Environmental Engineering Reference
In-Depth Information
Fig. 5 Measurement of sapling in Rhizophora (a) stand in Ghana,
Ada Songor Ramsar site and measurement of tree in Rhizophora stand
in Cameroon, Douala-Edea reserve, Cameroon (b) (photo Carole
Ntyam 2008 in Ghana and 2010 in Cameroon)
prop-root where the root no longer influences the diameter
of the stem. The diameter and height of each tree were,
respectively, recorded by measuring the circumference of
the tree using a flexible tape measure and by using cli-
nometers (Kathiresan 1997 ; English et al. 1997 ; Armah
et al. 2009 ). The diameter of each sapling or seedling was
recorded using calipers. Some sapling height was recorded
using a clinometer. The abundance of seedlings and sap-
lings was recorded in forty 2 9 2 m sampling plots, ten of
them selected randomly inside each of the four 100 m 2
(10 9 10 m) vegetation subplots (Kathiresan; English et al.
1997 ). Within each subplot, the number of seedlings and
saplings were taken as a measure of regeneration (Chen
et al. 2009 ; Din et al. 2008 ; Nfotabong Atheull 2011 ; Aheto
et al. 2011 ).
Fig. 6 Collection of litterfall in pure Rhizophora stands (photograph
Carole Ntyam 2010 Cameroon)
Litterfall Collection
Litterfall was collected in 1 m 2 litter traps constructed of
fibreglass screening (1 mm mesh) and installed at about
1 m, above ground to prevent loss from flooding (Fig. 6 ).
At each study site (20 9 20 m), four traps were placed, one
in the centre of each of the four 10 9 10 m vegetation
subplots. Litter collection was carried out on a monthly
basis for a period of 26 months starting from November
2008 to November 2010, in Ghana and Cameroon using the
method described by Odum and Heald ( 1975 ). At each
period, all loose material of recognizable identification was
collected within the traps (Nfotabong Atheull 2008 ; Kairo
and Bosire 2009 ; Conchedda et al. 2011 ; Twilley and Day
1999 ).
Data Analysis
Laboratory Analysis of Litterfall Components
Field sample analyses in Ghana were mainly done in Ghana
Atomic Energy Commission (GAEC) at the Chemistry
Department and in the University of Ghana (Soil Depart-
ment and Ecology Laboratory Centre). In Cameroon, lab-
oratory facilities of the IRAD institute and University of
Dschang were used for analysing the litter samples.
Litterfall collected from each subplot was set in a 60 C
oven to dry for at least 24 h until a constant mass was
reached and then separated into fractions (leaves, flowers,
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