A measure to enhance tree preservation in Fairfax County was unanimously approved Feb. 11 by the Board of Supervisors, giving builders mathematical incentives to save existing trees rather than cutting them down during construction and replacing them with very young trees.
The measure, approved unanimously, will go into effect April 15.
When builders save existing trees, a “multiplier” will be used to compute the percentage of tree cover for which they are credited at a building site.
“We give a developer a multiplier of 1.5 to 2.5 on that area they preserve, and apply it towards their [total] tree cover percentage,” said Michael Knapp, Fairfax County’s director of urban forestry.
The measure encourages builders to save existing trees because they are rewarded with slightly lowered percentages of tree canopy overall, in exchange for higher quality trees, Knapp says.
“The county gets higher-quality vegetation, as opposed to what is left over by serendipity,” Knapp said.
<mh>Tree Canopy
<bt>Zoning and subdivision ordinances require builders to restore the tree canopy at a building site to 20 percent over 10 years in low density residential areas and less — about 15 percent — in middle or high density residential areas.
“But if a developer could come up with an engineering reason, they could clear cut as long as the trees were replaced,” Knapp said.
In effect, the “de facto tree covering percentage was cut from 20 percent to between nine and 12 percent” because of the county's interpretation of Virginia code, said Knapp.
“The tree cover requirements were so low that it took the pressure off the building community to really look at preserving existing tree cover. There was less of an incentive,” Knapp said.
In terms of “biomass,” young replacement trees with a minimum height of five feet and a caliper of about two and a half inches “don’t even come close” to the quality of existing trees, Knapp said.
<mh>More Building By-Right
<bt>When developers ask for higher density than what is allowed under existing zoning, they often negotiate by offering to plant more trees — a tradeoff known as a “proffer.”
“In proffered rezonings, we get a higher percentage of tree cover,” said Knapp.
“But a lot of our infill is being lost to by-right development,” meaning that on smaller parcels of land, builders conform to existing zoning rather than asking the county for more.
Then, the county has no opportunity to negotiate higher density for more trees, Knapp said.
“Trees do make Fairfax County a better place to live,” said Eleanor Quigley of Alexandria, one of two speakers who signed up to speak in favor of amendments to the county’s zoning and subdivision ordinances.
Supervisor Stuart Mendelsohn (R-Dranesville), co-chair of the Tree Preservation task force that helped draft the changes, said the absence of opposing speakers showed the measures had broad support.
“These are significant changes. These are not window dressing,” Mendelsohn said.
“What is this going to cost Harry Homebuilder?” asked Elaine McConnell (R-Springfield).
“Overall [there will be] a reduction in cost,” said Knapp, because the amendments will “reduce the convoluted nature of the process.”