Actually, your landlord is correct. First of all, an "improvement" regarding real property is any permanent structure on the property which increases its value. In real estate law, an improvment goes with the property. In the case of a rental, an improvement such a the installation of a chain link fence by a tenant becomes the property of the landlord/owner. It is not the tenant's personal property. Perhaps, you can get your landlord to reimbusre for a portion of the cost of installation.