( Why ( ( pyramids ( of biomass ) ) ( are ( used ( over ( pyramids ( of numbers ) ) ) ) ) ) )
(ROOT (SBAR (WHADVP (WRB Why)) (S (NP (NP (NNS pyramids)) (PP (IN of) (NP (NNS biomass)))) (VP (VBP are) (VP (VBN used) (PP (IN over) (NP (NP (NNS pyramids)) (PP (IN of) (NP (NNS numbers))))))))))
Why pyramids of biomass are used over pyramids of numbers
(ROOT (S (NP (NNP Ecological) (NNS pyramids)) (VP (MD can) (VP (VB demonstrate) (NP (NP (DT the) (NN decrease)) (PP (IN in) (NP (NN energy) (, ,) (NNS biomass) (CC or) (NNS numbers)))) (PP (IN within) (NP (DT an) (NN ecosystem))))) (. .)))