Humid tropics

Figure 23.8 shows the maximum climatic conditions in different areas of the world. The humid tropical zones have high humidities but the dry bulb rarely exceeds 35°C. The deserts have an arid... 

Fig. 9-8 Histogram of dissolved solids of samples from the Orinoco and Amazon River basins and corresponding denudation rates for morpho-tectonic regions in the humid tropics of South America (Stal-lard, 1985). The approximate denudation scale is calculated as the product of dissolved solids concentrations, mean armual runoff (1 m/yr), and a correction factor to account for large ratios of suspended load in rivers that drain mountain belts and for the greater than average annual precipitation in the lowlands close to the equator. The correction factor was treated as a linear function of dissolved solids and ranged from 2 for the most dilute rivers (dissolved solids less than lOmg/L) to 4 for the most concentrated rivers (dissolved solids more than 1000 mg/L). Bedrock density is assumed to be 2.65 g/cm. (Reproduced with permission from R. F. Stallard (1988). Weathering and erosion in the humid tropics. In A. Lerman and M. Meybeck, Physical and Chemical Weathering in Geochemical Cycles," pp. 225-246, Kluwer Academic Publishers, Dordrecht, The Netherlands.)...

Larsen, M. C. and Simon, A (1993). A rainfall infen-sity-duration threshold for landslides in a humid-tropical environment, Puerto Rico. Geograf. Anna . 75A, 13-23. 

Simon, A., Larsen, M. C., and Hupp, C. R. (1990). The role of soil processes in determining mechanisms of slope failure and hillslope development in a humid-tropical forest, eastern Puerto Rico. Geomorphology 3, 263-286. 

Stallard, R. F. (1988). Weathering and erosion in the humid tropics. In "Physical and Chemical Weathering in Geochemical Cycles" (A. Lerman and M. Meybeck, eds), pp. 225-246. Kluwer Academic Publishers, Dordrecht, Holland, NATO ASI Series C Mathematical and Physical Sciences 251. 

Smectite is the first secondary mineral to form upon rock weathering in the semi-arid to sub-humid tropics. Smectite clay retains most of the ions, notably Ca2+ and Mg2+, released from weathering primary silicates. Iron, present as Fe2+ in primary minerals, is preserved in the smectite crystal lattice as Fe3+. The smectites become unstable as weathering proceeds and basic cations and silica are removed by leaching. Fe3+-compounds however remain in the soil, lending it a reddish color aluminum is retained in kaolinite and A1-oxides. Leached soil components accumulate at poorly drained, lower terrain positions where they precipitate and form new smectitic clays that remain stable as long as the pH is above neutral. Additional circumstances for the dominance of clays are ... 

Originally, SFI was developed to measure quality of soils of cacao fields (Alvim and Rosand 1974). Moran et al. (2000) extended its use in forest soils in the humid tropics, where the climate is classified as Am or Af (Koppen 1931). Recently, Doi and Sakurai (2004) found the applicability of SFI and SEF to evaluating soil quality in the SERS. 

Veldkamp E, Keller M (1997) Nitrogen oxide emissions from a banana plantation in the humid tropics. J Geophys Res 102 15889-15898... 

The low-Se ecosystems occur mainly in and near the temperate forest and forest steppe landscapes as an axis in China, and the relatively high-Se content in the ecosystems usually appear in the typical humid tropical and subtropical landscapes and typical temperate desert and steppe landscapes. 

Tracey, J. G. (1982) The Vegetation of the Humid Tropical Region of North Queensland. CSIRO, Melbourne. 

Here we present the results of a preliminary study to investigate the chemical composition of secretions from carpal glands of feral pigs living in densely vegetated, humid tropical lowland rainforest habitats with a view to exploiting semiochemicals to improve trapping efficiency and to identify repellents. 

Many submerged soils are developed in recent in alluvium and are often young or only weakly weathered (Section 1.3). The overall composition of the clay fraction is therefore often close to that of the parent sediment. Hence the following generalizations can be made for rice soils in the humid tropical lowlands (Kyuma, 1978 Binkman, 1985)... 

The main objective of this project was to study some of the ecological processes that occur during secondary succession in warm and humid tropics. This process is triggered after a perturbation in the tropical rain forest or the abandonment of crop land. ... 

The humid tropical climate of Cuba and the Yucatan Peninsula (Mexico) is characterized by an average air temperature always higher than 15°C, frequently high relative humidity, a summer or wet season (may to October) with frequent and heavy precipitations and a winter of dry season (november to april) with lower precipitations. 

Alkaloids derived from L-ornithine, L-lysine, and L-trypthophan occur in the Legume plant family (Fabaceae Juss.) (Table 9). This plant family is the third largest botanical family, with 650 genera and 18000 species in the humid tropics, sub-tropics, temperate and sub-arctic zones around the Globe". L-ornithine-derived alkaloids such as senecionine are present in the genus Crota Crotalaria L.). 

The lateritic hydrous nickel silicate ores are formed by the weathering of rocks rich in iron and magnesium in humid tropical areas. The repeated processes of dissolution and precipitation lead to a uniform dispersal of the nickel that is not amenable to concentration by physical means therefore, these ores are concentrated by chemical means such as leaching. Fateritic ores are less well defined than sulfide ores. The nickel content of lateritic ores is similar to that of sulfide ore and typically ranges from 1% to 3% nickel. Important lateritic deposits of nickel are located in Cuba, New Caledonia, Indonesia, Guatemala, the Dominican Republic, the Philippines, and Brazil. Fossil nickeliferous laterite... 

Veldkamp, E., M. Keller, and M. Nunez, Effects of Pasture Management on N20 and NO Emissions from Soils in the Humid Tropics of Costa Rica, Global Biogeochem. Cycles, 12, 71-79 (1998). 

Over 200 000 species of fungi have been characterised. The fungi are extremely responsive to environmental pressures and exhibit a high capacity to adapt to and colonise a variety of ecological niches. They can be found growing anywhere between the high mountains to the abyssal depths and from dry, polar regions to the hot, humid tropics. 

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