I think an easier to understand way to look at it is that every square meter of forest is enough to offset 1 or 2 watts of carbon based energy consumption if we assume that the trees don't die and decay, no forest fires, etc. We know that's not enough to sustain a modern civilization because past civilizations were dependent on energy from wood and coulndn't sustain a much lower standard of living even with a much lower population density. By contrast solar can sustain on the order of 100 watts per square meter and can do it even in areas without enough rainfall for forests.
The world has a lot of land, though. Before humans came along, there were roughly 6 trillion trees in the world. Now there are about 3 trillion, mainly due to forests being cut down for agriculture, wood, etc. Getting back the other 3 trillion trees would sequester an additional 75 gigatons of CO2 per year using your figure of 25kg/tree/year. Human activity emits 45gt/year according to his article.
That's an equivalent of less than 200km in a compact car or 2kg of beef.
I believe it makes more sense to pick the low hanging fruit which is making transportation more efficient and reducing the impact of food production.