Effect of Soil Characteristic to Soil Respiration Rate in Tropical. Forest and Plantation. Wan Rasidah Wan Abdul Kadir (FRIM). Minako Adachi (Gifu Univ.).
Effect of Soil Characteristic to Soil Respiration Rate in Tropical Forest and Plantation
Wan Rasidah Wan Abdul Kadir (FRIM)
Minako Adachi (Gifu Univ.) Yuichiro Yashiro (Gifu Univ.) Toshinori Okuda (NIES) Hiroshi Koizumi (Gifu Univ.)
Introduction The amount of soil organic carbon globally has been estimated more than three times the atmospheric pool, and more than four times the biotic pool in terrestrial ecosystems (Lal, 2001). The change of soil organic carbon after land use change should be notable subject. The deforestation and cultivation of tropical forest is usually accompanied by a decline in the amount of organic matter in both. In southeast Asia, the deforestation and cultivation released about 75% of the total release of carbon to the atmosphere in 1850-1995 (Houghton and Hackler, 1999). Soil respiration, CO2 efflux from soil surface, is one of the most important processes of carbon cycle in terrestrial ecosystems. Soil respiration rate consist of two belowground biotic activity ; the respiration of plant roots and soil microorganisms. Soil respiration rate varies spatially and temporally because the factors which affect the soil respiration rate are not uniform over large area: e.g. soil temperature (Epron et al. 1999), soil water content (Orchard and Cook 1983), belowground biomass and biological activities (Hanson et al. 2000), vegetation and climate (Raich and Schlesinger, 1992), and chemical and physical characteristics of soils (Koizumi et al. 1999; La Scala, et al. 2000). The objectives of this study are to clarify the following issues; 1) the annual amount of soil respiration in primary forest, secondary forest and agricultural forests. 2) the feature of soil carbon dynamics in primary forest as compared with those in other forest types. In this report, we address the relationship between soil respiration rate and soil character, especially soil porosity.
Method Site description The study sites are located at the primary and secondary forests in Pasoh forest Reserve (2°5’N, 102°18’W), and at the oil palm and rubber plantations adjacent to the Pasoh forest Reserve, Negeri Sembilan, Malaysia. The primary forests were dominated by the red meranti group of Dipterocarpaceae (Tang et al., 1996; Okuda et al., 2003). In the oil palm plantation, Elaeis guineensis were planted, and Hevera brasiliensis were planted in the rubber plantation.
Measurement Soil respiration rate was measured with a portable soil respiration measuring system (LI6400, LI-COR, NE, USA). Soil temperatures at 1cm and 5cm depth from the soil surface and 9
average soil water content at the depth of 5cm from the soil surface were measured simultaneously. The soil water contents were measured with a time domain reflectometry sensor (TDR; TRIME-FM, IMKO, Ettlingen, Germany). Soil samples were taken with soil sampler after measuring of soil respiration rate, solid, liquid and gaseous phase of soils were measured in the laboratory. In this report, soil water content indicated the value obtained by a time domain reflectometry sensor, and the liquid phase of soil indicated the value obtained from three phase distribution of soil. The CO2 concentrations in soil gas were measured with gas chromatography (TDC, GC-14B, Shimadzu, Japan). The soil gas was collected at a depth of 10 cm, 20 cm, 30 cm, 40 cm, 60 cm in the primary forest and rubber plantation, and 10 cm, 20 cm, 30 cm, 40 cm in the oil palm plantation, respectively. All statistical analyses were conducted using the StatView 5.0 software package (SAS Institute, N.C., USA). ANCOVA and a post hoc test (Fisher’s PLSD) were used to determine the differences in average soil respiration rates and environmental factors between the primary and secondary forests, and the oil palm plantation. ANOVA and multiple regression analyses were used to examine the relationships between soil respiration rates and environmental factors.
Results and Discussion
Table 1. Soil respiration rate and soil physical characters in the three different ecosystems Soil respiration rate Volume of Volume of Volume of Soil hardness liquid (%) (mm) solid (%) gas (%) Site （mg CO2 m2 hr-1) Primary forest 796.0 27.8 27.5 44.7 7.4 Oil palm plantation 516.6 49.2 29.5 21.3 10.1 Rubber plantation 405.8 54.0 30.0 16.0 10.4
Table 2 Corelation coefficient between soil respiration rates and soil physical characters
Soil respiration rate （mg CO2 m hr ) 2
Primary forest (n=16) Soil respiration rate Soil water content Volume of gas Volume of solid Volume of liquid
-0.791 0.762 -0.734 -0.735
Oil palm plantation (n=16) Soil respiration rate Soil water content Volume of gas Volume of solid Volume of liquid Rubber plantation (n=16) Soil respiration rate Soil water content Volume of gas Volume of solid Volume of liquid
-1
*** *** *** ***
Soil water contents （％）
Volume of gas (%)
Volume of solid (%)
Volume of liquid (%)
1.000 -0.789 *** 0.732 *** 0.779 ***
1.000 -0.946 *** -0.974 ***
1.000 0.847 ***
1.000
1.000 -0.636 0.586 * -0.733 ** -0.050
1.000 -0.625 ** 0.559 * 0.451
1.000 -0.914 *** -0.688 **
1.000 0.334
1.000
1.000 -0.451 0.550 * -0.407 -0.397
1.000 -0.570 * 0.022 0.884 ***
1.000 -0.782 *** -0.677 **
1.000 0.071
1.000
***; P
