Complexity – a religion?

Opublicerat och troligen aldrig avsänt mail till den kanadensiske skogsforskarenChristian Messier, som i boken ”Managing forests for complexity” hyllar teoriens urfader CS Holling.  

Thank you for a long and interesting answer. So, complexity is a religion – at least you have a pope (Holling)! Then you perhaps need a devil’s advocate too? I am aspiring for that position in your church, and I do here provide some work samples of unconvenient questions:

  1. You say that a normalized traditionally managed forest is “a house without many of its key inhabitant – all the rare and demanding species are absent”. But, the Science says that rare species are of no significant importance for the ecosystem function. As someone said: ”It is the relatively very few common species that makes the world go around”. The same researcher continues: ”Few, common species provide the basic ecosystem services that are crucial for our survival”. Is he right or wrong? I do not know, but it is seems quite logic that rare species, few in number as they per definition are, can’t make any substantial difference for the ecosystem’s function. So, if the rare species are gone, what’s the fuzz? Who will miss them? Not the ecosystem. Some nature-loving specialist?
  2. Is the ongoing pine-beetle epidemic in Northwest Canada really a consequence of low resilience in your old lodgepole pine stands? The definition of resilience given in your book is ”the ability for an ecosystem to recover after a disturbance”. Do we know today whether the ecosystem will recover or not after the pine-beetle disturbance? An uneducated guess is that it will be a forest again, with all of a normal forests common functions and species. So, if I am right, even the “normalized” lodgepole stands you had before the attack were by definition resilient. In my simple opinion, you are more talking about “resistence”, which is quite similar to “risk management” – which always has been a necessity in all traditional silviculture. Don’t put all eggs in the same basket!
  3. You say that “a varied and complex system is more productive…”. Is that really a universal law? This question has been much debated in Swedish forestry, and as long as we are talking about stem-wood production, no one has found such a relation. On the contrary, even-aged stands with the best single tree-species give the highest yield! And I have recently read about grasslands: It has long been taken as a truth that a mix of species gives the highest grass production. But, now researchers have found that this is primarily a “sample-effect”. The more species you have on a plot, the higher probability that you have included the single best species for this specific plot. And, if you pick out this best-performer and grow it as a monoculture, you get a substantially higher production than the mix.



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