The spring equinox represents the arrival of the change in season and the literal point where the opposite hemispheres of the earth have equal length of day and night. This year the equinox fell on March 20, and therefore the imbalance in the ratio has already begun to shift; impermanence.
Change of season is synonymous with change and adaptation. In yoga philosophy, twisting poses represent facilitating and ability to adapt to change; the greater the mobility and flexibility in the body (and the mind), the greater our preparedness for change.
Equinox pose tip: add Ardha Matsyendrasana (Half Lord of the Fishes) pose to your practice for a supportive spinal twist in line with the season.