Because, in geomantic omen, it is considered that the shape of trees is similar to that of human body, and plants grow well just like human body is strong. If the leaves of plants turn yellow, wither, fall off or the trunk withers, it is considered to be similar to the human body suffering from serious diseases. Over time, it will inevitably have an adverse impact on the health of residents.
However, the death of a tree has little effect on Feng Shui. But it may affect the beauty of the house, so it needs to be cleaned as soon as possible.