Volunteers from this charity group raised concerns after their bid to have Irongate Field in the Harlow Hill part of town designated as official 'green space' in the new Local Plan was rejected by Harrogate Borough Council.
As a result, PCG has formally asked in a letter to local councillors that Harrogate Council amends its draft Local Plan.
The PCG fears Irongate field is vulnerable for future development.
And the charity group has also queried some of the council's reasons for the decision, claiming there were errors by council officers in its designation of different areas.
The council had said that landowner, HBC Estates, had requested an amended site boundary to take account of the extant planning permission on Irongate Field but PCG suspected this actually referred to the Rotary Wood planning.
While admitting an "error", Coun Rebecca Burnet, HBC's cabinet member for planning, said the council's reasoning and methadology was sound on the future of the Irongate Field and said there were no development proposals for Irongate Field.
She said: "There is absolutely no dispute that Irongate Field is recognised as an area within the Pinewoods Management Plan, nor any question that the Pinewoods Conservation Group would have an equal interest in conserving all areas covered by that plan.
"However, the fact that the different sites are combined in this way for site management purposes does not mean that they are one site.
"The Irongate Field site is physically separate to the Pinewoods in terms of its location and is an open grassed field which is different in character to the wooded area - being located on the opposite side of Rotary Wood.
"Whilst the PCG made one submission to cover the three different management areas, it was appropriate for officers to consider the form and function of these different areas within their assessment work.
"In line with national policy the Council's methodology states that the areas submitted are expected to be fairly self-contained and to have clearly defined boundaries.
"The process also requires officers to determine whether a site is local in character and that it should not be an extensive tract of land. The approach taken on the Pinewoods submission is consistent with our approach across all LGS work on the plan.
"There is planning permission for Irongate Field. I understand that officers received an email from you on November 8 requesting clarification as to whether there was a misunderstanding in relation to the planning status of Irongate field.
"An email response was sent back to you confirming that the extant planning permission referenced in the document actually applies to the area of land known as Rotary Wood (application number 16/05254/OUTMAJ).
"You are, therefore, aware that this reference was simply a drafting error on our part, and the name Rotary Wood should have been used.
"However when officers were assessing and discussing this area of land they were clear at all times about the exact boundary of the extant permission and as such, this error in terminology had no bearing on the decision to exclude Irongate Field from the area of land to be designated as Local Green Space.
"I appreciate that you will remain disappointed that Irongate Field is not included in the LGS designation. You do have the opportunity to subit formal comments in relation to the designation of this site as part of the Publication Draft Plan consultation in January."
Neil Hind, chairperson of Pinewoods Conservation Group, said the group was not going to give up in their work to protect as much of the Pinewoods as possible.
He said: “Although we are pleased the council has accepted that drafting errors made, we are still disappointed they do not intend to amend the plan to include Irongate Field.
"We look forward to receiving details of the further information the council need to re-consider their position in the January consultation.
"Depending on that requirement we are likely to need to ask our members and local residents to make their views known for a third time. ”