Unfortunately, this is a common occurrence. A bird, having recently eaten a mulberry fruit or two, defecates while perched on a planted young woody ornamental, in this case a crabapple. The seeds wash down the trunk, germinate at the base of the desired ornamental sapling and, because of its more rapid growth, the mulberry (the orange-tan bark species) overtakes and ruins the planting. This is a form of grow-through. It happens because mulberry is a serious reseeder and because the person responsible for maintaining the site is ignorant, botanically uneducated and lazy. Notice also the intertwining, light brown barked, deadly nightshade.