An arborist report is a document that outlines the condition of a tree in question. It must be prepared by a certified arborist, and must outline the location, condition, and areas of concern regarding the health of the tree, as well as any problem areas. There can be two sources of tree damage: biotic, from living sources such as insects and fungi, and abiotic: from non-living sources such as construction activities, lightning, etc. Arborist reports note all the problems that the tree has and provides recommendations about possible solutions to these problems, such as fertilization, pest control, or pruning and removal.