( ( ( ( ( A fungus ) , ) ( such ( as ( this mushroom ) ) ) ) , ) ( ( is ( ( a decomposer ) ( of ( dead plants ) ) ) ) . ) )
(ROOT (S (NP (NP (DT A) (NN fungus)) (, ,) (PP (JJ such) (IN as) (NP (DT this) (NN mushroom))) (, ,)) (VP (VBZ is) (NP (NP (DT a) (NN decomposer)) (PP (IN of) (NP (JJ dead) (NNS plants))))) (. .)))
A fungus , such as this mushroom , is a decomposer of dead plants .
(ROOT (S (NP (NP (DT A) (NN role)) (PP (IN of) (NP (NP (NNS mushrooms)) (PP (IN in) (NP (NNS ecosystems)))))) (VP (VBZ is) (VP (VBG breaking) (PRT (RP down)) (NP (JJ dead) (NN plant) (NN material)))) (. .)))