Tropical environmental dynamics: A modeling perspective

The impact of climatic change on tropical vegetation is of global and regional concern because of the high biodiversity and the feedbacks to the carbon, water, and nutrient cycles. Tropical ecosystem functioning is governed by complex systems, that, in spite of their diversities, share in common structures and characteristic states which can be modeled (Aassine and Jay, 2002). Records of fluctuating biotic and chemical characteristics from numerous sedimentary archives, including oceans (Guilderson et al., 1994), continental lakes, bogs, swamps (Hooghiemstra and van der Hammen, 1998; Behling and Hooghiemstra, 2000; Haberle and Maslin, 1998), and ice caps (Thompson et al., 1995), demonstrate that tropical environments change at a range of time scales. One of the most recent extremes of these variations concerns the 100,000 glacial–interglacial cycles associated with the Quaternary geological period (i.e., the past 2.6 million years). Climate change involves massive reorganisation of global climate systems with major impacts on ecosystem form and function giving rise to complex interactions between the atmosphere, geosphere, hydrosphere, and biosphere (Kohfeld and Harrison, 2000). Models are essential tools to assess the potential response of vegetation to climate change, particularly where large spatial and temporal scales are considered (Ostendorf, 2001). Such changes can also be documented by accessing sedimentary archives, whereas the nature and implications of such changes can be investigated through modeling. Models using a space for time substitution are based on rich and detailed spatial information and have a very high level of empiricism (Ostendorf, 2001).