The purpose of landscaping and screening requirements is to improve certain set-back and yard areas, including off-street vehicular parking and open-lot sales and service areas, for all uses other than single-family, duplex, triplex or four-plex residential uses, and to aid in stabilizing the environment's ecological balance by contributing to the process of air purification, oxygen regeneration, ground water recharge and storm water runoff retardation, while at the same time aiding in noise, glare and heat abatement, and to protect and preserve the appearance, character and value of surrounding neighborhoods.