Ten pastures were paired with adjacent broadleaf tree stands to form the first set of paired plots to examine the effects of broadleaf plantations on soil carbon. Ten additional broadleaf tree plantations were paired with adjacent conifer stands to form paired plots to compare differences in soil carbon between conifer and broadleaf tree plantations following conversion from pasture. The location of conifer plots in the landscape precluded the pairing of conifer plantations with pastures. We used a chronosequence design, with forest plots ranging in age from 6 to 34 years since establishment. The broadleaf plantations consisted of seven Eucalyptus stands, one Liquidambar styraciflua L. stand, one Gmelina arborea Roxb. stand, and one stand of Dalbergia nigra Allem. ex Benth. (a native leguminous tree species). The original, predeforestation state of the soil was estimated by comparing an on-site residual native forest plot, we call a ‘‘Reference Forest,’’ paired with an adjacent pasture. We estimated the effect of plantation age on soil carbon based on the pattern among stands of increasing age and also examined the differences between paired
plots over time.