RESPONSES OF WETLAND TREE SPECIES TO HYDROLOGY AND SOILS

We conducted a study of the flood tolerance of nine wetland tree speci es on seven soil types. Seedlings were subjected to 11 months of conti nuous shallow inundation or moist soil conditions on three mineral soi ls, two organic soils, a manufactured soil designed to mimic the pract ice of layering muck over mineral soil, and a stockpiled topsoil. Taxo dium ascendens, T. distichum, Acer rubrum, and Pinus serotina suffered no mortality; Fraxinus caroliniana (1%), Liquidambar styraciflua (8%) , P. elliottii (8%), and Gordonia lasianthus (24%) suffered low to mod erate mortality; and Persea palustris (46%) suffered significant morta lity. In general, greatest net height and total biomass were achieved on moist organic soils, and least net height and total biomass were ac hieved on stockpiled topsoil and inundated soils. Responses to hydrolo gical conditions were less pronounced for Taxodium spp. If the results of this experiment are transferable to the field, then Acer rubrum, F raxinus caroliniana, Pinus serotina, Taxodium ascendens, and Taxodium distichum seedlings can reasonably be expected to survive at least one year under a broad range of hydrological and edaphic conditions. With the exception of Taxodium spp., first-year growth for the species of this study can be facilitated by maintaining moist but not inundated c onditions. These findings suggest that transfer of organic soils will benefit restoration and creation efforts, and that layering organic so il over mineral soil is more effective than using mineral soils or sto ckpiled topsoil.