The effects of clonal forestry on genetic diversity in wild and domesticated stands of forest trees

The level of genetic diversity maintained in a population is determined by the combined action of mutation, gene flow, genetic drift and selection. Forest tree breeding is a relatively recent phenomenon compared to most crop species and the material that is being deployed is, genetically, often very similar to wild-growing populations. The introduction of vegetative propagation has been hailed as a more efficient and flexible method than seed orchards to rapidly realize breeding progress and to adapt material to future climate change. What remains unclear is how a large deployment of vegetatively propagated material may affect the patterns of genetic diversity within and among forest stands. Here we review what is currently known about genetic diversity in managed and natural forest stands and specifically address the impacts of clonal forestry. To assess this we develop a quantitative model to describe the consequences of clone deployment on genetic and genotypic diversity in Swedish forests. We conclude with some remarks specific to Swedish conditions, likely scenarios for clonal deployment and finally some suggestions for future research priorities.