Plants play greater role than megaherbivore extinctions in changes to ecosystem structureApril 16, 2018
Plants may have exerted greater influence on our terrestrial ecosystems than the megaherbivores that used to roam our landscapes, according to new research.
Previously, scientists believed that the Late Quaternary extinction event, which took place between ~11,000 and 15,000 years ago across much of northern Europe, played a significant role in the subsequent expansion of woody plants and declining nitrogen availability over the last 10,000 years.
But in a new study, published in Ecology Letters, researchers suggest the changes had already started to occur in Britain and Ireland at the same time these mammals - such as the woolly mammoth, Giant Irish Deer, reindeer and wild horse - began to die out.
They also believe that natural fires had a greater role to play in these processes than previously thought, and that the natural burning of land should be taken into account when considering rewilding projects in the UK in order to ensure the sustainability of open, fertile habitats for grazing animals.
The research was conducted by academics at the University of Oxford, University of Plymouth, Queen's University Belfast, Swansea University and the Natural History Museum, London.
Dr Elizabeth Jeffers, from Oxford's Department of Zoology, led the study. She said: "Our results challenge the ecological argument underpinning trophic rewilding by showing that the fauna living in these regions at the end of the last glacial period were unable to stem the expansion of woody plants across the northern hemisphere."
For the study, scientists produced an unprecedented amount of ecological and climatic information (spanning the transition from the Late Pleistocene to the middle Holocene period, 16,000 to 4,800 years ago) for five study sites in England, Scotland and Ireland. Their dataset included: proxy measurements of plant and large herbivore biomass; nitrogen availability; growing season temperatures; and fire activity.
Two-thirds of the region's megaherbivore species became extinct during this time; using previously available fossil bone data of these species, the authors applied statistical modelling to their dataset in order to investigate the relative impacts of plants, herbivores, fire, and summer temperatures on ecosystem structure and function.
They found that shrubs were consistently one of the strongest predictors of ecosystem change, with increasing shrub biomass reducing ecosystem-scale nitrogen availability and promoting the growth and expansion of trees. Natural fires, not herbivory, were the most significant factor in reversing these effects, however, declining fire activity in the early Holocene enabled shrubs (and ultimately trees) to dominate terrestrial ecosystems.
The findings provide new empirical evidence for the long-term ecosystem engineering effects of woody plants and demonstrate the importance of burning for maintaining the structure and function of open ecosystems in northern biomes.
Dr Nicki Whitehouse, Associate Professor (Reader) in Physical Geography at the University of Plymouth and one of the senior authors of the study, added: "This research started when we became interested in the ecological consequences of the megaherbivore extinctions. It led us to look at a range of ecological processes that may have been affected by the loss of these species, including decreasing levels of nitrogen as a nutrient. "What we have found could have significant conservation management consequences; people talk about using large grazing animals to maintain open, fertile habitats, but in fact you need a range of different processes including burning. In the past, fire played an important role in maintaining some of our open ecosystems and grasslands and it should be considered again as an important management tool particularly as part of any rewilding programmes planned across the UK and beyond."
University of Plymouth
Related Nitrogen Articles:
A unique investigation highlights how excess nitrogen can trigger coral bleaching in the absence of heat stress.
Researchers have developed a large-scale method for calculating the nitrogen footprint of a university in the pursuit of reducing nitrogen pollution, which is linked to a cascade of negative impacts on the environment and human health, such as biodiversity loss, climate change, and smog.
As the most abundant gas in Earth's atmosphere, nitrogen has been an attractive option as a source of renewable energy.
Nitrogen deposition caused by human activities can lead to an increased phytoplankton production in boreal lakes.
An international team discovers that production of a potent greenhouse gas can be bypassed as soil nitrogen breaks down into unreactive atmospheric N2.
Cornell University researchers have discovered a biological mechanism that helps convert nitrogen-based fertilizer into nitrous oxide, an ozone-depleting greenhouse gas.
Nitrogen is everywhere: even in the air there is four times as much of it as oxygen.
Washington State University biologist Mechthild Tegeder has developed a way to dramatically increase the yield and quality of soybeans.
Excess nitrogen from agricultural runoff can enter surface waters with devastating effects.
What's good for crops is not always good for the environment.
Related Nitrogen Reading:
The Story of N: A Social History of the Nitrogen Cycle and the Challenge of Sustainability (Studies in Modern Science, Technology, and the Environment)
by Hugh S. Gorman (Author)
In The Story of N, Hugh S. Gorman analyzes the notion of sustainability from a fresh perspective—the integration of human activities with the biogeochemical cycling of nitrogen—and provides a supportive alternative to studying sustainability through the lens of climate change and the cycling of carbon. It is the first book to examine the social processes by which industrial societies learned to bypass a fundamental ecological limit and, later, began addressing the resulting concerns by... View Details
The Nitrogen Cycle (Let's Find Out! Our Dynamic Earth)
by Bobi Martin (Author)
From tiny organisms to plants and people, all living things need nitrogen. This engaging STEM resource introduces elementary school readers to the importance of the nitrogen cycle in clear, easy-to-follow text. Readers will learn why nitrogen is an essential nutrient for growth, where nitrogen is found, the important role legumes play in the nitrogen cycle, and more. Colorful illustrations and photographs add interest and additional information to each page. Compare and Contrast, Vocabulary, and Think About It sidebars support Common Core standards. This is a must-have book for any shelf. View Details
The Nitrogen Cycle (Earth's Cycles in Action)
by Diane Dakers (Author)
"Nitrogen is a common element found as a gas in the air we breathe as well as in other forms in water and soil. Nitrogen is essential for all life on Earth. This informative book explains how the Earth's supply of nitrogen moves in different forms in a cycle from the air to the soil to living things. Highly readable text and supportive images help explain such processes as fixation, nitrification, and dentrification, as well as the important role of bacteria in the nitrogen cycle. Feature boxes highlightexamples of the ways in which human activity, such as adding more nitrogen to the soil to... View Details
Nitrogen (True Books)
by Salvatore Tocci (Author)
Discusses the origin, discovery, special characteristics, and use of nitrogen in such products as explosives and fertilizers. View Details
Nitrogen in the Environment, Second Edition
by J.L. Hatfield (Editor), R.F. Follett (Editor)
Nitrogen is one of the most critical elements for all life forms. In agricultural systems it is essential for the production of crops for feed, food, and fiber. The ever-increasing world population requires increasing use of nitrogen in agriculture to supply human needs for dietary protein. Worldwide demand for nitrogen will increase as a direct response to increasing population.
Nitrogen in the Environment provides a wholistic perspective and comprehensive treatment of nitrogen. The scope of this book is diverse covering a range of topics and issues related to furthering our... View Details
Nitrogen (Understanding the Elements of the Periodic Table)
by Heather Hasan (Author)
Explains the characteristics of nitrogen, where it is found, how it is used by humans, and its relationship to other elements found in the periodic table. View Details
The World of Nitrogen
by Isaac Asimov (Author)
Has 47 figures, formulas, throughout principal text, with additional figures to prefatory section on reading organic chemistry formulas. Asimov's 6th expository work according to his book list on back flap. View Details
The Nitrogen Elements (Understanding the Elements of the Periodic Table)
by Greg Roza (Author)
Describes the elements of the periodic table with similar physical and molecular properties as nitrogen, including how they bond to form compounds and where they can be found in everyday objects. View Details
Nitrogen Capture: The Growth of an International Industry (1900–1940)
by Anthony S. Travis (Author)
This monograph provides an account of how the synthetic nitrogen industry became the forerunner of the 20th-century chemical industry in Europe, the United States and Asia. Based on an earlier SpringerBrief by the same author, which focused on the period of World War I, it expands considerably on the international aspects of the development of the synthetic nitrogen industry in the decade and a half following the war, including the new technologies that rivalled the Haber-Bosch ammonia process. Travis describes the tremendous global impact of fixed nitrogen (as calcium cyanamide and... View Details
by John Postgate (Author)
The fixation of nitrogen--the conversion of atmospheric nitrogen to a form that plants can use--is fundamental to the productivity of the biosphere and therefore to the ability of the expanding human population to feed itself. Although the existence and importance of the process of biological nitrogen fixation has been recognized for more than a century, scientific advances over the past few decades have radically altered our understanding of its nature and mechanisms. This book provides an introductory-level survey of biological nitrogen fixation, covering the role of the process in the... View Details