Featured Research

from universities, journals, and other organizations

Declines in ecosystem productivity fueled by nitrogen-induced species loss

Date:
July 3, 2013
Source:
University of California - Santa Barbara
Summary:
Humans have been affecting their environment since the ancestors of Homo sapiens first walked upright, but never has their impact been more detrimental than in the 21st century. Human-driven environmental disturbances, such as increasing levels of reactive nitrogen and carbon dioxide, have multiple effects, including changes in biodiversity, species composition, and ecosystem functioning. Pieces of this puzzle have been widely examined but this new study puts it all together by examining multiple elements.

This is the Cedar Creek Ecosystem Science Reserve in central Minnesota where the study took place.
Credit: Forest Isbell

Humans have been affecting their environment since the ancestors of Homo sapiens first walked upright, but never has their impact been more detrimental than in the 21st century. "The loss of biodiversity has much greater and more profound ecosystem impacts than had ever been imagined," said David Tilman, professor of ecology, biodiversity and ecosystem functioning at UC Santa Barbara's Bren School of Environmental Science & Management.

Human-driven environmental disturbances, such as increasing levels of reactive nitrogen and carbon dioxide (CO2), have multiple effects, including changes in biodiversity, species composition, and ecosystem functioning. Pieces of this puzzle have been widely examined but this new study puts it all together by examining multiple elements. The results were published July 1 in the Proceedings of the National Academy of Sciences.

According to the team's recent findings, adding nitrogen to grasslands led to an initial increase in ecosystem productivity. However, that increase proved unsustainable because the increased nitrogen resulted in a loss of plant diversity. "In combination with earlier studies, our results show that the loss of biodiversity, no matter what might cause it, is a major driver of ecosystem functioning," said Tilman.

The study analyzed 30 years of field data from the Nitrogen Enrichment Experiment in order to determine the temporal effect of nitrogen enrichment on the productivity, plant diversity, and species composition of naturally assembled grasslands at the Cedar Creek Ecosystem Science Reserve in central Minnesota. The results showed that while nitrogen enrichment initially increased plant productivity, eventually this effect declined, especially in the plots that received the most fertilizer. These returns diminished over time because fertilizing also drove declines in plant diversity.

In fact, the continuous addition of nitrogen fertilizer led to a loss of the dominant native perennial grass, Schizachyrium scoparium, which decreased productivity twice as much as did random species loss in a nearby biodiversity experiment. In contrast, elevated CO2 didn't decrease or change grassland plant diversity in any way and consistently promoted productivity over time.

According to the authors, previous studies have underestimated the impact of biodiversity on ecosystem functioning. "Many people expect that only rare or subordinate species will be lost and that their loss will have negligible effects on ecosystem functioning," says lead author Forest Isbell, a postdoctoral associate in the Department of Ecology, Evolution & Behavior at the University of Minnesota in Saint Paul. "But we found that the most common species were lost under fertilization, creating a substantial decrease in productivity over time."

Furthermore, the results of this study show that changes in biodiversity can be important intermediary drivers of the long-term effects of human-caused environmental changes on ecosystem functioning. For example, accounting for the effects of nitrogen on plant diversity could improve predictions of the long-term impacts of nitrogen on productivity. While the researchers expect their results will be relevant in other ecosystems, they also hope to explore the practical implications of their results for sustaining forage yields in diverse pastures and hay meadows. In particular, they hope to determine whether maintaining plant diversity over time can sustain the productivity of these managed grasslands.

This research was supported by grants from Department of Energy Program for Ecosystem Research, the Department of Energy National Institute for Climatic Change Research, the National Science Foundation Long-Term Ecological Research Program, the National Science Foundation Biocomplexity Coupled Biogeochemical Cycles Program, the National Science Foundation Long-Term Research in Environmental Biology Program, and by the University of Minnesota.


Story Source:

The above story is based on materials provided by University of California - Santa Barbara. Note: Materials may be edited for content and length.


Journal Reference:

  1. F. Isbell, P. B. Reich, D. Tilman, S. E. Hobbie, S. Polasky, S. Binder. Nutrient enrichment, biodiversity loss, and consequent declines in ecosystem productivity. Proceedings of the National Academy of Sciences, 2013; DOI: 10.1073/pnas.1310880110

Cite This Page:

University of California - Santa Barbara. "Declines in ecosystem productivity fueled by nitrogen-induced species loss." ScienceDaily. ScienceDaily, 3 July 2013. <www.sciencedaily.com/releases/2013/07/130703140517.htm>.
University of California - Santa Barbara. (2013, July 3). Declines in ecosystem productivity fueled by nitrogen-induced species loss. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2013/07/130703140517.htm
University of California - Santa Barbara. "Declines in ecosystem productivity fueled by nitrogen-induced species loss." ScienceDaily. www.sciencedaily.com/releases/2013/07/130703140517.htm (accessed July 31, 2014).

Share This




More Earth & Climate News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Big Waves In Arctic Ocean Threaten Polar Ice

Big Waves In Arctic Ocean Threaten Polar Ice

Newsy (July 30, 2014) Big waves in parts of the Arctic Ocean are unprecedented, mainly because they used to be covered in ice. Video provided by Newsy
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins