Environmental context influences the outcome of a plant–seed predator interaction


  • Annette Kolb,

  • Roosa Leimu,

  • Johan Ehrlén

A. Kolb (akolb@uni-bremen.de) and J. Ehrlén, Dept of Botany, Stockholm Univ., SE–106 91 Stockholm, Sweden. Present address for AK: Vegetation Ecology and Conservation Biology, FB 2, Univ. of Bremen, Leobener Str., DE–283 59 Bremen, Germany. – R. Leimu, Section of Ecology, Dept of Biology, Univ. of Turku, FI–200 14 Turku, Finland. Present address for RL: Inst. for Biochemistry and Biology, Univ. of Potsdam, Maulbeerallee 1, DE–144 69 Potsdam, Germany.


Mutualistic and antagonistic interactions with animals are known to influence the performance of plants in many ways. Much less is known about how such effects are influenced by the environment and how they translate into effects on plant population dynamics. In this study, we first quantified how pre-dispersal seed predation in the perennial herb Primula veris changes along a continuous gradient of canopy cover. We then used a deterministic demographic modeling approach to investigate how seed predation may influence population growth rate (λ) and how effects depend on environmentally-induced variation in plant demography. Intensity of seed predation increased with the degree of canopy cover, while sensitivity of λ to changes in seed production decreased. This translated into non-linear effects of seed predation on λ along the canopy cover gradient. Despite seed predation rates being highest in closed habitats, the negative effect of seed predation on λ was lower here than in slightly more open habitats. Our results demonstrate that knowledge of the intensity of plant-herbivore interactions does not suffice to infer how animals influence the population dynamics of plants and their distribution. Plant demographic sensitivity and its dependence on the environment need also to be taken into account when assessing the importance of plant–animal interactions.