1. Ahlgren, I. F. and Ahlgren, C. E. 1965 Effect of prescribed burning on soil microorganisms in a Minnesota jack pine forest. Ecology46, 304–310.
2. Allen, S. E. (Ed.) 1974 Chemical Analysis of Ecological Materials. Blackwell Scientific Publ. Oxford.
3. Birch, H. F. and Friend, M. T. 1956 The organic matter and nitrogen status of east African Soils. J. Soil Sci.7, 156–167.
4. Coulter, J. K. 1950 Organic matter in Malayan Soils: A preliminary study of the organic matter content in soil under virgin jungle, forest plantations and abandoned cultivated land. Malay. For.13, 189–202.
5. Ewel, J. J. 1976 Litter fall and leaf decomposition in a tropical forest succession in eastern Guatemala. J. Ecol.64, 203–308.