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The effect of grass plant size on basal frequency estimates
Author(s) -
COOK J. W.,
BRADY W. W.,
ALDON E. F.
Publication year - 1994
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.1365-2494.1994.tb02018.x
Subject(s) - basal area , basal (medicine) , relative species abundance , biology , abundance (ecology) , range (aeronautics) , ecology , environmental science , statistics , mathematics , materials science , insulin , endocrinology , composite material
Frequency data from different‐sized plots are generally accepted as being incomparable. However, how basal frequency data are influenced by plant basal diameter is not well known. Computer simulations were used to determine the influences of grass plant basal diameter on basal frequency data. Basal frequency, basal area and density were estimated with simulated 5 × 10 cm and 20 × 50 cm rectangular plots. Simulated plants had basal diameters ranging from 1.9 to 12.7 cm. Basal diameter had a significant effect on the relationship between frequency and both basal area and density. As differences in plant size increase, the effect on basal frequency becomes larger and the likelihood of an ecologically important influence also increases. Thus, frequency data should not be used to compare relative abundance of species, unless corrections are made for differences in plant basal diameter among species. Additionally, frequency data should not be used to monitor change in abundance of a species through time, unless mean plant basal diameter can be assumed to remain relatively constant. Basal frequency data could be used to ‘signal’ when change has occurred. Then, other sampling methods must be used to determine the nature and direction of change or relative species abundance. For frequency data, the simplicity of collection may be offset by difficulty in interpretation.