( ( Abstract ( Tropical ecosystems ) ) ( ( play ( ( a ( central role ) ) ( in ( the ( global ( carbon cycle ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Abstract) (NNP Tropical) (NNS ecosystems)) (VP (VBP play) (NP (NP (DT a) (JJ central) (NN role)) (PP (IN in) (NP (DT the) (JJ global) (NN carbon) (NN cycle))))) (. .)))
Abstract Tropical ecosystems play a central role in the global carbon cycle.
(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.