When and how could common gardens be useful in the ecological restoration of long-lived tropical plants as an aid to the selection of seed sources?

Background:The identification of genetic divergence among provenances is essential for designing seed zones for ecological restoration, but this is neither easy nor cheap, especially where tropical trees are concerned. Aims:In this study we sought to investigate the effectiveness of common garden and short-term reciprocal transplant experiments to identify genetic divergence in populations of Queen palm (Syagrus romanzoffiana). Methods:Seed harvesting was carried out in south-eastern Brazil, in natural remnants of seasonally dry forest, restinga and cerradão. Under common garden conditions, we examined the length of the cotyledonary petiole of three-month-old seedlings, and important sapling traits of 10-month-old nursery-grown individuals of the three above-mentioned seed provenances. Additionally, reciprocal transplants were carried out during 10 months for seasonally dry forest and cerradão seed lots. Results:In the common garden experiments, restinga seedlings had significantly shorter cotyledonary petioles, and cerradão saplings showed ca. 40% higher values for root, leaf blade, shoot and total dry mass, while saplings did not express genetic differences in reciprocal transplants, which is one of the four possible combined outcomes discussed here. Conclusions:Common garden experiments with long-lived tropical plant species used in ecological restoration can be advantageously used to improve the quality of the seed sources for restoration projects by detecting genetic divergence with a possible relation to local adaptation. [ABSTRACT FROM AUTHOR]