The answer to 'why is my tree erosion' is that tree erosion is a common issue caused by the loss of soil around the tree's roots, often due to heavy rain, runoff, or other environmental factors. Symptoms include exposed roots, soil washing away, and the tree becoming unstable or leaning.
To address tree erosion, you can try mulching the area around the tree to help retain soil, installing erosion control measures like retaining walls or terraces, or replanting ground cover vegetation. However, if the erosion is severe or the tree is in danger of falling, it's best to call a professional arborist or landscaper to assess the situation and recommend the appropriate solution.