Ecosystems

Jul 23, 2015

CEC Meeting a Win for Public Health in North America

climate change, Ecosystems, emissions, energy, environmental challenges, public health, water 7 Comments

Administrator Gina McCarthy closes the 2015 CEC Council Session in Boston.

Last week, I was thrilled to host the Canadian Environment Minister and Mexican Environment Deputy Secretary at the 22nd Regular Session of the Council for the Commission on Environmental Cooperation (CEC) in my hometown of Boston.

The CEC is an organization created by the United States, Canada and Mexico to address environmental concerns in North America—because pollution doesn’t carry a passport. As Chair, I represented the U.S. Government on the Council and took the lead in discussing our future as neighbors and allies in protecting public health and the environment.

Impacts from climate change like more extreme droughts, floods, fires, and storms threaten vulnerable communities in North America and beyond. And along the way, those who have the least suffer the most. That’s why our three nations are committed to working together to tackle climate challenges. I’m looking forward to continuing our cooperation this fall in Paris as we work to bring about concrete international action on climate.

At this year’s session, the Council endorsed a new 5-year blueprint to help us tackle environmental challenges our nations face together. We’ll focus on climate change: from adaptation to mitigation; from green energy to green growth; from sustainable communities to healthy ecosystems. The plan presents our shared priorities to make the most of each other’s efforts to address environmental challenges.

Looking toward the future, we discussed the possibility of using the CEC as a way to address climate impacts on other important environmental challenges like water quantity and quality, renewable energy, energy efficiency, and oceans.

During our conversations, EPA’s Trash Free Waters program caught the interest of the other ministers on the Council. Through community outreach and education, EPA is working to reduce the amount of litter that goes into our lakes, streams and oceans. We discussed ways we could build on its success and expand it to other cities in North America.

Administrator Gina McCarthy with Leona Aglukkaq, Canada’s Minister for the Environment, and Rodolfo Lacy Tamayo, Mexico’s Secretary for Environment and Natural Resources, at the 22nd Annual Council Session of the North American Commission for Environmental Cooperation.

The Council also reaffirmed the CEC’s Operational Plan for 2015–2016, which is focused on producing tangible outcomes and measurable results. The plan proposes 16 new projects that bring together our experts on work like reducing maritime shipping emissions to protect our health from air pollution, and strengthening protections for monarch butterflies and pollinators.

We named a new roster of experts on traditional ecological knowledge from Canada, Mexico and the United States. Alongside science, traditional knowledge helps us understand our environment, helping us better protect it. The experts will work with the CEC’s Joint Public Advisory Committee (JPAC) to advise the Council on ways to apply traditional ecological knowledge to the CEC’s operations and policy recommendations.

We also announced the third cycle of the North American Partnership for Environmental Community Action grants, a program that supports hands-on projects for low-income, underserved and indigenous communities across North America. The program supports communities’ climate-related activities and encourages the transition to a low-carbon economy.

We ended the meeting with Mexico assuming chairmanship for the upcoming year. It’s an honor to work with our neighbors to address environmental challenges head-on, and to make sure North America leads on global climate action. When we do, we protect our citizens’ health, our economy, and our way of life. Learn more here.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.

May 20, 2015

Wetlands Wednesday: Share My Surprising Trip Across Iowa

Ecosystems, water, Wetlands Wednesday 3 Comments

By Cynthia Cassel

The third leg of our journey to the fascinating wetlands of the four Region 7 states has surprises in store, as we continue our May series to celebrate the 25^th anniversary of National Wetlands Month. After my trip to Kansas’ wet meadows and farmed wetlands in last week’s blog, we now travel northeast to inviting Iowa.

In search of something to do that was slightly goofy while on a trip to the state, I planned a visit to the Amana Colonies in an effort to recreate Grant Wood’s famous American Gothic painting. We brought our own pitchfork and steel-rimmed glasses, and made complete fools of ourselves. Maybe not such a great idea, after all.

However, the rest of the trip all around Iowa was one of the best road trips we ever took. While admiring more of the beautiful green and gold croplands of the Heartland to be sure, we beheld a wonderful surprise: prairie potholes and fens.

Prairie Potholes and Fens

Washington State has an entire state park created around its potholes, but I never knew they existed in the Midwest until that trip. Seeming otherworldly, potholes look like craters created by shrapnel from a cosmic shotgun. We also marveled at the multitude of fens – rare, groundwater-fed places that feel like walking on a water bed. Think of peat bogs.

Prairie potholes and fens

So here’s a tip: Go see the Grant Wood home, but be sure to make time to visit the potholes and fens, and take note of the rare plants and animals support by these wetlands. And then go ahead and visit the rest of the state. There’s much to do and see in the beautiful state of Iowa!

Prairie potholes are wetlands (primarily freshwater marshes) that develop when snowmelt and rain fill the pockmarks left on the landscape by land-scouring glaciers. Groundwater input is also important. Submerged and floating aquatic plants take over the deeper water in the middle of the pothole, while bulrushes and cattails grow closer to shore. Wet, sedgy marshes lie next to the uplands. In addition, many species of migratory waterfowl are dependent on the potholes for breeding and feeding.

Flowering plants in Iowa wetland

Fens are alkaline (slightly acidic) wetlands less than 10 acres in size that are groundwater-fed and peat-forming. Their water supply is by surface water runoff and/or seepage from mineral soils. Fens are important sources of groundwater discharge and indicators of shallow aquifers. Most are found along stream terraces or at the base of slopes. Fens in headwater streams are difficult, if not impossible, to replace due to their unique hydrology. They’re often called “quakers” because the ground beneath them is saturated and spongy. A good jump on a fen will cause the ground to ripple for many feet.

These Iowa wetlands are important for environmental sustainability. Prairie potholes absorb surges of rain, snowmelt and floodwaters, thereby reducing the risk and severity of downstream flooding.

Cynthia Cassel has worked as a Senior Environmental Employment (SEE) Program grantee with EPA Region 7’s Wetlands and Streams Protection Team for 5½ years. She received her Bachelor of Science from Park University. Cynthia lives in Overland Park, Kan.

Editor's Note: The opinions expressed herein are those of the author alone. EPA does not verify the accuracy or science of the contents of the blog, nor does EPA endorse the opinions or positions expressed. You may share this post. However, please do not change the title or the content. If you do make changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.

May 15, 2015

Invasive Species Alert: Zebras on the Loose!

Ecosystems, environmental education, epa, water 0 Comments

By Angela Sena

I don’t mean the four-legged variety, but zebra mussels! They are an invasive mollusk species (Dreissena polymorpha) that have been found in many lakes and rivers across the Heartland. Zebra mussels have been discovered in scattered locations along the Missouri River, Lake Lotawana, Smithville Lake, Lake of the Ozarks in the Osage River, Bull Shoals Lake, and Lake Taneycomo in the White River, just to name a few. For those who are water recreationists – boaters, anglers, water skiers, sailors or canoeists – we all need to keep our eyes open for this species and help prevent their spread since there is no known way to stop them once they get a foothold.

Zebra mussels (Dreissena polymorpha)

Zebra mussels are a group of freshwater mussels with triangular shells and dark bands with prominent ridges. A concavity (or hollow) about midway allows the animal to secrete byssal threads, which allow it to attach to almost any solid surface. They often clump together, and adults are generally ¼ to 1 inch in length. Zebra mussels are native to the Caspian Sea region of Asia, and were accidentally introduced to North America from ballast water of an international ship. They have tremendous reproductive capabilities: a female zebra mussel can produce more than a million eggs during spawning season. The eggs hatch into a larval form (veligers), which are not visible to the human eye, making their detection and eradication difficult. At three weeks, the sand grain-sized larvae start to settle and attach, and feel like sandpaper on solid surfaces.

This invasive species can hitchhike by attaching to boat, canoe and watercraft hulls, lower units and propellers, axles, engine drive units, trolling motors, hitches, and anchor chains. They can also survive in boat bilge water, livewells, bait buckets, and engine cooling water systems. Aside from being an inconvenience for your water craft equipment, they negatively impact the economy by clogging power plant intakes and industrial and public drinking water intakes, and damaging boat hulls and motors. Zebra mussels also harm native ecosystems, and decimate native freshwater mussels and other aquatic animals.

If you enjoy spending your summers on a lake, just like my family, then we all need to do our part. Water recreationalists can help by preventing the spread of the species with a few simple steps:

Clean – Remove all plants, animals and mud, and thoroughly wash all equipment with hot water spray (104 degrees), especially in small crevices or hidden areas. Most car washes will suffice. If you can’t wash at that temperature, a 10-percent solution of bleach will do.
Drain – Eliminate all water before leaving the lake, including livewells and transom
Dry – Allow sufficient time for drying between water events – at least 48 hours.
Dispose – Dispose of unused bait in a trash receptacle.
Report – Report any sitings of these species. The U.S. Geological Survey maintains a Nonindigenous Aquatic Species (NAS) website for zebra mussels that shows an up-to-date map of recorded occurrences, and includes a “Report a Sighting” link that allows you to submit a report if you find them.

USGS Where Are the Mussels

However, if you do spot a mussel when you’re out enjoying a lake or stream, don’t worry. Not all mussels are unwelcome. In fact, most mussels here in the Heartland are a good thing. Check out these previous Big Blue Thread blogs by EPA’s Craig Thompson: Mussels in the Blue, Mussels in the Blue II: Relative Abundance of Species in the Blue, and Mussels in the Blue III: Water Quality and Threats.

Angela Sena serves as an Environmental Protection Specialist with the Water, Wetlands, and Pesticides Division at EPA Region 7. She has a degree in environmental science and management, and is a native New Mexican and avid outdoorswoman.

Apr 16, 2015

It’s Arrested Urban Watershed Development

Ecosystems, food chains, narragansett bay, Nutrients, urban watersheds, watershed development 0 Comments

By Annie Zwerneman

They say April showers bring May flowers – but what happens to the rain that doesn’t end up watering plants?

In areas where the natural vegetation has been replaced by buildings, pavement, and other types of human development, a good deal of that rain water doesn’t get absorbed. Instead, it flows across the watershed, picking up pollutants and nutrients as it goes. In large urban areas, the natural systems can quickly become overwhelmed, leading to trouble in the form of impaired water bodies downstream, increased erosion, and damaged ecosystems.

EPA interns sampling a stream near Providence, RI.

EPA scientists helped address the growing concern for these pollutants by testing the waters in streams throughout the northeastern United States. A team of EPA researchers, led by Nathan Smucker and Anne Kuhn, set out to understand how we can better manage pollution that negatively affects valuable freshwater resources.

Smucker, Kuhn, and their team selected sites to research that were evenly distributed throughout the heavily urbanized Narragansett Bay watershed. Specific sites were picked in order to capture a complete range of low to high development in watersheds that drain to the bay.

The science team focused on how important components of stream food webs and water quality were affected by urbanization. In conjunction with other EPA research in the region, they found that riparian vegetation was integral to reducing negative impacts on algae and macroinvertebrates associated with watershed development. Stream ecosystems and food chains are further impacted when riparian vegetation is destroyed by development or erosion. Their research showed that if vegetation buffers are maintained next to streams, some of the negative effects of watershed development can be reduced.

Results from the research and literature review analysis will provide insight into preventative actions for decision makers that are building or developing on watersheds and aid with managing stream resources in watersheds with existing development. By identifying how past development has affected stream ecosystems, we can predict what might happen as ongoing development occurs, and we can work proactively on strategies to keep ecosystems intact and pollution at bay.

About the Author: Annie Zwerneman is an intern for the EPA’s Office of Research and Development.

Apr 10, 2015

Cherry Blossoms: A Sure Sign of Spring and Maybe Climate Change

Cherry Blossom, Cherry Blossom Festival, cherry trees, climate change, Ecosystems, natural resources 0 Comments

By Krystal Laymon

When I moved to the District of Columbia last spring, I couldn’t wait for the roughly 3,750 cherry trees surrounding the Tidal Basin and many of our major national monuments to burst into bloom. Tourists and residents flock to the area every year to hurriedly snap a few photos, because these beautiful flowers have a short life cycle with a peak bloom of only a couple of days.

The bloom schedule of the cherry trees, like most plants, is phenological, which means that the timing of their bloom is dependent on the conditions of their environment. While the East Coast has experienced colder-than-normal temperatures and several inches of snow late in the season, it has not deterred this year’s cherry blossoms from blooming.

In fact, over the past 90 years, the cherry blossoms have actually been blooming earlier. The figure below presents data from the National Park Service that shows the annual peak bloom date – when 70% of the blossoms are in full bloom – for these cherry trees from 1921-2014. Look at the black line that helps to show the trajectory of change in that peak bloom date over time. It shows that, since 1921, peak bloom dates have shifted earlier by approximately 5 days. This is due to in part to increasing average seasonal temperatures, particularly in March, over this time period. The Washington Post even performed a local temperature analysis in 2012 which showed that “Washington’s average March temperature has warmed 2.3 degrees in the last 90 years.”

Tracking cherry blossom bloom trends isn’t just important for scheduling the District’s annual Cherry Blossom Festival. Indicators of the start of spring, like leaf and bloom dates, will become increasingly important for determining how climate change may affect seasonal patterns, and for tracking related impacts on ecosystems and natural resources.

This March in DC, we’ve experienced some cold sweeps, and as a result this year’s projected peak bloom date of April 11-14 is later than expected. However, this short-term blip belies the longer-term pattern of longer growing seasons and earlier bloom times – which is a key concept to understand when it comes to climate change. Year-to-year, seasonal occurrences such as bloom times or thaws may vary widely, but the long term trends tell the real story — and this national treasure is telling us by opening its petals, and blooming.

Peak Bloom Date for Cherry Trees Around Washington, D.C.’s Tidal Basin, 1921–2014
Data source: National Park Service, 2014

About the author: Krystal Laymon is a former ORISE Fellow in EPA’s Climate Change Division. She has a background in environmental policy and communications. Krystal received her Master in Environmental Science and Policy at Columbia University and currently resides in Washington, DC with a turtle named Ollie.

National Park Service. 2013. Bloom schedule. Accessed December 6, 2013. www.nps.gov/cherry/cherry-blossom-bloom.htm.

Nov 24, 2014

The Importance of Effective Community Engagement for Sustainable Infrastructure

Clean Water, Ecosystems, Infrastructure Task Force’s, Native American Heritage Month, public health, Sewage, solid waster, water 0 Comments

By Hiwot Gebremariam

Maintaining water infrastructure is a constant challenge, but effective community engagement practices can help. I am a first-hand witness of the usefulness of these practices. Growing up in Ethiopia, I saw community bathrooms and water wells properly maintained only when communities were appropriately consulted and empowered.

I notice parallel situations in my career, too. While working for the United Nations in 2009/2010 on promoting public-private partnerships, I remember a water and sewerage project in Dar Es Salaam, Tanzania that failed because consumers were not properly consulted on user rates.

At EPA, I am part of the Infrastructure Task Force’s solid waste sub-workgroup that investigates strategies for engaging with American Indian/Alaska Native tribes and villages to promote sustainable solutions for solid waste issues, including open dumps. Indeed, evidence shows that utilities need to undertake effective community engagement to achieve sustainability goals.

This is also seen in some programs that I work on: the Clean Water Indian Set-Aside, Alaska Rural and Native Village Grant Program and the U.S.-Mexico Tribal Border Infrastructure Grant Program. The positive impacts of these programs, which increase access to safe drinking water and wastewater services, are being seen in public health and ecosystems’ improvements.

To sustainably maintain this infrastructure, effective community engagement practices are universally essential. Community engagement should consider communities’ specific needs, technical capacities, cultural and socioeconomic conditions. They should involve community members and social institutions at all phases in the decision-making process from the design, construction and completion to the operation and maintenance of projects.

At the National Environmental Justice Advisory Council public meeting held in early October this year, participants, including tribal representatives, echoed this argument. EPA is undertaking initiatives to enhance meaningful community engagement. As we observe Native American Heritage Month this November, I remain proud to participate in EPA’s initiatives that provide needed infrastructure in tribal areas and to work with people who constantly aim to make a difference.

About the author: Hiwot Gebremariam has two graduate degrees in economics and environmental science and policy analysis. She currently works as an Oak Ridge Institute for Science and Education (ORISE) research participant in EPA’s Office of Wastewater Management. She grew up in Ethiopia and now lives in Maryland with her husband and three boys.

Nov 12, 2014

EPA Researchers in Duluth Profiled by White House for Protecting Honey Bee Habitat

chemical exposures, Ecosystems, honey bees, National Pollinator Health Task Force, native grasses, pollinators, pollution 2 Comments

By Lek Kadeli

About 10 years ago, EPA’s Research Laboratory in Duluth, Minnesota, turned 1.9 acres of manicured lawn back into native prairie, seeded with native grasses and wildflowers. This lab, recognized across the scientific community, centers its research on the effects of pollution and chemical exposures on the environment – particularly aquatic ecosystems, fish and wildlife.

The results of restoring the prairie have been inspiring. The lab saves $3,500 in maintenance costs every year, and EPA staff get to see butterflies, birds and spring and summer blooms that brighten their workdays. Instead of the periodic roar of lawnmowers, they can stroll the grounds during their breaks in quiet solitude, maybe even catching an occasional glimpse of deer, fox and other wildlife.

These 1.9 acres of prairie have also provided an important place for bees and other pollinators to thrive – and this relationship between the pollinators flying about and the habitat of native plants recently caught the attention of the White House. EPA’s Duluth Lab was highlighted in the recently-released White House document, Supporting the Health of Honey Bees and Other Pollinators. The document supports President Obama’s memorandum recognizing the critical role pollinators play in food production and our economy.

Honey bee pollination alone adds more than $15 billion in value to the nation’s agricultural crops each year, but populations of honey bees and other pollinators have declined over the past 50 years. EPA has taken a number of actions to protect pollinators – and there’s more to come.

There will be two listening sessions in the Washington, DC metro area, on November 12th and November 17th, where people can provide input into a federal strategy to be developed by the National Pollinator Health Task Force. The task force is co-chaired by EPA Administrator Gina McCarthy and Secretary of Agriculture Tom Vilsack.

Key parts of the strategy will include a research action plan, public-private partnerships, public education about the importance of a healthy environment that includes pollinators, and ways to increase and improve pollinator habitat. Learn more about the listening sessions here.

The EPA has a vital part to play in protecting bees and other pollinators. Some lucky employees looking for inspiration for their work can get it just by stepping away from their desks for a stroll.

Aug 20, 2014

Studying Stream Restoration

Ecosystems, stream impairment, stream restoration, urban development, watershed development 0 Comments

By Marguerite Huber

Stream running through a lush, forested landscape

Forested stream

When I was younger, there was a prairie and stream behind my house. I ran and played there all the time with my friends until a house was built in its place. The lot was transformed from a wild, overgrown landscape to a manicured lawn. With the prairie gone and stream no longer enticing our adventures, we stopped playing there.

When homes and roads are built, they affect the habitat, quantity, and quality of water in downstream ecosystems (as well as natural places for kids to play!). Additionally, it causes an increase in nutrients like the fertilizer from that manicured lawn, and sediments, metals, and other pollutants making development a leading factor in stream impairment.

Local communities are increasingly turning to engineered techniques intended to reduce or eliminate the impacts of development on streams and other aquatic ecosystems. But do such efforts work?

Urban stream

EPA scientists Naomi Detenbeck and Nathan Smucker set out to evaluate how well “out-of-stream” restoration actions (those actions that take place in the watershed as opposed to within streams) work and to identify any general trends found in the scientific literature. They examined the response of water quality, habitat and hydrology, and ecological structure and function to development and restoration.

The scientists used statistical analysis to identify more than 40-years’ worth of published scientific literature on effective ways to protect streams from the unintended impacts of activities that harm streams. Starting with more than 1,400 papers, they pared it down to thirty-eight that covered forty-four restoration projects.

Smucker and Detenbeck found that the projects covered a number of stream restoration actions such as riparian buffers, human-made wetlands, and stormwater ponds. The projects looked at the bigger picture of managing streams by focusing on their watersheds. These “out-of-stream” approaches are important because efforts that have focused solely on habitat restoration within streams have had limited success.

Pooling together data from all the papers, the researchers found that biodiversity was reduced by more than half in unrestored urban streams and measures of things such as reducing erosion, nitrogen fixation, and other ecosystems services were significantly greater in restored streams than unrestored.

Even if it is impossible to fully restore streams, preventative actions can still be taken to protect downstream ecosystems in watersheds that are facing future development. In addition, tracking restoration projects (like the ones used in the studies) and ongoing monitoring would benefit future efforts to protect, restore, and manage streams.

Knowing what works and what doesn’t can help government agencies, policymakers, and citizens recognize and evaluate potential environmental outcomes resulting from their actions and decisions. It can also aid in setting restoration goals, prioritizing sites to monitor, and guiding future decisions and development as populations continue to grow.

About the Author: Marguerite Huber is a student contractor with EPA’s Science Communications Team.

Feb 27, 2014

A New Beginning: Headwater Research

Around the Water Cooler, carbon sequestration, catchments, climate, ecosystem, Ecosystem Research, ecosystem services, Ecosystems, headwater, Nutrients Management, Safe and Sustainable Water, water filtration, water quality 3 Comments

By Marguerite Huber

I like beginnings. They are a fresh start and influence our lives further down the road. Just like how we have new beginnings, all rivers have influential beginnings too. In a network of rivers up in the mountains, headwater streams are the uppermost streams furthest from the river’s endpoint or merger with another stream. They are the very beginning of miles and miles of rivers and have a great impact on what flows downstream.

Headwater streams and their catchments, or drainage basins, are necessary for the maintenance of healthy and productive streams and rivers. Headwater catchments also provide numerous ecosystem services to humans and the surrounding environment. These benefits include biodiversity, climate regulation, recreation, timber and crop production, and water supply and purification.

EPA researchers studied the importance of headwater catchments by focusing on the quantity and value of a few ecosystem services, and then projected that importance from a regional to national scale. They focused on three ecosystem services (water supply, climate regulation, and water purification) for 568 headwater streams and their catchments.

To assess the potential economic value of headwater catchments’ ecosystem services, researchers used published economic value estimates based on commodity price (water supply), market value (climate regulation), and damage cost avoidance (water purification).

They found the economic value of each ecosystem service as follows:

$470,000 – The average yearly value of water supplied through each headwater catchment.
$553, 000 – The average yearly value of climate regulation (through carbon sequestration) of each headwater catchment.
$29,759,000 – The average yearly value of improving water quality by reducing nutrient pollution.

Overall, the weighted average economic value for headwater catchments in the United States was $31 million per year per catchment. It is essential to note that the national importance of headwater catchments is even higher since the 568 catchments studied are only a statistical representation of the more than 2 million headwater catchments in the continental United States. I think it’s safe to say these beginnings provide some serious benefits!

About the author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.

Nov 20, 2013

Climate Change, Nitrogen and Biological Diversity

biodiversity, biogeochemical cycles, biological diversity, climate change, climate change research, ecology, Ecosystems, EPA Climate Change Science, nitrogen 1 Comment

By Chris Clark, Ph.D.

When I visit our national parks, hike in the woods or backpack in the mountains, one of the things I enjoy most is the natural beauty that surrounds me—especially the plants. I’m a plant person, which is hard for some people to understand. (“They don’t do anything” many of my friends quip.) But, to me, that couldn’t be further from the truth.

Three of the most prevalent dangers to plant biodiversity are habitat loss, climate change and nitrogen deposition.

Plants form the foundation for all robust ecosystems, supporting healthy biogeochemical cycles (how materials—for example, fallen leaves—move through systems and are chemically altered by both biological and geological forces), clean air and water, and all higher life forms. To me, this gives plants a quiet kind of majesty that is beautiful to witness.

All the different types of plant species in an ecosystem, from the largest trees to the tiniest wildflowers, play a role in the healthy functioning of that system. In the systems that I studied as a graduate student, the grasslands of Minnesota, it blew me away how many different species co-existed in one square meter of space. What once was just “green grass” became a teeming system of life to me.

Three of the most prevalent dangers to plant biodiversity nationwide are habitat loss, climate change and nitrogen deposition. These stressors can lead to changes that may reduce plant biodiversity, which can cascade through systems and affect other processes and services.

The work I do at EPA is important because it can help preserve ecosystems. I look at different stressors, like climate change and nitrogen deposition, and their impacts on ecosystems. I identify the types of changes that occur and the rate at which the changes are happening. If we understand this, we will be better poised to support and inform policy decisions that enhance the sustainability of our natural resources and avoid irrevocable damages.

For a recent project, I looked at how nitrogen deposition impacts plant biodiversity on land nationwide. My collaborators and I examined “critical loads” (the upper limit of nitrogen an ecosystem can handle) from different regions of the U.S. We then used computer modeling to estimate when deposition was too high and what the effect might be.

The results showed that many regions had nitrogen deposition amounts that may be too high, with losses of species ranging from one to 30 percent using a “worst-case scenario” approach. When we used a “best-case scenario” approach, we estimated minimal losses. We had to use both of these scenarios because scientists don’t know exactly where in this range the critical loads are, and for which systems.

Before our study, no one knew what the ramifications could be of such a range. Refining these estimates of critical load thus is a very important area of future research.

Our results were recently published in the journal Ecology. Future work will build on this project to look at different aspects of the climate change-nitrogen relationship. As a whole, the research will help promote a better understanding of how climate change and nitrogen deposition may impact our natural environment; this, in turn, will help policy makers mitigate these impacts. That’s important to me, and probably to anyone, who enjoys walking in the woods, backpacking or any other outdoor activity.

About the Author: EPA research scientist Chris Clark, Ph.D., works on a diversity of issues related to climate change, including biodiversity, biofuels, and urban resilience.

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