Genetic diversity and structure in Austrocedrus chilensis populations: Implications for dryland forest restoration

SOUTO C.P., HEINEMANN K., KITZBERGER T., NEWTON A.C. & A.C. PREMOLI

RESTORATION ECOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2012 vol. 20 p. 568 - 575

1061-2971

Genetic variation of individuals and populations is the logical base for restoration, but rarely is available ahead of time. In South America, 94% of dry-temperate lands present some degree of desertification risks and restoration needs. We analyzed geographic patterns of genetic variation in Austrocedrus chilensis (Cupressaceae), a dominant conifer of the steppe-forest ecotone in the eastern Andes, to elaborate appropiate restoration suggestions. We sampled 67 locations in Argentina, estimating genetic parameters to disentangle the effects of historical factors, i.e. glaciations and fire, affecting diversity, inbreeding, and gene-flow patterns using 12 allozyme loci. Species composition at each stand were used as surrogate of habitat types. Genetic diversity decreased southward particularly on eastern patchy populations while high genetic admixture was measured in western continuous populations reflecting postglacial migrations from northern and eastern sources. Higher inbreeding (FIS> 0.14) and the impact of recent bottlenecks was measured in small-patchy northern populations in concordance with a more extensive fire history than southern populations. Gene flow is moderate (FST = 0.12) and negatively correlated with patterns of species divergence hitherto suggesting a shallow effect of natural selection in such plastic species. Under perspectives of climate change in drylands, restoration actions on Austrocedrus should differ latitudinally. Small inbred yet genetically diverse northern populations should be the subject of passive restoration efforts, while careful experimental design such as common gardens established even beyond the species? range should be developed towards the south. Historical, and environmental pressures generate the observed patterns of genetic variation in tree species and should be considered as basic guidance for restoration efforts.