More than 800 people have signed a petition opposing a link road from Hartford to Godmanchester.
The Wildlife Trust raised concerns about proposals for a new route between Hartford Road and the A14 junction at Godmanchester, a potential scheme included in Cambridgeshire County Council's Long Term Transport Strategy.
The road, designed to improve access to a 3,750-home development at RAF Wyton, would either go through the trust's Cow Lane Nature Reserve or through Godmanchester East Side Common, a Site of Special Scientific Interest (SSSI).
A six-week consultation about the strategy, which includes a new A141 to relieve pressure to the north of Huntingdon, extension to the busway routes, cycle and walking route and an upgraded A428, is being launched by the county tomorrow (Thursday).
The trust, which started a petition two weeks ago, said it has already received more than 800 signatures.
A spokesman said: "Those who have responded feel as strongly as we do that the impact on local wildlife of a road through this sensitive stretch of the Ouse Valley would be unacceptable.
"We would encourage all those who care about local wildlife to support our campaign against this road plan - if we can make it to 1,000 people united against this proposal it would make a strong statement to Cambridgeshire County Council that they need to go back to the drawing board on this one."
Dearbhla Lawson, head of transport and infrastructure policy and funding at CCC, said: "The economy of Cambridgeshire is vital to the national economy. Therefore, an effective, sustainable transport network is vital for the prosperity of Cambridgeshire and the UK.
"The strategy, as part of the Local Transport Plan, sets out the key transport requirements needed to enhance accessibility, facilitate growth and the county's continued economic prosperity. As well as improvements to rail, bus, walking and cycling, a key ambition is to improve accessibility on the strategic network and address constraints on the A14, A428, A10 and A47."
INFORMATION: To sign the petition, visit www.wildlifebcn.org/godmanchester-petition.
The first exhibition takes place tomorrow at the Civic Suite at Pathfinder House, Huntingdon, 4pm-6.30pm, with another on June 18 at Huntingdon Sainsbury's 3pm-7pm and a final one at Godmanchester Community Primary School, in Park Lane, 3pm to 6.30pm.