The Oaks of McHenry County : Oak Ecosystems – A Vanishing McHenry County Legacy
In December of 2007, the McHenry County Conservation District completed a two-year watershed study charting the distribution and change of oak dominated ecosystems county wide from 1837 to 2005. The project utilized four separate temporal map layers in a geographic information systems (GIS) format to produce oak coverage in 1837, 1872, 1939 and 2005.
The layers, based on the public land survey, the 1872 McHenry County Atlas, and 1939 and 2005 aerial photography showed the dramatic loss of oaks from 143,000 acres (36% of the county’s land base) at the time of settlement to 18,000 acres (4.5%) in 2005.
Even more dramatic was the individual mapping of every remaining oak stand one acre in size or larger. Of 2,888 remaining stands countywide, less than 200 were 25 acres in size or larger and only eight contained 100 acres of contiguous oak cover or more.
This data mapping showed not only where oak remnants were lost to tree removal, but also to discern where residential development has fragmented oak remnants beyond their ability to maintain themselves as functioning natural communities.
The stark realities associated with oak loss revealed by the study have spurred a remarkable series of efforts by local agencies and volunteers to arrest and reverse the decline.