Factors affecting 13C/12C ratios of inland halophytes. II. Ecophysiological interpretations of patterns in the field

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Abstract
By measuring .delta.13C values, 9 of 42 species inhabiting saline sites in Alberta were found to be C4 plants. None of these, however, are dominant species in wet saline situations. A salinity gradient was studied along a transect to provide improved field data on .delta.13C variations among C3 halophytes. Soils were dominated by sulphates of sodium and, less so, magnesium. Soil water potential .**GRAPHIC**. was highest at a depth of about 10 cm and, on a daily basis, changed little. The .delta.13C values of Puccinella nuttalliana (Schultes) Hitch. were well correlated with .**GRAPHIC**. The same appeared true for Salicornia europaea L. ssp. rubra (Nels.) Brietung. In a scattergram representing five major species, a close correlation was also evident for Hordeum jubatum L. The relationship could not be extended to Triglochin maritima L. and Sonchus arvensis L., but values for these two species were not separable from those of P. nuttalliana and H. jubatum. Salicornia europaea ssp. rubra, however, differed by having .delta.13C values that were markedly more negative. Although partly associated with cover by other species, this tendency may reflect a lower water-use efficiency as afforded by a greater reliance on the uptake of readily available salt for osmotic adjustment.