M.S. Ghilarov’s Principle, or Biomass Equivalence Rule, as a Conservation Law in Ecology

Resumo

Abstract—It may seem surprising that there are conservation laws in ecology as in physics, although these laws are less accurate than in physics and hold only on average, i.e., on large spatial scales (macroecology). One such law is the biomass equivalence rule, which was proposed by Sheldon et al. and later confirmed by Tseitlin and others. According to this rule, the biomass of marine pelagic organisms remains approximately equal in equal intervals of log-transformed body- size spanning the range from bacteria to whales. However, as noted by Tseitlin, long before the work of Sheldon et al. a similar pattern was discovered by M.S. Ghilarov for soil organisms. In his paper of 1944, Ghilarov unequivocally wrote: “The ‘biomass’ of soil organisms of different natural body-size groups is approximately of the same order of magnitude: the product of the number of organisms belonging to a given size group times their linear size cubed varies very little.” Here, I show that Ghilarov’s “natural” body-size groups in the range from bacteria to myriapods and insects occupy approximately equal size intervals on a logarithmic scale. It turns out that equal logarithmic intervals of body-size contain approximately equal biomasses for both soil and pelagic organisms. The priority of the discovery of this rule belongs to Ghilarov. After Tseitlin, I propose to call it Ghilarov’s principle. Furthermore, I suggest that Ghilarov’s principle holds not only for soil and pelagic organisms but also for other organisms inhabiting sufficiently homogeneous and extended habitats.