Throw A Log On It
Still life with viburnum, sensitive fern and log.
When looking at our yards as a place to build habitat, we naturally look to plants, first. After all, the berries on plants feed birds, the pollen and nectar in flowers feed pollinators--plants are essential to the wildlife garden. But how do you set up conditions for long term success for your plants? How can you build soil that isn't in constant need of amendments?
One answer is to provide food for soil flora and microorganisms. One way of providing this food is to mulch beds so that soil moisture is moderated, and shelter is given to the surface of the soil--which invites those organisms to play. But another thing you can do is give these little, sometimes unappetizing critters a more "permanent" shelter structure--a hunk of dead tree.
Tree hunks decay at different rates depending on weather and the activity of plants, animals, insects and bacteria, to name a few. In addition, the species of tree itself will have an impact--hardwoods will take longer to decay, in general, than softwoods. And of course, if the dead hunk of tree is black locust--well, that might take a
The primary job of this hunk of wood is to be an insect house.
On the forest floor, decomposing logs may be a hazard to hikers, but they are vital to the overall diversity of life found in the forest. One-fifth of all woodland creatures live in them! That's a bunch of critters! Most of these are small or very small, and therefore not nearly as exciting as oh, say--a mountain lion. But the role these dead hunks of wood play is essential to habitat and it is easy to replicate this habitat in the home garden.
For instance, in the photo at right, this old piece of spruce tree marks a change in elevation between one part of a shrub/tree border and another. Behind the log the soil is about six inches higher than the front side of the log. When walking in the landscape, you would have to look hard to see this log--it is hidden by shrubs, trees and irises. Small holes from tiny beetles are all over it.
Dead log critters tilling the soil and adding "deposits."
This next photo shows soil directly beneath a log that has been in position for almost two years. If you look closely, you'll see a slug on the left and centipede near the top right. Notice how rich and crumbly it looks. Probably just a massive pile of insect poo, which my azaleas greatly appreciate! Logs suck in moisture when it is available and then release it slowly into the ground during drier spells. Think of it as a soaker hose on a timer. Which does not mean that you're going to want to litter your yard with a truck load of logs, but maybe you can see how a few might be helpful, especially if they go into place during the non-planting seasons, so they have reached a greater level of absorbency before drought season. The more decomposed/broken down they are, the spongier they get--making them even more effective as soil moisture moderators. They also excel at filling the bottom of raised beds--breaking down slowly, but in the meantime holding moisture for the gardens planted on top of them.
These spruce logs have been abused by pileated woodpeckers.
Old dead hunks of wood can become homes to small mammals like shrews and (even better) to toads and amphibians. I like to think of toads as slug-eating machines. Therefore, I am wildly hopeful that once I put in my toad-friendly water feature, my yard will benefit from many happy toads. (
*update, 8/2013--even without the water feature, the logs are helping. Finally have toads this year!
But I digress.
You can use logs to create terracing much like you would use garden boulders. The difference is that logs will need a bit of a trench so they can be partially buried, if the hunks are relatively small. After "heeling in" the log chunks, plant on the uphill side of the log. The logs will help trap water for your new plants while they get established.
A mixed log and rock terrace edge in a meadow planting.
Adding logs to the landscape can be an actual design feature. Or it might be a necessity, if you end up with huge chunks of dead tree. That was the case with us when neighbors on both sides took down spruce trees. In addition to all the spruce, we also took down a silver maple tree (not the strongest of trees) and replaced it with a sourwood. The maple was only a foot in diameter at the base when we took it down, but you'd be amazed (well, maybe you wouldn't!) how much log can be acquired from one tree! The maple was dealt with partly in the fire pit (ashes were composted) and partly through "installation" in the yard.
Having some logs within your landscape will definitely improve your songbird activity. Many of the creatures that like to consume logs are things that songbirds like to consume. I absolutely adore watching the wrens and song sparrow "work" a log for insects. As the bark loosens, they will sometimes disappear right under it as they poke around for juicy bits. If you love birds, you will definitely want to add some dead tree hunks to your habitat! Be sure to check the Smithsonian link in the resources for some excellent photos of some of the organisms that munch down on old dead hunks of wood.
Hard to tell this guy is hanging out in an old log, isn't it?
Logs are an almost essential addition to the landscape in a woodland garden, but meadows or border gardens can take advantage of them, as well. For a meadow, try getting hold of a long, twisty branch to lay near a birdbath or bird feeder on a post or hook. This will give your birds a foraging spot to catch insects that are after the seed hulls littering the area under the bird feeder, or a landing spot from which to enter The Bath. In a border garden, try using some small logs as edging. Either way, you will be supporting diversity in your home habitat in some surprising ways. So get out there and throw a log on your yard!