A Quantitative Analysis of the Weed Flora on Arable Land

Abstract

A total of 95 sq. m. quadrats arranged in 19 5-sq.-m. plots were examined in a field with a history of uniform crop production. 12 spp. were listed and the number of occurrences of each species accounted for in every quadrat. The data were compared with Poisson distribution and the agreement, between observed and calculated values tested by the x2. Over dispersion (patchiness) was great for species with high mean frequencies but for those with low mean frequencies the distribution was not distinguishable from random dispersion. This led to the conclusion that the nature of distribution of weed species on arable land is dependent on the mean density of the species and the mode of reproduction. Individuals with high mean density and vegetative methods of propagation are not distributed at random.