CHAPTER EIGHT
Body size and scale invariance:
multifractals in invertebrate
communities
PETER E.SCHMID
Queen Mary, University of London
University of ViennaJENNY M.SCHMID-ARAYA
Queen Mary, University of LondonIntroduction
As ecologists seek conceptual syntheses to understand the mechanistic and func-
tional processes that underlie empirical community patterns in different ecosys-
tems, they are developing concepts that depict complexity on a number of universal
themes. General patterns in the statistical distributions of species and individuals
within and across ecosystems provide information about the organizing principles
underlying ecosystem structure. Interrelations between species richness, popula-
tion density, body-size and distribution ranges are of central concern in ecology and
have been widely debated (Brown, 1995 ; Brown, Allen & Gillooly, this volume). To
represent the structure of ecosystems adequately, species composition and popula-
tion size are the most appropriate attributes containing information that is closely
correlated with the organism’s size.
Attributes of body size may affect many ecological characteristics, such as
resource use and allocation in communities, reflecting their complex internal
structure. Feeding patterns that result in resource partitioning among species of a
benthic species assemblage demonstrate strong body-size dependence (Schmid &
Schmid-Araya, 1997 ; Woodward & Warren, this volume). Information on species
population and body-size distribution (BSD) of communities is frequently given for
the larger or is toxonomically not well resolved, organisms inhabiting an ecosys-
tem, therefore resulting in veiled, often highly scattered and incomplete, distribu-
tions. In contrast, the size distributionof well-resolved species communities may
reflect the different evolutionary traits underlying diverse scaling domains.
Therefore, more realistic expectations for real-world species and abundance dis-
tributions are obtained using scale-dependent definitions of individual species’
spatial and/or size structure within communities.
Empirical evidence has been mounting that a number of dynamic sys-
tems in disciplines as diverse as physics, economics and ecology have certain
Body Size: The Structure and Function of Aquatic Ecosystems, eds. Alan G. Hildrew, David G. Raffaelli and Ronni
Edmonds-Brown. Published by Cambridge University Press.#British Ecological Society 2007.