( ( A ( biogeochemical cycle ) ) ( ( shows ( ( the cycling ) ( of ( matter ( between ( ( ( ( abiotic and ) biotic ) components ) ( in ( an ecosystem ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT A) (JJ biogeochemical) (NN cycle)) (VP (VBZ shows) (NP (NP (DT the) (NN cycling)) (PP (IN of) (NP (NP (NN matter)) (PP (IN between) (NP (NP (ADJP (JJ abiotic) (CC and) (JJ biotic)) (NNS components)) (PP (IN in) (NP (DT an) (NN ecosystem))))))))) (. .)))
A biogeochemical cycle shows the cycling of matter between abiotic and biotic components in an ecosystem.
(ROOT (S (NP (NP (DT A) (JJ primary) (NN role)) (PP (IN of) (NP (NP (NNS decomposers)) (PP (IN in) (NP (DT an) (NN ecosystem)))))) (VP (VBZ is) (SBAR (IN that) (S (NP (PRP they)) (VP (VBZ cycle) (NP (NN matter)) (PP (IN by) (S (VP (VBG returning) (NP (NN carbon) (CC and) (JJ other) (NN matter)) (PP (TO to) (NP (DT the) (NN ecosystem)))))))))) (. .)))
A primary role of decomposers in an ecosystem is that they cycle matter by returning carbon and other matter to the ecosystem.