A comparison between individual agroforestry systems
and pastures did not distinguish any differences
for mineralizable C (CMIN) (data not shown). A
pooled comparison between agroforestry systems
and pasture, however, demonstrated that the latter
had significantly greater CMIN in the 0±5 cm depth
(Table 4). Greater CMIN in the surface of pasture
plots might be attributed to factors affecting soil
organic matter quality, such as higher root biomass
and turnover in the topsoil of permanent pastures
(Lugo and Brown, 1993) and greater content of lignin
in tree litter. Lignin content is one of the major factors
controlling litter decomposition (Meentemeyer, 1978).