Map showing tree coverage loss 2000-2020

Interview with Bruce Ellingsen p1: What is a sustainable rate of consumption for forestry?

In respect to British Columbia’s old growth trees, “Most of what is left is in the difficult-to-access areas and the not so productive sites. Most of the best and easy to get is gone” – Bruce Ellingsen, one of the founders of the Cortes Community Forest Co-operative. 

In the first of two articles about current forestry practices, Ellingsen looks to dynamics in nature for indicators toward a more sustainable harvesting rate.

Polar Bears appear to have taking a sustainable number of ringed seals for thousands of years – Photo by Mario Hoppmann via NASA

A 2003 report from the Ministry of Forests states, “Only about 2% of B.C. has been permanently converted to agriculture, urban areas and other forms of development. That means B.C. has almost the same amount of forest as it did prior to European settlement.” 

43% of BC’s forests were said to be old growth, which it defined as between 120 to 140 years in the interior where fire is a frequent and natural occurrence and 250 years on the coast. 

This old document also states, “Due to B.C.’s relatively short history of logging, most logging still takes place in forests that have never been harvested, including older forests. This will change over time as more second growth (or previously harvested) trees reach an appropriate size for harvesting.” 

The yellow ring in the butts of these second growth logs is sapwood, which largely disappears as trees mature (See Quality Forestry always takes Time) – cropped photo courtesy Wilderness Committee

Landsat satellite data published by the University of Maryland (and reproduced at the top of this page), show that there has been alarming rate of loss of the forests on Vancouver Island and in the interior of British Columbia during just the past 20 years.  Less easily accessible forests in the north of the province, or in the difficult access Coastal and Rocky mountains areas, are relatively untouched. 

If you look at the above website it will give you a good, visual reminder of why our current management approach is not sustainable. 

The Ministry’s opinion is beginning to shift. Last year, the province’s Old Growth Technical Advisory Panel reported that less than 20% of the old growth remain. That’s less than half the amount reported only 18 years earlier. Many are suggesting it has a long way to go.

“Humans are managing our forests and future generations are going to be impacted by our choices. The historical record of our management, especially over the last century, is dismal. If we seriously want our forest ecosystems to be sustainable, then we’ve got to look to long-term dynamics in sustainable natural systems for indicators to guide our management.” said Bruce Ellingsen. 

Ellingsen says he initially got the idea of getting guidance from nature from a 1990 verbal report on a Nature of Things program about a 17-year study of the dynamics between Peregrine Falcons and Ancient Murrelets. Researchers concluded that the Peregrines were probably taking around 15 to 20% of the mean annual seabird population increase for their reproductive needs.

“That reflected a sustainable level of consumption or extraction that had been going on there for thousands of years. That got me looking for other studies of sustainable dynamics in natural systems to see if there was a similarity or not,” explained Ellingsen.

He discovered a similar predation rate between polar bears and ringed seals (95% of polar bear diet), after a visit to Churchill, Manitoba, in 2003. Studies by Dr Ian Sterling and colleagues, studying polar bears since the early 1970s, concluded that every year polar bears were consuming between 13% and 22% of the seal population.

“There’s another indicator from a sustainable dynamic that’s been going on for millennia, if not tens of thousands of years.” said Ellingsen.

Leaf cutter ants only take 13% to 20% of the vegetation around them – Photo by Eli Duke via Flickr (CC BY SA, 2.0 License)

A similar statistic was reported in a New York times article about Central America’s Leaf Cutter Ants. “Biologists believe some 15% of the leaf production of the tropical forest disappears down the nests of leaf cutter ants.” Leaf cutter ants have been around for 50 – 60 Million years, a strong example of a sustainable relationship.

Another report, by Dr. Tom Reimchen, U. Vic., mentions studies done for over 40 years by A.R.E. Sinclair of the population dynamics in the Serengeti which showed that the combined social and solitary cats take about 16% of the total prey biomass each year.

The only human example found comes from the Southern New Zealand rocky off shore islands where Maori’s, for over 700 years, have been harvesting about 18% of the young seabirds each year. “This has been going on for about 700 years and obviously you can start to say that’s a reasonably sustainable dynamic for a population that is reproducing annually,” said Ellingsen. 

“These examples of dynamics in long-term sustainable relationships, all landing in the narrow range of 15 – 20% of the annual incremental growth of a population, strongly suggest to me that we should be mimicking this approach when we set out to manage or forests.“

Saplings like these, in one of the Squirrel Cove cutblocks on Cortes Island, are not detected by Landsat satellite imagery – Photo by Roy L Hales

He added that forestry ecologists like Herb Hammond, of the Silva Forest Foundation, and Jerry Franklin, from the University of Washington, who have discussed sustainability for three decades, agree that not more than 25% of the mean annual increment (MAI) is “surplus” to the ecological function over the long term to maintain the system. So, removing a maximum of 15 – 20% of the MAI is a sound, conservation-based approach. Cortes Currents also contacted two other Cortesians involved in forestry, one of whom deferred to Ellingsen and the other has yet to reply. 

Mosaic will be unveiling its three-year plan for logging Cortes island on Thursday, January 27th, 2022. A company spokesman emailed that they might consider an interview after that.

Cortes Currents also contacted two other Cortesians involved in forestry, one of whom deferred to Ellingson and the other has yet to reply. 

(Click here for part 2 of the interview)

Top photo credit: Results from time-series analysis of Landsat images characterizing forest extent and change 2000-2020 – courtesy University of Maryland, Department of Geographical Sciences

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