If the land is managed as a park or preserve, contact the management team and ask about volunteer or planning committee opportunities. There are often plenty of ways to help ongoing and existing projects about issues you care about. You could assist with grant writing, social media and traditional media communications, organizing, fundraising, planning and document reviewing. If the land is privately owned, approach the landowner with the concern you are observing. It may be helpful to provide some potential solutions and offers of help.