Interannual variability of germination and cone/seed morphometric characteristics in the endemic Grecian fir (Abies cephalonica) over an 8-year-long study

Abstract

Abies cephalonica cone and seed morphometric characteristics as well as seed germination behaviour were investigated during an 8-year-long diachronic study (2007–2015). The research was carried out in Parnitha National Park, in the part of this Greek endemic, silver fir population that was spared from an unprecedented wildfire (2007). A statistically significant interannual and among-tree variation of cone traits has been identified, except for cone diameter. Cone length is correlated to the number of seeds per cone, while the percentage of empty seeds has been consistently high, with extreme values of 29.3 and 81.8% in a masting (2015) and lean crop (2009) year, respectively. There is also a considerable proportion of dead (including infected) and non-germinated seeds, and the eventual germinable fraction is well below 25% with spikes in masting years (39.4 and 60.9% in 2010 and 2015, respectively). Untreated seeds have been tested at a wide range of constant and alternating temperatures and germination is completed within 4–5 weeks at T ≥ 15°C and ca 15 weeks at 5–10°C. A chilling pretreatment of 4–8 weeks (at 2–4°C) concludes germination at 15–20°C within 2 weeks. A significant white light requirement has been observed for untreated seeds at 15–20°C, while germination was light indifferent at lower or higher temperatures. Data obtained in this study confirm the present, field seed germination during springtime; we may also predict an earlier germination (late autumn to mid-winter) in forest gaps, under the predicted, warmer conditions in the future.

Determination of the Environmental Factors that Affect the Growth and Survival of Greek Fir Seedlings

“…The high variability among seedlings leading to low within year explanatory power persists, even in later years when the number of surviving ones was a fraction of the number planted in the first place. The seed material used to produce the seedlings comes from a natural forest and Greek fir is known for its high intraspecies variability [53][54][55]. Thus, we hypothesised that variability in growth rates among seedlings would be high and the hypothesis was indeed confirmed.…”

Germination Behavior and Early Seedling Growth in Abies pinsapo Boiss. Seeds

“…Nevertheless, a significant temperature × light interaction was found, thereby revealing a variable influence of light depending on the germination temperature. This interaction, although with different temperature effects, was also described in Picea abies [ 33 ], Abies cephalonica [ 34 ] and Pinus sylvestris [ 19 ]. As reported in Pinus brutia [ 23 ], light broadened the germination temperature.…”

Masting and regeneration dynamics of Abies cephalonica, the Greek endemic silver fir

“…The leanest crop was reported for the year immediately following the masting year, with a remarkable reduction in reproduction (only 2% of cone-bearing trees, 0.08 cones per tree). These findings are further accentuated by additional reproductive traits of A. cephalonica ; seed viability and germinability attain significantly higher values during masting years, while unsound and poorly germinating seeds are produced during the lean ones (Daskalakou et al ., 2018). Similar results regarding cone production have been reported for A. alba Mill., the closest European relative to A. cephalonica , with an average percentage of trees without cones below 2.5% in a high production year and above 81.5% in the year of lowest production (Davi et al ., 2016).…”

“…In fire-free conditions, large fluctuations of A. cephalonica seedling density were attributed to mast seeding and habitat characteristics (Politi et al, 2009(Politi et al, , 2011 and further explained by betterquality seeds (i.e. with higher seed viability and germinability levels) produced during masting years (Daskalakou et al, 2018).…”