Humid Tropical Environments

Transcription

1 Humid Tropical Environments Alison J. Reading Russell D. Thompson Andrew C. Millington BLACKWELL Oxford UK & Cambridge USA

2 Contents Preface Acknowledgements xi xiii 1 Introduction Defining the humid tropics The importance of the humid tropics Perceptions of the humid tropics 9 2 The Humid Tropical Atmosphere Introduction Atmospheric circulation systems Weather disturbances Synoptic-scale weather disturbances Easterly waves Tropical cyclones The monsoon circulation Other weather and climate controls Land and sea breezes The orographic factor The role of El Nino and the southern oscillation in extreme weather events 45 3 Humid Tropical Climates Introduction Radiation and energy balances Temperature Humidity and cloud cover Evaporation and evapotranspiration Rainfall Seasonally Variability Intensity, duration and frequency Spatial and diurnal variations Water balance > 78

3 vi Humid Tropical Environments 4 Humid Tropical Soils Introduction Soil-forming processes in the humid tropics Soil classification Soil distribution Red soils Ferralsols and ferric acrisols Lixisols Nitisols Red soils at high altitudes Hydromorphic soils Fluvisols Gleysols The effects of flooding on fluvisols and gleysols Arenosols and regosols Arenosols Regosols Andosols Leptosols Histosols Humid Tropical Vegetation Introduction Humid tropical vegetation: classification and distribution Classification The importance of global vegetation classification schemes The main types of humid tropical vegetation Tropical forest formations Rain forest ecology Forest structure Flora Fauna Species richness and biodiversity Changes with altitude Forest microclimate Solar radiation Temperature Moisture Nutrient cycling Major components of nutrient cycling Nutrient fluxes Nutrient stores Forest dynamics , Other types of humid tropical vegetation Wet coastal ecosystems 175

4 Contents ^_ vi Freshwater swamps and flooded forests Heath forests The palaeogeography of humid tropical vegetation Floristics and plate tectonics Humid tropical vegetation during the late Tertiary Humid tropical vegetation during the Quaternary Humid Tropical Landscapes Introduction Weathering Processes and landforms characteristic of old and tectonically stable parts of the tropics Duricrusts The residual landscape Residual hills Processes and landforms characteristic of young and tectonically active regions Soil creep Rapid mass movements Subsidence Depositional landforms Drainage networks Tropical karst Polygonal karst landscapes Tower karst landscapes Tropical coasts Coral coasts Algal mats Mangroves The Humid Tropical Hydrosphere The hydrological cycle Interception Evaporation and transpiration Infiltration and percolation Runoff processes Overland flow generation Throughflow Runoff models in the humid tropics Pipeflow Sediment transport Sediment transport by surface wash Sediment transport by rivers Solute transport in the humid tropics 258

5 viii Humid Tropical Environments 7.5 High magnitude events and large-scale changes in humid tropical catchments 265 Environmental Resources and Hazards in the Humid Tropics Resources and resource utilization Mineral resources Ores as products of humid tropical weathering processes Hypogene deposits and supergene enrichment Relative and absolute enrichment by weathering and denudation Placers as transported mineral deposits Environmental consequences of material extraction Environmental hazards Tectonic events as environmental hazards Earthquakes Volcanoes Lahars Tsunami Landslide hazards Atmospheric extremes as hazards Droughts Floods Tropical cyclones Soils and vegetation resources and sustainable management Soil erosion and sediment yield Slope erosion and gullying Mass movements Sediment yield Soil disturbance, erosion and sediment yield due to commercial logging activities Soil and vegetation interactions after disturbance Soil nutrient responses to logging Nutrient responses to forest fires Nutrient responses during conversion of forest to pasture Nutrient status under plantation cropping The effects of shifting cultivation on soils and vegetation Changes in nutrient levels Changes in the soil fauna 309, Vegetation succession in shifting cultivation systems 311

6 Contents ix 9 Environmental Issues Facing the Humid Tropics Deforestation - trends and prospects Forest areas and deforestation rates Forest cover and deforestation rates in Latin America Forest cover and deforestation rates in Africa Forest cover and deforestation rates in Asia, Australasia and Oceania Mapping tropical forests and monitoring deforestation from space Hydrological consequences of deforestation Climatological consequences of deforestation Causes of deforestation Sierra Leone The Brazilian Amazon Peninsular Malaya and Borneo (Malaysia, Indonesia and Brunei) Destruction of mangroves Deforestation - a summary Conservation of plant resources Deforestation - ways forward The changing atmosphere Evidence of contemporary atmospheric change Causes of climatic change The greenhouse effect and global warming Future global warming in the humid tropics: predictive approaches The predictions of global climate models Sea-level rise due to predicted global warming The effect on mangroves The effect on coral reefs Sea-level rise in island states: a case study of the Maldives Republic Sea-level rise in continental lowlands: a case study of Bangladesh Sea-level rise and water resources Global warming and agricultural potential International concern and action to alleviate the effects of climate change The future in the humid tropics 361 Further reading 362 Bibliography 366 Index 420