While Yang energy represents vitality for living creatures, one could infer from the fact that Yang energy can evolve into energies similar to the Light System and Fire attribute that it may not necessarily be beneficial to the plants intrinsic to it.
Although these plants can utilize Yang energy to enhance their own strength, Zhou Tian believed that to avoid self-immolation, they must also take some preventative measures.
Based on Zhou Tian's observation, if his hypothesis is correct, the reason these Giant Trees remain unscathed is due to their ability to absorb sufficient Yin energy from the soil in the Ancient Ruins Space to maintain the balance of Yin and Yang attributes within their bodies. If this balance is disrupted—while a Yin dominance may not pose a problem—once Yang dominates, those Giant Trees will definitely self-immolate.