Required sample size for estimating soil respiration rates in large areas of two tropical forests and of two types of plantation in Malaysia

We estimated the required sample sizes for estimating large-scale soil respiration (for areas from 1 to 2 ha) in four ecosystems (primary and secondary forests, and oil palm and rubber plantations) in Malaysia. The soil respiration rates were 769 ± 329 mg CO₂ m^-2 h^-1 in the primary forest (2 ha, 50 sample points), 708 ± 300 mg CO₂ m^-2 h^-1 in the secondary forest (2 ha, 50 points), 815 ± 363 mg CO₂ m^-2 h^-1 in the oil palm plantation (1 ha, 25 points), and 450 ± 178 mg CO₂ m ^-2 h^-1 in the rubber plantation (1 ha, 25 points). According to our sample size analysis, the number of measurement points required to determine the mean soil respiration rate at each site with an error in the mean of no more than 10% ranged from 67 to 85 at the 95% probability level. These results suggest that evaluating the spatial heterogeneity of soil respiration rates in the tropics may require more measurement points than in temperate forests.