Bald Cypress Root Response to Water Table Fluctuation: A Source of Soil Reduction Microsites.

Soil reduction microsites are areas of high microbial activity surrounding pockets of decomposing plant matter, and are known to be major drivers of reduction processes such as denitrification and iron reduction and translocation. In wetland soils with fluctuating water tables, deep root growth during the dry season and subsequent root death with shallow water tables during the wet season can contribute to the creation of new reduction microsites. However, few studies have examined the pattern of root growth and death in wetland soils in greenhouse settings or in situ.  The objectives of this study were to i) observe patterns of root growth and death associated with fluctuations in the water table in situ and stagnant ponding of water in a greenhouse setting, and ii) determine the effect of soil type, mineral vs organic, on root growth and death. This two-part study included a root-box rhizotron study using 20 bald cypress (Taxodium distichum) saplings in a greenhouse setting, and an in situ minirhizotron study examining the patterns of root growth and death in 16 eight year old bald cypress trees in a restored Carolina bay wetland. Both studies included two soil types – Spodosols (mineral) and Histosols (organic). Results from this study will help develop a better understanding of patterns of root growth and death in saturated soil conditions, and the formation of soil reduction microsites.