XXXX and xylem vulnerability in deciduous and evergreen Mediterranean trees influenced by proximity to a carbon dioxide spring.

@entity713 @entity887 @entity515
We investigated how proximity to natural @entity515 springs affected the seasonal patterns of xylem @entity887 in Quercus ilex L., Quercus pubescens Willd., Fraxinus ornus L., Populus tremula L. and Arbutus unedo L., which differ in leaf phenology and wood anatomy. @entity887 was evaluated in both artificially dehydrated branches and in hydrated apical branches collected at monthly intervals during a 20-month sampling period. Initial specific @entity713 was also evaluated. We found species-dependent differences in xylem hydraulic properties in response to elevated @entity515 concentration. Populus tremula was the most embolized and A. unedo was the least embolized of the species examined. Effects of elevated @entity515 were significant in Q. pubescens, P. tremula and A. unedo, whereas the overall response to elevated @entity515 was less evident in F. ornus and Q. ilex. Specific @entity713 differed among species but not between sites, although the interaction between species and site was significant. Differences in xylem vulnerability between trees growing near to the @entity515 spring and those growing in control areas were small. Although differences in hydraulic properties in response to elevated @entity515 concentration were small, they may be of great importance in determining future community composition in Mediterranean-type forest ecosystems. The possible causes and ecological significance of such differences are discussed in relation to elevated @entity515 concentration and other environmental conditions.
