Which of the following solar terms reflects the phenological phenomenon of natural organisms?

Those natural phenomena which are influenced by the environment (climate, hydrology, soil) and have an annual cycle are all phenological phenomena, including three aspects: first, the germination, leaf spreading, flowering, leaf discoloration and defoliation of various plants; Second, the first song, the last song, leaving, hibernation, etc. of migratory birds, insects and other animals. ; Some hydrometeorological phenomena, such as first frost, last frost, freezing, melting, first snow and first snow.