Lack of sexual reproduction within mountain steppe populations of the clonal shrub Juniperus sabina L. in semi-arid southern Mongolia

The present study describes the reproductive ecology of the prostrate shrub Juniperus sabina in dry mountain steppes of southern Mongolia where stands are located at the drought-limit of the species’ distributional range. Even though cones are produced in large numbers, the larger part of those collected for the study had incompletely developed embryos, and only 2.5% were viable. In germination experiments only 3 out of 2100 intact seeds germinated, suggesting that germination would be unlikely under field conditions. Correspondingly, nearly no seedlings or saplings were found in the field. Ample evidence was found for clonal growth. Patches of similar sexes of J. sabina were spatially associated in the field. RAPD-fingerprinting demonstrated that patches were constituted by a single genet. As mean current growth rates were between 1.8 and 6.8 cm year−1, we estimated that the largest patches found in the study area had minimum ages of 770–2940 years. Thus, establishment of seedlings may have taken place in periods defined by more favourable climatic conditions, whereas dry phases have apparently been survived by clonal growth. This combination of rare sexual reproduction with extended periods of exclusively vegetative reproduction could be a widespread strategy in the harsh conditions of the central Asian drylands.