Water-Use Strategies and Habitat Adaptation of Four Tree Species in Karstic Climax Forest in Maolan

The technique of stable hydrogen and oxygen isotope tracing has become an important means to study the mechanism water movement due its high sensitivity traceability. In this study, four dominant tree species in karst forest Maolan, Guizhou Province, were selected, their water-use strategies maintenance diversity investigated using technique. results show that: (1) regional precipitation varied evidently with alternation seasons, i.e., values δD δ18O had a positive bias spring negative summer autumn. value deuterium excess (d-excess) was between 11.67‰ 31.02‰, mean 22.98‰. (2) soil temperature (ST), content (SWC) precipitation, which have significant correlation, imposed joint impact on dynamics evaporative fractionation. (3) line-conditioned (LC-excess) seasonally different bodies, relative fractionation rhizosphere deciduous stronger than that evergreen species, isotopes leaf summer. However, latter former (4) most potential source for terrain (71%), followed by epikarstic water, made up effective supplement (29%). (5) Finally, trees life forms capacity proportion terms sources greater from variable strategies. This may be major water-limiting maintains photosynthesis leaves (leaves are plants continue grow via photosynthesis) constrains fall dormant stop growing). These lead conclusion karstic forests resist stress adjust towards each adapt harsh habitat through root plasticity defoliation.