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Frequency distributions of sward height under sheep grazing
Author(s) -
Barthram G. T.,
Duff E. I.,
Elston D. A.,
Griffiths J. H.,
Common T. G.,
Marriott C. A.
Publication year - 2005
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.2005.00444.x
Subject(s) - grazing , weibull distribution , distribution (mathematics) , gamma distribution , frequency distribution , normal distribution , temperate climate , mathematics , biology , agronomy , statistics , ecology , mathematical analysis
Cattle and sheep can create and maintain a mixture of relatively tall and short patches in grass swards through selective grazing. In swards that are grazed by cattle this heterogeneous structure can result in the frequencies of height measurements having a skewed distribution that has variously been better described by the double‐normal distribution the gamma distribution and the Weibull distribution than by the more common normal distribution. The fit of these statistical distributions, and the adequacy of the potentially useful log‐normal distribution, to sward height frequencies were tested in sown temperate swards grazed by sheep and compared within a single sward. It was concluded that the single‐normal and Weibull distributions were inadequate and that overall the log‐normal and gamma distributions had the best fit to the measurements.