Time-stability of soil water through boreal (60-68°N) gradient

•We studied soil water conditions through boreal gradient.•Time-stability of soil water was found to apply to multi-year data.•Soil texture was one of the most critical drivers for time-stability of soil water.

SummaryThe time-stability concept suggests that the spatial pattern of the soil water content does not change with time when the observations are ranked according to the magnitude of the soil water. The time-stability holds for soils in agricultural fields and forest compartments, yet broader scale effects of boreal climate on time-stability are poorly understood. We studied the spatial persistence of soil water through the boreal climatic gradient (60-68°N) on the Baltic Shield using multi-year (2002-2010) automatic monitoring at sites (up to 18 in number) with diverse soil texture and land use. We found that the soils exhibited significant time-stability, Spearman's rank correlation coefficients rs = 0.94-0.95, p < 0.01, for the whole climatic gradient. This applied to the soil depth of 0-100 cm and the growing seasons when a soil temperature threshold value of +3.2 °C was used. Our observation helps in estimation and modeling the effects of climate change along the boreal biogeographical zones.