Kernohan said he was not against more pitches being built, but suggested a brownfield site would be more suitable for redevelopment.
He said Burlish Meadows was an acid grassland, a rare habitat in Worcestershire.
"There are some scarce species that you don't get in other areas in the county," he said. "One butterfly, the white letter hairstreak, occurs here, and it's one of the few places I know in Worcestershire where it occurs.
"There's a rare plant here called tower mustard that only occurs in less than 30 sites across the whole of Britain.
"To lose such biodiversity would be be terrible."
Harriers' plans include four full-size pitches, three of which would be artificial, and two junior pitches.
Owner Richard Lane said the new pitches would have a "lasting impact" on the community.
"Every day, our academy and foundation coaches see the positive difference football can make through coaching, education and our work across the community," he said.
"This proposal would allow us to build on that for many years to come."
