It is often said that the BLM is not managing their lands sustainably and they are “over-cutting”. Elsewhere in this blog we have explained how one determines the amount of timber that can be sustained over time. Using those concepts, is the BLM overcutting? The answer is, it depends. It depends on if the BLM is managing its land consistent with the assumptions made in doing the sustained yield calculation.
For example, if the sustained yield calculation was based on managing 2 million acres and was one billion board feet per year and for various reasons the BLM felt it could only manage 1.5 million acres and they still were selling one billion board feet then, yes, they would be overcutting IF all 2 million acres were established and maintained under the same assumptions as were made when doing the sustained yield calculation. If on the other hand, the 1.5 million acres contained a higher volume than the managed stand used in the sustained yield calculation, they would not be overcutting and could maintain a sale level of one billion board feet until that excess inventory was gone. Are you confused yet?
Let’s use an example. Using the process described in the previous blog, the BLM calculates that the average acre within the one billion board foot sustained yield calculation was based on growing a 21” tree in 60 years for an average volume per acre of 40,000 bf. If the 2 million acres within their land base consisted entirely of stands under 60 years old and were being managed in a manner that their volume per acre at 60 years was 40,000 bf, then if they continued to harvest one billion board feet per year when their land base was reduced by 25% then they would be overcutting. If the land base is reduced by 25%, the sustained yield would go down 25% to 750,000 bf if the potential of all acres is identical.
Now let’s assume that the 1.5 million acres the BLM is left with after removing 25% from the land base contained stands that were older than 60 and contained 80,000 bf/ac. This is way more than what is expected under the sustained yield scenario. In this case, every acre cut contains twice the volume of a sustained yield acre. The BLM would not be overcutting if they maintained a harvest of one billion board feet. They could actually harvest 1.5 billion BF for 60 years from those 1.5 million acres at which time they would have to reduce their harvest to 750,000 bf which is what the managed stands can sustain over time.
Another instance where they could harvest above their sustained yield level is if they aren’t managing their lands using the land management practices that were assumed to be used when doing the sustained yield calculation. For instance, they might not plant areas with the same genetic characteristic, might not apply fertilizer, might not control stocking or might not regenerate and plant new trees as assumed in the sustained yield calculation. Under these conditions, the lands would not be growing as anticipated and they could be over cutting.
The industry is worried that this might be the case as the BLM has not followed the management practices that were assumed when they did their sustained yield calculation 20 years ago. Since the NWFP was adopted, the BLM has not regenerated and planted new trees as anticipated but rather relied on thinning existing stands to produce their ASQ. While this has increased the standing inventory beyond what was anticipated, it has created a 20 year age gap that will affect future sustained yield calculations.
The BLM has never “over-cut” their lands as the vast majority of their stands contain way more volume than the sustained yield acre as in the example above. Claims that they are doing so are merely attempts to discredit the agency and deceive the general public and have no basis in reality. -Ross Mickey