Ecological mechanisms associated with the positive diversity-productivity relationship in an N-limited grassland

D. A. Fornara, D. Tilman

    Research output: Contribution to journalArticle

    97 Citations (Scopus)

    Abstract

    In a 13-year grassland biodiversity experiment in Minnesota, USA, we addressed two main questions: What set of ecological mechanisms caused aboveground productivity to become; 340% greater in highly diverse plant mixtures than in the average monoculture? Why did the effect of diversity on productivity become so much stronger through time? Because our grassland system is N limited, we simultaneously measured critical variables associated with the storage and cycling of this element, such as plant and soil N pools, soil N availability, soil N mineralization rates, and plant N-use efficiency, as well as the initial soil N concentration of each diversity plot when the experiment was established in 1994. We used linear and multiple regression analyses to test for potential effects of these variables on aboveground productivity and to address whether and how such variables were in turn affected by plant species diversity and functional composition across years and also at different time intervals within the same year. We found that seven variables simultaneously controlled productivity: (1) initial total soil nitrogen (N) of each plot, (2) diversity-dependent increases in total soil N through time, ( 3) soil N mineralization rates, (4) soil nitrate (NO3-) utilization, (5) increases in plant N-use efficiency at greater plant diversity, (6) legume presence, and (7) higher species numbers. The surprising continued significance of higher plant diversity may occur because of its effects on seasonal capture of soil NO3- and moisture and on the accumulation of root-N pools, all of which may have also increased productivity through time at higher species numbers.
    LanguageEnglish
    Pages408-418
    JournalEcology
    Volume90
    Issue number2
    Publication statusPublished - Feb 2009

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    grasslands
    soil
    mineralization
    legumes
    nitrates
    biodiversity
    species diversity
    nitrogen
    testing

    Cite this

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    Ecological mechanisms associated with the positive diversity-productivity relationship in an N-limited grassland. / Fornara, D. A.; Tilman, D.

    In: Ecology, Vol. 90, No. 2, 02.2009, p. 408-418.

    Research output: Contribution to journalArticle

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