Growth and invasive potential of Sapium sebiferum (Euphorbiaceae) within the coastal prairie region: The effects of soil and moisture regime

The introduced tree Sapium Schiferum (Euphorbiaceae) is considered a seriou s threat to the preservation of the coastal prairie region of Louisiana and Texas, although it is currently uncommon in the western part of the region . The objective of this study was to evaluate the potential effects of loca tion, soils, and available moisture on the growth and survival of S. sebife rum in coastal prairie. In a field experiment. S. sebiferum mortality was s ignificantly greater at a western site than at central and eastern sites. T he greatest mortality and least growth of surviving plants occurred on a so il from the western region, regardless of site. A greenhouse study also fou nd that S. sebiferum growth was lowest on the western soil. Watering freque ncy significantly affected S. sebiferum growth, except on the western soil. Sapium sebiferum growth responded to both nitrogen and phosphorus addition s for all soils. Soil analyses revealed the highest sand, sodium, and phosp horus contents, and much higher electrical conductivity in the western soil . it is concluded that the soil examined from the western region is unfavor able for S. sebiferum growth, though not to the extent to preclude S. sebif erum completely. Evidence suggests that soil salinity may be the primary ca use of the poor S. sebiferum growth at the western site.