( ( Grow ( as ( the population ) ) ) ( grows . ) )
(ROOT (S (NP (NP (NNP Grow)) (PP (IN as) (NP (DT the) (NN population)))) (VP (VBZ grows)) (. .)))
Grow as the population grows.
(ROOT (S (SBAR (IN As) (S (NP (DT the) (NN population)) (VP (VBZ grows)))) (, ,) (NP (NP (NN competition)) (PP (IN for) (NP (NN food)))) (VP (VBZ grows)) (. .)))