Talk to the Committtee. Eventually, those trees will require maintenance and that cost will be shared by all owners. So it’s in the interests of the Committee to ensure that the responsibility for those trees is understood and properly documented from the start. No one can plant trees on common property without permission. The tenant may have received permission from the landlord, who may have received permission from the Committee. So first find out if any permission was sought and/or received. If there was none, then the Committee may agree to ask the landlord to remove the trees and repair the lawn. I believe it’s up to the landlord to recover costs from the tenant.
If the landlord doesn’t act, then the Committee may be able to arrange for the tree removal to be charged to the landlord. Alternatively, the Committee could establish a by-law giving ongoing maintenance responsibility for those trees to the lot that planted them.