Consequences of plant population size and density for plant-pollinator interactions and plant performance

Mustajarvi, K Siikamaki, P Rytkonen, S Lammi, A

K. Mustajarvi et al., Consequences of plant population size and density for plant-pollinator interactions and plant performance, J ECOLOGY, 89(1), 2001, pp. 80-87

43

INGLESE

Article

Environment/Ecology

JOURNAL OF ECOLOGY

0022-0477 → ACNP

89

1

2001

80 - 87

ISI

0022-0477(200102)89:1<80:COPPSA>2.0.ZU;2-Z

1 Habitat fragmentation and the resulting decline in the local abundance of plant species can affect biological interactions. We examined the effects of abundance on plant-pollinator interactions by observing the pollinator s ervice and subsequent reproductive output of a mostly outbreeding, but self -compatible, plant, Lychnis viscaria, in experimental populations of differ ent sizes (number of individuals) and densities (distance between individua ls). 2 Bumblebees, the main pollinators of L. viscaria, preferred larger populat ions, but visitation rates were higher in sparser populations. Pollinators were attracted to the larger inflorescences in sparse populations, which we re also more visible due to their larger area for a given size. 3 Bumblebees probed more flowers within plants in sparse populations, proba bly due to the larger inflorescences and longer flight distances between in dividuals. 4 Subsequent reproductive success (capsule production) was higher in sparse populations, due to differences in pollination success and resource compet ition, and their interaction. In self-compatible species, such as L. viscar ia, reproductive success may be determined more by resource availability, w hereas self-incompatible plants may be more sensitive to changes in pollina tor abundance. 5 We conclude that plant-pollinator interactions are sensitive to changes i n both the size and spatial arrangement of plant populations, which can aff ect their demography and genetics. In this study, species density had a gre ater effect than size and the unexpectedly beneficial effects of low densit y may be due to greater resource availability.