Are Soils in Degraded Dipterocarp Forest Ecosystems Deteriorated? A Comparison of Imperata Grasslands, Degraded Secondary Forests, and Primary Forests
Many primary forests in the tropical regions of the world have been converted into degraded secondary forests and grasslands of species such asImperata cylindrica.The main destructive agents responsible include illegal logging, slash-and-burn cultivation, extensive cattle grazing and natural forest fires (Fatawi and Mori, Chapter 1, this volume). Understanding the soil characteristics of these degraded forest ecosystems is important not only for the conversion of these areas into more productive land but also for evaluating the effects of forest degradation on global climatic change. However, information on the soils of degraded ecosystems is very scarce and many theories on the soil fertility ofImperatagrasslands are still under debate. For instance, it has been reported that in the Philippines degraded grassland soils are severely eroded, extremely acidic, low in organic matter and lacking in key elements, particularly N, P and Mg (Ohta 1988, Dela Cruz 1986). Dela Cruz (1986) concluded that the poor chemical properties of these areas made forest regeneration inImperatagrasslands technically difficult, expensive and time consuming. However, Soepardi (1980) who investigated the chemical and physical properties of soils fromImperatagrasslands in four locations on Sumatra, two on Java and one on Kalimantan concluded thatImperatasoils are not infertile to such a great extent and that grasses can even improve the fertility and physical properties of surface soils. These contradictions suggest that there may be a large degree of variation in the fertility ofImperatagrassland soils. In order to fully understand the soils of these degraded land areas, we need to know how soil characteristics vary and be able make generalisations about the relationship between soil fertility and other soil parameters.
KeywordsClay Content Secondary Forest Primary Forest Stock Level Forest Degradation
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- Dela Cruz RE (1986) Constraints and strategies for the regeneration ofImperatagrassland. In: Forest Regeneration in Southeast Asia, Biotrop special pub, Seameo-Biotrop, Bogor, Indonesia, 25:23–34Google Scholar
- Kiyono Y (1994) Degradation of tropical rainforests of East Kalimantan by man’s impact—Forests in areas of swidden agriculture (in Japanese). The Tropical Forestry 29:46–54Google Scholar
- Soepardi G (1980) Alang-alang(Imperata cylindrica(L.) Beauv.) and soil fertility. In Proc. of Biotrop workshop onImperataBiotrop special pub No. 5, Biotrop,Bogor,Indonesia,pp 57–69Google Scholar
- Soil Survey Staff (1997) Keys to Soil Taxonomy, 7th edn, USDA Soil Conservation Service, Pocahontas Press, Inc., VirginiaGoogle Scholar