A wood or not a wood, that is the question

On the Twitter account of Groen (the Flemish Green Party), I found this message:

twitter groen boswijzer

Translated from Dutch:

More woods are disappearing in Flandres every year

The new wood barometer is available. In Flanders, more woods are being cleared than planted. Contrary to what Minister of Nature Schauvlieghe keeps claiming. Retweet this image if you want more woods and green in your neighborhood →

I recognize the controversy. I already had a post on this subject in the first year of this blog. Just to summarize: the Minister of Environment, Nature and Agriculture had a new tool for counting the wooded area using high resolution images taken from the air. In 2013 they published the first numbers after the base line measurement of 2011 and claimed an increase of 8,262 hectares. Bos+ (a NGO) has a competing measurement system based on the information of “official” licenses & subsidies and claimed that there was not much of a difference. Groen claimed that there was a decrease. In the end they all had it right, they just used different definitions and therefor came with different numbers.

The counting method of the Minister was a very objective one. It specifically defined a wood as:

  • a collection of trees
  • trees are higher than 3 meters
  • in an area of at least 0.5 hectares
  • a length to width ratio of at least 2.5
  • a cover of at least 50%.
  • .

Although this is the most accurate tool available, it was strongly criticized by green organizations. For example it also took into account trees in fallow land or trees along roads, railways,… Every collection of 3 meter high trees on any area of at least 0.5 hectares is counted. Whether it was officially subsidized or not, whether it was officially licensed or not. On the other hand, the Minister (not rightfully) claimed that this increase was indicative for a better forest policy and forgot to communicate the margin of error (it was bigger than the measured increase). If you want to read the complete story, just follow the link above.

The tweet also linked to De Afspraak (a talk show on the Flemish television) and when looking for more information about that episode, I found that they also recently made a quiz called “Wood or not”, based on this measuring tool of the Minister. In this quiz they compiled 8 images of landscapes and challenged people to guess whether the tool of the Minister would recognize these landscapes as being woods or not. Although I expected the most extreme examples, I couldn’t resist to take the quiz…

The first problem that arose was that the definition of a “wood” was not explained. The intention was probably that people had their own definition and compared this with the results of the tool used by the Minister. I knew the definition and also realized that it is not our average everyday-life definition for “wood”. So it was my intention to follow the definition throughout the quiz to see where I would get.

Second problem was that the images were pretty small and sometimes hard to decipher, making it difficult to assess the landscape just relying on the image and/or the description. Anyway, this is how I answered based on the definition and why:

  1. Is Antwerp Zoo a wood?
    boswijzer kwis vraag1

    The questioning is very suggestive to say the least. But I want to do the quiz based on the definition and on not a subjective view. There are many large trees in the Zoo, so I wouldn’t be surprised that some areas would fit that description. So when I have to answer on basis of the definition, then my answer would be: yes.

  2. This is the Ter Durmen park in Ghent. But is it also defined as a wood?
    boswijzer kwis vraag 2

    On the picture I see large patches of grass and some trees. If the rest is also like this, then my answer on basis of the definition would be: no.

  3. And what about the Park of Laken? A wood or not?
    boswijzer kwis vraag 3

    I see a lot of grass, a single tree and some lower trees. If the rest of the park also looks that way, my answer would definitely be: no.

  4. When the Ghelamco Arena was built, they also had to decide whether this fallow land – meanwhile transformed into a roundabout – was a wood or not. Did it get in the report?
    boswijzer kwis vraag 4

    This one is a bit puzzling. The photo shows a construction site in which the vegetation has been already cleared, but the description says that it was a fallow land before that. In Belgium, when an area of land is abandoned, over time trees will grow on it and if long enough, it is entirely possible that could fit the description (the system doesn’t differentiate between human planted trees or trees on fallow land). But in fact, with the information given in this quiz, the question is not answerable. It depends on how long that area was abandoned. Given the situation I gamble: yes, but it is only a guess.

  5. These greenhouses in Merksplas don’t look green, but plants are grown there. Is this reason enough to be called a wood?
    boswijzer kwis vraag 5

    If it were indeed plants that were grown in those greenhouses (and no trees) I would answer: no. My gut feeling says that this could be tricky. If this is somehow counted as being a wood, those who criticize the system would have a valid point and more quality control would be needed. With the information given and the definition what it should measure, I stick with: no.

  6. These trees grow on the Naples- and London Street in Antwerp. Is it enough to form a wood?
    boswijzer kwis vraag 6

    Seems rather large trees over a larger area, so I would answer: yes.

  7. Are you in a wood when you are playing a round of golf in the Limburg Golf & Country Club?
    boswijzer kwis vraag 7

    I see many collections of trees at this terrain, so I guess that the answer will be: yes

  8. And finally: Park Spoor Noord in Antwerp. It does not take very long anymore before you can sunbathe again at this lovely green park. But wooded area or not?
    boswijzer kwis vraag 8

    In only see some sparse trees. If the park was like that during the survey, according to the definition my answer would be a no-brainer: no.

All in all, it was not so easy, even if one knows the definition. The images were rather small, were covered for a large part with the words “ja” (yes) / “nee” (no) and one had insufficient information to make an assessment.

I seem to have all questions right, except question 5 (the question with the greenhouse). Probably the tool errs in this situation. But this is probably eassily solved with extra quality control and there aren’t that many greenhouses anyway, so I guess the effect would be negligible.

After finishing the quiz I got this message about my score:

boswijzer kwis resultaat

Translation from Dutch:

You know what you are talking about. And especially where Joke Schauvliege (the Minister) talks about.

Well, not exactly. I just knew which definition was used and therefor the answers were rather straight forward. Without the definition, I am sure that my score would be rather low. It was clear that the author of the quiz has a different definition and this showed in how the questions were constructed. For someone with this definition, the examples would be quite puzzling, which was probably the motive to create this quiz. I guess most people would have that feeling when they took the quiz without knowing which definition was used.

Although my daily definition will be close to that of the author of the quiz, I think the definition of the Minister makes sense. It is much more objective than the other methods of measuring woods and should in theory be better than what we have now (if remote sensing problems can be dealt with). It is also partly automated and better comparable with other measurements. It will of course have disadvantages too, like it doesn’t give any information about the quality of the wood (for example recreation), but Flanders being so densely populated, every area with large trees counts. Whether it is planted by humans, in a residential area or just growing in the wild.


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