Soil moisture variations from boreal forests to tundra

• Main Authors: Kemppinen, Julia, Niittynen, Pekka, Rissanen, Tuuli, Tyystjärvi, Vilna, Aalto, Juha, Luoto, Miska
• Format: Report
• Language: unknown
• Published: 2022
• Subjects: Tundra
• Online Access: https://zenodo.org/record/6418661; https://doi.org/10.5281/zenodo.6418661

Soil moisture has a profound influence on life on Earth, and this vital water resource varies across space and time. Here, we explore soil moisture variations in boreal forest and tundra environments, with a particular focus on the relationship between soil moisture mean (variation within a study area) and standard deviation (SD; temporal variation within a measurement site). We installed data loggers up to 14 cm depth at 503 measurement sites within seven study areas across northern Europe. We recorded 6 138 528 measurements to capture spatial and temporal soil moisture variations of the snowless season from April to September. We found general unimodal mean-SD relationships within and across the areas indicating that dry or wet sites had less temporal variation than intermediate sites. At all seven areas, the unimodal pattern was found over the entire measurement period. Pairwise distances in a spatio-temporal soil moisture space were more related to topographic differences between the sites (R2 = 0.106), but not to geographical or climatic differences (R2 = 0.003, R2 = 0.003). This indicates that similar spatio-temporal variations in soil moisture are present also over large geographical (>1000 km) and climatic gradients. We also found more spatial than temporal variation within the areas. These results demonstrate the high soil moisture heterogeneity across boreal forest and tundra environments.