We. Kunin, POPULATION-SIZE AND DENSITY EFFECTS IN POLLINATION - POLLINATOR FORAGING AND PLANT REPRODUCTIVE SUCCESS IN EXPERIMENTAL ARRAYS OF BRASSICA KABER, Journal of Ecology, 85(2), 1997, pp. 225-234
1 The term 'density-dependence' is often applied rather loosely to a v
ariety of aspects of local abundance. 'Density' is most commonly measu
red as the size of a local population and/or the (average) spacing bet
ween the individuals within it. These parameters are interrelated and
correlated in most natural populations. Yet species interactions and p
opulation dynamics may be affected differently by these different aspe
cts of abundance. 2 Field experiments were performed to tesi the effec
ts of two components of local abundance on pollination in the self-inc
ompatible annual plant, Brassica kaber. In one experiment, populations
of uniform density but differing size were planted out, whilst in a s
econd study both the density and size of populations were varied. 3 Th
e number of individuals in a population had no effect on pollinator vi
sitation or subsequent seed set in either experiment. 4 Population den
sity, however, had strong effects on both visitation and reproductive
success. 5 The position of a plant within a population had an impact o
n pollinator constancy in the second experiment, but had no effect on
visitation rates or reproductive success.