( ( Food availability ) ( ( restricts ( wolf numbers ) ) . ) )
(ROOT (S (NP (NNP Food) (NN availability)) (VP (VBZ restricts) (NP (NN wolf) (NNS numbers))) (. .)))
Food availability restricts wolf numbers.
(ROOT (S (NP (NP (DT The) (NN amount)) (PP (IN of) (NP (NP (NN food)) (ADJP (JJ available) (PP (IN in) (NP (DT the) (NN area))))))) (ADVP (RB best)) (VP (VBZ determines) (NP (NP (DT the) (NN number)) (PP (IN of) (NP (NP (NNS wolves)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (VP (VB live) (PP (IN in) (NP (DT an) (NN area))))))))))) (. .)))