( ( ( ( Models ( of ( carbon flux ) ) ) ( in ( ( tropical ecosystems ) ( with emphasis ) ) ) ) ( on ( ( the role ) ( in ( the ( global ( carbon cycle ) ) ) ) ) ) ) . )
(ROOT (NP (NP (NNS Models)) (PP (IN of) (NP (NN carbon) (NN flux))) (PP (IN in) (NP (NP (JJ tropical) (NNS ecosystems)) (PP (IN with) (NP (NN emphasis))))) (PP (IN on) (NP (NP (DT the) (NN role)) (PP (IN in) (NP (DT the) (JJ global) (NN carbon) (NN cycle))))) (. .)))
Models of carbon flux in tropical ecosystems with emphasis on the 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.