Jan Deutscher

Given the ongoing climate warming that can lead to water scarcity, water retention has been on the forefront of forest ecosystem services. Water harvesting pits on forest roads are one of the possible engineering measures that can help mitigate some of the negative impacts forest roads have on the hydrological regime of the forest ecosystem. The aim of the research is to inform the scientific and professional public about the function and potential of water harvesting pits under forest road culverts and to offer insight into the significance of expected benefits of these objects for water retention and improvement of forest stand hydrological conditions. In this study, standard engineering methods were used to design and build water harvesting pits connected and not connected to culvert mouths and to equip the whole surrounding area with soil moisture and water level sensors. During the two-year study period, a number of irrigation experiments were also performed. The goal was to observe and evaluate the distribution of water from the pits to the surrounding soil and forest stands. Even though water harvesting pits and similar water retention objects on the forest road network seem very beneficial on paper, data from our research does not fully support it. According to our results, the benefits obtained seem much smaller than originally expected to a point that the viability of such measures is probably very low both from the forest stand and water management standpoint. More research is definitely needed in a wider variety of conditions and with a longer time frame.

This article presents guidelines for assessing the optimal dimensions of forest road pipe culverts, based on input of actual and experimental data to standard engineering techniques. In doing so, we assess the need for (i) changes in the parametrisation of inputs (i.e. culvert micro-catchment dimensions, rainfall and resultant culvert flow, and culvert flow rates during culvert hydraulic dimensioning), and (ii) the need to redesign culvert outlets in relation to flow speed. Our results demonstrate that values for most inputs presently used under current technical practice for forest road pipe culvert sizing are significantly higher than those achieved under experimental conditions. The data on outlet flow velocities strongly suggests that strengthening of culvert outlet aprons will be crucial for their future operation.

Bank erosion can lead to land loss and increased sedimentation rates, which can alter the important ecosystem services of the water body. Currently, innovative nature-friendly approaches to bank stabilization have been encouraged over the “hard” civil engineering measures. In this study, the impulse for implementing an innovative stabilization technique arose when parts of the banks of the Hulín postmining sandpit were transformed into a two-meter-high erosion wall, and a technical stabilization structure was neither feasible nor appreciated by the general public for recreation or nature protection. Therefore, a new design of a so-called "half-bowl" sloping with additive nature-friendly stabilization measures SMs (grassing, willow cuttings, gravel bed, etc.) was tested. The evaluation of individual SMs consisted of: 1. visual assessment; 2. wave run-up modeling; and 3. granulometric analyses. All three tests indicated that a good degree of stability was achieved. At the same time, a comparison to biological (mild sloping with grassing) and technical (retaining wall) alternatives was also carried out. Both the low financial cost and relatively low land area requirements indicate that this approach offers a promising nature-friendly solution for bank stabilization in similar lakes.

This research focused on comparing two spruce-dominated micro-watersheds with relatively similar natural conditions, located in different forest vegetation zones (FVZ). We followed two hydrologically different years 2023 and 2024, and observed differences in the amount and characteristics of extreme runoff events, which we primarily interpret as the effect of forest stands referring to their hydric functions. The local nature of the study and the short time period should be seen in the broader context of global climate change as contribution to the understanding of the changing role of forest stands in flood protection and also to the issue of extensive changes in tree species composition. Our results highlight the fact that spruce catchments in the lower altitudes (3rd FVZ) achieve significantly lower water management efficiency than spruce catchments closer to their ecological optimum (5th FVZ). This finding is important because it reminds us that challenges connected to spruce management cannot be categorically generalized but must be evaluated in local conditions. This applies, among other things, to extensive changes in tree species composition, which can have a significant positive effect on hydric conditions in the long term, but this effect can only be expected with a lag of several years.

In this study, we investigate the combined effect of different rainfall‐runoff event types and antecedent soil moisture (ASM) on runoff processes in the headwater elementary discharge area of a small forested upland catchment. The study focuses on (i) the relationship between soil moisture thresholds and runoff generation; (ii) the combined effect of ASM and tree vicinity and (iii) the relationship between different rainfall‐runoff event types and different types of runoff (baseflow and stormflow). The results suggest that ASM has a strong impact on local runoff generation processes. Soil water content (35%–36%) threshold exceedance was related to stormflow runoff generation caused by the activation of quick preferential flow paths in the soil during storm events, especially in the upper and the deepest soil layers. At the same time, unexpected non‐linear increases in baseflow runoff ratios were documented during dry, precipitation‐free, periods and when the 31%–34% soil moisture threshold was exceeded, presumably due to the hydrological connection of farther slope areas during these conditions. Multiple stormflow periods, which exhibited the lowest runoff coefficient, were the most significant events in terms of water retention and soil water recharge due to increased vertical hydrological connectivity enabling more rapid transport to deeper soil layers. However, this rainfall type occurred least often over the study period. The important role of forest stands (individual trees) in creating spatial patterns of soil moisture and preferential infiltration paths to deeper soil layers was also confirmed. These results contribute towards a better conceptualisation of hydrological behaviour in elementary headwater discharge areas and highlight the potential dangers associated with expected increases in extreme weather events.

This paper examines changes in?soil physical and chemical properties in?relation to?tree proximity on?different slopes. Topsoil and subsoil were sampled at?12 research plots on?four slope types, the soil pits being placed at?the base of?a?tree...

We performed a comparative paired catchment study of three headwater upland forest micro-catchments with different forest types in the precipitation-abundant year 2020. The analysis was based on baseflow separation and resulting baseflow index (BFI). The year 2020 was intentionally chosen as a way to reflect the expected effects of climate change in the region where more extreme hydroclimatic events are expected. Our team demonstrated that in case of hydroclimatic extremes, there are significant differences in the runoff response from these catchments, depending especially on the tree species composition in the forest stands. Three forest types with the predominance of European beech (Fagus sylvatica), Norway spruce (Picea abies), and mixed forest were analyzed. The observed different values of BFI were interpreted in relation to the ability of forest stands to retain water and slow runoff in extreme runoff events determined by the stormflow component as an indication of their flood control efficiency. A significantly worse flood control efficiency and an overreaction of runoff response to precipitation events were observed in the spruce catchment. This also suggests that the spruce catchment is more prone to suffer from drought since twice as much water was lost from the system during extreme hydroclimatic events as opposed to the other two with less spruce in the stands and less water is thus available for groundwater recharge.

In an upland forested micro-catchment during the growing season, we tested soil responses to precipitation events as well as soil water content (SWC). We asked ourselves if what is the difference of SWC response to precipitation events depending on the presence and proximity of a tree? The environmental heterogeneity of the small 7.5-ha headwater area was captured by soil probes at specific locations: (i) probe measurements of SWC at 10-, 30-, 60-, and 100-cm depths; (ii) resolution of near-tree (NT) and between-tree (BT) positions; and (iii) resolution of four slope classes. The results revealed significant differences between the hydrological responses of the soil. NT soils had faster infiltration but were also faster to dry out when compared to BT soils, which were less affected by the presence of trees. Water input threshold values, measured as the precipitation amount needed to cause a significant increase in SWC, were also significantly different, with NT positions always lower than BT positions. Total infiltration of the topmost NT and BT soil layers reached 185 and 156 mm during the study period, corresponding to 43% and 36% of the total 434 mm of precipitation, respectively. Infiltration into the deepest horizon was significantly higher in NT soils, where it reached 114 mm (26%) as opposed to 9 mm (2%) in BT soils, and was indicative of significant vertical hydraulic bypass flow in the proximity of trees. These observations contribute to better understanding the hydrological processes, their nonlinearity, and the expansion of conceptual hydrological models.

The aim of this article is to present the basic theses about the function and potential of infiltration pits under culvert mouths on forest roads. The methodology consisted of a combination of literature review and own in situ experiments. Experimental verification was carried out on sections of forest roads on two training forest enterprises (TFE) at Kostelec nad Černými lesy and Masarykův les Křtiny (Czech Republic). At each location, two infiltration pits were built in a paired design with a uniform retention volume. One of the pits was always located under a pipe culvert. The control pit was located approx. 30 m far from it, in the same pedological and vegetation conditions without a centralized inflow. Measurements from the study period (autumn 2022) indicated that the infiltration pits under the culverts had unexpectedly low efficiency in retaining and infiltrating surface runoff. Mostly, due to the fact that in the analyzed period the surface runoff was minimal, even though precipitation did occur. During the study period, the infiltration pits did not reach the expected potential to support the hydric regime of the landscape.