Cameron Judith Peters

Submerged in two feet of water, Siobhan Fennessy, bundled in a thick coat, scarf and high green rain boots, comfortably moves through a thick forest of native cattails and red-osier dogwoods, instinctually discovering invisible paths as she weaves her way into a marshy wetland. In the agricultural heart of Ohio, early April seems to waver on the periphery of spring, revealing a canvas still filled with winter’s dark golden browns and evergreen. Impervious to the harsh wind and falling snow, the thick sediment that sucks in my boots with each step, Fennessy, a world-renowned wetlands researcher at Kenyon College, excitedly calls the names of plant species as we pass. Often stopping to bend down and point out an emerging flower bud, or thousands of tiny seeds resting on a plant’s stem, Fennessy uncovers a silent world buzzing with genetic diversity, carbon rich biota engaging in mind-blowing chemical and biological processes.

As chemicals from the surrounding farmland flow through this wetland, tiny microorganisms absorb and filter the pollutants, breaking down and neutralizing them before they enter a stream or river. Low oxygen in the soil slows decomposition, allowing thick organic matter and soil to accumulate in layers. Like a freezer, wetlands are long-term super-storages of carbon, nitrogen, alongside other nutrients and chemicals. With all of this organic matter, life thrives.

Covering only 5-8% of the globe, wetlands are deceptively mighty. Holding up to 30% of all global carbon, wetlands regulate biodiversity, climate and water quality. On the brink of water and land, wetlands’ transitional state, defying clear boundaries, proves to be one of their most vital qualities, yet it also makes them one of the most historically challenging ecosystems to define. Over the course of the 20th century, more than half of the world’s wetlands have been eradicated, primarily due to draining and filling for agriculture, the development of homes, and human development. With one foot in the field and the other in a conference room, Fennessy has worked, for the past two decades, to quantify the services wetlands provide, how human activities affects those services, and, more recently, how they are valued, providing new lenses for understanding wetlands on national and even global scales. With these issues, the translation of scientific research into policy holds the highest of stakes.  

“I feel like I work right on the edge,”  Fennessy considers, pausing for a moment, as if visualizing the delicate boundary between politics and science. “We are feeding information to those in policy,” she continues, referring to her role as an expert and lead author on IPBES – the Intergovernmental Panel on Biodiversity and Ecosystem Services – a United Nations sponsored panel that creates assessments documenting the current state of the environment.

“When I started this work 20 years ago, I used to say there were only two problems: one is the x-axis and one is the y-axis.” Sitting in her small third floor office, surrounded in a cocoon of books, Fennessy takes out a pen. She draws two lines.

The resulting graph is familiar, a simple x-y plot. Intersecting horizontal and vertical axes demarcate the graph’s strict boundaries, like a fence nailed into the ground, meeting at a perfect 90-degree angle.

The y-axis stands for “ecosystem services and biodiversity.” Imagine an environment: a soil biome filled with complex microbes and plant vegetation, or a swampy wetland shaped by changing hydraulic patterns, or a forest canopy that shapes all life below in mutually dependent interactions. Each ecosystem creates “ecosystem services,” natural services derived from the environment from which humans’ benefit. Within a wetland these can include nutrient-rich soil which aids agriculture, a result of decomposition and clean drinking water which filters through the soil as it moves through space. Or, the intake and storage of carbon from the air, a powerful benefit that negates climate warming. Ecosystem services are intimately dependent on biodiversity, which, in turn, impacts the diversity of species that inhabit the natural world. Think the mutual relationship between bees and flowers, producing our fruits and vegetables. Ecosystem services and biodiversity. Both equally critical as they are complexly intertwined with the health of the environment.

The y-axis title: “Disturbance (humans).” Humans depend on the natural environment for everything we do. When we create, we draw on its resources for materials, space, inspiration. When we destroy, we draw on its resources for materials, space, inspiration. When we shape the environment, we create ripples of disturbance. The y-axis title: “Disturbance (humans).” Sometimes, human disturbance is permanent.

Cradled within the graph, the first line offers a model for the response of ecosystems to human disturbance. It begins at the top of the page, barely touching the y-axis at the epitome of ecosystem services. The line moves diagonally down the page at a steep and steady slope. Yet, the line stops when it reaches the x-axis: it is here, due to human disturbance, that ecosystem services are most deteriorated. Sometimes, human disturbance is complete. A space does not regain the physical, chemical and biological character lost.   

The second line marks another possibility for the way that ecosystems could react to human disturbance. This line starts at the height of ecosystem health. It remains steady, smoothly moving about a third of the way across the graph. Human actions seem irrelevant. Unconnected. Suddenly, unexpectedly, the line, reaching an invisible threshold, plunges downward at a 45-degree drop, curving the line away about two centimeters from the axis boundary. The line continues. It remains steady. It refuses to move up or down. Severally compromised, Ecosystem services and biodiversity persist. Humans have drastically diminished the environment’s capacity to support life. “We don’t know a lot about how ecosystems react to human disturbance,” Professor Fennessy continues. “By knowing about these levels, you can set targets for restored sites.”   

Three weeks later, as we walk around the ark of the circular wetland, life thrives. Yet, this has not always been true. Residing on a small farm, a friend of Fennessy’s and former colleague, Howard Sacks, participates in a reserve program sponsored by the U.S. Department of Agriculture, a strategy of restoration that provides farmers with financial incentives to restore former wetlands and the benefits they provide. With the removal of an immense cement cylinder drain, originally built to dry the land for agriculture, water began pooling back in, restoring natural hydrology. Wetland seeds, lying in wait beneath the soil for decades, reemerged in a surprising testament to ecosystem resilience. With this diversity, ecosystem processes and the services they provide recover. 20 years after beginning restoration, the wetland is beginning to reform the landscape. However, this process is far from over. According to a study published in 2017 by Scientific Reports, soil nitrogen recovery in restored wetlands is only 50% of that in natural wetlands. This incomplete recovery inhibits a full recovery ecosystem services. Looking up at the sloping hill from our place in the water, the transition from grassy fields to small shrubs into the taller wetland grasses reveals clear boundaries between wetland and farm.

Reimagining the way wetland data is collected, Fennessy, in collaboration with former student and post-doc Amanda Nahlik, a current Environmental Protection Agency (EPA) researcher, set out to collect the first estimates of wetland carbon storage in the U.S. based on unbiased, large scale sampling. Training over 100 researchers from across the country, the two set off on what turned into an eight-year project, collecting and analyzing soil cores from 967 wetland sites across the U.S. Holding about 1% of the global soil carbon, these sites varied from the Eastern mountains to the Florida mangroves.

At each site, deep carbon was analyzed in narrow 120-centimeter soil cores. With most soil carbon stored at 30cm below ground or deeper a complete measurement was secured. This critical step ensured that when the data was scaled up to a national level, accuracy would be maintained. Alongside soil depth, the team recorded human disturbance. Stresses that included ditches and levees that shift or stop the flow of water through the environment were measured against a scale.

Once Fennessy’s data, funded by the EPA, was publicly released conclusions could be drawn. “Just having the numbers, and being able to make that estimate, it was a long time coming” recalls Fennessy. “The signature of [human] disturbance was very distinct and very significant. And what we didn’t expect was that we would see changes at depth as well.” This depth was significant because prior to this study, little had been measured about the way depth impacts the amount of carbon the soil holds. Not only did Fennessy discover a correlation between carbon loss and human disturbance, but also “estimates that show conversion of peatlands to other land uses could [rapidly] release the equivalent of 175-500 years of methane emissions if destroyed,” a major cause of climate warming. Storing ten-times more carbon then costal zones, inland wetlands emerged as high value ecosystems not substantially studied prior to Fennessy’s study.

Yet, the condition of wetlands today is deeply rooted in a history of human involvement. Emerging from banks of the fertile floodplains, like the Nile River, some of the earliest civilizations have utilized wetland services. Today, 40% of global ecosystem services are provided for by wetlands, water quality being one of the highest ranked. In fact, almost ½ of the world relies on rice as their main source of calories, a staple food grown in submerged patties. Rice fields were introduced to the U.S. in the upland swamps of South Carolina. In these hot, swampy fields, slaves produced the majority of rice for the next 200 years, coming to end during the Civil War, after which production shifted westward towards Arkansas and California. While wetlands provide some of the most fundamentally vital services, European culture has historically viewed them as wasted space, leading to their drainage and conversion into agricultural fields and development sites for communities, a perspective shared by a large part of the Western world. In fact, according to Fennessy, 90% of wetlands have been drained in Ohio alone, mostly for agriculture.

The term “wetland” originated from the U.S. Fish and Wildlife Services in the 1950s to describe spaces previously distinguished as swamps, bogs, peatlands, fens, and marshes – terms still used by many European scientists. However, from the very beginning, this term was vague. While it was universally agreed that wetlands would describe ecosystems covered by water for a large portion of time, specifics like how much water, time, and geographic space, were inconclusive.

In fact, in 1988, over 50 definitions existed across the U.S. As a result, legal ambiguities over ecosystem protection led to stagnation in the conference room. Without agreement over what spaces would be protected as wetlands, continued resource depletion devastated the ecosystems. 

According to a 2005 study, continuous development destroys 1% of coastal wetlands a year. Other problems like wetland drainage, and the overloading of nutrients (like fertilizer), a process called eutrophication, lead to long-term issues such as the introduction of invasive species, pollution and salinization.

A growing, palpable excitement builds inside a large hotel conference room in Medellin, Colombia. One hundred of the leading global experts in fields ranging from biology, economics, anthropology, chemistry, and engineering sit in anticipation. It’s early March, and Fennessy sits alongside her colleagues at the last IPBES meeting before the official release of the Land Degradation and Restoration Assessment. Once released, policy makers across the world will have access to these environmental report-cards. Enclosed within the assessments lay the current state of the global land degradation and restoration.

For the past six years, Fennesy has immersed herself in the work of collecting and interpreting the quantitative data on ecosystem health and their current trends, serving on not just one, but two teams -- the Land Degradation Assessment and Restoration Global Assessment, and the America’s Assessment of Biodiversity and Ecosystem Services (which she also heads as a lead author). Fennessy is energized by the possibilities of the IPBES. “It’s science to inform policy. And trying to support policies that make a difference on the ground. Because policy drives a lot of stuff out there.” Even after the data has been collected, the stakes are high. “It’s a struggle. How do you package information so that you can get the complexity across, be quantitative, but make it understandable for people who are not immersed in this material as scientists all the time? How do you communicate that so that it can be useful for people?”

Reaching policy makers today is vital. “We are seriously compromising our ability to live well into the future. I think we will start to see more and more systematic displacement of people and the consequences of losing ecosystems and biodiversity.

“A recent estimate revealed that we have 50 years of top soil left. How are we going to grow crops? That is catastrophic.”

With increasingly warmer temperatures each year, soil grows dry, cracking between your fingers. With low precipitation, carbon, buried deep in the ground for thousands of years, reacts with oxygen and is sucked up into the atmosphere. “This is exactly what is being witnessed in Indonesia” states Fennessy.

Deciding to cut down on their carbon emissions, Germany recently switched their fuel of choice to biodiesel, sourced from palm trees, a cleaner and more renewable fuel source. However, to profit from Germany’s demands for palm oil, Indonesia replaced forested peatlands with palm plantations. They built ditches to drain the soil, meeting the needs of arid growing palm trees. As the soil continues to dry out, devastating peat fires have sprung up. In one year more carbon has been liberated from the soil there then all of the carbon emissions released from Germany combined.

“We need to recognize that these ecosystems have value,” states Fennessy. “If we are going to survive as a species, we need to leave ecosystems intact. We need to protect and restore the biodiversity that generates the benefits we receive from these environments.” Protecting wetland ecosystems saves not only the environment, but also ourselves.

References

T. A. Ontl, and L. A. Schulte, “Soil Carbon Storage,” Nature Education Knowledge, 2012.

A.M. Nahlik and M.S. Fennessy, "Carbon Storage in US Wetlands," Nature Communications, 2016.

LF Yu, Y. Huang, FF Sun, and WJ Sun, "A Synthesis of Soil Carbon and Nitrogen Recovery After Wetland Restoration and Creation in the United States." Scientific Reports, 2017.

 “About: What is IPBES?” IPBES, Accessed May 06, 2018, https://www.ipbes.net/about.

A.M. Nahlik and M.S. Fennessy, "Carbon Storage in US Wetlands," Nature Communications, 2016.

Donal D. Hook, “Wetlands: History, Current Status, and Future,” Environmental Toxicology and Chemistry, 1993.

JB Zedler and S. Kercher, "Wetland Resources: Status, Trends, Ecosystem Services, and Restorability," Annual Review of Environment and Resources, 2005.