What if a petitioning property owner violates the policy by removing trees or otherwise degrading the natural resources? Does that prevent annexation?

A violation of the policy will certainly be a factor in the City Council granting or denying an annexation request. However, the policy provides that the City Council may approve such an annexation (and ignore the violation) if the best interest of the community is served. If the subject parcel is a valuable addition to the city in spite of the loss of natural resources (e.g., the site is already served by public facilities and the owner will provide needed housing), the property may be annexed.