By Brandi Goss, Marissa L. Baskett, and Robert A. Lusardi
Humans might be the ultimate ecosystem engineers in the sense that we constantly modify ecosystems and change the processes which drive them. In some cases, this can harm biodiversity by displacing native ecosystem engineers which deliver important benefits for other species and bolster both habitat and species diversity (Romero et al. 2015). Humans also can leverage their ecosystem engineering to benefit biodiversity, such as through mimicking ecosystem engineering structures as part of restoration. Our recent paper (Goss et al. 2025) reviews how mimicked ecosystem engineer structures might help meet restoration goals, and potential risks with the use of these human-engineered structures.
Ecosystem Engineer Restoration in the Anthropocene
In many cases, traditional aquatic biodiversity restoration, such as woody debris installations or channel re-configurations, might be insufficient for improving biodiversity (Palmer 2010). So aquatic restorationists have pioneered process-based restoration, i.e., attempting to restore the range of processes which drive ecosystem health, rather than thinking about individual ecosystem components in isolation (Beechie et al. 2010). Ecosystem engineers can be a key driver of ecosystem processes and could be the pinnacle of process-based restoration. For example, beaver dams shape the distribution of water in aquatic and terrestrial ecosystems as well as the exchange of surface and groundwater. They can provide fish with refuge habitat from high and low flows as well as buffer temperature changes. They can affect the movement of fire on the landscape and provide fire refugia for terrestrial species. They can influence the availability of invertebrate prey for both aquatic and terrestrial predators. These are a few known effects of beaver dams on aquatic and terrestrial processes, showing their importance to ecosystem functioning. However, while ecosystem engineer restoration is a powerful tool for restoring degraded ecosystems (Byers et al. 2006), reintroductions of ecosystem engineers might be limited by current habitat availability or other stressors (Blumstein and Swaisgood 2020).
Novel approaches to ecosystem engineer restoration might be needed to restore ecosystem processes when native engineers are not present, or support reintroduction efforts which could lead to a self-sustaining ecosystem. For example, beaver dam analogs (BDAs), or man-made beaver dam mimics, are being explored as an alternative to beaver reintroduction when reintroduction is infeasible or a bridge to reintroduction when the physical, ecological, or social context of a restoration site requires novel approaches. Initial research on BDAs has shown promising results for fish growth and productivity (Bouwes et al. 2018), thermal buffering (Corline et al. 2024), aquatic invertebrate communities (Corline et al. 2024), and surface-groundwater exchange (Wade et al. 2020). Several researchers at the Center for Watershed Sciences are now at the forefront of understanding this relatively new restoration technique and how it might affect aquatic food webs, how it compares to natural beaver dam structures, and how BDAs might aid coho populations. Research on these structures covers a range of process types and scales and BDAs are one of the better researched mimics of terrestrial ecosystem engineers (Goss et al. 2025, Figure 1).
Ecosystem Engineer Restoration – Mind the Gap
Research on artificial mimicry of ecosystem engineering can improve this restoration approach. There are two main types of ecosystem engineers, allogenic engineers which alter habitat availability through their behavior (e.g., moving materials around to create dams which modify hydrology), and autogenic engineers which create habitat with their bodies (e.g., corals which provide surfaces for other species to colonize, creating complex reef structures). Currently, research on mimicry of marine autogenic engineer structures (such as artificial coral reefs) outpaces research on mimicry of terrestrial allogenic engineer structures (such as artificial burrows), particularly regarding the breadth of process types studied for a given artificial structure type (Goss et al. 2025, Figure 1). For example, research on artificial coral reefs covers the effects of different designs as well as the effects of artificial reefs on physical processes, population dynamics, community composition, and ecosystem services. By contrast, our recent publication “Opportunities, research gaps, and risks in allogenic ecosystem engineer mimicry” (Goss et al. 2025) found that research on artificial burrows as a group, not even for a single species, only covered some design characteristics and impacts of artificial burrows on some focal species such as burrowing owls.
Is Artificial Mimicry Risky?
There are always risks in restoration, which must be weighed against the risks of inaction. A structured decision-making approach can help managers and landowners assess the risks and benefits of a suite of actions in light of management objectives identified by stakeholders (Hemming et al. 2022). This approach to environmental decision-making is bolstered when projects take an adaptive management approach (Williams and Brown 2014), integrating scientific hypothesis testing into restoration work by estimating project outcomes and testing if the management action achieved those outcomes. This process of knowledge gathering facilitates more accurate prediction of outcomes in later rounds of decision-making.
A key risk of artificial mimicry of ecosystem engineering is evolutionary traps (Goss et al. 2025). Evolutionary traps might occur when a restoration action changes the landscape to deliver an environmental cue to an organism that in the past might have triggered a response by that organism which is now disadvantageous. For example, BDA installations might lead to fish strandings as droughts become more common by providing good rearing habitat for juvenile salmonids that could dry during drought.
Research in several areas could help reduce the risk of evolutionary traps and other unintended consequences of artificial structures and might be incorporated into adaptive management for project implementation. We highlight such research gaps and opportunities to improve the application of artificial structures in Goss et al. (2025). Gaps discussed include: 1) more direct comparisons between the effects of natural and artificial structures, 2) how design and placement of artificial structures affect management outcomes, 3) how artificial structures perform at different spatial, temporal, and ecological scales, and 4) when artificial structures result in co-benefits for landowners and ecosystems.
Aquatic Ecosystem Engineer Mimicry Research
While there are risks to more active and experimental management, artificial mimicry might be an important tool for restoration, particularly in ecosystems with great degradation or conflicts with human interests. For example, landowners can provide input on installation sites to minimize effects on human land use while providing ecosystem benefits. This exemplifies a reconciliation approach to restoration where ecosystems are designed to balance both biodiversity and human needs. Mimicked beaver dam structures might also help where habitat is not suitable for beaver due to lack of food resources, but where BDAs might support growth of riparian vegetation, providing those food resources and refugia from predation.
Because of the importance of water for both ecological and human communities and the experimental nature of installing artificial structures, aquatic artificial ecosystem engineer structures such as BDAs could be an important research nexus to understand a range of environmental, social, and theoretical problems in restoration work. Such research could bring together scientists, managers, and landowners by emphasizing the production of co-benefits for ecosystems and landowners while reducing unintended consequences.
For the full paper, please see Goss et al. 2025: http://doi.org/10.1111/cobi.70018
About the Authors
Brandi Goss is a PhD candidate in the Graduate Group in Ecology. Dr. Marissa L. Baskett is a Professor and Associate Director of Research for the Coastal and Marine Sciences Institute. Dr. Robert A. Lusardi is an Assistant Professor in the Department of Wildlife, Fish, and Conservation Biology and Associate Director at the Center for Watershed Sciences.
Further Reading
Beechie, T., Sear, D., Olden, J., Pess, G., Buffington, J., Moir, H., Roni, P., Pollock, M. 2010. Process-based principles for restoring river ecosystems. BioScience. 60:3; 209-222.
Goss, B., Baskett, M. L., Lusardi, R. A. 2025. Opportunities, research gaps, and risks in allogenic ecosystem engineer mimicry. Conservation Biology. http://doi.org/10.1111/cobi.70018
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