NOVA SCOTIA REPORT:
Crop Tree Pruning
by Alan O’Brien

One of the newer silviculture treatments in Nova Scotia is crop tree pruning. This operation involves removing the lower limbs/branches from the bole/trunk of the selected crop tree. Manual or motorized saws can be used. This is a quality or value added treatment, which promotes growth of clear timber on selected trees. The end result at harvest would hopefully be a veneer product.

The pre- treatment stand qualifying standards are a 8m height minimum and greater than 125 of the prospective pruning species per hectare. The prospective pruning species include two conifers (eastern white pine and red pine) and five deciduous species (sugar maple, northern red oak, yellow birch, white birch and white ash). There is interestingly enough no maximum age or height restrictions set down by the provincial department of Natural Resources.

The post treatment stands are to contain less than 125 trees per hectare of the previously mentioned selected species, pruned to a height of 5m. The same area can be treated at ten-year intervals if enough of the prospective species remain in the stand. In theory a fully stocked pure white pine could be pruned every ten years for two centuries depending on mortality and densities. Most naturally occurring mix wood stands would not present an opportunity for this many interventions due to the lack of selected species. Sugar maple form pure stands in NS and are long-life trees. These stands would also present the opportunity for many pruning interventions.

The trees being selected for pruning need good form (straight bole), must be free of natural defects, and be located in a free to grow location. The persons carrying out the pruning need to be able to discern the different tree species in all seasons. Hence oak gets pruned and aspen does not. The prospective trees to be pruned should be the trees with the smallest limbs and fewest.

When pruning in young white pine stands (8-10 m) it is more ergonomic to prune numerous stems in close proximity. Space and range of motion is increased as limbs are removed from trees.
This silviculture treatment is a fairly easy sell to private woodlot owners with little disturbance to the stand being treated. Their only complaint was the number of trees that were pruned, since they would have liked more treated.