The answer to 'why is my tree erosion' is that tree erosion is typically caused by soil loss around the tree's root system. This can happen due to factors like heavy rain, flooding, or poor drainage that washes away the soil, or from foot traffic and landscaping activities that compact the soil. Symptoms include exposed tree roots, leaning or unstable trees, and soil loss around the base.
To fix tree erosion, you'll need to address the underlying cause. This may involve improving drainage, adding soil and mulch around the tree, or installing barriers to protect the roots. In severe cases, you may need to replant the tree in a better location. If the erosion is extensive or the tree is in danger of falling, it's best to call a professional arborist to assess the situation and recommend the best solution.