Its a symbiotic relationship, we don't survive without them and they don't survive without animals that spread their seeds and provide the CO2. Life is interlinked in this way in a huge number of things we can't separate ourselves from nature both the impact we have had in changing the biodiversity and in the necessity of that biodiversity providing this diverse range of plants and animals. Its why its so heartbreaking we are wiping out species at a rate never seen before and causing a mass extinction event which might include us if we keep up at this increasing rate of damage.