( ( ( ( ( ( ( Cutting ( the roots ) ) ( that ( ( supply water ) ( makes ( ( the tree ) ( vulnerable ( to drought ) ) ) ) ) ) ) , ) and ) also ) ( to ( pests ( that ( attack ( water-stressed trees ) ) ) ) ) ) . )
(ROOT (S (S (VP (VBG Cutting) (NP (DT the) (NNS roots)) (SBAR (IN that) (S (NP (NN supply) (NN water)) (VP (VBZ makes) (S (NP (DT the) (NN tree)) (ADJP (JJ vulnerable) (PP (TO to) (NP (NN drought)))))))))) (, ,) (CC and) (ADVP (RB also)) (S (VP (TO to) (VP (VB pests) (S (NP (DT that)) (VP (VB attack) (NP (JJ water-stressed) (NNS trees))))))) (. .)))
Cutting the roots that supply water makes the tree vulnerable to drought, and also to pests that attack water-stressed trees.
(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)))))) (. .)))