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1 Polish Journal of Ecology

1 2006

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Development of genetic structures in a norway spruce (Picea abies Karst.) population colonizing the abandoned agricultural land : a look back and a look ahead

Gomory Dušan, Fabrika Marek, Chudy Frantisek, Paule Ladislav

Polish Journal of Ecology

2006

Vol. 54, nr 1

127-136

Changes in the genetic variation and spatial genetic structures were modelled in a Norway spruce (Picea abies Karst.) population colonizing abandoned pasture area of 100 hectares at the locality Prislopy, Pol'ana Mts. (Carpathians, Central Slovakia, 48[degrees] 38[minutes] N, 19[degrees] 25[minutes] E, approx. 900 m a.s.l.). The development in the past was reconstructed on the basis of a series of historical aerial photographs, reflecting primarily the population growth and the colonization process. The future development was predicted using the individual-tree model SIBYLA developed by Fabrika (2003), whereby it reflects the future density-dependent mortality. No significant changes of the allelic richness or gene diversity were observed during the whole period of modelling (1956 to 2065). Fixation index (reflecting the degree of inbreeding) has steadily increased since the initial stage up to the present, and is predicted to increase further, indicating the accumulation of inbres individuals due to the formation of spatially continuous kin groups. This assumption is supported by the development of spatial genetic structures (non-random distribution of genotypes). The distograms of the number of alleles in common (NAC) showed that spatially proximate individuals share significantly more alleles than expected under random distribution of genotypes. Spatial genetic structures were formed at the very early stage of colonization, have persisted until the present and are predicted to be even enhanced in the future. Isolation by distance due to a limited seed dispersal, strong fertility variation and facilitation of seedling establishment in the vicinity of early colonizers are proposed as explanation. The results indicate that Norway spruce, although being the component of many climax forest communities, is capable under certain circumstances to behave as a very efficient pioneer. The species disperses enough seeds on medium distances to reach suitable sites within open areas and establish as seedlings, whereas a strong seed dispersal at short distances and modification of environment near the early colonizers allow the extension of kin groups and gradual occupation of the whole available space.