PARENT SESSION
Oral Session #26: Conservation Ecology: Terrestrial.
Presiding: P. Kleintjes
Tuesday, August 6. 8:00 AM to 11:30 AM. Greenlee Meeting Room, TCC.
Habitat fragmentation affects the wetland specialist Primula farinosa in NE - Switzerland.
Fischer, Markus*,1, Lienert, Judit1, 1 Institut fuer Umweltwissenschaften, Zurich, Switzerland
ABSTRACT- We assessed habitat fragmentation effects combined with edge effects on density, population structure, fitness components and biotic interactions of the locally abundant, distylous fen plant Primula farinosa in 27 populations of different size (100-100000 flowering plants) and degree of isolation in Switzerland. The density of reproductive adults, of sub-adults (seedlings and juveniles) and total density increased significantly with increasing population size. Moreover, geographic isolation of populations reduced the densities of different age states by 26%-46%. Capsule frugivory decreased, and the likelihood of infection by the smut fungus Urocystis primulicola increased with increasing population size, and smut infection was more likely in isolated populations. Furthermore, the density of vegetative adults, sub-adults and total density were reduced by 34%-55% at the edge compared with the centre of populations, and the proportions of vegetative adults and sub-adults were also much lower at the edges. Seed set was 11% lower at the edges, while stems were slightly taller and herbivory was strongly increased by over 50%. Beneficial effects of increasing population size on plant densities were only detectable in the centre of populations. In less isolated populations, edge plants were larger than centre plants, but suffered from increased leaf herbivory. Flower morph proportions were independent of habitat fragmentation and had no effect on reproductive success, despite reduced flower diameter and higher number of ovules of pin morph plants. We conclude that habitat fragmentation negatively affects populations of P. farinosa mainly via effects on plant density. Moreover, poorer performance of P. farinosa at the edge of populations suggests that negative effects of fragmentation would further increase with ongoing fragmentation, even for this abundant species.
KEY WORDS: habitat fragmentation, biotic interactions, demography