Seed weight and elevation influence germination of a keystone high Andean tree species

Abstract

The use of quality seeds is the basis for reforestation and ecosystem restoration programs; however, in the Andes few species have been evaluated to determine the factors that influence seed quality and most native trees used for restoration are not produced using seeds. We evaluate seed physical and physiological characteristics in the keystone high Andean tree species Polylepis incana and relate to the mother tree and the microsite characteristics. An analysis based on seed lots by weight, germination tests in nursery, incubator and tetrazolium tests were carried out in 12812 seeds. Our results indicate that seeds of higher weight and those coming from higher elevation have better germination performance, while dasometric variables of the mother tree and the other environmental variables (slope, % rock and light hours) were not associated to seed performance. Moreover, seed weight was negatively associated to increase of slope and light hours received by the mother tree. Also, tetrazolium tests and fruit dissection showed that the average germination (≈ 30%) is due to a very high value of degraded (38.7%), empty (19.1%) and non-viable (12.7%) seeds. We conclude Polylepis incana saplings can be produced using seeds in combination with cuttings, and that it is possible to select trees with environmental conditions that favor seed performance. We also advise collecting seeds from as many trees as possible to ensure genetic diversity and establish more resilient populations in a context of climate change.