Lookin’ Out My Backdoor

Land use and development is something that occupies my mind on an almost daily basis. How am I using space? How are we as a society using this or that space? How can we do it better? As a species we have a tremendous impact on the natural world around us, and to disregard how we use the land seems irresponsible. With that in mind, I’m going to talk about the place we have been living for the last five-ish years, and what it was like when we got here.

  The facts

We live in Livonia, a suburb outside of Detroit, on a corner lot of about ⅓ of an acre. We have a two story house, a two and a half car garage, and a small shed. As of 2011, when I moved in, the total lot area could be broken down as follows: 30% impervious surface, 61.5% lawn, and 8.5% garden/other, with 31.5% canopy cover. Over the last five years I have had one large tree and a couple small ones (less than 10’) removed, expanded part of the patio and removed a different part, put in a 6’x8’ greenhouse, converted a sizeable lawn area to garden space, and changed the plant communities in the existing gardens. The total lot area can now be broken down as: 30.5% impervious surface, 51% lawn, and 18.5% garden/other, with only 23% canopy cover.

But what does it mean?

Some (potentially) new words, and lots of numbers. Let’s define some things so we’re on the same page. Impervious surface: any surface that will not absorb rainwater; examples include the roof of a building, concrete and asphalt, really hard packed clay, etc. Lawn: any area of non-native grass that is regularly mown to maintain a low height. Garden/other includes any areas I’ve planted with flowers or vegetables, as well as sections where I dumped a bunch of stone and then pretty much disregarded, as well as the pond area I put in. Canopy cover: any area where a raindrop is most likely to hit a tree leaf on its way to the ground; this can overlap with other surfaces. I consider these different surface types to be important because they affect how usable the space is by wildlife, and how rainwater moves on the land, which in turn affect how well the ecology of a place can perform services that humans find valuable. For example, the more water that can be absorbed by the soil during a rainstorm, the less demand that space puts on the stormwater infrastructure; or, the more insects that can use a space for egg-laying or as a food source the more songbirds can survive in the area for people to enjoy. I have two main goals for the land I have influence over: hold water and provide wildlife habitat.

Water

Pre-human occupation, a collection of raindrops would typically hit some vegetative matter on their way to the ground. In a forest area they would hit tree leaves, in a field it would be tall grasses and wildflowers. The plant material would get more and more wet until the surface couldn’t hold anymore water, then any successive drops would drip off or roll down and make their way to the ground. Once on the ground the water droplets would seep into the soil, following the paths of plant roots or tunnels created by animals large and small (like microscopic small). The soil absorbs water, more and more until all the pore spaces are full, at which point no more water can get into the ground. Any water that hits after that point flows downhill over the surface until it either finds some dry dirt, evaporates or reaches a water body. The water that’s in the soil either gets absorbed by a plant and used to do plant things, evaporates as the soil dries out (not much leaving that way), or slowly percolates down to the water table where it joins the existing groundwater. The groundwater flows quite slowly in one direction or another based on pressures from various things, and eventually finds a spot where the land surface gets low enough for the water to slip out, which is typically into a stream or river, sometimes a lake. That’s the gist; started in the sky, hit some stuff, ran on or in the ground until it eventually found it’s water droplet brothers and sisters in a river or lake.

Now what happens in urban environments is that rather than hitting vegetation on the way down, raindrops more often hit either an impervious surface or a lawn. When it hits an impervious surface the water will quickly move down hill until it finds a storm drain. Water that hits lawn will at first seep into the soil, following the root system of the grass, but lawn grass roots aren’t very deep, and there are far fewer animals, large or small, that can survive in a lawn, so there’s fewer tunnels as well. The water can’t get very far into the soil, and there are fewer pore spaces so the soil can’t hold as much water as it would otherwise. After the soil is full any more water that comes down heads downhill as per usual until it makes its way to storm drain or directly into a water body. Once in the storm system water is quickly directed to the nearest water body. This results in increased flashiness of rivers, meaning water levels go up really fast when it rains and drop back down really fast when it stops. Flashiness is bad for the wildlife that live in and near the river, as well as the people living nearby. Additionally, as water moves over impervious surfaces it picks up all manner of crud that’s on the ground, transporting it the river. It’s a bad deal.

It feels like I’m way off topic here, but it’s important to me that others understand why I’m trying to do what I do with my land. To look at it without the proper background information it may just seem like I’m doing stuff haphazardly, but it all has intention and scientifically based motivation. I want to hold water on land, because it delays the rate at which stormwater is discharged into the waterways. I can’t really reduce the amount of impervious surface I have (I like having a roof over my head), but I can change the direction in which some of the water flows when it hits. I have two downspouts now that are directed into garden beds, which will absorb more of the water than when they were dumping onto the lawn. I put a pond in next to my garage to catch some of the water coming off. The pond holds that until I need to water my tomatoes, when I’ll dip a 5 gallon bucket in there and pull some out. By replacing my lawn with garden beds full of deep rooted plants I’m increasing the surface area of soil that can absorb water to a farther depth. I’m not holding as much water as a forest, but I’m moving in that direction.

Wildlife

Pre-human occupation, wildlife had full reign over all the space. This first paragraph about wildlife is way shorter than the first paragraph about water.

Now, in urban environments people are around, taking up a bunch of space, pushing out the locals. It’s a bad deal. I like having butterflies and bees and grasshoppers and songbirds and seed-eating rodents and snakes and frogs and hawks and flower flies and foxes and rabbits and turtles and ground hogs and predacious diving beetles and crab spiders around. There’s room for all of us if we make room for them, so I’m trying to do that.

When we first moved into this place in 2011 the garden beds had been untended for a while, so were overgrown, but the stuff that had been planted there was all “pretty flowers”. It was a typical american garden, but the problem with a typical american garden is that most of the plants aren’t from America, let alone Michigan (in my case), but were instead from predominantly Europe, and a little from Asia. “So what?” So, my local bugs don’t eat those plants. “Good.” Bad. If the plants can’t support the insect community then there’s no insect community to support the songbirds or the frogs or the predacious diving beetles. And if the frog or songbird populations are suppressed then the insects that don’t eat plants, like mosquitoes, can get out of control. It’s called a food web, and it’s really complex, and it always always always starts with plants. The native flora has co-evolved with the native fauna, and the community as a whole is healthiest when they can all work together like they’ve been doing for the last ten thousand years or so. My non-vegetable garden space is devoted almost exclusively to native plants. There are a few shrubs that were planted before I showed I up, and some of the old stuff has stuck around tenaciously, but for the most part I have native wildflowers that are supporting their own little community in my yard.

My yard is barely a blip on the radar of the local wildlife and watershed, but if I can hold that little bit more water, or provide that little extra food source, then at least I’m doing something. And if one other person sees what I’m doing, and understands why, then maybe they’ll do it too, and now we’ve doubled the impact. Snowball.

This was really long-winded, and I’m sorry for that, but now you have some idea of where our yard was, where it is now, and why I’m moving it in that direction. This post is really meant to provide context for future yard and garden posts, so keep an eye out for those, that way all your time reading this one wasn’t wasted.
Disclaimer

I know I can sound kind of condescending when I’m giving definitions and stuff like that, but it’s just because I want to be sure we’re all on the same page. Check out my post “They’re Only Words” for more on this.