Common Patterns of Spatial Variations in the Tropics
The Chapter highlights the fact that there is a common pattern of spatial variation in tropical forests across the three continents and elaborates this fact taking specific example of tropical rainforests, the most complex of all formations. What seems to
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Common Patterns of Spatial Variations in the Tropics
11.1 Similarities in Forest Formations Across the Continents The findings presented in the chapter are based on research conducted by the author on the common patterns of spatial variation in tropical forests across the three continents. What seems to be a bewildering chaos of vegetation does have in fact an organized structure. Ecological studies also show evidence of striking similarities among the formations. We will take in this chapter the most complex forest type, viz., the rainforests as an illustration. According to Richards (1971), they are composed of similar synusiae or communities of tree species with homogeneous characteristics and show great similarity in their spatial arrangement. Species of corresponding synusiae in different geographical regions, besides being alike in life-form, are to a considerable extent alike in physiognomy (see Fig. 11.1). The fundamental pattern of structure is thus the same throughout the whole extent of the rain forest. Thanks to this, the knowledge acquired in one region or country could serve a very useful purpose for survey planning in another region or country. The chapter would limit to rain forests, the most complex of all forest formations. Similar information is available on forest formations in the drier regions of the tropics in the FAO Forestry Paper 51/1.
Fig. 11.1 Distribution of tropical rain forest in the equatorial belt (Source: Smithsonian) K. D. Singh, Capacity Building for the Planning, Assessment, and Systematic Observations of Forests, Environmental Science and Engineering, DOI: 10.1007/978-3-642-32292-1_11, Springer-Verlag Berlin Heidelberg 2013
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Common Patterns of Spatial Variations in the Tropics
11.2 Macro-Variation Patterns and Their Significance for Stratification The factors causing major changes at formation level can be divided into two broad groups, natural and cultural. Among the natural factors climate is relatively uniform. Soil and topography appear as the main agents for causing variation. Some common types are: • Climax rain forest (usually on well-drained soils and below elevations of 500–800 m). • Mangrove forest. • Swamp forest. • Periodically flooded forest. • Riparian forest. • Hill forest (usually at altitudes above 500–800 m). • Forest on tropical podsols. • Forest on coastal sand. Cultural factors (positive or negative influence of man) cause further changes in the natural rain forest vegetation. The following broad types of land use can be distinguished: • • • • • •
Primary rain forest (influenced less by man). Logged-over forest. Secondary forest (resulting from abandoned shifting cultivation). Mixed forest-grassland association. Managed forest (natural and manmade). Other non-forest classes.
The gains in precision reported due to stratification by the FAO Sarawak Forest Inventory Project at macro-level are shown in Table 11.1 (FAO 1973). The precision refers to the net industrial volume of all species 18 in. (45 cm) and more in diameter (95 % confidenc
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