Effects of tidal inundation and predation on Avicennia germinans seedling establishment and survival in a sub-tropical mangal/salt marsh community

摘要: The black mangrove, Avicennia germinans, occurs sympatric withSpartina alterniflora in coastal Louisiana. Zonation exists alongan elevational gradient with A. germinans dominant at higherelevation creekbanks and S. interior, lowerelevation sites greater depth duration of flooding.Establishment seedlings was examined cagesthat excluded predators limited horizontal, but not vertical,movement propagules by the tides showed that blackmangrove could readily establish Spartina zone. Survivalof after one year cages notsignificantly different between two zones, weresignificantly taller Thus, neitherinundation per se nor other abiotic factors alone accountfor absence interior marsh. Althoughpropagules were dispersed into both a net removal ofuncaged from plots zone (–1.3 ± 0.6m-2 d-1) compared to addition (+0.5 0.4 m-2d-1) indicated retention propagulesdiffered zones. Causes mortality decay (Spartina> zone), desiccation (Avicennia > andpredation (Spartina zone). Although few propaguleswere completely consumed (snails crabs), damageto cotyledons promoted decay. results suggest tidalaction limits settlement propagulesin zone, combination predator damage andfrequent flooding leads rapid strandthere.