I would like to propose a gradual transition from landscaping our cities and neighborhoods from an eye pleasing point of view to a sustainable point of view.  Instead of planting exotic species of trees for pleasure, plant an apple tree which flowers beautifully AND gives back with fruit for humans and animals and mulch for any other plants growing below the canopy.  Other plants can benefit from the shade of an apple tree and also give back to this delicate ecological circle;  it is called a guild.  Guilds help us get the most return out of a small space which is PERFECT for urban sustainability efforts.  The most popular guild is "The Three Sisters" guild: corn, beans, and squash.  "Each of these plants support and benefits the others.  The beans draw nitrogen from the air and, via symbiotic bacteria, convert the nitrogran to plant-available form, boosting the growth of all three vegetables.  The cornstalks form a trellis for the bean vines to climb.  The rambling squash, with its broad leaves, forms a living parasol that densely covers the ground, inhibiting weeks and keeping the soil cool and moist." (Giai's Garden, Second Edition:  A guide to Home Scale Permaculture. Hemenway, 2009).  Imagine how many people in our communities could be fed just by using established guilds, creating new guilds, and using Permaculture methods in our urban landscaping.  Who wouldn't enjoy walking to class and being able to pick blueberries off a blueberry bush, mulberries off a mulberry tree, or a cucumber from a cucumber plant that's thriving in the part sun/shade of a crabapple tree?  We should all aim to leave the Earth a little better off than when we came into it and this is how I propose to make the Earth a little better for future generations.  Perhaps when my children get to college, they will be able to pick berries on their way to class, donate the bounty to area shelters, or expand on my vision and help other communities establish the same kind of sustainable / Permacultural way of living and interacting with their fellow man.