How well do logged forests recover?

Photo credit to tlupic of flickr
Photo credit to tlupic on flickr

Logging  is one of the most widespread threats to tropical forests. It doesn’t seem to be disastrous for forest biodiversity, although that is somewhat unclear as I have discussed previously. However, it does reduce carbon storage because of the removal of trees – causing carbon emissions, which is bad – no matter what some people would prefer you to believe.

Even if you think climate change is green hype there are reasons to worry about logging.  The time given to logged foreststo recover is often not enough to allow timber species to recover properly. If this is widespread, it would put the long term sustainability of logging practices in the tropics in doubt.

Recovery of biodiversity, carbon, timber stocks and a whole host of other things are vital to work out how long forests should be left to recover between each logging period. Despite this there is actually relatively little data on recovery following logging, and this is particularly lacking from Africa.

To fill this gap researchers from France, Belgium, Central African Republic and Gabon looked at the recovery of a logged forest in Central Africa over more than 20 years. This involved setting up a logging experiment  in the forests near M’Biaki in the Central African Republic, which looks something like this. The area has been monitored for changes in biomass and timber stocks since logging took place in 1984 in forest that was unlogged, logged and logged and then trees thinned out during recovery to encourage growth.

Change in (a) aboveground biomass and (b) timber stock over time after logging. Figure taken from Gourlet-Fleury et al 2013.
Change in (a) aboveground biomass and (b) timber stock over time after logging. Figure taken from Gourlet-Fleury et al 2013.

Predictably logging forests sharply reduced their biomass and timber stock, with biomass reduced by about 30% and timber stock by 50%. More interestingly biomass then increased back to levels similar to undisturbed forests in  by 2011, while timber stock did not.

This is alarming because this forest was logged  much less intensively than those on other continents, but still did not recover its timber stocks. We should be worried by this. It means that even at the relatively low intensities of logging that happen in Central Africa, it might not be sustainable.

The authors’ argue that in order to make logging more sustainable the diameter at which trees are cut should be increased, whilst encouraging thinning to promote regrowth. I agree. However, we also need innovative solutions that go beyond those proposed already.

Reduced Impact Logging, which aims to reduce the amount of damage done to non-timber trees may help carbon stocks, but is less likely to aid timber stock recovery. A possible solution for tropical logging may be a combination of reduced logging techniques with planting of timber species which have been grown off site, in a similar way to that done by restoration projects. This could be lead by more researchers engaging with logging companies and encouraging projects to benefit sustainability of biodiversity and timber.

At the moment the problem of logging is similar to that of fisheries:  forests provide a resource that is difficult limit access to and is difficult to track once exploited. As well as improving logging practices it is vital that we improve governance, but if I knew how to do that I wouldn’t be sat here writing a blog for free.

We do need to make progress on this issue though, we can’t stick everything in protected areas – that smacks of green colonialism and people need to get resources in one way or another. Idealists may accuse those who work with logging companies of dining with the devil. Fair enough. But we’re not going to solve these problems by ignoring them.

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4 thoughts on “How well do logged forests recover?

  1. Even though most of these logged forests are re planted, they are deforested far to quick to have sustainable re growth.
    This is very profitable for these multi national organisations and I doubt it will be properly controlled until it is too late.
    I do a lot of research on this subject as it is of great personal interest to myself.
    I am a tree surgeon at http://www.westbeams.co.uk/ This is our company page. Please feel free to contact me for further information.
    oli

    1. This is a good point. But I think it all depends on where you are and what the intensity of logging is.

      In Africa I think a lot of it is relatively sustainable, but in SE Asia it is very far from this.

      What research do you do?

      I am currently working on an analysis of logged forests that hopefully should be done soonish. I will write more about it here when it’s done.

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