The macrofauna of the soils on the west ridge of Gunung Mulu in 4th Division, Sarawak, were sampled during February and March 1978. The eleven sampling sites ranged from near the base of the mountain at 130 m a.s.1. to the summit at 2.376 m.Altitudinal changes from lowland rain forest (mixed dipterocarp forest) to lower montane and upper montane rain forests are concomitant with changes in soil from red yellow podzolics and regosols to peaty gley podzolics and organic peats.The abundance of the total macrofauna declined from 2,579 individuals m(-2) at 130 m to 145 m(-2) at 2,376 m. Declining population densities of ants and termites correlated significantly with increasing altitude but the effect on other groups was variable. Changes in total biomass were erratic and varied from 4.1-6.2 g m(-2) (alc. w.w.) in the dipterocarp forest soils to 5.8 g m(-2) in the lower montane, 9.3-20.2 g m(-2) in the upper montane (tall facies) and 1.9-9.5 g m(-2) in the upper montane (short and summit facies). Only the decline in the biomass of termites and ants correlated significantly with altitude. Other groups remained fairly constant, varied erratically or increased in the middle altitudes.The dipterocarp forest soil macrofaunal biomass was dominated by termites, beetles and earthworms (Megascolecidae and Moniligastridae), with ants the dominant predators. The lower montane forest was a transitional and ill-defined zone on the mountain and the soil macrofauna was also transitional to some extent. Termite biomass fell substantially and earthworms replaced them as the dominant detritivores, with beetles in a secondary role. Formicidae remained as the major predators. With the inception of peats in the upper montane forest (tall facies), the macrofauna was dominated by Coleoptera with earthworms, Diptera larvae and Blattodea in lesser roles. With increasing exposure in the upper montane forests (short and summit facies), several major groups disappeared altogether. The soils were dominated by Blattodea with Coleoptera and Megascolecidae of lesser importance. Chilopoda and Arachnida replaced Formicidae as the dominant predators.
To estimate the rate of consumption of leaf litter by termites on the forest floor of Pasoh Forest Reserve, Negeri Sembilan, West Malaysia, newly fallen leaves were marked and distributed on the ground. The loss of leaf area due to termites was determined either photometrically or visually. An average of 1.70% of the total surface area of the leaf litter disappeared per week in experiment 1 and 1.25% in experiment 2 in Plot 1, and 2.9% per day in other plots located near the mounds of Macrotermes carbonarius. The amount of leaf litter accumulation in the Ao layer was estimated at about 2.3 t/ha at Plot 1, so it was likely that an amount equivalent to about 32% of the daily leaf-litter fall was transported by M. carbonarius to their mounds in experiment 1 and 22% in experiment 2. It was considered that the termites had an important role in the detritus food chain of the ecosystem.
SO2-fumigation experiments were conducted with plants of pea (Pisum sativum) and corn (Zea mays) recognized to be, respectively, sensitive and tolerant to the gas. Accumulation of inorganic sulfur in the tissues revealed that the pea takes up considerably greater amounts of SO2 than corn. Porometer measurements and transpiration coefficients show that this greater SO2 uptake is partly related to the lower leaf diffusion resistance of peas. Additional internal sinks for SO2 uptake are discussed in order to give a complete explanation of the differential SO2 uptake of the two species.
1. Density of nests, population number, biomass, nitrogen and carbon content, calorific content and respiration rate of termites were studied at Pasoh Forest, West Malaysia mainly with four dominant species of epigeous nest builders, Macrotermes carbonarius, Dicuspiditermes nemorosus type-a, type-b and Homallotermes foraminifer, to reveal their role in the ecosystem. 2. The density of nests or mounds was 15-41/ha in M. carbonarius, 60-110/ha in the two types of D. nemorosus and 85-165/ha in H. foraminifer. 3. The population number per nest or mound was about 88,000 in M. carbonarius, 45,000 in D. nemorosus type-a, 47,000 in D. nemorosus type-b and 13,000 in H. foraminifer. The population number per hectare was about 1.8x10(6) for M. carbonarius, 4.3x10(6) for D. nemorosus type-a, 5.2x10(6) for D. nemorosus type-b and 2.1x10(6) for H. foraminifer. 4. The ratio in number of workers to soldiers was 6.4 for M. carbonarius, 19.0 for D. nemorosus type-a, 23.1 for D. nemorosus type-b and 8.9 for H. foraminifer. The ratio in number of adults (workers plus soldiers) to larvae was 1.4 for M. carbonarius, 0.59 for D. nemorosus type-a, 1.76 for D. nemorosus type-b and 3.84 for H. foraminifer. 5. The number of adults per nest of D. nemorosus type-a, type-b and H. foraminifer was linearly correlated with the weight of nest on the log-log coordinates. 6. The ratio of dry body weight to live weight was 0.24-0.30 for workers, 0.19-0.29 for soldiers and 0.15-0.22 for larvae. 7. The ash content of termite body was 26-66% for workers, 2-24% for soldiers and 1-4% for larvae. 8. The carbon content ranged from 45% to 66% of ash-free dry weight and the nitrogen content from 5.6% to 12.6%. 9. The mean calorific value of termite body was 5.3 gcal/mg in workers and soldiers on an ash-free weight basis, but was greater in nymphs and winged reproductives in the nest (6.7-6.9 gcal/mg) owing probably to their large fat storage. 10. The relation of CO2 evolution rate to temperature in these termites was similar to what has been found in other insects. 11. The total biomass of the four termite species was estimated at 6.01 kg ash-free dry weight/ha, equivalent to 0.55 kg nitrogen/ha and 3.09 kg carbon/ha. 12. The role of the fungi cultivated by M. carbonarius on their fungus combs was discussed in relation to the nutrition of termites and the decomposition of leaf-litter with special reference to their nitrogen metabolism. The high nitrogen content of fungus spherules growing on fungus combs seemed to have an important bearing on the nutrition of termites. 13. It was concluded that the termites played a very important role in the organic matter decomposition cycle of Pasoh Forest.