Effects of Saturated Soil on Seedling Growth of Some Bottomland Hardwood Species

The effects of flooding forest tree roots have been reported variously as being of little or no consequence, or as immediately detrimental to growth. Hunt (1951) subjected pine seedlings to different soil moistures in a range from flooded to wilting percentage and found a very slight differential in growth as a result of treatment at the end of seven months. Parker (1950) reported that flooding the root systems of dogwood resulted in serious injury within a week, but white oak, red oak, and overcup oak survived for several weeks. Kramer (1951) found yellow-poplar quite susceptible to flooding injury in the brief span of two weeks. Hunt, Parker, and Kramer all used potted seedlings that were from one to three years old. Hunt's conclusions were based upon mortality and growth (dry weight), while Parker used transpiration rates as a basis of comparison. Kramer observed mortality, foliar discoloration, degree of wilting, and epinastic manifestations for his conclusions. Yeager (1949) made a detailed seven-year study of the effects of permanent flooding accompanying hydroelectric development, channel improvement, and flood and erosion control. In his observations of river-bottom hardwoods characteristic of the upper Mississippi River valley, he found that actual flooding (as opposed to just a raising of the water table) of timber areas resulted in practically complete tree mortality. Trees growing vigorously showed the geratest resistance to flooding, while small trees with low vigor and overmature trees were affected in a relatively short time. Yeager reported willow, cottonwood, elm, and silver maple reproduction becoming established on mud flats after most of the original stand (consisting in part of these same species) had been killed. Previously existing reproduction of these species was killed by the impoundment. Depending on the amount of rainfall, drainage characteristics of the soil, and proximity of the water table, it seems certain that most lowland or drainage areas, if not flooded, would at least be subject to soil saturation of a few days' duration every spring. Yeager suggests a shift from forest vegetation to marsh conditions with permanent flooding, but flooding of relatively brief duration