Millions of pounds of European funding could be denied to communities if new Welsh government plans are implemented, the National Trust has claimed.
The Welsh government last week outlined its investment priorities for future European funding programmes.
The National Trust said despite providing one in every six jobs in Wales, the environment sector would lose out under the plans.
But the Welsh government said a decision on funding had yet to be made.
The National Trust criticised the plans outlined last Wednesday by Deputy Minister for Agriculture, Food, Fisheries Alun Davies.
Mr Davies was setting out his priorities for future European programmes which include structural funds for the poorest parts of Wales and the Rural Development Programme.
The conservation charity said that under the plans there would be no European funding for "managed access to the countryside and coast and initiatives developing the natural, historic and cultural environment".
"It is astonishing that the deputy minister should announce he will bolster the economy by hitting the environment sector - which actually provides one in every six jobs in Wales," said director of National Trust Wales Justin Albert.
"Such a decision would also, quite obviously, have a significant impact on Welsh tourism which as an industry is worth £1.8bn a year to Wales, and is largely reliant on our countryside, coastline, natural, historic and cultural environment."
Last weekend the Wales Coast Path opened, the world's first of its type to cover an entire country.
The National Trust said that under Mr Davies's proposals the path would have not received any European grant aid.
A spokesman for the Welsh government said: "The total level of Rural Development Programme funding will depend upon decisions taken on the overall EU budget later this year.
"The announcement last Tuesday demonstrates the Welsh government's commitment to finding a balance between funding agri-environmental schemes and investing in diversifying and growing the economy of rural Wales.
"We will be making further announcements on our approach to Common Agriculture Policy and the Rural Development Programme in the next few weeks."
Mr Davies said in his statement last week that the European programmes must deliver "a single-minded focus on delivering sustainable growth and jobs for businesses and people across Wales".
"We must all face up to the challenge of making tough choices about how and where we should invest resources," he said.
"Resources cannot be spread thinly across a broad range of interventions. We need to invest in areas which have genuine potential to transform our economic prospects."