So they set about clearing the land for agriculture, setting fire to massive tracts of forest.
( So ( they ( ( ( ( set ( about ( clearing ( ( the land ) ( for agriculture ) ) ) ) ) , ) ( ( setting fire ) ( to ( ( massive tracts ) ( of forest ) ) ) ) ) . ) ) )
(ROOT (S (IN So) (NP (PRP they)) (VP (VBD set) (PP (IN about) (S (VP (VBG clearing) (NP (NP (DT the) (NN land)) (PP (IN for) (NP (NN agriculture))))))) (, ,) (S (VP (VBG setting) (NP (NN fire)) (PP (TO to) (NP (NP (JJ massive) (NNS tracts)) (PP (IN of) (NP (NN forest)))))))) (. .)))
Forests were cleared with fire.
( Forests ( ( were ( cleared ( with fire ) ) ) . ) )
(ROOT (S (NP (NNS Forests)) (VP (VBD were) (VP (VBN cleared) (PP (IN with) (NP (NN fire))))) (. .)))