A mature forest has 100 trees per acre. They're doing 40 per square meter! This is certainly kickstarting tree growth, but you end up with a thicket instead of a mature forest.
I do not have the expertise to validate this claim. But I don't think that they're suggesting that in 10 years there will still be 4 trees per square meter, or even one per square meter.
http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/liriode...
Where did you see this? I see
> three to five saplings per square meter
and
> 300 trees of 42 species in a 93-square-meter plot
I wouldn't nitpick but it's an order of magnitude.
Still, there are 4000+ square meters to an acre. That remains two orders of magnitude larger than a mature forest should have.
In fact, 100 trees per acre is the minimum to be classified as a forest in a particular program, and that's in Southern California, which is especially sparse land for trees. http://mountainsfoundation.org/uploads/media_items/landowner...