Response of resin canal area of with different ages to climate change in Taiyue Mountains, China.

To investigate the responses of resin canal area of with different ages to climate change, we analyzed the relationship between the resin canal area and climate factors from 1972 to 2017 in plantation at young age, middle age, near-mature, mature, and over-mature periods in Taiyue Mountains, Shanxi Province. The results showed that 55.7% to 75.2% of resin canal occurred in earlywood. The mature and over-mature periods had the largest resin channel area, sequentially followed by near mature, middle age, and young age periods. Annual mean latewood resin canal area increased significantly in near-mature period and mature period, but not in other periods. There was a significant negative correlation between earlywood resin canal area and minimum temperature during the growing season (May to July) for trees at middle age period. Earlywood resin canal area of mature trees showed significant negative correlation with minimum temperature during the growing season, but significant positive correlation with drought (PDSI) in the non-growing season (previous September to current April). The total area of earlywood resin canal at the young, near-mature, and mature periods was less influenced by climate than other periods. The minimum growing season temperature was a limiting factor to earlywood resin canal growth, while the non-growing season drought gradually became a limiting factor for earlywood resin canal with increasing tree age. The total area of earlywood resin canal decreased with increasing non-growing season drought and increasing growing season minimum temperature. In the context of global warming, the earlywood resin canal area may gradually decrease at all five periods, and the most reduction in the over-mature stage.