PARENT SESSION
Oral Session #64: Plant Population Ecology.
Presiding: S. Collins
Wednesday, August 7. 1:00 PM to 4:45 PM. Gila Meeting Room, TCC.

Does habitat fragmentation affect fitness and biotic interactions in the common plant Lychnis flos-cuculi?

GALEUCHET, DAVID^*,1, PERRET, CATHERINE¹, FISCHER, MARKUS¹, ¹ University of Zurich, Zurich, ZH, Switzerland

ABSTRACT- After habitat fragmentation, negative effects of small size and high geographic isolation of populations on fitness and biotic interactions were documented for rare plant species, whereas effects on more common species are largely unknown. In the common Lychnis flos-cuculi we investigated plant fitness and levels of biotic interactions for 28 populations of different size (40-51'000 flowering individuals in 2000), isolation, and altitude (865-1350 m) in NE Switzerland. In July 2000, differentiation between the populations was highly significant for most fitness estimators (p <0.001). Reproductive fitness estimators decreased with increasing altitude of a population (p <0.05) and were generally independent of population size. Seed mass and the size measures number of rosette leaves and length of longest stem leaf were even negatively correlated with population size (p <0.05). In isolated populations rosette size and stem height were larger than in not isolated populations (p <0.01), possibly due to higher nutrient impact from surrounding fertilised areas. On the other hand, in smaller populations a higher mean percentage of the leaf most damaged by herbivores was missing (p <0.05). Moreover, small populations were less dense than large ones (p<0.05). In conclusion, populations differed in conditions and performance of Lychnis, and while negative and positive effects of habitat fragmentation were present, they were much smaller than effects of altitude.

KEY WORDS: habitat fragmentation, fitness decrease, Lychnis flos-cuculi, Switzerland