( ( During ( periods ( of drought ) ) ) ( , ( ( be ( sure ( to ( ( water ( ( trees and ) shrubs ) ) thoroughly ) ) ) ) . ) ) )
(ROOT (S (PP (IN During) (NP (NP (NNS periods)) (PP (IN of) (NP (NN drought))))) (, ,) (VP (VB be) (ADJP (JJ sure) (S (VP (TO to) (VP (VB water) (NP (NNS trees) (CC and) (NNS shrubs)) (ADVP (RB thoroughly))))))) (. .)))
During periods of drought, be sure to water trees and shrubs thoroughly.
(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)))))) (. .)))