Climate Change, Nitrogen and Biological Diversity

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.

Prairie scene

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.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

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Go Green-Scaping!

About the author: Lina Younes has been working for EPA since 2002 and chairs EPA’s Multilingual Communications Task Force. Prior to joining EPA, she was the Washington bureau chief for two Puerto Rican newspapers and she has worked for several government agencies.

Lea la versión en español a continuación de esta entrada en inglés.

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Photo of pink orchids cluster.When I lived in Puerto Rico, there were flowers plants and trees everywhere. Beautiful orchids, bouganvilleas, flamboyanes (flaming trees), palm trees—a true painter’s palette. My close relatives were gifted with green thumbs. It seemed they could produce a full plant from a little twig.

Unfortunately, I was not as lucky. I confess that living in a tropical setting, it was an adjustment to relocate to a region where we have four seasons and with seasonal flowers. Last year when we were remodeling the house, I let my husband redesign the decks, but I asked that he leave the landscaping to me.

Working at EPA, I was convinced that I had to practice what I preach. The whole concept of greenscaping is a practice we highly recommend. This type of gardening not only contributes to the natural beauty, but it also protects the environment.

Photo of the backyard with trees and the house' deck.Before buying plants and designing the landscape, I studied which are
the native plants to the area of Maryland. (PDF) (24 pages, 279KB).

By selecting native plants, you minimize the use of water as well as the use of fertilizers and pesticides. I also selected several varieties of evergreens to ensure some type of foliage year round. I also studied which were the ideal plants for the type of soil I have to reduce maintenance and labor—remember I mentioned that I don’t have a green thumb.

In sum, gardening can be a very positive experience for environmental protection. One of the projects for this summer will be composting. I’ll let you know how that goes.

¡Viva la jardinería ecológica!

Photo of pink orchids cluster.Cuando vivía en Puerto Rico, habían flores y árboles por doquier. Hermosas orquídeas, trinitarias, flamoyanes*, palmas—una verdadera paleta de pintor. Mis familiares cercanos tenían mucha suerte sembrando las plantas. Parecía que podían producir una planta de un simple gancho.

Lamentablemente, yo no he tenido la misma suerte. Confieso que viniendo de un ambiente tropical, fue un ajuste vivir en una región donde tenemos cuatro temporadas con plantas típicas de cada estación. El año pasado cuando estábamos haciendo unas remodelaciones en la casa, dejé que mi esposo diseñara los balcones, pero le pedí que me dejara el diseño del jardín a mí.

Trabajando en la Agencia de Protección Ambiental, estaba convencida que tenía que practicar lo que predico. Todo el concepto de jardinería ecológica (PDF) (16 pages, 2.7 MB) o como se dice en inglés “greenscaping” es algo que recomendamos. Este tipo de jardinería no tan sólo contribuye a la belleza natural del lugar sino también ayuda a proteger el medio ambiente.

Photo of the backyard with trees and the house' deck.Antes de hacer el diseño, estudié cuáles eran las plantas nativas del área de Maryland. (PDF) (24 pages, 279KB)

Al seleccionar las plantas nativas se reduce la necesidad de utilizar agua en exceso así como la necesidad de utilizar fertilizantes y pesticidas. También estudié cuáles eran las plantas ideales para el tipo de terreno y las que requerirían menor mantenimiento—recuerden que comenté que no tengo la misma habilidad con las plantas como mis familiares.

En fin, la jardinería puede ser una actividad positiva para la protección ambiental. Uno de mis proyectos para este verano será el compostaje, el abono orgánico. Ya les contaré.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.