Journal ArticleDOI
The dynamics of a grassland ecosystem: botanical equilibrium in the park grass experiment
TLDR
No regular or irregular cycles of component biomass operating between years were detected and it is inferred that populations were regulated by processes operating within individual years.Abstract:
SUMMARY (1) The published results of the Park Grass Experiment (PGE), begun in 1856, provide up to 30 yr of annual data which may be used to determine whether the botanical composition of these grasslands was at equilibrium. Data covering a period exceeding 80 yr are available to test for relationships between hay yield (biomass), species diversity, species number and time. (2) Species diversity and species number show negative relationships with plot biomass and with pH. These relationships were constant over time. The effects of biomass and pH on species number and species diversity were additive. (3) Analysis of the flora of nine plots, each divided into grasses, legumes and a miscellaneous component showed that these components were at equilibrium. (4) The effect of various endogenous factors on this botanical equilibrium was examined. No regular or irregular cycles of component biomass operating between years were detected and it is inferred that populations were regulated by processes operating within individual years. (5) The biomasses of all three components were positively correlated within an unfertilized plot but the floristic components of plots receiving a fertilizer treatment showed few within-plot correlations. By contrast between-plot correlations of components were common for all plots with the exception of those recel.iig nitrogen fertilizer. (6) The mechanisms of population regulation which maintained the Park Grass ecosystem at equilibrium are discussed and tests for these are proposed.read more
Citations
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Journal ArticleDOI
Human alteration of the global nitrogen cycle: sources and consequences
Peter M. Vitousek,John D. Aber,Robert W. Howarth,Gene E. Likens,Pamela A. Matson,David W. Schindler,William H. Schlesinger,David Tilman +7 more
TL;DR: In this article, a review of available scientific evidence shows that human alterations of the nitrogen cycle have approximately doubled the rate of nitrogen input into the terrestrial nitrogen cycle, with these rates still increasing; increased concentrations of the potent greenhouse gas N 2O globally, and increased concentration of other oxides of nitrogen that drive the formation of photochemical smog over large regions of Earth.
Journal ArticleDOI
Hidden treatments in ecological experiments: re-evaluating the ecosystem function of biodiversity.
TL;DR: Case studies re-evaluating three different types of biodiversity experiments demonstrate that the increases found in such ecosystem properties as productivity, nutrient use efficiency, and stability were actually caused by “hidden treatments” that altered plant biomass and productivity.
Journal ArticleDOI
What is the observed relationship between species richness and productivity
Gary G. Mittelbach,Christopher F. Steiner,Samuel M. Scheiner,Katherine L. Gross,Heather L. Reynolds,Robert B. Waide,Michael R. Willig,Stanley I. Dodson,Laura Gough +8 more
TL;DR: The relationship between species richness and productivity has been extensively studied in the literature as discussed by the authors, with a focus on positive, negative, or curvilinear relationships between productivity and species diversity.
Journal ArticleDOI
Impact of nitrogen deposition on the species richness of grasslands
TL;DR: A transect of 68 acid grasslands across Great Britain, covering the lower range of ambient annual nitrogen deposition in the industrialized world, indicates that long-term, chronic nitrogen deposition has significantly reduced plant species richness.
Journal ArticleDOI
Technical Report: Human Alteration of the Global Nitrogen Cycle: Sources and Consequences
Peter M. Vitousek,John D. Aber,Robert W. Howarth,Gene E. Likens,Pamela A. Matson,David W. Schindler,William H. Schlesinger,David Tilman +7 more
TL;DR: This report is confident that human alterations of the nitrogen cycle have increased the quantity of organic carbon stored within terrestrial ecosystems and caused changes in the composition and functioning of estuarine and nearshore ecosystems, and contributed to long-term declines in coastal marine fisheries.
References
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Book
Nonparametric statistics for the behavioral sciences
TL;DR: This is the revision of the classic text in the field, adding two new chapters and thoroughly updating all others as discussed by the authors, and the original structure is retained, and the book continues to serve as a combined text/reference.
Book
Stability and Complexity in Model Ecosystems
Robert M. May,N. MacDonald +1 more
TL;DR: Preface vii Preface to the Second Edition Biology Edition 1.