Seed germination traits of Pinus heldreichii in two Greek populations and implications for conservation

Seed germination traits were assessed on Pinus heldreichii H. Christ, a Tertiary relict, high-elevation Mediterranean pine, endemic in the western Balkan Peninsula and southern Italy; it is naturally grown at the northern Greece mountains, but also found in shrubby form above the timberline. Closed and mature cones were collected (October) for three consecutive years from Pin-dos Range and Mt. Olympus populations. Cone and seed morphological traits were recorded along with the seedling cotyledon number. Seed germination tests were performed under various ecologically meaningful temperatures and light regimes; climate change effects on seed germination and seedling development were assessed based on two climate scenarios. Final seed germination was moderate (similar to 55%) on both, untreated seed lots at most favourable conditions (15 and 20 degrees C). Although cold stratification is not an absolute requirement, seed germination rate and final percentage are promoted by both a month of cold stratification (at least 30 or 45 days) and white light. The predicted climate change suggests that a prolonged drought period (>3 months) might turn out by the end of the century in the populations studied. Although the temperature increase might not have significant effects in the germination window of the species. The rainfall decrease will inevitably expose the young seedlings to the summer drought, thus increasing the potential mortality rate. Both ex situ (e.g., germplasm conservation) and in situ measures of conservation are recommended for the species survival in Greece, with a particular focus on the populations established at lower altitudes.

Automated summary

Seed germination traits of Pinus heldreichii H. Christ were assessed, and it was found that both cold stratification and white light promote seed germination rate and final percentage. The predicted climate change, including prolonged drought and temperature increase, may have negative effects on seed germination and seedling growth of this species, highlighting the need for conservation measures.