下定植、存活并保持更高的生存优势。

Clonal water integration characteristics and ecological significance of Populus euphratica Oliv. in hyper-arid habitats

Clonal integration is one of the most important strategies of clonal plants to effectively use heterogeneous resources and adapt to adverse habitats for colonization and survival.Using Populus euphratica Oliv.from the lower reaches of Tarim River as research material,we studied its clonal water integration and ecological significance based on multiple field investigation methods,stable isotopic tracing,and ecophysiology monitoring experiments.Results showed obvious water integration between adult mother P.euphratica and young daughter ramets,which was characterized by acropetal water transport.Water integration was influenced by the physiological rhythm of the mother trees and spacer length connecting the adult and young daughter trees.Compared with P.euphratica seedlings,the young ramets could take more water from deep soil layers,like its adult mother tree,due to clonal integration.This,in turn,contributed to better water acquisition capability,better hydraulic conductivity performance,higher leaf water content,and higher leaf water potential of young ramets than that of seedlings.This water acquisition strategy in hyper-arid habitats allows young ramets to maintain higher photochemical efficiency and photosynthetic activity than that of seedlings,and consequently contributes to higher survival advantages for young ramets than for seedlings.