Some Behavior Features of Dielectric Properties of Water in Birch Wood at a Frequency of 1.41 GHz

Trees have a profound impact on human life that makes their year-round monitoring with dielectric characteristics (DCs) of wood water as controlled parameters of great importance. This article deals with studying some behavior features of DCs of different-type wood water in various phenophases under varying moisture, temperature, and concentrations of dissolved substances. It presents the measurement results of DCs (1.41 GHz) of freshly cut branches of birch sampled from the same tree in different phenophases of 2018-2020. DCs carry the information on the phase composition of water present in plant tissue, volume fractions of bound and free water, concentrations, and types of dissolved substances. For various phenophases, the dependences of refractive (n) and absorption (kappa) indices on volume fraction of water in wood (W) for whole branches are approximated by piecewise broken lines with one (W-1) or two (W-1 and W-2) break points. We identify three categories of wood water with different DCs and estimate the dielectric properties of bound and free water in wood tissue in different phenophases using the refractive model. The established seasonal dependences (n, kappa) (W, T) and the developed dielectric model make it possible to calculate DCs of wood water.