Response of reflectance to dielectric properties of bare tills

Parent tills are routinely exposed as a result of mechanical sitepreparation during post-harvest forest regeneration in northern Fennoscandia. Scots pine (Pinus sylvestris L.), the species most often chosen for artificial reforestation, only thrives on sites with low soil moisture content (_v). Hence objective methods are needed to measure _v of bare tills to provide information on suitability of a site for pine. We studied the relationship between the spectral reflectance (350-2500 nm) and dielectric permittivity (, as dependent on the soil _v) of tills varying in clay fraction content (2.4-5.5%), fine fraction content (23.5-47.1%) and organic matter content (OMC, 0.6-5.8%). Laboratory measured data, analysed with correlation and regression analysis and mixed effect modelling, showed a significant negative correlation between reflectance (500-2500 nm) and the soil  (i.e. soil _v). In addition, the proposed generic exponential models (y=ae^bx+c) explained the reflectance-soil  relationship well (adjusted goodness of fit 0.8-0.85) for tills with low OMC (<1.7%). The results suggest that high-resolution remotely sensed data can provide an effective alternative to traditional soil surveys for recognition of soil _v patterns on clear-cut mechanically prepared sites.