August 25, 2020 10:58 am Leave your thoughts
One of the projects I’m working on this summer is a sheep grazing pilot project. While grazing is sometimes used for brush control in other parts of the world, it doesn’t generally happen in Alberta. However, there isn’t a lot of data available to tell us why this is. So, we are trying to assess whether sheep grazing is an effective and practical way to control competition in young cut blocks in Weyerhaeuser’s forest management area.
As I outlined in an earlier post, competition is a major problem for regenerating cut blocks. Small conifer trees can be overtopped by other vegetation. As a result, the trees struggle to compete for light, water, and nutrients. This can increase tree mortality and decrease growth rates, which reduces regeneration success. Sheep grazing removes a lot of the overtopping vegetation, which may result in a longer-term reduction in competition for the regenerating trees.
This pilot project has 950 sheep turned out into cut blocks, overseen by shepherds and Ken Price’s world-class sheepdogs. Ken has two kinds of dogs: herding dogs and guard dogs. The guard dogs’ job is to keep the sheep and shepherds safe, while the herding dogs move the sheep and keep them grouped together.
|This is Roger. He is one of the guard dogs, but he’s really a gentle giant who likes being pet more than anything.|
|This is Little Sid. Sid is one of the Border Collies who herd the sheep.|
|This is Sue, who is also a Border Collie. Sue loves to herd sheep and is entirely single-minded about it.|
Shepherds are such an important part of this project. A big concern that foresters have about grazing is that the sheep may eat the crop trees. There’s no use in applying a competition control measure that kills crop trees, after all. But modern herding techniques may help protect crop trees from being damaged by the grazing process.
|Me and Sue.|
My role in this project is to manage all the data we collect on the cutblocks, before and after grazing. We are using three measurements to determine how well the grazing program is working:
- A tree damage grid survey. We are doing this survey to determine where in the cut block is stocked with conifers and deciduous trees, as well as to assess any damage done by the grazing treatment.
- A competition assessment grid survey. We are using the Comeau Competition Index I wrote about in my second blog post to assess the amount of light competition on our crop trees.
- A biomass collection. We are collecting all the above-ground vegetation in 50cm x 50cm square plots in order to estimate how much biomass is removed by the grazing treatment.
This project is ongoing, so we don’t have firm results just yet. Visually, there is a striking difference between an area before it is grazed and that same area afterwards. I’m looking forward to seeing what our data reveals.
|Before and after grazing.|