Latitude patterns in fine root morphological and anatomical traits across root orders of Pinus koraiensis

The fine root system of trees can be divided into orders that reflect the comparative positions within the root system (the 1st order being the most distal) and the functional roles of fine roots that allow adaption to different environments. The intraspecific variation of fine root traits with the roots if different orders at regional scale has rarely been studied. We investigated the morphological and anatomical traits of the first five order fine roots of Pinus koraiensis at four different sites along latitudinal gradients in temperature and precipitation. The results showed that as the root order increased, the function of fine roots changed from being mainly responsible for absorption to mainly responsible for transportation. The effect of latitude on fine root traits was dependent on root order. The adaptation strategies for fine roots at different latitudes were regulated by environmental combinations and there were significant trade-offs between absorptive and transport roots at regional scale. The results emphasize the variation and cooperation of the fine root traits of P. koraiensis with the root order at different latitudes.