P. massoniana and R. regia. P. massoniana had the lowest understory biomass
at 10 g m−2 but similar litter biomass to the other forest types.
R. regia also had very little understory biomass and litter. Litter biomass
was highest in the shrubland at 1020 g m−2
, whereas the mass of litter
in the forest plantations—except for R. regia—ranged from 180 to 325 g
m−2 (Table 1). Understory dry mass and litter dry mass were signifi-
cantly correlated, but this was largely due to the one point from the
shrubland plots (Fig. 3).
Mean percent ground cover was highest in the shrubland plots at
91%, while ground cover in the forest plots ranged from 55% in
Roystonea to 83% in the indigenous forest. Cassava and lemon grass
had 63% and 79% ground cover, respectively, indicating no clear difference
in ground cover between the latter stages of these crops and the
various forest types (Table 1). Mean percent ground cover was correlated
with understory biomass (r = 0.51) and inversely correlated with
canopy openness (r = −0.44), but these correlations were not statistically
significant.
Soil texture did not vary greatly among the land-use types, as percent
silt plus clay was always at least 74% (Table 2). Lemon grass had
the lowest mean clay content and the highest mean sand content,
whereas cassava had the highest mean clay content and the lowest percent
sand (Table 2). Notably, the bare land also had relatively high mean
percent sand at nearly 26% (Table 2).
Soil bulk densities ranged from 0.86 to 1.31 g cm−3 with the highest
bulk density being in the shrubland (1.31 g cm−3
), followed by R. regia
(1.18 g cm−3
) (Table 2). Soil bulk densities in the forest land types
ranged from 0.98 to 1.18 g cm−3
, with the highest density in the
R. regia stands and the lowest in P. massoniana and Acacia ssp.
Soil hardness was highest in the lemon grass and bare lands at more
than 18 MPa. The forest and shrub lands generally had values below
11 mm except for the Roystonea plots at 13 mm and the A. mangium
plots at 12 mm (Table 2). There was no clear pattern in mean soil
water content between the plots (Table 2), and this can be attributed
to the varying rainfall over the sampling period