Bioscience Evidence 2024, Vol.14, No.4, 172-183 http://bioscipublisher.com/index.php/be 176 peak rainfall and peak flow (Puttock et al., 2021). This flow attenuation effect is significant even during large storm events, with beaver dams capable of reducing average flood flows by up to 60% (Puttock et al., 2021; Chen and Mai, 2024). Additionally, beaver dams provide temporary surface water storage, which helps to maintain low flow conditions during dry periods and enhances the resilience of the ecosystem to drought (Pearce et al., 2021). The ability of beaver dams to store and slowly release water contributes to a more stable hydrological regime, mitigating the impacts of both floods and droughts (Westbrook, 2019; Rønnquist and Westbrook, 2021). In summary, beaver dams significantly alter water flow and storage, enhance groundwater recharge and surface water dynamics, and provide critical flood mitigation and drought resilience benefits. These hydrological impacts underscore the transformative role of beavers as ecosystem engineers in shaping river corridor hydrology and enhancing ecosystem resilience. 6 Biodiversity Enhancements 6.1 Creation of diverse aquatic and terrestrial habitats Beavers are renowned ecosystem engineers, primarily through their dam-building activities, which significantly alter the hydrology and geomorphology of river corridors. These modifications create a mosaic of aquatic and terrestrial habitats that support a wide range of species. For instance, beaver dams increase the extent of open water, creating ponds and wetlands that provide habitats for various aquatic organisms (Larsen et al., 2021). The transformation of terrestrial areas into aquatic ecosystems and the creation of early successional habitats are particularly beneficial for species such as water beetles, which thrive in the heterogeneous environments created by beaver activity (Nummi et al., 2021). Additionally, the increased habitat complexity and heterogeneity resulting from beaver engineering activities promote biodiversity at multiple scales, enhancing both aquatic and terrestrial ecosystems (Willby et al., 2018). Figure 2 Conceptual models of the influence of beaver dams on surface and subsurface hydrology (Adopted from Larsen et al., 2021) Image caption: A) specifies different types of beaver dams and through flow; B) Conceptualization of hydrological feedbacks as a result of beaver dam construction on surface and groundwater flow paths and storages. C) illustrates potential hyporheic exchange pathways (Adopted from Larsen et al., 2021) 6.2 Increase in plant and animal species richness The presence of beavers has been shown to significantly increase species richness and abundance across various taxa. For example, studies have demonstrated that beaver-engineered habitats support higher species richness and abundance of terrestrial and semi-aquatic mammals compared to non-beaver areas. This includes notable increases
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