Site Assessment
Before you decide exactly what plants to add to (or subtract from) the property you manage, it is most helpful to identify the condtions you will be asking those plants to live in. If you assess your site first, you can select plants that are capable of thriving there. While it is possible to keep a wide rane of plants alive (at least fora time), gardening for conservation means selecting plants that will thrive with minimal input.
I was impressed with the importance of observation when studying permaculture design, with the common wisdom in these circles being that you should observe a site for at least a year before making major changes. This rings especially true here in Northern Michigan, where our four distinct seasons bring drastically different conditions.
This doesn't mean you shouldn't do anything for a year! Supressing weeds, planting thoughtfully selected seeds, and watering are just a few things you can jump right in and do on any land after a single session of observation. Major changes that need more observation time would be things like installing a brick patio, planting trees, or regrading the garden.
If you haven't already been there a year, a great way to learn about the seasonal conditions of your property is to talk to your neighbors! In Traverse City, an immediate neighbor with an enviable garden can be especially helpful, but anyone who has lived nearby longer than you may have valuable observations to share. Keep in mind, neighboring properties don't always share properties; if you have to change elivation to talk toyour neighbor, they probably have slightly different conditions than you. Neighbors can help you learn about local soil conditions, areas prone to flood, wind patterns, and where snow is piled or pushed in the winter.
Keeping a site journal will help you remember plants, frost dates, and great ideas. Any notebook & pen will do, your garden log doesn't have to be pinterest worthy.
Light
Many factors influence how much light a plant will recieve. Before you delve into site specifics, take a moment to orient yourself here on the planet Earth in relationship to the sun. Here in Traverse City, we're practically sitting on the 45th parallel, which is the halfway point between the North Pole and the Equator. That means, in the summer we have an abundance of sunlight, which comes from directly overhead mid-day. In the winter, the sun is situated much further south, and stays close to the southern horizon from sunrise to sunset.
With this information, you can assess the annual fluxuation in light on your site, any time of year. Facing directly south, imagine the path of the sun in the middle of summer, from directly East (your left) to West (your right). Note any buildings, trees, or eves that would block light from reaching the ground during any point of the suns daily path. Nearby trees and buildings may provide partial or full shade. You will also want to consider the path of the sun in the spring and fall. During the beginning and end of the growing season, the sun will be shining from futher south, which will allow light to reach further into south-facing features, and cast longer shadows on the north side of buildings.
Even though plant growth grinds to a hault in the winter, you may also may even want to consider the sun's position near the winter solstice. If you have a garden area (especially near a thermal mass like concrete or a building) that recieves direct sunlight in the middle of winter, this place will be the first to thaw and the last to freeze. This could be a good area to experiment with range extension of plants native to southern Michigan.
Diminished sunlight in the early spring and late fall seems to limit plant growth as much as temperature during those seasons. Even though it may be warm and wet enough in November & April for plants that like "cool seasons", you won't see much plant growth during those times because there isn't enough light for much photosynthesis.
Temperature
The temperature in Traverse City's is moderated by it's situation in the landscape. Because Traverse City is at the base of a large bay (Grand Traverse Bay) and surrounds a decent sized lake (Boardman-Lake), our frost free growing season is 29 days longer than nearby Kalkaska. That's basically an extra month of prime growing time!
Temperatures can range quite a bit within Traverse City. Especially in the spring, it may be much cooler near Grand Traverse Bay as only a few blocks inland to the south. Our average annual temperature peaks at 80° in July, and plummits to 15° in February, and temperatures have been known to climb above 100°, and drop to lows below -30° (NOAA).
Soil
There are many tools we can use to assess the quality of our soil, which will help us select plants that will thrive on our site. For example, if you have very sandy soil like me, you can safely lean towards plants that like "well drained" soil, and avoid plants that "don't mind having wet feet".
Start your soil assessment by diging up a handful of soil, soil and adding a bit of water if it is dry. Does it stick together? If you can form it into a ribbon when you roll it, you've got some clay in your soil for sure. If it totally falls apart, it's mostly sand. If it sticks a bit but crumbles easily, you may have some of that mythical loam. Another DIY soil test is to add some to a jar with water. Shake it up and let it settle; the different soil components (sand, silt, clay, and organic matter) will self-seperate into visual layers in the jar!
I also recommend having your soil lab tested. I had my soil tested through McGough's, and was happy with with my service. Be advised, soil tests for gardens are often presented from a perspective of "What do we need to add to this soil to get it to grow the plants I want". When you are gardening for conservation, you may want to change the question to "Given these test results, what plant life is my soil best suited for?"
Urban Influences
When you garden or landscape in an incorporated area like Traverse City, make sure you consider these important factors.
Ordinances
The bulk of Traverse City's ordinances regarding landscaping apply only to properties with two or more dwellings. That means, individual homeowners are laregly free to plant as they prefer on their own properties. If they do apply to your property, Traverse City's landscaping ordinances larelgy aim to maintain some of the natural charachter of our region, such as requiring a certain number of trees per parking space.
While some municipalities have pretty ridiculous and prohibitive codes regarding landscaping, Traverse City seems to allow and even encourage thouthful vegetation besides lawn grass! The city has even recently planted echinacea in the road verge in Slabtown. So long as plants are maintained, don't interfere with traffic visibility, and stay clear of blocking sidewalks and fire hydrants, lawn grass is not your only landscaping option!
Utilities
We have both burried utility lines, and old-school "power lines" in the sky here in Traverse City.
Underground Utilities
In Michigan, you must call Miss Dig three business days before you begin an excavation project, which even includes digging a hole to plant a tree. You don't need official plans, permits, or to pay for this service. Simply call them with your address, and they'll mark all the underground utilities with color coded flags within a few days. You can still plant right over underground utility lines, you just need to know where they are so you can dig carefully by hand, and select appropritate plants. It's wise to make a map of where they mark, and be sure to call again if seasons have passed since your last flagging, because utility lines are subject to rearrangement.
Above Ground Utilities
Traverse City still has a good number of utility lines up in the sky. These lines run well within the range of many mature trees, so don't plant trees underneath that want to become towering giants.
Aesthetics
It is wise to have some consideration for your neighbors line of sight, when gardening with conservation in mind. Some balance may need to be struck between what nature wants, and what your neighbors want. For example, while it might be best for birds and bugs to leave seedheads standing all winter, this isn't appropriate in every landscape. Gardening for conservation in the city involves a little extra sweeping, trimming, and raking compared to managing habitat in a rural setting.