There has been a recent increase in both interest and activity regarding tree planting at old-field sites in Ontario. (In this book, “old fields” refer to abandoned fields or pastures that are no longer being managed for agriculture.) This is due, in part, to the need to mitigate the impacts of a changing climate by sequestering carbon in trees in the form of wood and wood products. Afforestation is defined as “the planting of trees on sites that were formerly used for agricultural production”. Although Ontario has a rich history of afforestation that dates back to the late 1800s, much knowledge and mentoring was lost through the 1990s during a decline in government-sponsored tree planting programs.