Effects of flooding on root and shoot production of bald cypress in large experimental enclosures

Abstract

Effects of hydroperiod on root production of Taxodium distichum were different for 1-yr-old seedlings and 3-yr-old saplings. After one growing season, root and shoot biomass was highest in the periodically flooded (PF) treatment. After three growing seasons there were no significant differences in total biomass but there were differences in root-to-shoot ratios. Improved growth in the continuously flooded (CF) treatment began in the second growing season and coincided with morphological adaptations to flooding, eg production of water roots, development of intercellular air species, and distinctly different root-system morphologies. PF cypress allocated more carbon to roots than did continuously flooded cypress and developed deeper root systems. A relatively deep rooting zone may have provided PF saplings access to water and dissolved nutrients within the water table (50-60 cm deep during summer). Continuously flooded plants had low root-to-shoot ratios and shallow root systems. A relatively shallow rooting zone with ample water and nutrients allowed CF cypress to allocate relatively more biomass to leaves. After 3-yr, total productivity in the two treatments was not significantly different, yet belowground production was greater in periodically flooded saplings, and there was a tendency for higher aboveground production in continuously flooded saplings. -from Authors