Johannes M. H. Knops
University of Nebraska–Lincoln
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Publication
Featured researches published by Johannes M. H. Knops.
Nature | 2006
David Tilman; Peter B. Reich; Johannes M. H. Knops
Human-driven ecosystem simplification has highlighted questions about how the number of species in an ecosystem influences its functioning. Although biodiversity is now known to affect ecosystem productivity, its effects on stability are debated. Here we present a long-term experimental field test of the diversity–stability hypothesis. During a decade of data collection in an experiment that directly controlled the number of perennial prairie species, growing-season climate varied considerably, causing year-to-year variation in abundances of plant species and in ecosystem productivity. We found that greater numbers of plant species led to greater temporal stability of ecosystem annual aboveground plant production. In particular, the decadal temporal stability of the ecosystem, whether measured with intervals of two, five or ten years, was significantly greater at higher plant diversity and tended to increase as plots matured. Ecosystem stability was also positively dependent on root mass, which is a measure of perenniating biomass. Temporal stability of the ecosystem increased with diversity, despite a lower temporal stability of individual species, because of both portfolio (statistical averaging) and overyielding effects. However, we found no evidence of a covariance effect. Our results indicate that the reliable, efficient and sustainable supply of some foods (for example, livestock fodder), biofuels and ecosystem services can be enhanced by the use of biodiversity.
Nature | 2006
Peter B. Reich; Sarah E. Hobbie; Tali D. Lee; David S. Ellsworth; Jason B. West; David Tilman; Johannes M. H. Knops; Shahid Naeem; Jared Trost
Enhanced plant biomass accumulation in response to elevated atmospheric CO2 concentration could dampen the future rate of increase in CO2 levels and associated climate warming. However, it is unknown whether CO2-induced stimulation of plant growth and biomass accumulation will be sustained or whether limited nitrogen (N) availability constrains greater plant growth in a CO2-enriched world. Here we show, after a six-year field study of perennial grassland species grown under ambient and elevated levels of CO2 and N, that low availability of N progressively suppresses the positive response of plant biomass to elevated CO2. Initially, the stimulation of total plant biomass by elevated CO2 was no greater at enriched than at ambient N supply. After four to six years, however, elevated CO2 stimulated plant biomass much less under ambient than enriched N supply. This response was consistent with the temporally divergent effects of elevated CO2 on soil and plant N dynamics at differing levels of N supply. Our results indicate that variability in availability of soil N and deposition of atmospheric N are both likely to influence the response of plant biomass accumulation to elevated atmospheric CO2. Given that limitations to productivity resulting from the insufficient availability of N are widespread in both unmanaged and managed vegetation, soil N supply is probably an important constraint on global terrestrial responses to elevated CO2.
The American Naturalist | 2000
Walter D. Koenig; Johannes M. H. Knops
We tested whether annual seed production (masting or mast fruiting) in Northern Hemisphere trees is an evolved strategy or a consequence of resource tracking by comparing masting patterns with those of annual rainfall and mean summer temperatures, two environmental variables likely to correlate with available resources. There were generally significant negative autocorrelations between the seed crop in year x and year \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape
Ecology Letters | 2009
Nick M. Haddad; Gregory M. Crutsinger; Kevin Gross; John Haarstad; Johannes M. H. Knops; David Tilman
Proceedings of the Royal Society of London. Series B, Biological Sciences | 2007
Joseph Fargione; David Tilman; Ray Dybzinski; Janneke Hille Ris Lambers; Christopher M. Clark; W. Stanley Harpole; Johannes M. H. Knops; Peter B. Reich; Michel Loreau
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Nature | 2016
James B. Grace; T. Michael Anderson; Eric W. Seabloom; Elizabeth T. Borer; Peter B. Adler; W. Stanley Harpole; Yann Hautier; Helmut Hillebrand; Eric M. Lind; Meelis Pärtel; Jonathan D. Bakker; Yvonne M. Buckley; Michael J. Crawley; Ellen I. Damschen; Kendi F. Davies; Philip A. Fay; Jennifer Firn; Daniel S. Gruner; Andy Hector; Johannes M. H. Knops; Andrew S. MacDougall; Brett A. Melbourne; John W. Morgan; John L. Orrock; Suzanne M. Prober; Melinda D. Smith
PLOS ONE | 2013
Lydia R. O’Halloran; Elizabeth T. Borer; Eric W. Seabloom; Andrew S. MacDougall; Elsa E. Cleland; Rebecca L. McCulley; Sarah E. Hobbie; W. Stan Harpole; Nicole M. DeCrappeo; Chengjin Chu; Jonathan D. Bakker; Kendi F. Davies; Guozhen Du; Jennifer Firn; Nicole Hagenah; Kirsten S. Hofmockel; Johannes M. H. Knops; Wei Li; Brett A. Melbourne; John W. Morgan; John L. Orrock; Suzanne M. Prober; Carly J. Stevens
\end{document} (year \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape
Plant and Soil | 2005
Feike A. Dijkstra; Sarah E. Hobbie; Peter B. Reich; Johannes M. H. Knops
Nature plants | 2015
Philip A. Fay; Suzanne M. Prober; W. Stanley Harpole; Johannes M. H. Knops; Jonathan D. Bakker; Elizabeth T. Borer; Eric M. Lind; Andrew S. MacDougall; Eric W. Seabloom; Peter D. Wragg; Peter B. Adler; Dana M. Blumenthal; Yvonne M. Buckley; Chengjin Chu; Elsa E. Cleland; Scott L. Collins; Kendi F. Davies; Guozhen Du; Xiaohui Feng; Jennifer Firn; Daniel S. Gruner; Nicole Hagenah; Yann Hautier; Robert W. Heckman; Virginia L. Jin; Kevin P. Kirkman; Julia A. Klein; Laura M. Ladwig; Qi Li; Rebecca L. McCulley
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Proceedings of the National Academy of Sciences of the United States of America | 2007
Johannes M. H. Knops; Walter D. Koenig; William J. Carmen