( ( Keystone species ) ( ( ( play ( crucial roles ) ) ( in ( ( maintaining ( ecological communities ) ) ( by ( ( affecting ( many ( other organisms ) ) ) ( within ( those ecosystems ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NN Keystone) (NNS species)) (VP (VBP play) (NP (JJ crucial) (NNS roles)) (PP (IN in) (S (VP (VBG maintaining) (NP (JJ ecological) (NNS communities)) (PP (IN by) (S (VP (VBG affecting) (NP (JJ many) (JJ other) (NNS organisms)) (PP (IN within) (NP (DT those) (NNS ecosystems)))))))))) (. .)))
Keystone species play crucial roles in maintaining ecological communities by affecting many other organisms within those ecosystems.
(ROOT (S (NP (NNP Beneficial) (NNS fungi)) (VP (VBP play) (NP (NP (DT a) (JJ crucial) (NN role)) (PP (IN in) (NP (NP (NN balance)) (PP (IN of) (NP (NNS ecosystems))))))) (. .)))
Beneficial fungi play a crucial role in balance of ecosystems.