Diffusion phenomena

I spent about an hour in the garden yesterday evening. It was my desire to see some of the critters who were eating my cabbage plants.

While sitting there, it got me to thinking about a class of physical phenomena described by "diffusion equations".

Heat transfer is one of those problems*. Suppose you have a sheet of steel sitting in the sun and then you place an ice-cube on it. For the sake of simplicity let's say you placed the ice-cube somewhere near the middle.

Heat would migrate through the conductive, steel sheet toward the cold spot and proceed to melt the ice-cube.

The profile of the temperature would be very similar to the surface of an ice cream shake as you suck material out with a straw.

The reason sitting in the garden waiting for Peter Cottontail triggered those thoughts is that conventional wisdom is that population density of wildlife is analogous to heat transfer. I can keep disciplining varmints and they will keep flowing in.

I am my own worst enemy

I freely admit that many of my "management" decisions exacerbated my problems.

Going back to our steel sheet analogy. The ice-cube would melt more slowly if it was sitting on a sheet of plywood because wood is far less conductive than steel.

My gardens and orchards are "conductive" to varmints. The asparagus patch is weedy. I tolerate some "weeds" beneath the trees in my orchard. I have a motley planting of hazelnuts, raspberry bushes, rugosa rose and pawpaws. 

I also have "reservoirs". I have brush piles and woodchuck holes, foundations and standing buildings.

If harvesting a head of cabbage for every seed I plant were a necessity, I would burn the brush piles. I would gas**-and-plug the woodchuck holes, perhaps netting a woodchuck or bunny to roast for dinner in the process. I would obsessively mow the grass to 2" and herbicide or mulch beneath the orchard trees to eliminate cover.

But since I have neighbors who would not commit to the same level of control, it would not be enough. The pressure on the garden would be far lower but there would still be pressure.

The bunnies can be kept out with a short fence. The woodchucks, not so much. Stitching back to our analogy, the fence is like a slab of expanded polystyrene foam between the ice-cube and the steel sheet.

The upside, for me, is that I have a succulent pasture adjacent to the garden. If the garden is more work to get into than the pasture, they will (mostly) bypass the garden and content themselves with clover and ryegrass.

So I have ample opportunities to sit under the hazelnuts at the edge of my garden waiting for the critters. I keep a twenty-two page lecture in hand to persuade them to not come back.

*Diffusion is also seen in water (and crude oil) flow through soil and rocks, fertilizer distributing through soil, spread of species in new environments and so on.

**A common garden sprayer filled with cloudy ammonia is an effective way to clear burrows of critters. Stick the wand as far down the hole as you can reach and spray a goodly blast. If you are handy you can fabricate an extended wand.