Good stewards care for them and use them well so long as time permits. This has implications for personal management of nutrition, exercise, sleep and general attention to personal health. Think of all your personal assets and consider how well you are cultivating, caring for, and preserving them, and think also of how you are using those assets in the service of others. Think as well of the natural environment that literally surrounds you on land, air, and sea. Your stewardship responsibility looks out, and up, and all around.
Sustainability is the word to keep in mind.
Since life itself is dependent on this environment, it must be used, but used with great care to assure that it will be there to sustain the life of future generations so long as God wills humans to inhabit the earth. No, there is a human responsibility for the preservation of plant and animal life too, but our faith tradition understands God's plan as providing plant and animal life for the enrichment of human life. Hence in caring for nature, humans care for themselves. Stewardship is a wonderful word that holds great potential for prompting, if not pushing us to work together to build an even more wonderful world.