S. R. Pezeshki | Search USGS

USGS1997

Effects of salinity on baldcypress seedlings: Physiological responses and their relation to salinity tolerance

Growth and physiological responses of 15 open-pollinated families of baldcypress ( Taxodium distichum var. distichum ) subjected to flooding with saline water were evaluated in this study. Ten of the families were from coastal sites in Louisiana and Alabama, USA that have elevated levels of soil-water salinity. The other five families were from inland, freshwater sites in Louisiana. Seedlings from all families tolerated flooding with water of low (2 g 1 −1 ) salinity. Differences in biomass among families became most apparent at the highest salinity levels (6 and 8 g 1 −1 ). Overall, increasing salinity reduced leaf biomass more than root biomass, which in turn was reduced more than stem biomass. A subset of seedlings from the main greenhouse experiment was periodically placed indoors under artificial light, and measurements were made of gas exchange and leaf water potential. Also, tissue concentrations of Cl − , Na + , K + , and Ca 2+ were determined at the end of the greenhouse experiment. Significant intraspecific variation was found for nearly all the physiological parameters evaluated, but only leaf concentrations of Na + and Cl − were correlated with an index of family-level differences in salt tolerance.

Alabama, Louisiana↗

USGS1996

Interaction of flooding and salinity stress on baldcypress ( Taxodium distichum )

Coastal wetlands of the southeastern United States are threatened by increases in flooding and salinity as a result of both natural processes and man-induced hydrologic alterations. Furthermore, global climate change scenarios suggest that, as a consequence of rising sea levels, much larger areas of coastal wetlands may be affected by flooding and salinity in the next 50 to 100 years. In this paper, we review studies designed to improve our ability to predict and ameliorate the impacts of increased flooding and salinity stress on baldcypress ( Taxodium distichum (L.) Rich.), which is a dominant species of many coastal forested wetlands. Specifically, we review studies on species-level responses to flooding and salinity stress, alone and in combination, we summarize two studies on intraspecific variation in response to flooding and salinity stress, we analyze the physiological mechanisms thought to be responsible for the interaction between flooding and salinity stress, and we discuss the implications for coastal wetland loss and the prospects for developing salt-tolerant lines of baldcypress.

Louisiana↗