Ecohydrology最新文献

Urban trees provide essential ecosystem services, notably air cooling through transpiration, which helps mitigate the urban heat island effect and enhances cities' climate resilience. However, the complex spatial variability within urban areas and extreme weather events like droughts can disrupt trees' ecohydrological dynamics. In a study conducted in Freiburg, Germany, we investigated transpiration processes in Norway maple (Acer platanoides) and small-leaved lime (Tilia cordata) across diverse urban locations, including parks, parking lots, grass verges and tree pits. We assessed the effects of four distinct drought periods on transpiration and compared differences between tree species and growing sites. Small-leaved lime exhibited a 5% greater reduction in transpiration during drought periods compared to Norway maple, which experienced a 34% decline in transpiration during peak sap flow compared to nondrought periods. Tree pits with 90% surface sealing induced the most significant drought-induced transpiration reduction for small-leaved lime (58%), with both species displaying the lowest transpiration to potential evapotranspiration ratio in these locations. Significant differences were observed in the diurnal sap velocity patterns for both species. We highlighted the site-specific impact of surface sealing on transpiration during droughts, as well as the significant relationship between soil water deficit and relative transpiration rates. This study provides crucial insights into common urban tree species' responses to drought-induced transpiration across varied urban settings, emphasising the role of surface sealing. Continuous monitoring of diverse urban tree species is essential for building extensive databases and enhancing our understanding of tree water relations in diverse urban landscapes.

Isotope mixing models have become increasingly prevalent in the partitioning of root water uptake. However, many models fail to incorporate site physical information in a physically meaningful manner, whereas others adopt discrete approaches to segmenting the soil profile rather than continuous approaches that aptly treat the soil as a continuum of physical properties and conditions. Here, we present the novel ‘multimodal physically-based root water uptake isotope mixing estimation’ model (Multi-PRIME). The model utilizes a flexible, continuous and multimodal probability density function in conjunction with water-stable isotopes and additional site physical information, combined in a process-based linear mixing framework. To evaluate the approach, estimates of water uptake from boreal forest Pinus banksiana trees were compared with those of the PRIME and MixSIAR approaches. The models yielded comparable results; however, because of the highly flexible nature of its semi-nonparametric water uptake function, Multi-PRIME reduced the bias and uncertainty associated with soil segmentation of the discrete model MixSIAR and with the specification of parametric functions and initial parameter values of the PRIME model. Furthermore, the multimodal nature of Multi-PRIME provided a superior ability to describe water uptake patterns in cases with multiple potential source regions of uptake. In addition, due to its continuous and process-based nature, Multi-PRIME surpassed the discrete, empirically-based MixSIAR in both accuracy and certainty. These findings illustrate the benefits of adopting a process-based modelling framework that utilizes a semi-nonparametric, continuous and multimodal water uptake function, thereby providing an improvement in our ability to confidently estimate water uptake apportionment.

Alosa fallax (Lacépède, 1803) is an anadromous fish which utilizes European rivers for spawning. As many anadromous species, Twaite shad populations are declining due to river damming and hydromorphological alterations, which impact their spawning sites. In this study, we developed mesohabitat suitability criteria for the spawning period of A. fallax by analysing the geomorphic units (GUs), with their local habitat attribute, in which the fish prefers to spawn. The study was conducted in the Tagliamento River (NE Italy). Habitat depiction was performed following the MesoHABitat SImulation Model (MesoHABSIM) approach. High-resolution spatial information from Uncrewed Aerial Systems (UAS), a two-dimensional (2D) hydrodynamic model and field data collected during the spawning period were utilized for habitat attribute evaluation. The association between spawning sites and GUs characteristics was explored by training a classification random forest (RF) model. The final parsimonious RF model demonstrated high accuracy (98.8%) and true skill statistic (97.6%), indicating that A. fallax prefers glides and riffles with shallow depths (0.15–0.45 m), moderate current velocities (0.30–0.75 m/s) and small-sized sediment (diameter 0.2–6 cm) for spawning. Using an infrared camera, 72 surface mating events were distinctly recorded between 11.30 PM and 02.15 AM over two nights, demonstrating the technique's suitability for observing shad mating activity. The video analysis revealed that the monitored A. fallax population exhibited similar mating behaviour to other European shads (e.g., Alosa alosa). This study provides useful insights to develop novel management approaches for preserving or restoring the spawning habitat of the A. fallax, supporting its conservation.

Headwater watersheds and forests play a crucial role in ensuring water security for the western United States. Reducing forest biomass from the current overgrown forests can mitigate the severity and impact of wildfires and offer additional competing ecohydrological benefits. A reduction in canopy interception and transpiration following forest treatments can lead to an increase in available water for the remaining trees and runoff. However, the impact of forest management on water balance can be highly variable due to differences in climate, topography, location and vegetation. In this study, we used the Soil Water Assessment Tool Plus model to investigate how decisions regarding location, intensity and scale of forest treatments can affect both evapotranspiration and streamflow in a large watershed such as the upper Kings River Basin (3998 km²). The model was parameterized using a multiobjective calibration of streamflow, snow water equivalent and evapotranspiration. Various forest treatment scenarios were simulated across different years and regions in the landscape. Modelling results show that during dry years, streamflow gains from biomass reduction are primarily originated from energy-limited regions (i.e., 82% of total streamflow increase in the first year). In water-limited regions, the water is prioritized for sustaining remaining trees, improving forest health and recharging subsurface storage, rather than increasing streamflow. During wet years, the contribution to streamflow from biomass reduction comes from both energy- and water-limited areas. These findings emphasize the importance of evaluating forest treatments on a larger scale. The competing benefits for forests and downstream users are driven by the energy and water limitations of the vegetation targeted by forest treatments, as well as the climate variability that modulates the water availability and forest recovery time.

Ecohydrology engineering provides a valuable framework for addressing emerging environmental challenges by integrating ecological and environmental engineering principles. In this study, we discuss the potential of parsimonious, physically based ecohydrological models through the lens of three case studies: sustainable irrigation, urban heat island mitigation via green roofs and mangrove restoration for climate change mitigation. First, we investigate sustainable irrigation strategies, illustrating the trade-offs between water conservation and soil salinization. This highlights the delicate balance required to optimize crop yield while mitigating soil degradation. Second, we explore the role of green roofs in urban heat island mitigation, showing how vegetation and water dynamics on rooftops can enhance latent heat flux, thereby potentially reducing urban temperatures and improving building energy efficiency. Lastly, we assess the climate mitigation potential of mangrove restoration, accounting for the impacts of salinization and sea-level rise. We demonstrate that carbon sequestration in mangrove ecosystems may be strongly limited by productivity reduction due to salinity and reduced area availability under sea-level rise. These case studies illustrate the strengths of simplified ecohydrological models in capturing critical feedbacks and interdependencies between water and biota across diverse environments. By prioritizing adaptive, resilient strategies, EE offers a practical pathway for developing innovative, context-sensitive solutions that leverage ecosystem dynamics to address pressing environmental issues.