The Ontario government reports that 87% of land in Ontario is publicly owned, i.e., Crown Land. The Ontario Landowners Association has, for many years, interpreted this to mean that the remaining 13% was privately owned. However, this figure may be much smaller when we figure in other owners and other factors which affect private-ownership.
According to www.pellet.org/images/Forest_Facts.pdf, the 13% held by others is shared amongst First Nations lands (628 thousand hectares), the Federal government (85 thousand hectares), and private landowners (13.4 million hectares) so private ownership is still pretty close to 13%. (Total hectares in Ontario is 107.6 million hectares).
Not so bad until you consider that governments are working hard to “control” private property. Over the years we have had species at risk, wetlands designations, areas of naturally and scientific interest, and so on.
Now they have come up with the mother of all designations: Natural Heritage Systems (NHS). These areas are designated through Official Plans throughout Ontario. In the case of Ottawa, where I live, the NHS designations came into effect in November 2012 in Official Plan Amendment (OPA) 109. The designation covers significant swaths of rural private property. See, for example, the green areas on this map of West Ottawa http://documents.ottawa.ca/sites/documents.ottawa.ca/files/schedule_L3_west_en.pdf.
From what I can determine, the NHS seem to concentrate around forested areas. When by-laws such as the Site Alteration By-law are combined with the NHS, we have what appears to be an extensive tree cutting by-law.
If we assume that all privately-owned forested lands are now NHS areas we can calculate what percentage we have lost to government control. Lost in the sense that in NHS areas, you must seek permission from the municipality to do anything in these areas.
The Province of Ontario reports that 7,224, 445 hectares of forested land is privately owned. Subtract this from the 13.4 million hectares of land owned privately and we are left with 6,175,555 hectares or around 5.7%.
See https://www.sfmcanada.org/images/Publications/EN/Ontario_info_Provinces_and_territories_EN.pdf for more information on forested area in Ontario.