Page 164 - Enzymes in Tropical Soils

152 Enzymes In Tropical Soils

properties were also degraded. The soil enzymatic property also drastically
changed as a consequence of the changes in some major soil properties like pH,
organic C, and total N. As previously discussed, the activities of soil enzymes in the
cultivated lands and plantations were much lower than those in the primary and
the secondary forests (Salam et al., 1998d; 1999d). Long cultivation of soils also
decreases the soil enzymatic activities (Salam et al., 1999e). The examples to be
shown will be the case in Lampung, Sumatra, Indonesia. However, similar patterns
occur or may occur in other areas in Indonesia or in other parts of the world as
forest clearing continues (Acosta-Matinez et al., 2007; Jha et al., 1992). As cited
previously, Jha et al. (1992) showed that the activity of soil phosphatase was higher
in undisturbed forests than those in the regions that had encountered
deforestation.

10.1 Land-Use Conversion in West Lampung

Anthropogenic activities has drastically changed Lampung areas in the last
five decades. Lampung which was originally covered by the primary forest has
changed to the secondary forest and a big part of it now has been converted to
plantations and other uses such as residence area and cultivated lands. The
composition of West Lampung area, for example, is shown in Table 10.1,
comparing the composition between that existing lag-uses in 1978, 1984, and 1990,
only about 12 years duration.
Table 10.1 clearly shows that in 1978 the primary forest covered 32.60% of
the area. In only 6 years, the coverage decreased to 21.39% in 1984 and decreased
to 12.72% during the following 12 years in 1990 (Salam et al., 1998d). The
decreases were also observed in grasslands and shifting cultivation lands.
Grassland decreased from 18.44% in 1978 to 1.12% in 1990, after only 12 years.
The secondary forest decreased from 16.20% in 1978 to 10.79% in 1984. A
significant increase in the secondary forest in the period of 1984 to 1990 is
probably due to primary forest conversion to secondary forest or replanting by
reboisation project conducted by the goverment.
On the other hand, the monoculture plantation, particularly those planted
with coffee, increased drastically from 20.83% in 1978 to 41.77% during six years in
1984 (Salam at al., 1998d). The coverage of mixed plantation also increased
drastically from less than 1% in 1978 – 1984 to almost 20% in 1990. The increase in
coverage was also observed for paddy fields, residence areas, and ponds.

Abdul Kadir Salam - 2014