Natural Seedling Recruitment and Regeneration in Deforested and
Sand-Filled Mangrove Forest at Eagle Island, Niger Delta Nigeria
Abstract
Seed recruitment is a major driver of mangrove restoration globally. It
is hypothesized that soil condition and channel hydrology can accelerate
seedling recruitment and regeneration after a major disturbance. Species
abundance, diversity indices, microbial and chemical concentrations in
sand-filled mangrove forest was studied. Eight plots (area = 3902.16 m2)
were established with ten transects in each plot in a random block
design to investigate the effect of soil conditions on seedling growth.
A total of 1, 886 seedlings were physically counted. Seedling abundance
was significantly different between red (Rizophora racemosa), white
(Laguncularia racemosa) and black (Avicennia germinans) mangroves and
nypa palm (nypa fruticans). The most dominant species was black
mangroves and the least dominant species was nypa palm. Muddy soils had
the most abundant species while sandy soils had the least abundant
species. Furthermore, semi-muddy soils had the highest species diversity
(H = 0.948) whereas muddy soils had the least species diversity (H =
0.022). The soil metal concentration has no correlation with seed
abundance and occur in the order
Iron>Nitrate>Copper>Cadmium. Soil
with high species diversity had high soil microbial population; however,
seedling abundance was correlated with soil nutrients and not heavy
metals. Small seeds are easily recruited while good soil condition plus
existing hydrological connection facilitated natural seedling
regeneration in the disturbed mangrove forest.