Cross-Vanes and Willow-Staking, Part 2

When we got to the site on our first day, Mike, our collaborator from UCC, was already sharpening his chainsaw on the tailgate of his pickup. Our first couple of days would be spent cutting willow branches form willow trees along the banks of the creeks. The basic idea behind willow-staking is that if you harvest and prepare the stakes correctly, you can hammer three-foot-long sections of willow branch into the bank of a creek and they will bud and turn into trees. The “new” trees spread their roots throughout the soil and hold the soil in place. This is a simple and effective long-term solution to soil erosion. And very cheap, too.

So, Mike, his jindo, my crew and I set off into Rodeo Creek cutting a few straight limbs from most willows that could afford it, hauling the limbs up the bank, and dragging them to our staging area by the trucks. We then cut branches with diameters of 3 inches or more into three-foot-long stakes – each with a 45-degree cut at the bottom. After about three days of soaking in water, the willow would be ready for staking. In the meantime, we started working on the cross-vanes.

Placed directly in the creek, cross-vanes are V-like structures that prevent soil erosion by reducing stress on the banks. You situate the bottom of the V, the lowest point of the structure, in the middle of the creek. The tops of the V you spread out downstream to the banks at inclines of 2-7%. As water flows over the cross-vane, it loses energy and velocity, which, in addition to reducing the cutting power of the creek, encourages sediment deposition. When water hits the cross-vane near each bank, it curls back and is forced to pass the cross-vane in the center of the creek; as the water hits the structure and curls back, it drops sediment, preserving the bank.

Normally, cross-vanes are made out of stones; however, with no stones available, we constructed ours out of the small branches and twigs left over from our willow-stake harvesting. Mike chose a spot on Rodeo Creek’s tributary where, due to the steep grade, the water picked up greater velocity. What originally was a nice hike to the site became many arduous treks, since it took numerous tarp-loads to transport all of our materials. We began each cross-vane by establishing a frame that consisted of two rows of closely-placed wood stakes. Next, we gathered the willow twigs into bunches, which we laid in between the two rows of stakes. We locked the branches and twigs into place by crossing the alternating stakes. Each structure took about an hour and a half to construct. Since steeper grades means faster flowing water, we placed cross-vanes closer together in these higher-energy portions of the creek to better reduce the water’s cutting power. When we returned for our second day of building the structures, we already saw small effects by our first batch of cross-vanes: the pools in between the cross-vanes were increasing in size. Newts use pools to spawn, and, yes, we noticed a couple doing just that!

Some of our soaking willow stakes were already budding when we returned to them three days later. If you look closely at a tree branch, you’ll see little nodes all up and down it. These are points where new limbs can branch out. When you cut off the top of the branch, as we had done and as is done in pruning, energy and nutrients get redirected to the nodes. What we saw on our stakes were leafy green bulges at each node, which meant the stakes were already shooting out new branches. They were on their way to becoming new trees.

We hauled our five hundred or so stakes back down to Rodeo Creek and began hammering them into the banks using sledges and single-jacks. We spaced them about a yard or so apart in sections Mike designated using flags. The 45-degree cut in the stakes helped us get them into the ground, but some still split under the pounding sledges, unfortunately. It took about two days total to plant the willow-stakes.

There are several great benefits to cross-vane construction and willow-staking besides their ecological and economic effectiveness. We harvested the materials from a locally native plant and used nearly of what we took. What branches we didn’t use we left to decompose back into the same soil from which they grew. The materials came from the soil and were produced directly by the sun’s energy, and they were transported by human muscle; therefore, both production and transportation of the materials were local and sustainable, with no waste. Additionally, the cross-vanes and willow-stakes suited the landscape – they fit in. Not only were they not visually oppressive, they were actually aesthetically pleasing. The cross-vanes, especially, looked like a piece by the artist Andy Goldsworthy.

The project made us better workers and a better crew. And it confirmed a view that I’ve developed and held since my year working with Oakland’s youth, namely, that shared, hard work that taps into the emotional, physical, and creative power of each individual and that produces good, tangible results is the best strengthener and nurturer of community bonds.