The term “ecosystem engineer” seems to have been coined by Clive G. Jones, John H. Lawton, and Moshe Shachak in a 1994 paper entitled Organisms as Ecosystem Engineers. In this paper they used beavers as the landmark example of a species that has impacts beyond their physical form. That is to say, while all species impact their ecosystems by eating some things and being eaten by others, some special species live and behave in ways that cause widespread changes. In some cases this results to major modifications to the original environment. In others, like my backyard beavers, their actions actually generate new ecosystems within the larger environment.

When they first move into an area and bring down trees, beavers are selective. They tend to choose certain species over others and this serves to change population dynamics in the surrounding woodland. The large rodents then turn their cut timber into water blocking dams which convert swift running streams into still and tranquil ponds. This change drowns some plants while watering others. My own beaver pond is filled with the still standing skeletons of drowned pines while those growing around the pond’s edge reap the rewards of an elevated water table. Swift-current specialists who are of no concern to the beavers abandon the tributary blocked by the dam. These effects can be shockingly far reaching. Migratory salmon, for instance, returning to their natal tributaries from a life at sea stop using rivers with upstream beaver dams and in the Arctic at least, beluga whales who specialize in hunting those salmon stop entering the dammed rivers as well. The ecosystem modifications don’t stop there. A host of subtle and varied changes begin to take place. Still-water specialists move into the niche abandoned by the swift-water specialists. Sediment brought downstream begins to collect in the pond, bringing with it a rich supply of nutrients. Grasses and brushy plants take advantage of the lack of competition from trees and the newly fertilized soil. It is a vibrant cascade of changes as life adapts and shifts to capitalize on the novel environment.

Beavers are the gold standard by which we understand ecosystem engineers, but they are far from the sole example. When the concept was originally proposed, it was suggested that ecosystem engineers fall into two distinct categories, allogenic and autogenic. The distinction is fairly simple. Allogenic engineers, like the beavers, shape the environment through their actions. The goals of their actions are the attainment of food and shelter but the results of these actions are far-reaching, dramatic, and exist on a scale far beyond what is considered normal for a species of their general size and population density. As for the autogenic engineers, they are the species that modify the environment simply by existing. The simplest autogenic examples are trees. The primary factor that makes a forest ecosystem a forest ecosystem is the presence and persistence of trees. The diverse and interconnected life of a forest ecosystem is intrinsically dependent upon the existence of the trees. A forest quite literally cannot exist without trees. As with the beavers, the impact of the pines in my backyard stretches far beyond the nutrients they consume and those they supply. Their massive structures provide shelter for animals, many of which the trees are completely oblivious too. The leaf litter of fallen pine needles and sloughed bark provides cover for innumerable insects and smaller animals while also providing a nutrient source and seed bed for germinating plants. The vast shaded areas they create prohibit colonization by some shade-intolerant plants and provide ideal living conditions for others. As with the beavers, the list of effects to an ecosystem generated by trees is both lengthy and subtle.

As it turns out, many of the species in the Safari West collection qualify as ecosystem engineers as well. In that initial paper published by Jones et al, they mentioned crested porcupines as allogenic engineers. The two species of crested porcupine are found throughout much of Subsaharan Africa and into the Indian subcontinent. Like beavers, they are large rodents with industrious attitudes. Crested porcupines aren’t builders however, they’re excavators. They dig large holes in their constant quest for edible tubers and roots and over time, those holes accumulate runoff and organic matter, which turns them into ideal spots for germinating seeds. Studies have shown vastly increased plant diversity in porcupine pits as compared to control plots.

The many hoofed animals that make their home at Safari West have also been called ecosystem engineers although their engineering contributions are less friendly toward humans than others we’ve considered. In Africa, heavy-bodied hoofed animals congregate around water holes and rivers across the continent. As they do, their hooves create deep impressions in the mud that then fill with warm stagnant water; the ideal breeding ground for mosquitos. It has been argued that without the abundance of larval nurseries inadvertently constructed by thirsty ungulates, the mosquitos of Africa would be far less ubiquitous than they are. In a less itchy example, it has also been suggested that massive herds of ungulates, like our zebras and wildebeest, have the additional engineering impact of widespread fertilizing and tilling action on the soil. Essentially, as these large migratory herds move, they transfer nutrients from where they cropped a mouthful of grass to where they dropped their dung. The action of literally millions of hooves on this fertilized soil tills and turns it, preparing the land for new growth; an effect similar to how we humans plow and fertilize our fields. These actions have little to no direct impact on the herds but indirectly impact available resources for other organisms within the ecosystem.

These few examples are interesting but they also hint at a potential problem with the idea of ecosystem engineers. If we look closely enough, won’t we find that all organisms shape their environment in some form or another? After all, hoofed animals aren’t the only things to leave footprints in the mud and shrubs also produce leaf litter and shade. In point of fact, this idea has long been a major point of contention in the academic community. The general consensus now is that in order to qualify as an ecosystem engineer, an organism must make a substantial impact on its environment, on par with or exceeding the impacts of purely physical forces (erosion, wind, fire, etc). This makes for a vague and readily contested definition but it doesn’t diminish the primary point which is this: we humans and the other forms of life crawling, swimming, and flying around this planet are not mere occupants on this world. We are equal parts inhabitants, destroyers, and ultimately, builders of the ecosystems in which we live our lives.

Now that we’ve established the role that these ecosystem engineers play, it’s appropriate to wonder: what does this have to do with conservation? I believe that part of what makes the fight to save the endangered species and ecosystems of this world so difficult and frustrating stems from a misconception in how the world works. Species are born, evolve, succeed, fail, and go extinct all the time. These ongoing processes are part of the natural pattern of life and came into play the moment the very first single-celled organisms bloomed into existence. Just as children are meant to grow into adults, so species are meant to develop and change as they interact with each other and their environment. Likewise, the ecosystems these interacting species make up will shift and transform, grow and recede, ebb and flow as the underlying interactions governing their existence vary.

For example, once not all that long ago, my backyard was an unbroken stretch of forest. The pines and the aspens struggled with one another for their place in the sun. Some thrived, others starved, and the forest remained healthy and strong. Then a pair of beavers moved in and started logging. Had I lived here then, I may have viewed those beavers as an invasive species, a destructive pest wreaking havoc on the stability of the forest. They cut down some trees and drowned others. They flooded the forest floor and in their wake other species of plant and animal, alien to that stretch of forest moved in. The system changed.

Now my backyard contains a luscious pond. Greenery abounds and with it I get to enjoy the chirping and trilling of many species of bird. I get to watch the deer wading in the shallows. I get to watch the corn lilies and ranger’s buttons and wolfsbane blooming in the bright springtime sun. It’s a healthy and vibrant ecosystem and one which never would’ve existed under a paradigm of conservation focused on the idea of preserving what is right now at the expense of what once was or potentially could be.

Eventually, the beavers will leave. Maybe the primary pair will die and none of their offspring will take their place, or we’ll have an exceptionally wet spring and their dams will fail and wash away, or maybe one of the local coyotes will catch them unaware someday. One way or another, at some point, the time of the beavers in this location will come to a close. When it does, the dams will break down and the pond will drain. The stream will cut a new course across a swath of open land rich with accumulated sediment and sunlight. A meadow will form filled with tall grasses and the herbivores that graze on them. The entire habitat will shift from what it is now into something new. To be honest, I do not look forward to that day. In time, the aspens and pines that wait patiently on the edge of the pond will drop seeds in that someday meadow. Over time it will be recolonized by the forest. The ecosystem will change yet again. The key to a healthy ecosystem isn’t stasis but stability. The pond isn’t permanent and the meadow that replaces it won’t be either. The important thing is that when one of those habitats fade, something must arise in its place.

Too often, those of us who care about the natural world focus on how it is in the now. We want to preserve the world as it exists in the brief moments in which we are lucky enough to experience it. Alternatively, we want to turn back the clock to some idealized and Edenic past. This is a false paradigm. The idea of “ecosystem engineers” may be a bit vague and scientifically problematic, but it is real enough to demonstrate the flaw in that idealized way of viewing the world. We should not, and in fact, cannot preserve the world in amber. When we focus our efforts on an endangered plant or animal, the question should be asked; is this species failing because of a breakdown in the system or is it failing because of the system itself?

Instead of frantically trying to catalog and preserve every rarefied or declining species, or repopulating them to an arbitrarily established historical norm, perhaps we should instead focus our attention on understanding the mechanisms that drive these changes. They won’t always stem from something that needs to be “fixed”. Our tendency is to view any loss as inherently negative, but when we do that, we neglect the reality that when one species fails, another succeeds. We may lament the loss of the dinosaurs, but we should do so while remaining aware that if they were still here today, we probably wouldn’t be. The beauty of life is not that it stays the same, but that it is always changing, always trying new things. We can mourn the changing of the world, but as we do, we should also be excited to discover what it will become next.

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2016 marks the 100-year-anniversary of the National Park Service (NPS). Since its inception a century ago, the NPS has been on the forefront of American conservation. Thanks largely to its successes in setting aside spaces for the protection of wildlife, we haven’t continued to see the major die offs and extinctions that marked the early history of the United States. While the herds of bison that once famously roamed in the millions through the American midwest may be largely gone, healthy and stable populations exist on managed lands in twelve states. Nearly half of these are found in Yellowstone National Park. The visibility and viability of our National Park System coupled with their well-documented successes have helped to create the current conservation culture and the methods it employs. Most of the time, the culture focuses its efforts on setting aside habitat and protecting animals where they live.

In 2001, the NPS published a report titled “Rethinking the National Parks for the 21st Century”. In it they outlined both the strengths and weaknesses of the park system as it exists and noted the following:

“Actions to preserve biodiversity cannot be limited to park areas, for parks are often parts of larger ecosystems that encompass them. To encourage ecological stewardship outside the parks, the Service should cooperate extensively with its neighbors—federal agencies, states, counties, cities, tribes, the private sector, even other countries. Parks cannot survive as islands of biodiversity. They need to be linked with other natural areas through wildlife migratory corridors and greenways.”

This report makes explicit the realization that changes in major migrations are likely to have major impacts on the ecosystems they pass through as well, including those that are otherwise protected.

Wildebeest are famous migratory species and one which we are lucky enough to have here at Safari West. Every year, a massive herd of grazers (including zebra, Thomson’s gazelles, and a million or so wildebeest) roam up and down the Serengeti; taking part in one of the largest land migrations on the planet. As these massive herds travel they provide sustenance for innumerable predators. Lion prides with established territories take full advantage of this moveable feast as it winds through their territories. Giant crocodiles in the Mara River wait patiently for the feeding frenzy that occurs with the arrival of the herds. Should a highway project or urban development interrupt this migration, stopping all those ungulates in their tracks, it would trigger an ecological disaster. The huge numbers of herbivores would quickly overgraze the territory they had stopped in, damaging the environment and leading to starvation. Ahead of the broken migration, the predators would suffer. They’d begin to apply increased pressure on other prey species within the ecosystem and in all likelihood, populations would decline on both sides.

Wildebeest contribute to the ecosystem in other ways as well. Millions of wildebeest produce millions of pounds of manure and spread it far and wide as they travel. Not only does the savanna gain free fertilizer, it is also tilled by the motion of millions of sharp hooves. This constant cropping and fertilizing benefits the plant life of the Serengeti immensely. The Serengeti without this valuable soil amending service would be a much different place.

In North America, we’ve seen ecosystems shift as a result of failed migration already. Consider one of our most famous wild spectacles, the annual salmon run. Most Pacific and Atlantic salmon species have a life cycle that is highly dependent on migration. Born in tributaries and streams far from the ocean, young salmon move downstream to the sea where they mature. After several years and as they approach the end of their life cycle, the salmon return to the river mouths and commence a long upstream swim to their birthplaces. In some cases, this migration takes them from the Pacific coast inland as far as Idaho (a 900-mile swim against strong currents and rapids). Once they reach their natal streams, they breed and shortly thereafter, they die.

Salmon are very important animals economically and so benefit from regulations designed to prevent overfishing and keep the population strong. We’ve also become quite adept at supplementing wild born fish with fish from commercial hatcheries. As a result of these practices and others, salmon are under no immediate threat of extinction. This healthy population-count hides the fact that wild salmon populations have undergone a steep and steady decline over the last two centuries. Why? Because we failed to take migration into account. We’ve done a decent job limiting fishing and ensuring that there is always suitable breeding stock moving upstream, but we haven’t always been as good at protecting that freshwater pathway or the streams they start and end their lives in.

Salmon populations have been decimated by a number of anthropogenic causes, among the most famous of which are our dams. Dams have the two-fold impact of blocking mature salmon from swimming upstream while simultaneously directing downstream moving youngsters into power-generating turbines. We’ve made numerous strides to correct these problems, largely by adding “fish ladders” that adult salmon jump up to bypass dams and opening spillways for the youngsters to keep them from going through the turbines. All told, while the situation is improving a bit these days, salmon runs are barely a fraction of what they once were.

Still, the total population remains strong, and we can raise new salmon in commercial hatcheries, or even farm them outright if it comes down to it (environmentally disastrous but entirely possible), so does it matter if they no longer migrate upstream? The answer to this is a simple and straightforward, yes. The salmon migration is essentially a giant nutrient transfer system leading from the bountiful sea up into mountainous forests. As mature and heavy-bodied fish leave the ocean and swim upstream, one of two things usually happens. Either the fish die en route; perhaps caught by a bear or killed by disease, or they survive their marathon swim, make it to their spawning grounds, breed, and then die. Those that get eaten add their sea-sourced nutrients to the ecosystem directly. Those that die in other ways, decompose and fertilize the downstream habitat with nitrogen, phosphorus, and other nutrients. The salmon run is not only a critical piece of the salmon life cycle, it’s also an important source of nutrition that has major impacts on the river and forest ecosystem at large.

It’s interesting to note that while the loss of a migration results in a dynamically changed environment, migration itself is an evolutionary response to a dynamically changing environment. In a land of eternal spring, birds would have no need to fly south. If winter snows didn’t bury mountaintop vegetation, elk wouldn’t need to head to the valleys. If the Serengeti weren’t seasonally dry, wildebeest wouldn’t have to follow the rains. These things do happen, however, and life has found ways to adapt to the changes. In a dynamic world, movement is a key survival strategy. If the wildebeest stop migrating, their ecosystem will be fundamentally changed. If the ecosystem itself changes, however, if the dry seasons get longer, or the weather patterns move north, the wildebeest need to be able to move with them. The major problem with not considering migration when we think about conservation is that we often wind up boxing in our species at risk. If they cannot change with a changing world, they die.

Like the world at large, conservation has to be dynamic. We’ve conserved a lot through the careful creation and management of parks and preserves, but now we know that’s not enough. Now that we’ve learned that these parks cannot exist as islands cut off from the world, we’re adjusting our techniques. We’ve only just begun to step back and examine the systems that connect one protected patch of green to another but as we learn, we must incorporate that knowledge into our plans. The future of conservation lies not in slicing out plots of wild, but in learning how to protect the systems by which life continues to adapt to an ever-changing world.

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