Determination of Plant Densities

Abstract

E. J. MACHIN¹ appears to be unaware of the extensive study by G. E. Blackman² on the relation between plant density and percentage absence. In a theoretical appendix to this paper, I have pointed out that the most efficient size of quadrat corresponds to about 20 per cent absence, or a product of quadrat size and plant density of about 1·6 (the efficiency remains reasonable over a range of, say, 0·7–3·0, compared with the rather wider range 0·3–3·3 implied by Machin).