Blue bunch wheatgrass has been used to stabilize slopes in The Rise subdivision here in Vernon. The goal was to do so in an environmentally-friendly manner, to compensate for irreplaceable habitat lost in the making of the subdivision. Here we are, 15 years later. The slope below was planted, just as you see it. Most parts of the slope lost their bunchgrass in the last two years. Here it is hanging on. Sort of.
Notice a few things, if you will. 1. Any missing bunchgrass plant has not been replaced by seeding. The environment doesn’t allow for it. 2. The stones on the soil surface are indicative of erosion during rain and snow melt. The level of soil has gone done a couple centimetres over the last decade. In other words, the angle of the slope is wrong. Grass can’t fix that. 3. Moss, which could protect the soil, is getting no purchase, perhaps because of that erosion. 4. Mule deer, blockaded from any access to wetlands and the valley floor, are trampling the slope, one of the only transportation corridors left to them. 5. Voles are rapidly eroding the land. Do you see their winter trails above? For simplicity’s sake, here are the ones I noticed quickly:
That’s a lot of digging. It is being accentuated by deer. Pretty much any spot not covered by grass above has provided a foothold for deer.
The cutting and the imprints remain. Compare the image above with one from last March. What a rapid decline!
And it’s a shame, because the intent was genuine, and regulations were followed at great expense and with good intent. Still, it remains a lesson: bunchgrass doesn’t stabilize slopes. Only a complex, living, interwoven grassland does that, on slopes that have stabilized at an appropriate angle.
Even the addition of one other species, arrow-leafed balsam root, would have helped:
Balsam root has long snaky roots that fill in the spaces between the deep basket-shaped fibrous root balls of bunchgrass. The combination of the two goes a long way to stabilizing the slopes. Bunch grass can’t do this on its own. It is not sod.