Decline in forest cover

By Razib Khan | August 24, 2010 12:29 pm

I’ve spent most of my life in relatively forested areas, and took forestry courses in secondary school (which is why I can still distinguish doug fir from spruce by looking at the needles). In my youth I even had friends who were loggers during the summer. But I haven’t taken a deep scientific interest in forests for a long time. So I decided to look at the Google public data set to get a sense of long term trends.

As you can see, there hasn’t been much of an aggregate decline in forests. How about the nations with a lot of forest cover?

I was surprised that the slopes didn’t have a stronger negative value. What about you? If this is your area of expertise, what’s going on? Are we trading climax ecosystems for second growth and lumber plantations? I was surprised that the USA had nearly as much forest cover as Canada, but I guess a lot of the Great White North is tundra.

Also, removing Russia to make the scale easier, and adding China and India, you can see the impact of the recent Chinese reforestation drive pretty clearly:

CATEGORIZED UNDER: Environment
MORE ABOUT: Environment, Forests
  • http://sep.stanford.edu/sep/jon/ Jon Claerbout

    It will get more exciting as the fossil fuels deplete over the coming decades.

  • Chris T

    The United States actually gained 50,000 sq. km since 1990 and China gained 400,000. Bet you won’t hear about that from environmentalists.

  • John Emerson

    The places you hear being talked about are Brazil, SE Asia (not graphed), and Indonesia.

    Environmentalists talk about N. American forests all the time, trying to keep them from being logged and loggers complain about environmentalists locking up the forests, so the US / Canada numbers aren’t so surprising.

    How is a clearcut classified? It’s not exactly a non-forest.

  • ChH

    I would think Environmentalists would be thrilled about logging. What better way to sequester carbon! Mature trees aren’t sequestering carbon any more – they’re about neutral. But if you cut it down and build something out of it, you sequester that carbon and leave room for more trees to grow to take new carbon out of the atmosphere.

    And then, if it’s time to demolish and/or throw away the thing you built, send the debris to a biomass-burning power station so electrical power can be generated from it instead of fossil fuels.

  • Sandgroper

    Malaysia is quite interesting for a comparison against Indonesia and Myanmar – an 8% reduction from 1990 to 2007, same as Papua New Guinea. Sabah and Sarawak have been quite heavily logged, but nothing compared to Indonesia with a 23% decrease and Myanmar with 20%.

    It’s also interesting to plot Australia against China. Australia has a major problem with soil salination due to clear felling of large areas of farmland, and a reforestation effort would help with that, but it has gone in the opposite direction to China. In absolute terms the lines actually cross in 1995.

    I think what we are seeing is that there has been a decline in the rates of logging and a shift away from clear felling in Western countries and a shift to renewable plantations in the past 20 years, at the expense of tropical hardwoods in SE Asia and Brazil, but that doesn’t jump out of the global data at you because of the negligible decline in the Russian Federation, which is huge in absolute terms and masks the detail in smaller countries, and the big increase in China.

    So when environmentalists talk about loss of tropical rain forest, that’s what they are referring to – pretty big reductions due to clear felling of tropical hardwoods, of the order of 20-25% in some SE Asian countries over the period, and about 10% in Brazil, which is big in absolute terms.

  • http://brianforwater.org Brian Schmidt

    ChH- you might consider doing some research into the effects of deforestation on CO2 emissions (hint – don’t forget the soil).

    As Razib implies, a graph of primary forest, or even native tree-dominated forest in tropical countries, would be very different from the aggregate trends he’s found.

    Go walk a rubber tree plantation in SE Asia – line after line of evenly spaced trees, ground cleared of plants and even of weeds, nothing but rubber trees. It replaced a jungle, but wouldn’t show up as a problem on these charts.

  • Sandgroper

    #6 And oil palm plantations.

  • Steve Gilmore

    There has been ongoing debate as to the accuracy of estimates regarding the “baseline” by which deforestation is measured, and past figures are frequently corrected as new surveys take advantage of better and more comprehensive data.

    Not sure where the world bank take’s it data from but the data collected and published in the FAO Tropical Forest Resource Assessment are viewed by many as the most consistent and appropriate country-by-country report of tropical deforestation, the only other significant global data set is the FAO Production Series that suffers from a lack of standardized definitions and inconsistencies in both classification and reporting.

    Check out tropical west Africa and Indonesia.

    The definition of deforestation varies too, but even with a definition around which consensus existed one would still have to contend with different measurement techniques and consequently different estimates. Even when examining modern measurements using remote sensing data you find conflicting estimates depending on resolution and sampling coverage.

    Likewise satellite imagery while providing striking visual evidence of land change often overlooks changes in forest ecosystem such as logging that takes places below the upper canopy.

    National deforestation estimates are frequently based on a survey, the results of which are dependent on the efficiency of the design; sample sizes, methodology etc. Regular and detailed census of deforested areas are rarely possible and while techniques such as adaptive cluster sampling raise the accuracy of national surveys the size of sampling area is frequently constrained by issues of cost.

    The comment above about China adding forest area is largely plantations where original forest used to stand. You find this in lots of African countries, where reported forest area takes into account commercial plantations that bear no relation to the pre-existing biome.

  • Andy Kerr

    Forest cover does not equal forest quality. Clearcutting an old-growth forest and replacing it with a timber plantation results in no net change in forest cover, but does result in a net loss of forest quality.

  • Don

    I am quite relieved that comments have fingered the evil environmentalists, who are of course the greatest threat to the future.

  • Chris T

    This can really be said for all activists, but focusing on the negative while ignoring the positive can lead to people thinking that a situation is much worse than it actually is. This can lead to overreactions that waste time and resources and possibly create even bigger problems.

  • waqas

    the time period you selected (from 1990 to 2007) is too short to draw any valid conclusions, plus it is the period when environmentalism became a political movement n gained mass support…n who can authenticate the russian figures?

  • Ronald Brak

    Who can authenticate the Russian figures? Well, for some reason, in the United States there are a vast number of satellite photos of Russia dating back over 50 years.

  • outeast

    ChH

    I would think Environmentalists would be thrilled about logging. What better way to sequester carbon!

    Don’t really want to get drawn into this, but your ‘Environmentalist’ is somewhat strawlike. Only a (vocal!) minority of ‘environmentalists’ are concerned above and beyond all else by the issue of carbon – it’s certainly only one reason that people want to conserve old forest (ecosystem preservation is a much bigger driver, as can be readily seen from the fact that forest preservation drives long predate mainstream awareness of AGW). Indeed, many of the scientists who are veering towards the AGW sceptic side of the field (Pielke jr, say) expressly argue that non-CC issues such as land use are more threatening to the environment than CC (not that I’m saying they are anti-logging, as I just don’t know).

    In any the extent to which lumber is an effective carbon sink is… debateable, let’s say. It’s only effective for as long as the wood takes to decay or be destroyed as waste, for obvious reasons; and in most contexts that’s not very long (decades at most, and often far less – disposable chopsticks and paper don’t last long). So that’s not really a very strong argument.

    That’s not to say there isn’t a debate to be had – indeed, such a debate is ongoing and the has been and it a ton of research into these issues. But…

  • Chris T

    “Indeed, many of the scientists who are veering towards the AGW sceptic side of the field (Pielke jr, say) ”

    I’ve been following Pielke Jr. and he has categorically not skeptical of the scientific basis for climate change. What he is is very critical of the way the science has been politicized. Quite a few scientific organizations or scientists have been making claims the science doesn’t support or acting as though science can compel specific political actions.

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This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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