Spatial distribution of tropical wetlands in Central Brazil as influenced by geological and geomorphological settings |
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| Institution: | 1. Universidade Federal de Goiás-IESA-LABOGEF, Campus II, 74001-970 Goiânia-GO, Brazil;2. Pontifícia Universidade Católica de Goiás-Centro de Biologia Aquática, Campus II, 74605010, Av. Engler s/n Jardim Mariliza, Goiânia-GO, Brazil;1. Instituto Nacional de Pesquisas Espaciais – INPE, São José dos Campos, 12245-970, SP, Brazil;2. Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, 05508-900, SP, Brazil;3. Instituto Federal de Goiás (IFG), Goiânica, 74055-110, GO, Brazil;1. Centre of Oceanography of the Faculty of Sciences of the University of Lisbon (CO), Campo Grande, Lisbon 1749-016, Portugal;2. Physics Department & Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Campus de Santiago, Aveiro 3810-193, Portugal;3. Animal Biology Department, Faculty of Sciences of the University of Lisbon (CO), Campo Grande, Lisbon 1749-016, Portugal;4. Biology Department & Centre for Environmental and Marine Studies (CESAM), University of Aveiro, Campus de Santiago, Aveiro 3810-193, Portugal;5. Institute of Marine Research–Marine and Environment Research Centre (IMAR-CMA), c/o Department of Zoology, Faculty of Sciences and Technology, University of Coimbra, Coimbra 3000, Portugal;1. Department of Zoology and Botany, São Paulo State University, UNESP, Campus São José do Rio Preto, São Paulo 15054-000, Brazil;2. Department of Biology, São Paulo State University, UNESP, Campus São José do Rio Preto, São Paulo 15054-000, Brazil;1. Centro de Investigaciones Geológicas, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata (UNLP), Calle 64 #3 (entre 119 y 120), La Plata, 1900 Buenos Aires, Argentina;2. Centro Nacional Patagónico, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Boulevard Almirante Brown 2915, Puerto Madryn U9120ACD, Chubut, Argentina |
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| Abstract: | Tropical wetlands in Central Brazil are located in savanna areas and are made up of more terrestrial-type wetlands – campo limpo úmido (grassland-type savanna), campo sujo úmido (shrub-type savanna), mata galeria (riverine forest); as well as more aquatic-type wetlands – vereda (valley-side marsh with palm groves of Mauritia flexuosa), várzea (backswamp), lake, and river. They are regulated by a seasonal climatic regime characterized by a wet-rainy season from October to March and then followed by a dry season. Underground water is abundant and rivers frequently overflow during the rainy season. Many of these wetlands which are protected by law are significant regulators of water quality. In order to predict tropical wetland function and draw up environmental management policies, it is important to understand how abiotic and biotic factors influence tropical wetland origin and spatial distribution. In this large-scale study we set out to investigate the influence that geological and geormorphological settings, i.e. geological substrates and geomorphological units, have on the spatial distribution of tropical wetlands in Central Brazil. Two watersheds, the Caiapó and Piracanjuba, were selected in order to carry out the study. They present different types of rock and unconsolidated surface materials. Planation surface, escarpment and steep slope, gentle slope, and aggradation are the dominant geomorphological units in the watersheds. Principal component analysis was conducted in order to determine the influence of the selected abiotic variables on the spatial distribution of tropical wetlands. The study showed that the presence of sedimentary and low-grade metamorphic rocks and planation surface strongly influence the spatial distribution of the more terrestrial-type wetlands. Geological and geomorphological settings explain about 60% of the variability in the spatial distribution of these wetland types. No clear effect of the abiotic variables selected was observed on the more aquatic-type wetlands. An association between stratified layers or planar geological surfaces, groundwater discharge zones, and slope breaks is suggested to explain the influence of the geological and geomorphological settings on the wetlands under review. The study demonstrated the importance of considering abiotic factors, not usually included in classification schemes, to further understand the spatial distribution of tropical wetlands. |
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