Abstract:
The importance of species diversity for ecosystem
function has emerged as a key question for conservation
biology. Recently, there has been a shift from
examining the role of species richness in isolation towards
understanding how species interact to effect ecosystem
function. Here, we briefly review theoretical predictions
regarding species contributions to functional diversity and
redundancy and further use simulated data to test combined
effects of species richness, number of functional traits, and
species differences within these traits on unique species contributions to functional diversity and redundancy, as
well as on the overall functional diversity and redundancy
within species assemblages. Our results highlighted that
species richness and species functional attributes interact in
their effects on functional diversity. Moreover, our simulations
suggested that functional differences among species
have limited effects on the proportion of redundancy of
species contributions as well as on the overall redundancy
within species assemblages, but that redundancy rather was
determined by number of traits and species richness. Our
simulations finally indicated scale dependence in the
relative effects of species richness and functional attributes,
which suggest that the relative influence of these factors
may affect individual contributions differently compared to
the overall ecosystem function of species assemblages. We
suggest that studies on the relationship between biological
diversity and ecosystem function will benefit from focusing
on multiple processes and ecological interactions, and that
the relative functional attributes of species will have pivotal
roles for the ecosystem function of a given species
assembly.
