( Water-use-efficiency ( ( ( ( was also ) greatly ) ( ( ( increased ( by ( the ( elevated ( CO 2 ) ) ) ) ) , ) ( thereby ( enabling ( ( the trees ) ( ( ( ( to better ) ( withstand ( ( extended periods ) ( of drought ) ) ) ) and ) ( to ( ( expand ( their ranges ) ) ( as ( ( the ( air 's ) ) ( CO ( 2 ( content rises ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NN Water-use-efficiency)) (VP (VBD was) (ADVP (RB also)) (ADVP (RB greatly)) (VP (VBN increased) (PP (IN by) (NP (DT the) (JJ elevated) (NNP CO) (CD 2))) (, ,) (S (ADVP (RB thereby)) (VP (VBG enabling) (S (NP (DT the) (NNS trees)) (VP (VP (TO to) (ADVP (RBR better)) (VP (VB withstand) (NP (NP (JJ extended) (NNS periods)) (PP (IN of) (NP (NN drought)))))) (CC and) (VP (TO to) (VP (VB expand) (NP (PRP$ their) (NNS ranges)) (PP (IN as) (NP (NP (DT the) (NN air) (POS 's)) (NNP CO) (CD 2) (NN content) (NNS rises))))))))))) (. .)))
Water-use-efficiency was also greatly increased by the elevated CO 2 , thereby enabling the trees to better withstand extended periods of drought and to expand their ranges as the air's CO 2 content rises.
(ROOT (S (SBAR (IN Because) (S (NP (NNS trees)) (VP (VBP add) (NP (NN water) (NN vapor)) (PP (TO to) (NP (NN air)))))) (, ,) (S (VP (VBG cutting) (PRT (RP down)) (NP (NNS forests)))) (VP (VBZ leads) (PP (TO to) (NP (NP (JJR longer) (NNS periods)) (PP (IN of) (NP (NN drought)))))) (. .)))