( He ( ( describes ( some ( of ( ( ( ( the ( most ( common systems ) ) ) ( ( through which ) ( elements ( flow globally ) ) ) ) , ) ( such ( as ( the ( carbon ( and ( nitrogen cycles ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBZ describes) (NP (NP (DT some)) (PP (IN of) (NP (NP (DT the) (RBS most) (JJ common) (NNS systems)) (SBAR (WHPP (IN through) (WHNP (WDT which))) (S (NP (NNS elements)) (VP (VBP flow) (ADVP (RB globally))))) (, ,) (PP (JJ such) (IN as) (NP (DT the) (NN carbon) (CC and) (NN nitrogen) (NNS cycles))))))) (. .)))
He describes some of the most common systems through which elements flow globally, such as the carbon and nitrogen cycles.
(ROOT (S (NP (NNP Carbon)) (VP (VBZ is) (NP (NP (DT the) (ADJP (RBS most) (VBN found)) (NN element)) (PP (IN in) (NP (VBG living) (NNS organisms))))) (. .)))