s:1892:"%T Importance of silvopastoral systems for mitigation of climate change and harnessing of environmental benefits 
%A Ibrahim M 
%A Guerra J L 
%A Casasola F 
%A Neely C L 
%X Forest ecosystems are estimated to absorb up to 3 Pg of carbon (C) annually. In recent years, however, a significant portion has been returned to the atmosphere through deforestation and forest fires. For example, tropical deforestation in the 1980s is estimated to have accounted for up to a quarter of all C emissions stemming from human activities (FAO, 2003). In Central America, more than 9 million ha of primary forest was deforested for expansion of pasture and more than half of this area is degraded (Szott, Ibrahim and Beer, 2000). Pasture degradation leads to a decline of the natural resource base (e.g. decreased biodiversity, soil and water quality); m ore rapid runoff and hence higher peak flows and sedimentation of rivers; and lower productivity, increased rural poverty and vulnerability and further land-use pressure. It is also related to a significant reduction in soil C stocks and is among one of the main reasons for the large C footprint associated with cattle ranching in Latin America (Ibrahim et al., 2007). On the other hand, many studies in Latin America conclude that improved grasses and legume pastures can fix similar amounts of C to that of forest systems (Tarre et al ., 2001; Ibrahim et al. , 2007; Amézquita et al., 2008), and that they are associated with increased animal productivity (Ibrahim, 1994). However, the root systems of grasses are generally concentrated in the upper soil layers (0–40 cm depth) and there is little soil-derived C associated with grasses in the deeper soil layers (Nepstad et al ., 1994). Furthermore, large-scale cultivation of simplified grass monocultures results in agricultural landscapes that are more vulnerable to climate change. 
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