The Association for Public Service Excellence (APSE) found that local authority managers are worried the squeeze on funds will cause a multitude of problems.
The group's annual state-of-the-market survey for parks services focused on the aftermath of the comprehensive spending review.
Half of those polled expected budgets to fall, while 48 per cent said cuts would be substantial. Just over a third expected a slight decrease in the number of parks through asset transfers.
Worst hit will be upkeep, with less grounds maintenance expected. The park managers feared service and standards would fall.
Items listed as at risk included floral displays, regional shows, ornamental grass cutting, bowling greens and high-amenity areas. Others said landscaping and country parks will suffer, there will be fewer parks and facilities and there will be less park-specific community engagement.
However, expansion was expected in areas such as the merging of services with other councils, partnerships with community groups and conservation and efforts to help adjust to climate change.
Parks adviser Debbie Johns said: "Resources are tight but we hope the value of parks and green spaces will be recognised and the number and quality of parks will not drop. APSE is working with its members to ensure parks provide maximum value for diminishing resources. It is encouraging that parks managers are identifying ways in which their services can be expanded to achieve that."
The APSE survey also revealed more than nine-tenths of local authorities recycled green waste.
- 59 per cent say climate change will mean more grass cutting.
- 74 per cent say allotments are not just a fad but here to stay.
- 70 per cent say community sector involvement in managing parks is increasing.