Juniper Tectonic Features and Their Annual Ring Width Response to Precipitation in Lijiang, Yunnan Province, China

This study examines Lijiang Juniper from Yunnan Province. Through visual inspection, cross-section analysis, and separation tests, it analyzes the macroscopic and microscopic characteristics of Juniper wood from Baoshan Township, Lijiang City. The annual ring width of Juniper wood was determined using a tree-ring analyzer. The results showed that: macroscopically, the heartwood and sapwood of Juniper were clearly differentiated; the transition from earlywood to latewood was slow; the boundary of the growth rings was obvious, and the air-dry density was 0.771 g/cm³. Microscopically, the number of rimmed pores on the tubular cells was large, the lumen of the tubular cells contained invaginations, and the cross-field pores were of platyrrhizal type; the wood rays were uniseriate, with a height of two to five cells; axial thin-walled tissues were scattered; and large traumatic resin tracts were present. On the morphological characteristics of cellular fibers, the characteristic values of Juniper wood, such as tubular cell length, tubular cell width, tubular cell wall thickness, internal diameter of tubular cells, and height of wood rays, were determined. Based on their mean, standard deviation, and extreme deviation, it was concluded that the Lijiang Juniper was an excellent raw material for paper making. The ages of seven Juniper trees in Baoshan Township were also analyzed and determined by the tree annual ring analyzer. The response relationship between annual ring width and precipitation was discussed, with Juniper BSX-2 and BSX-3 as examples. It was found that the fit between annual ring width and precipitation was high, and the correlation coefficients were 0.605 and 0.678. The correlation between the annual ring width of Juniper and the amount of precipitation was strong at the 0.05 level. This indicates that Juniper’s radial growth is more sensitive to water supply.