Environmental undertakings in the Conservatives’ manifesto include putting in place stronger protections for our natural landscapes, launching a programme of pocket parks, ensuring public forests and woodland are kept in trust and providing free maps of all open-access green space.
But Ashbrook said while the manifesto sounds promising, "it relies on public funding which is shrinking fast".
"The continuing swingeing cuts to local authorities’ and national park authorities’ budgets mean that our fragile and vital landscapes, open spaces and public paths will suffer as never before."
She went on to criticise highway authorities for "farming out their work to profit-chasing contractors for whom our public paths are small beer" and of councils looking to commercialise open spaces such Clapham, Ealing and Chobham Commons.
"Public funding of our spaces and paths should be boosted, as an investment in our health and well-being."
The society has published a tool kit to help communities save their local spaces. It consists of three handbooks: How to win local green space through neighbourhood plans, Community assets and protecting open space; and Local green space designation.
They apply to England only and can be downloaded from the society's website.
It has also written to all English planning authorities calling on them to designate land as local green space through neighbourhood plans, rather than waiting to be asked to do so.