( ( Populations ( of organisms ) ) ( ( are ( ( kept ( to ( ( a ( habitat 's ) ) ( carrying capacity ) ) ) ) ( by ( factors ( that ( limit ( their growth ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NP (NNS Populations)) (PP (IN of) (NP (NNS organisms)))) (VP (VBP are) (VP (VBN kept) (PP (TO to) (NP (NP (DT a) (NN habitat) (POS 's)) (NN carrying) (NN capacity))) (PP (IN by) (NP (NP (NNS factors)) (SBAR (WHNP (WDT that)) (S (VP (VBP limit) (NP (PRP$ their) (NN growth))))))))) (. .)))
Populations of organisms are kept to a habitat's carrying capacity by factors that limit their growth.
(ROOT (S (NP (NNS Humans)) (VP (VBP are) (ADJP (JJ unique) (PP (IN in) (NP (PRP$ their) (NN ability) (S (VP (TO to) (VP (VB alter) (NP (PRP$ their) (NN environment)) (PP (IN with) (NP (NP (DT the) (JJ conscious) (NN purpose)) (PP (IN of) (NP (NP (JJ increasing) (VBG carrying) (NN capacity)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ acts) (PP (IN as) (NP (NP (DT a) (JJ limiting) (NN factor)) (PP (IN on) (NP (NP (NNS populations)) (PP (IN in) (NP (NN general))))))))))))))))))))) (. .)))