The problem is trees are short-term (even the long-lived ones) and only a part of the solution because they are a part of the carbon cycle. We need to remove carbon from the carbon cycle.
Another part of the solution is pyrolysis of industrial plant waste into biochar/charcoal. This stable form of carbon can last thousands of years underground and does not need any fancy technology or equipment.
And grass, and bushes, and all things green that grow. The phytoplankton in the ocean actually process more CO2 than anything else on the planet. That's one reason why ocean warming is so concerning.
Tree planting has been the most popular nature-based tactic so far — to little success. A growing body of research and investigations has found that offsetting emissions with forestry projects has largely failed. The trees often don’t survive long enough to make a meaningful dent in atmospheric CO2, for example, and then there’s double counting when more than one group claims the carbon credits.
The neat thing is when a tree dies and starts releasing it again, the trees around it absorb it, and here's the best part: They plant new trees all on their own.
While trees are great and you have a point, we can't just put trees everywhere without consideration of native species. Much of the U.S. for example is prairie/grasslands that doesn't have a high tree density and the carbon is cycled much faster. Also of concern (not my concern but somebody's) is the property value of land used for trees instead of profit.
A acre of hemp regrown every year and a biochar retort could sequester far more carbon than an acre of forest over a given period and can be done on "wastelands". Biochar IMHO is the only carbon sequestration method that actually makes sense.