( ( For ( ( long periods ) ( of drought ) ) ) ( it ( ( is ( necessary ( to ( store ( ( ( excessively large ) volumes ) ( of water ) ) ) ) ) ) . ) ) )
(ROOT (S (PP (IN For) (NP (NP (JJ long) (NNS periods)) (PP (IN of) (NP (NN drought))))) (NP (PRP it)) (VP (VBZ is) (ADJP (JJ necessary) (S (VP (TO to) (VP (VB store) (NP (NP (ADJP (RB excessively) (JJ large)) (NNS volumes)) (PP (IN of) (NP (NN water))))))))) (. .)))
For long periods of drought it is necessary to store excessively large volumes of water.
(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)))))) (. .)))