Effects of salinity on leaf delta C-13 in three dominant mangrove species along salinity gradients in an estuarine wetland, southeast China
- 生命科学－已发表论文 
Many previous studies demonstrate that carbon stable isotope composition (usually expressed as isotopic ratio, delta C-13) can reflect the integrated response of physiological processes to environment, but little is known of the variation in delta C-13 of mangrove plants as affected by salinity, especially in response to long term saline environment. The variation in delta C-13 of three dominant mangroves growing in long-term saline environments in the field was assessed. Mature leaves of Avicennia marina (Forsk) Vierh., Kandelia candel (L.) Duce., and Aegiceras corniculatum Blanco. were collected at seven sample sites covering seven salinity levels (14.07%-19.83%) at a natural mangrove wetland located in southeast China. The delta C-13 values varied from -31.46% to -27.33 parts per thousand, with increasing salinity, reflecting the typical C-3 pathway of CO2 fixation. The delta C-13 was positively related to salinity in K. candel and A. marina, and the reverse was observed in A. corniculatum, even though the correlations were not statistically significant for A. corniculatum and A. marina. The mean delta C-13 at high salinity was, in descending order, K candel > A. marina > A. corniculatum. It is concluded that responses of delta C-13 to salinity is species-dependent and assessment of carbon isotopic composition is helpful for evaluating the salt tolerance of mangrove species, but it should be used with caution when comparing the salt tolerance between different species, particularly when they have the different patterns of delta C-13 in response to salinity.