Thoughts From Engineers: Investigating Biodiversity and Resilience

Extreme weather events such as the 2018-2020 drought in central Europe, the 2022 heat wave and drought in the wider European region, and other record-breaking events across the planet are becoming common. The International Panel on Climate Change issued statements in recent years regarding the effect such weather and climate-driven events have had on ecosystems, rates of species decline and biodiversity across the globe. Some in the scientific community suspect that the more biodiverse an ecosystem, the better it’s positioned to withstand—and potentially even dampen—the most damaging effects of climate-driven weather events.

These relationships and interactions may seem comparatively inconsequential in view of the urgency surrounding issues such as the design of hospitals or water-treatment facilities, yet strategies to bolster the resilience of our communities increasingly integrate nature-based solutions such as green roofs, vegetated bioretention systems, urban forests and more. Whether we’re using vegetation to reinforce slope stability in coastal zones, provide reprieve from summer heat with tree canopy or aim for larger-scale management strategies that span broad geographic regions, research that provides some insight into relevant interactions gains importance with each extreme storm.

Professor Mahecha at Leipzig University and researchers from several universities (bit.ly/EcosystemClimateImpacts), for example, reviewed existing climate studies to draw conclusions about how biodiversity and extreme weather events could affect one another. The following summarizes key findings, but more importantly underscores that existing research falls short in answering important questions.

Biodiversity Basics

Biodiversity is a broad term that captures different types of variability within a community, ranging from genetic and taxonomic diversity, functional diversity (variety in ecosystem processes), structural diversity (relating to dimensional characteristics), and landscape diversity (relating to different arrangements of ecosystems on a landscape). To illustrate biodiversity at work, consider an example from the field of hydrology: When a rainstorm strikes, the structure of vegetation on a slope—consisting of various plant heights at different densities and distributions along the hillside—plays an important role in intercepting and controlling the water flow and general hydrological dynamics of the event.

But extreme events may impact more than just the structure of vegetation; extreme events also can affect functional properties—such as the ability to take up nutrients or assimilate CO2. When air temperatures increase, plants release water into the air and cool the local environment through the process of transpiration, effectively modifying (at least in that microclimate) some aspects of that weather event. If the extreme event becomes more intense—a prolonged drought for example—these functional processes are affected and ensuing shifts in biodiversity through time can further modify these pathways. Mahecha’s team suspects that different types of biodiverse communities have an “edge” under extreme conditions and that this advantage allows them to resist the impacts of the most extreme weather events.

Interconnections and Feedback Loops

The overarching conclusion is that there are many unknowns. Existing research appears to show that biodiversity and the associated land-surface energy dynamics may affect specific types of extreme events, but the dynamics aren’t well understood. Mahecha’s article states “despite the apparent logical relationship between biodiversity, vegetation attributes, fire-atmosphere dynamics, and their impact on subsequent extreme events, scientific evidence that quantifies these links and their effects on ecosystem resistance and resilience remains sparse.”

Research shows that ecosystem functionality is affected by climate extremes, but whether this warrants a management approach that deliberately increases functional diversity needs to be further investigated. This team also strongly advocates for research that assesses how different types of biodiversity create buffers against climate extremes in quantifiable ways. These studies, the team argues, need to be done at a variety of temporal and spatial scales—within local green infrastructure installations and larger catchments as well.

Data Drive the Way Forward

We’re preparing for the future by revising precipitation estimates and refining climate models to better predict complex atmospheric dynamics. The 3D hydrography program launched by the U.S. Geological Survey as well as NASA satellite programs are only a couple of the many initiatives designed to drive data collection and much-needed analyses. Issues raised by Mahecha’s paper would benefit from a multi-disciplinary approach that blends the expertise of hydrometeorologists, ecologists, engineers and other professionals.

Our understanding of what makes the systems of our lives resilient in the face of climate extremes is evolving and so, too, is our definition of what makes a city functional and livable. Fifty years ago, we wouldn’t have equated trees with important city infrastructure, yet today a stand of trees, capable of creating a microclimate that significantly lowers air temperature, can be arguably lifesaving. In general, we tend to overlook our dependence on the health and integrity of the many different types of ecological communities of which we’re a part. Mahecha’s paper advocates for more research that analyzes the complex relationships among ecosystems and climate-driven weather events and the extent to which they may shape one another. The sustainability, resilience, and livability of our cities will benefit from a better understanding of the feedback loops and atmospheric drivers at the intersection of biodiversity and climate change.