news-26 September 2023-written by:Marieke Karssen

In 2022, food forests were included separately in the national soil animal test for the first time. Originally, this test -like so many citizen science or citizen science tests- was designed for normal citizens and their backyards. And that is often a place where humans are busy taming nature or at least keeping it at a certain stage.

Why the worm is (probably) losing ground in food forests

Below ground level

Food forests are substantially different places. They are not mowed, not hoeed, not plowed and not fertilized. Moreover, they have only been explored for a few years.

Even in the NIOO-KNAW national soil animal day test, food forests have only been participating separately since last year and there, see image below, the food forest seemed less biodiverse than the backyard. Surely we want to put this message into perspective: in the backyard the earthworm won, in the food forests the spider.

Three major studies on food forests are underway. Two of them are already starting to come up with some results. The National Monitoring Program has just presented its first three-year report, and the citizen science project on our platform is also coming out with first three-year results by the end of this year.

What emerges in both surveys: both the variation in herb layer biodiversity (our biodiversity test) and earthworm presence (the soil diurnal test) form an equal curve: a big spurt upward at the beginning: lots of different flowers and herbs and lots of earthworms, and then a steady decline.

This is most likely due to two things: the increase of fungi in the soil and the slow but steady decrease in direct sunlight. Also, there are relatively many food forests on sandy soil and fewer worms live there anyway.

No one really knows yet, but the interesting thing is that both our outcomes and those of the National Monitoring Program seem to be going in the same direction. All the more important to keep researching right now!

In the infographic above about the 2022 results, you can now see that food forests had low biodiversity. So that may not be entirely true: they just had a bit few earthworms and (we think) the little spiders are not that easy to count and find.

So, when you measure this year: don't forget to keep looking for all forms of predators. Those are sometimes really tiny spiders, piss beds, or centipedes. The more of those animals you find, the stronger your ecosystem is. Because predators are only there when there is something for them to eat. We often can't see that food, but believe us: they wouldn't be there if the food wasn't there. Of course, earthworms are also an important indicator that your forest is doing well, but our plea here is that the earthworm is certainly not the only indicator of a healthy ecosystem.

Have fun. You have until Oct. 9 to do your research. So it should work out this year.

How can you participate if you have not yet registered your food forest on Food from the Woods?

Very simple: first create a free profile and create -also for free- your food forest project and within it at least one tree plot. How to do it? That's pretty self-explanatory or can be found in the field guide you can download on the food forest monitoring page. If you have questions, email Have you created your tree plot? Then read on below.

How do you do the soil animal test?

Take the field guide and go into your food forest. Find the tree plot you made or plan to make and, with the soil animal map in hand, spend at least fifteen minutes and no more than half an hour looking carefully for the soil animals you can find and write down what you see. Then log into your account, and go to your food forest project. Choose the same tree plot there and fill in what you found. It doesn't get any more complicated than that.