According to Chinese Medicine's Five Element Theory, the Wood element is associated with the Spring season. The Yin organ associated with the Wood element is the Liver. In Between Heaven And Earth: A Guide To Chinese Medicine, the authors Harriet Beinfield, LAc and Efrem Korngold, LAc, OMD best explain the relationship between the Liver and the spring season:
The Liver, whose Qi is akin to the phase of Wood, instigates movement and arouses the mind by allowing tension and pressure to build. As spring initiates the rising of sap in the trees, so the Liver lift the Blood and Qi. Alternatively, gathering and releasing the Blood, the Liver modulates the intensity and force of all motion and process.
To better understand this relationship between Wood, spring and the Liver organ, it's important to understand that one of the most important functions of the Liver is to filter impurities from the Blood. Like a tree pulling up water and any impurities from the earth in order to create sap, the Liver pulls in Blood and its impurities (from medications, toxins, alcohol, etc) in a similar way thanks to the many veins that converge together to form the hepatic portal vein that leads to the Liver.
Maintaining a healthy Wood element means eating a clean diet, limiting alcohol consumption and managing stress. Acupuncture is wonderful for supporting a health Wood element, especially because maintaining a healthy balance between all Five Elements is important for overall health.