( ( ( ( Number and ) type ) ( of ( beneficial arthropods ) ) ) ( present . ) )
(ROOT (S (NP (NP (NN Number) (CC and) (NN type)) (PP (IN of) (NP (JJ beneficial) (NNS arthropods)))) (VP (VBP present)) (. .)))
Number and type of beneficial arthropods present.
(ROOT (S (NP (DT A) (-LRB- -LRB-) (NN n) (-RRB- -RRB-) (NN beneficial) (NN relationship)) (VP (VBZ exists) (SBAR (WHADVP (WRB when)) (S (NP (NP (DT a) (JJ certain) (NN type)) (PP (IN of) (NP (NP (NN tree) (POS 's)) (NNS roots)))) (VP (VBP need) (S (NP (DT a) (NN fungus)) (VP (VB present) (SBAR (IN in) (NN order) (S (VP (TO to) (VP (VB grow) (ADVP (RB normally)))))))))))) (. .)))
A(n) beneficial relationship exists when a certain type of tree’s roots need a fungus present in order to grow normally.