Recent experimental work on latewood loblolly pine cell wall layers strongly supports that diffusion through unmodified wood cell walls is a solid polymer diffusion process, where motions within the polymer structure are limiting to transport. Using synchrotron X-ray fluorescence microscopy (XFM) and a custom-built RH chamber, Zelinka and coworkers directly observed that there is a 60-85% RH threshold for mineral ion diffusion in individual wood cell wall layers . At levels below this level of hydration, there is simply no room in the wood nanostructure to permit diffusion, whereas enough water intercalates into the wood structure at greater humidity to plasticize the wood polymers and facilitate mineral ion diffusion. Interestingly, the 60-85% RH range also corresponds to the 50-85% RH range for the moistureinduced glass transition in amorphous polysaccharides . Using nanoindentation dynamic mechanical analysis, it is possible to assess the moisture-and time-dependence of the molecular relaxations corresponding to the glass transition . These molecular relaxations correlate directly to ionic conductivity measurements made on similar wood cell wall layers, demonstrating that ionic conductivity is being controlled by the molecular relaxations . This manifests concretely in time-lapse XFM imaging, from which it is possible to determine moisture-dependent ion diffusion constants . The direct connection to moisture content highlights how structural changes at the atomic scale propagate forward to higher order observables.