Differences in Soil Physical and Chemical Properties of Rehabilitated and Secondary Forests
ABSTRACT Problem statement: The soil properties of tropical rain forest in Southeast Asia have been characterized by several researchers; however empirical data on soil characteristics under rehabilitation program are still limited or even lacking. This research is important to determine the soil physical and chemical properties of a rehabilitated degraded forest land 19 years after planting with various indigenous species in comparison with adjacent secondary forests and to elucidate the soil fertility status in rehabilitated and secondary forests by using Soil Fertility Index (SFI) and Soil Evaluation Factor (SEF). Approach: Soil samples were collected from both locations which were rehabilitated forest and secondary forest (Nirwana forest) at University Putra Malaysia, Bintulu Sarawak Campus. The plot size of each experimental site was 20×20 m. An auger was used to take soil samples from two depths, namely 0-10 and 10-20 cm. For soil profile, the soil samples were collected from different depths up to 100 cm according to the soil horizons. The samples were air-dried, homogenized and sieved to pass a 2 mm mesh sieve for further analysis. The physical analysis consisted of bulk density and soil moisture content. For chemical analysis, soil acidity, soil organic matter, total organic carbon, available P, exchangeable Al, exchangeable ammonium and nitrate, exchangeable cations (Ca, Mg, K) and Cation Exchange Capacity (CEC) were determined. The soil fertility status was determined based on SFI and SEF values for both rehabilitated and secondary forests. Results: The bulk density of the rehabilitated forest ranged between 0.70 and 1.29 g cm-3 and that of the secondary forest was 0.64-0.76 g cm-3. The soil moisture content of the rehabilitated forest was 23.31-51.03% while that of secondary forest was 41.06-41.49%. The range pH (water) of the rehabilitated forest was 4.5-5.0 and that of the secondary forest range was 4.2-4.3. Furthermore, the content of SOM in the rehabilitated forest was 2.5-5.8%. On other hand, the range for the secondary was 4.1-4.6%. The exchangeable Al of the rehabilitated forest was 0.8-2.5 cmolckg-1 and that of the secondary forest was 1.6-1.7 cmolckg-1. The CEC of the rehabilitated forest was 1.4-11.8 cmolckg-1, while that of the secondary forest was 4.3-4.5 cmolckg-1. Based on SFI and SEF values, the secondary forest had a lower fertility status compared to the rehabilitated forest. Moreover, the SEF value of the secondary forest was below 5, while some of the plots of rehabilitated forest had the SEF values greater than 5. Conclusion: It can be concluded that both rehabilitated and secondary forests have significant differences based on selected physical and chemical properties. Moreover, the soil fertility status at rehabilitated plots was comparatively higher than secondary forest indicating a good potential of Miyawaki forest rehabilitation technique in rehabilitating and replenishing soil fertility status of degraded forest land.
Article: Impact of long-term forest enrichment planting on the biological status of soil in a deforested dipterocarp forest in Perak, Malaysia.[show abstract] [hide abstract]
ABSTRACT: Deforestation leads to the deterioration of soil fertility which occurs rapidly under tropical climates. Forest rehabilitation is one of the approaches to restore soil fertility and increase the productivity of degraded areas. The objective of this study was to evaluate and compare soil biological properties under enrichment planting and secondary forests at Tapah Hill Forest Reserve, Perak after 42 years of planting. Both areas were excessively logged in the 1950s and left idle without any appropriate forest management until 1968 when rehabilitation program was initiated. Six subplots (20 m × 20 m) were established within each enrichment planting (F1) and secondary forest (F2) plots, after which soil was sampled at depths of 0-15 cm (topsoil) and 15-30 cm (subsoil). Results showed that total mean microbial enzymatic activity, as well as biomass C and N content, was significantly higher in F1 compared to F2. The results, despite sample variability, suggest that the rehabilitation program improves the soil biological activities where high rate of soil organic matter, organic C, N, suitable soil acidity range, and abundance of forest litter is believed to be the predisposing factor promoting higher population of microbial in F1 as compared to F2. In conclusion total microbial enzymatic activity, biomass C and biomass N evaluation were higher in enrichment planting plot compared to secondary forest. After 42 years of planting, rehabilitation or enrichment planting helps to restore the productivity of planted forest in terms of biological parameters.TheScientificWorldJOURNAL 01/2012; 2012:641346. · 1.66 Impact Factor