Climatic Change and Seasonally Dry Tropical Forests
Abstract
Recent emphasis in research on Latin American tropical forests dominates our understanding of how seasonally dry tropical forests (SDTFs) may respond to climatic change and also of how changes in land use and fire incidence may interact with this response. As a consequence, our analysis focuses mainly on how Latin American SDTF may interact with climate over the twenty-first century and the wider context within which this interaction may occur, especially with respect to rain forest. In Latin America, SDTFs generally occur where rainfall is less than 1600 millimeters per year and where the dry season is substantial, lasting at least 4 to 6 months during which precipitation is generally less than 100 millimeters per month (Gentry 1995). Apart from rainfall, SDTFs are also associated with specific edaphic factors, notably nutrient-rich soils (Ratter et al. 1973; Furley 1992; Vargas et al. 2008). In contrast, Neotropical savannas, while often occurring under identical climatic conditions, are found on nutrient-poor soils that are usually high in aluminum and sometimes seasonally flooded (fig. 16-1). Savannas and SDTFs are further distinguished ecologically by deciduousness, structure, and fire resistance. Savanna trees are frequently evergreen, whereas most SDTF species are deciduous or semideciduous. Savannas are open, grass-rich vegetation, whereas SDTFs have a closed canopy with few understory grasses. Without human intervention, although SDTF trees may occasionally possess fire adaptations (e.g., thick corky bark), they lack the widespread fire-resistant features above and below ground that are characteristic of the woody flora of Neotropical savannas, which frequently burn during the dry season because of the presence of flammable C4 grasses (Taiz and Zeiger 2006). While SDTF, savanna, and rain forest have complex relationships and perhaps represent points on a continuum of vegetation types, there are in general clear ecological differences between savanna and SDTF that must be taken into account when considering the effects of climate on tropical forests.
Citation
Meir, P.; Pennington, R.T. Climatic Change and Seasonally Dry Tropical Forests. In: Dirzo, R.; Young, H.S.; Mooney, H.A.; Ceballos, G. (Eds) Seasonally Dry Tropical Forests. Island Press/Center for Resource Economics, (2011) 279-299. ISBN 978-1-61091-021-7