BIOMASS AND LITTERFALL OF CERIOPS-TAGAL AND RHIZOPHORA-MUCRONATA IN THE MANGROVE FOREST OF GAZI BAY, KENYA

Biomass and (leaf) litter production of stands of Rhizophora mucronata and Ceriops tagal were assessed in an East African mangrove forest. I nundation frequency of the R. mucronata stand was twice a day (on aver age 575 min day(-1)), whereas the C. tagal stand was inundated only du ring spring tides (on average 116 min day(-1)). The highest above-grou nd biomass (24.9 +/- 4.0 kg dry weight m(-2)) was present in the R. mu cronata stand, in which leaf litter production was 2.51 +/- 1.15 g DW m(-2) day(-1). Above-ground biomass and leaf litterfall in the C. taga l stand were 4.01 +/- 0.34 kg DW m(-2) and 1.05 +/- 0.49 g DW m(-2) da y(-1), respectively. There was a distinct seasonal pattern in litterfa ll in both stands, with lower litterfall values in the wet season. Chl oride concentrations were relatively high in senescent leaves, compare d with those in green leaves. The decreased litterfall during the wet periods may be related to a reduced accumulation of chloride in the le aves. The difference in inundation frequency between the R. mucronata and C. tagal stands is expected to cause a more substantial tidal expo rt of fallen leaves from the R. mucronata stand. As nitrogen resorptio n before defoliation was similar for C. tagal (50.9%) and R. mucronata (50.1%), tidal flushing may cause larger nitrogen losses from the R. mucronata stand.