Page 26 - Governing Congo Basin Forests in a Changing Climate • Olufunso Somorin

Chapter 1
1.1.1 Tropical Forests and Climate Change: the Congo Basin Forests
Globally, forests cover approximately 30% of the earth’s surface and these are either primary or modified natural forests (Houghton, 2005; Kirilenko and Sedjo, 2007; Bonan, 2008). When grouped according to their ecological types, tropical forests constitute the major forest type followed by the boreal, temperate and sub-tropical respectively (FAO, 2006). Forests play a major role in the regulation of the climate through physical, chemical and biological processes that have an effect on planetary energetics, the hydrological cycle, and atmospheric composition (Bonan, 2008). Although forests store carbon, they can also be a major source of carbon emissions to the atmosphere. This happens when forest areas are converted to other land uses and soils are cultivated (Bodegom van et al., 2009). Societies have always been involved in activities that modify natural landscapes (land-use change) which consequently led to changes in carbon storage densities in forests, savannahs and grasslands. The major types of land- use systems that affect carbon storage are: (i) the permanent clearance of forest for pastures and arable crops; (ii) shifting cultivation that may vary in extent and intensity as populations increase or decline; (iii) logging with subsequent forest regeneration or replanting; and (iv) abandonment of agriculture and replacement by regrowth or planting of secondary forest (i.e. deforestation, afforestation and reforestation) (Malhi et al., 2002).
Like any other ecosystem, forest ecosystems as well as the services they provide are going to be affected by climate change. The exposure and sensitivity of the forest determine the extent to which the forests will be affected by impacts of climate change. A combination of climate change, with associated disturbances (such as flooding, drought, wild fire, insects), and other global change drivers (such as land-use change, pollution, overexploitation of resources) are going to affect many ecosystems (IPCC, 2007). These effects could either be positive or negative. In addition, the vulnerability of a forest also depends on its internal capacity to adapt to unprecedented rates of climatic changes (adaptive capacity) (Locatelli et al., 2011). The adaptive capacity of an ecosystem is related to the diversity of functional groups within the ecosystem and the diversity of species within groups (Locatelli et al., 2008). In a nutshell, vulnerability and adaptive capacity, which are like two sides of a coin, are the building blocks of adaptation.
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