Trees grow on graves. First of all, it can be explained that as children or descendants, they did not visit graves regularly in Tomb-Sweeping Day or at other times. As we all know, when a tree grows up, it certainly takes a long time to grow into a tree, and if future generations go to visit graves to worship their ancestors every year in Tomb-Sweeping Day. Then, it is impossible to plant trees on the grave. It can be seen from this point that, as a descendant, China's traditional moral concept is a manifestation of unfilial behavior.
Secondly, the growth of trees needs a lot of nutrients, which will absorb the nutrients in the grave, that is, the surrounding soil. From the perspective of geomantic omen, this is equivalent to the local water being drained, which means that the geomantic water is gone, only the wind is left. For future generations, it also has a great impact, either on wealth or on other fortunes.
You know, a tree's root system will be very developed, with many roots, big roots and small roots. So if it grows on a grave, its roots will grow downward, and the longer and deeper it grows, the more it grows on the coffin. Slowly, the roots of the system will grow into the coffin, affecting the ancestors. According to geomantic omen, the "home" of ancestors is threatened, which will also affect future generations.