INBREEDING orchids could be saved by a visionary new masterplan for Oxford's most threatened green space.

The Vision for the Lye Valley aims to join up conservation efforts on the parts of the nature reserve under different ownership.

That includes reconnecting two shrinking populations of Marsh helleborine orchids on the north fen and south fen, currently separated by an uninhabitable dry zone.

These orchids, which are nationally scarce, used to flourish across the whole of the Lye Valley when it was covered by lime-rich wetland, but over the years parts of the wetland have been taken over by trees which dry the soil and block out the sun.

To make its life even more difficult the Marsh helleborine is only populated by hoverflies, and the hundreds of metres now separating the two isolated populations in Lye Valley is too far for a tiny hoverfly to travel.

To try and help the orchids and the dozens of other rare flowers and insects on the reserve, the Friends of Lye Valley group want to lop down some of these trees.

But in order to do that, the group will need permission from the land owners – including the Churchill hospital.

Group founder and ecologist Dr Judy Webb said: "This is something people get very hot under the collar about: people like trees and they don't realise trees can be weeds.

"But trees will kill the short flowers because they are thugs: they take all the water and light and create shade."

The Friends of Lye Valley have been chopping down trees to conserve in the north fen for years because they have permission from the landowner – Oxford City Council.

But other parts of the valley, further south, are owned by six neighbouring properties and even Oxford University Hospitals Trust, which owns the Churchill.

The group hope The Vision for the Lye Valley will present a comprehensive argument for why they need to cut down trees, and get all landowners on board.

Hospitals spokesman Roy Probert said: "We’d be happy for conservation work to be carried out on our land, and our estates department would be willing to talk to the Friends of Lye Valley nature reserve about what this entails."

Dr Webb said the vision project had been prompted by a slew of planning applications in recent years to build houses on the green spaces around the Lye Valley which, even though they are not in the nature reserve itself, are in its rainwater catchment zone which keeps the wetland wet.

She said: "We felt we were constantly reeling from one planning application or another and we realised 'hang on - we need a joined-up plan for protecting the rainwater catchment for the valley'."

The group hope their finished vision can be adopted into Oxford City Council's next Local Plan for development and become official planning regulation.

They also hope having a coherent vision will held them apply for grant funding.

Dr Webb added: "Unless there is some overarching agreement from landowners, we will keep getting hundreds of planning applications for the bits around the valley.

"Either we make a special case for protecting these most important areas or we give up and go home."