In geosciences, soil-water interactions are defined by soil water potential, which provides a quantitative estimate of the soil water thermodynamic state. Due to the interactions between water and soil particles, soil water has different physical properties than free water; hence, analyzing soil water may require different methods and approaches. Typically, soil water potential is defined as the sum of three independent functions: gravitational, osmotic, and matric. However, there is a problem with this definition because the osmotic and matric potentials exhibit coupling effects. Moreover, due to its high values, the matric potential dominates the total potential, whereas the gravitational potential may appear negligible. However, gravity may lead to different flow mechanisms altering the soil's mechanical behavior. As a result, it may not be valid to calculate the total water potential as the algebraic sum of the different potentials. There are also mathematical challenges in the common use of water potential; as soil saturation decreases, water potential can reach thousands of kPa, which requires mathematical balancing in the equations by multiplying it by a variable with a value near zero. However, multiples of numbers of different magnitudes are problematic from a mathematical perspective, especially when applied to numerical analysis. This paper discusses the strengths and limitations of the definitions and mathematical formulations of this variable.

In an increasingly dry environment, it is crucial to understand how tree species use soil water and cope with drought. However, there is still a knowledge gap regarding the relationships between species-specific stomatal behaviour, spatial root distribution, and root water uptake (RWU) dynamics. Our study aimed to investigate above- and below-ground aspects of water use during soil drying periods in four temperate tree species that differ in stomatal behaviour: two isohydric tracheid-bearing conifers, Scots pine and Norway spruce, and two more anisohydric deciduous species, the diffuse-porous European beech, and the ring-porous Downy oak. From 2015 to 2020, soil-tree-atmosphere-continuum parameters were measured for each species in monospecific forests where trees had no access to groundwater. The hourly time series included data on air temperature, vapor pressure deficit, soil water potential, soil hydraulic conductivity, and RWU to a depth of 2 m. Analysis of drought responses included data on stem radius, leaf water potential, estimated osmotically active compounds, and drought damage. Our study reveals an inherent coordination between stomatal regulation, fine root distribution and water uptake. Compared to conifers, the more anisohydric water use of oak and beech was associated with less strict stomatal closure, greater investment in deep roots, four times higher maximum RWU, a shift of RWU to deeper soil layers as the topsoil dried, and a more pronounced soil drying below 1 m depth. Soil hydraulic conductivity started to limit RWU when values fell below 10-3 to 10-5 cm/d, depending on the soil. As drought progressed,oak and beech may also have benefited from their leaf osmoregulatory capacity, but at the cost of xylem embolism with around 50 % loss of hydraulic conductivity when soil water potential dropped below -1.25 MPa. Consideration of species -specific water use is crucial for forest management and vegetation modelling to improve forest resilience to drought.

Over the past decades, anthropogenic disturbance of geological structures has been significantly documented in Slovakia, mainly driven by the national economy's demand for mining resources. Among these resources, brown coal, primarily mined in the Upper Nitra coal basin in the Prievidza district (Slovakia), has been essential. Mining activities around town of Handlov & aacute;, and villages of Ko & scaron;, C & iacute;ge & lcaron; and Sebedra & zcaron;ie, particularly at the C & iacute;ge & lcaron; coal mine, have induced several geological defects. These defects, characterised by large cracks and local landslides, disrupt the hydrogeological conditions, significantly impacting the soil water regime stability of the forest ecosystems in these damaged areas. This study investigates the variability and dynamics of the soil water potential in a mining-affected site (Ra & ccaron;kov laz) compared to an intact reference area (& Ccaron;ertove chodn & iacute;ky) between 2020 and 2022. Our findings suggest that mining activities could have substantial implications for the soil water regime and, consequently, the ecological stability of forest ecosystems.