To aid in the creation and updating of Fairfield's Big Tree Registry, the Forest Commission holds a "Biggest Tree Contest" each year challenging Fairfield residents to nominate significant trees throughout the city. Trees are judged based on height, circumference and average canopy area.
The commission recognized its first year's winners December 2002.
Records of the biggest trees are maintained for the different species with the winning trees verified by the Forest Commission.
Big Tree Registry
| Common Name | Cir^ | Height+ | Avg# | Score | Location | Year |
| Bur Oak | 251 | 106 | 96 | 381 | Polo Springs Court | 2003 |
| Shumard Oak | 224 | 130 | 88.5 | 376 | Port Union Road | 2005 |
| Cottonwood | 220 | 85 | 70 | 323 | Dixie Highway | 2005 |
| Sycamore | 198 | 80 | 88 | 300 | Happy Valley Court | 2002 |
| White Oak | 173 | 101 | 70 | 292 | Pleasant Avenue | 2003 |
| Silver Maple | 170 | 100 | 50 | 283 | Vinnedge | 2002 |
| White Ash | 169 | 98 | 55 | 281 | Celadon Avenue | 2003 |
| Blue Ash | 164 | 91 | 57 | 269 | Symmes Rd | 2002 |
| Chinkapin Oak | 188 | 67 | 44 | 266 | Resor Rd | 2002 |
| Green Ash | 129 | 100 | 70 | 247 | Tolleywood Dr. | 2002 |
| Shumard Oak | 134 | 82 | 67 | 233 | Wyoming | 2002 |
| Northern Red Oak | 131 | 82 | 72 | 231 | Symmes Road | 2004 |
| Catalpa | 153 | 65 | 46 | 230 | Milona | 2005 |
| American Elm | 136.5 | 56 | 86.5 | 214 | Bach Lane | 2004 |
| Black Walnut | 121 | 70 | 76 | 210 | Palm Springs | 2002 |
| Linden ** | 120 | 68 | 49 | 200 | Symmes Road | 2004 |
| Tulip Poplar | 91.5 | 80 | 43.5 | 182 | Hunter Road | 2003 |
| Box Elder | 88 | 70 | 67 | 175 | Christine Dr | 2002 |
| White Pine | 86 | 76 | 46.5 | 174 | Symmes Rd. | 2004 |
| Weeping Willow | 95 | 63 | 52 | 171 | Becker Dr. | 2003 |
| Osage Orange | 95 | 60 | 59 | 170 | Shady Lane | 2004 |
| Kentucky Coffee Tree | 81 | 75 | 31.5 | 164 | Shady Lane | 2004 |
| Bitternut Hickory | 91 | 60 | 46 | 163 | Blackburn Ave. | 2002 |
| Hard (Black) Maple | 87 | 61 | 53 | 161 | Murray | 2004 |
| Honey Locust | 69.5 | 72 | 66 | 158 | Genevieve Place | 2003 |
| Chinese Elm | 89 | 52 | 58 | 156 | Anthony Wayne Ave | 2002 |
| Thornless Honey Locust | 74 | 69 | 48 | 155 | Frieda Drive | 2004 |
| Colorado Blue Spruce | 75 | 62 | 24 | 143 | River Road | 2003 |
| Pin Oak | 72 | 59 | 43 | 142 | West Dalton | 2004 |
| Little Leaf Linden | 83 | 45 | 41 | 138 | Winton Road | 2005 |
| Norway Spruce | 69 | 60 | 31 | 137 | Winton Road | 2003 |
| Sweetgum | 73 | 55 | 37.5 | 137 | Corydale | 2004 |
| Pecan | 64 | 56 | 50 | 133 | Winton Road | 2003 |
| Pignut Hickory | 54 | 69 | 32.5 | 131 | Woodside Dr. | 2005 |
| Hackberry | 51 | 69 | 36.5 | 129 | Genevieve Place | 2003 |
| American Beech | 73 | 40 | 56 | 127 | Applewood | 2005 |
| River Birch | 40 | 75 | 43 | 126 | Twin Lakes Drive | 2003 |
| Staghorn Sumac | 70 | 44 | 32 | 122 | Freida Drive | 2005 |
| Eastern Red Cedar | 64 | 50 | 20 | 119 | Congress Hill Lane | 2002 |
| Corkscrew Willow | 61 | 48.5 | 31.5 | 117 | Ambassador Drive | 2003 |
| Buckeye | 46 | 48 | 37.5 | 103 | Resor Road | 2004 |
| Yellowwood | 41 | 49 | 50 | 103 | Celadon Avenue | 2003 |
| Shagbark Hickory | 45 | 44 | 50 | 102 | Williamsburg Way | 2002 |
| Common Apple | 57 | 32 | 42 | 100 | Rolling Hills Blvd | 2002 |
| Sugar Maple | 48 | 34.5 | 52 | 96 | Winton Road | 2003 |
| Pear | 49 | 35 | 40 | 94 | Woodridge | 2005 |
| Ginkgo | 35 | 41 | 31 | 84 | Ambassador Drive | 2003 |
| Magnolia | 36 | 25 | 42.5 | 72 | Ambassador Drive | 2002 |
| Redbud | 33 | 28 | 38 | 71 | Williamsburg Way | 2002 |
| Saucer Magnolia | 20 | 26 | 33.5 | 54 | Corydale | 2004 |
^ Circumference (inches)
+ Height (feet)
# Average Canopy Diameter (feet)