Neal will tell the Saving Your Service conference that the £6.2bn of cuts and 22 bills unveiled by the Queen signposted "challenging times ahead".
The CABE head of public space, strategy and design said: "Commentators suggest we are moving from an age of plenty to one of austerity. Many park managers would probably claim this so-called age of plenty passed them by," he told Horticulture Week on the eve of the event, hosted by GreenSpace on 8 June.
"As a non-statutory service, with little hope of ring-fenced budgets, those responsible for parks and open-space services will need to refocus their efforts, restate their social value and reposition their service to respond to the changing political and economic climate."
Neal added that research on park services by CABE revealed "hardly anyone had proper records of expenditure and few could make the link between expenditure and quality".
He explained that while park services were "notoriously difficult" to evaluate, there was more research on the multiple economic, social and environmental benefits that accrue from investing in them.
Determining the appreciation of local parks is crucial in calculating residents' satisfaction with their local council, he said. "Such evidence makes a direct connection with the Conservatives' pledge to create a 'Big Society'. The Queen's Speech included the decentralisation and localism bill.
"This proposes to release increasing control to local councils and communities to set their own priorities for investing and controlling local public services.
"Now is an excellent time for park managers to build a strong, locally-focused evidence base that clearly defines the priorities local communities have for their green spaces."
- For details, call 0118 946 9068 or visit www.green-space.org.uk