Effect Of Logging Operation On Carbon Storage And Chemical Properties Of Tropical Peat Swamp Forest Soil In Sarawak

The tropical peat swamp forests are disturbed and the tendency for soil degradation is very high. The objectives of this study were to determine whether the logging operations affects soil carbon storage and soil chemical properties of tropical peat swamp forest. Soil sampling was conducted before and after logging operation at 0 15 cm depth on 6 plots with 0.1 hectare each plot at Batang Igan forest in Sibu, Sarawak. The soil samples were analyzed at Laboratory of Soil, UPMKB for acidity, organic matter content, total carbon, total nitrogen, total phosphorus, cation exchange capacity (CEC), available potassium and C/N ration, before and after logging operation on peat swamp forest. Data was analyzed by using Statistical Analysis System (SAS) version 9. 2. As the result, the availability of unstable carbon and stable carbon controlled by soil acidity on undisturbed peat swamp forest thereby the accumulation of unstable carbon as well as stable carbon occurs if soil pH declines and vice versa. However, stable carbon associated well with soil acidity (P < 0.05, r = -0.52). The C/P ratio positively correlated with humic acid and stable carbon on both before and after logging conditions. Nevertheless, that association was prominently on logged peat swamp forest. An indication that even this peat swamp forest had been logged, humification still strongly maintained. However, the similarity of stable carbon of logged peat swamp forest with stable carbon of undisturbed peat swamp forest indicates an ineffectiveness humification of logged peat swamp forest. For chemical properties, the tropical peat swamp forest indicate its specific natural state such as rich in soil pH KCl and insignificant C/N ratio, soil pH water, cation exchange capacity, soil organic matter, total carbon, total nitrogen, total phosphorus, and available potassium being significant different between before and after timber harvesting. This tropical peat swamp forest also acidic soil in range 3.2 - 4.0 % and had large amounts of total carbon (before 48.85%, after 48.30%), low CEC (before 68.04 cmol/kg, after 46.17 cmol/kg), high soil organic matter content (before 97.70, after 96.59%), low mineral nitrogen (before: 0.79%, after 1.18), and high C/N ratio (before 74.04%, after 53.25%) low phosphorus (before 219. 20 mg/L, after 312 mg/L) and low available K (before 330.60 mg/L, after 613.90). The low nitrogen and phosphorus suggests that this peat swamp forest typically represent shallow peat. This research concluded that logging operation on sensitive forest with peat soil using heavy machinery increased the bulk density, hence it compacted the soil. Soil acidity has important role in preserving soil carbon storage of this natural peat swamp forest, especially stable carbon. For the chemical properties, this study found the comparison before and after of some parameter were significant different, such as pH - water, CEC, SOM, Total C, Total N, Total P and available K. Meanwhile, some parameter are not significant different, such as pH KCl and C/N Ratio.