Time is one of humanity’s greatest blind spots. We experience it as days, months, or years. But nature functions on much grander scales, measured in centuries, millennia and even longer intervals often lumped together as “deep time.” As paleontologists, we were trained to think in deep time. Yet, as conservationists, we’ve come to realize that time can be confounding.
Humanity’s shortsightedness around time creates major constraints on modern conservation. As the climate and biodiversity crises accelerate, we are urgently working to protect and regenerate ecosystems without understanding how they functioned when they were truly thriving. Indeed, most conservation efforts today, whether reintroducing extirpated species or setting protection priorities, generally consider timescales of a century or less, almost as if species somehow did not exist before Western scientists “discovered” them, and with no good idea if, at that moment, the ecosystem was at its peak.
Evaluating ecosystems based solely on their recent past is part of a larger trend known as shifting baseline syndrome—the tendency for accepted norms in a given place to shift almost imperceptibly over time. Usually for the worse.
A deep time perspective can improve conservation efforts, and our work could make those perspectives easier to visualize.
In recent years, shifting baselines in California and elsewhere have had dire repercussions. For decades, forest management practices throughout the Sierra Nevada called for all-out suppression of even the mildest forest fires, based on the persistent belief—supported by economic interests and aesthetics—that fire was bad for both people and nonhuman nature. These practices resulted in the build up of dense trees, brambles, and other woody kindling that have fueled devastating wildfires.
Until recently we ignored the forest management strategies Indigenous communities had successfully deployed for millennia, in particular the application of small-scale controlled burns. Fire, it turns out, has always been an integral ingredient in healthy forest ecosystems, spurring new growth by thinning the understory, enriching the soil and, for many tree species, aiding their reproduction. Today, we’re beginning to see widespread application of Indigenous knowledge to forest management, tapping into this ancient wisdom.
But how can we know what an ecosystem looked like 100 years ago? 1,000 years ago? One pathway is through modern mathematical modeling. Along with another paleontologist, Roxanne Banker, we have married this kind of modeling with streams of long-term data—for example, natural history museum collections, Indigenous ecological knowledge and the fossil record—and discovered a possible way to preserve the ecosystem of California’s kelp forest, now nearly destroyed. The key factor turns out to be an extinct sea mammal.
Over the past decade, kelp forests, which provide habitat for countless species and prevent coastal erosion by buffering waves, have lost more than 90 percent of their historical range. The cause for this precipitous decline, like the ecosystem itself, is complex. One dominant factor has been the unchecked proliferation of kelp-consuming purple sea urchins. After two of their major predators, sea otters and sunflower sea stars, were pushed to the brink of extinction by 19th-century fur trading and a 2014 ocean warming event, these spiny invertebrates flourished unchecked. The end result has been transformation of complex, three-dimensional kelp forests into large-two dimensional expanses of so-called “urchin barrens.”
Yet, by examining how North Pacific kelp forests existed long before the 19th century, we found that there is a deeper, untold story that could impact kelp forest regeneration. It turns out that we’ve largely ignored the presence of a keystone species and its role in maintaining the harmony of this ecosystem. This oversight is somewhat surprising, given that this creature weighed four tons.
Our model described the interactions between giant kelp and understory algae competing for light and space on the seafloor, sea urchins that consume both kelp and algae, and sunflower sea stars and sea otters that prey on the urchins. We then used the model to predict how the system responds to marine heat waves and outbreaks of sea star wasting disease, recreating the events of the past 10 years. Then we ran the model again, but this time with the four-ton sea creature—the Steller’s sea cow—added in.
This massive herbivore, closely related to the modern-day manatee, lived in near-shore marine settings throughout much of the Pacific Rim. These megamammals inhabited coastal kelp forests, filling their massive bellies with fronds from the upper kelp canopy. All this pruning allowed light to penetrate to the sea bottom, which in turn stimulated growth not only of kelp, but of other kinds of organisms as well, generating a more diverse, resilient understory. In re-creating that vanished historical system that included the Steller’s sea cow, we could see a more diverse forest where the understory competed better with kelp. This forest would have been more resilient against modern stressors.
So, rather than focusing solely on removing urchins or reintroducing sea otters, we might consider deploying teams of humans to selectively harvest kelp fronds, as the Steller’s sea cow once did, to allow light to encourage fresh growth in these underwater forests. Kelp is a culinary delicacy, after all, and the harvest could be sold to grocery outlets and restaurants.
In short, what we assume we know about an ecosystem based on the recent past may impede our ability to fully understand and protect it. Instead of suppressing fires, it is often preferable to employ prescribed burns to bring “good fire” safely back to California’s forests. We advocate for applying similar modeling studies to other ecosystems and conservation efforts. Deep time and an understanding of past ecosystems could significantly change how we carry out conservation work.
No matter where you live, chances are that when you gaze out the window, you’re looking at an ecosystem that is severely degraded compared to 50 years ago, let alone a century or millennium. To ensure that our boldest conservation efforts are successful, we must begin looking at time as an essential tool. We are all characters in an epic story that has been unfolding for millions upon millions of years. The decisions we make today will shape how the future unfolds. It’s high time we embraced our role in this ever-evolving drama and established vital through lines from past to future.
This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.
ABOUT THE AUTHOR(S)
Scott D. Sampson, trained as a dinosaur paleontologist and paleobiologist, serves as executive director at the California Academy of Sciences in San Francisco.
Peter D. Roopnarine, an evolutionary biologist whose work focuses on eco-evolutionary dynamics, serves as curator of geology at the California Academy of Sciences in San Francisco.
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