Variation of Cones Production in a Silver Fir (Abies alba Mill.) Clonal Seed Orchard

Abstract

The current study is the first to describe fertility dynamics in a Silver fir (Abies alba Mill.) seed orchard and among the few reporting related information from a mature seed orchard. The research aim was to evaluate the female cone production in order to provide support to future management measures. Observations were conducted in a clonal seed orchard from the Eastern Carpathians over six years; all the ramets of 44 clones and the zero-inflated data were analyzed with generalized lineal mixed effects models in a Bayesian framework. The results indicated a higher influence of the year and probably of the sensitivity to climate, and less variability between clones, in both the Poisson and zero-inflated components of cones production. The repeatability of mean annual clone production suggests moderate continuity of cone crops in the production rank of individual clones, while the estimates of heritability were under a moderate genetic control. The values of heritability were influenced by the reporting scale (latent vs. original data scale); therefore, caution in the analysis of non-Gaussian data and in comparisons of heritability between seed orchards is required. The variation of the female cone production was higher than expected for a seed orchard, but with marked variation across years, similar to other related indicators, patterns specific to mature, and productive commercial seed orchards. Several management options to be applied in the future were also discussed.

Impact of Crown Closure on Cone Production and Effective Number of Parents in Natural Stands of Taurus Cedar (Cedrus libani A. Rich.)

“…As the result of a recent study indicating a higher influence of the year and probably of the sensitivity to climate, there was less variability between clones for cone production in a silver fir (Abies alba Mill.) seed orchard [24]. It was also reported that the repeatability of mean annual clone production suggested the moderate continuity of cone crops in the production rank of individual clones, while heritability was under genetic control [24].…”

Silver Fir (Abies alba Mill.): Review of Ecological Insights, Forest Management Strategies, and Climate Change’s Impact on European Forests

“…Seed years occur at two-year intervals at lower altitudes, while at higher altitudes, they occur every 3-5 years [289,290]. The differences in fir fertility of cones in Romania reached up to 11.2 times when comparing good mass years to poor years [291]. The mean dispersal distances of seeds from trees ranged from 9.9 m in pure fir stands to 21.5 m in mixed forest in Spain [292].…”

“…Fir seeds should be collected at morphological (hard) maturity, which precedes physiological maturity, when the seeds can germinate [298]. Fir cones are usually collected manually by picking from standing or felled trees [303] or from seed orchards established for this purpose [291]. Using Czechia as an example, the expanding production of silver fir seed material points to rising demand for fir seed material in the context of an increased need for seedlings for the reforestation of large clearings following the 2017-2019 bark beetle calamity ( [67]; Table 3).…”

Diversitatea genetică în plantaje clonale de primă generație de brad (Abies alba Mill.) din România

“…Pentru menţinerea nivelului de diversitate genetică şi în loturile de seminţe, amestecarea diferitelor fonduri de gene este un mijloc eficient, deşi acest aspect este condiţionat de o serie de mecanisme privind sincronizarea înfloririi, unde adaptarea regională ar putea avea un rol important. Studii realizate în ceea ce privește fructificația și rata de panmixie în plantaje de brad au indicat că totuși participarea clonelor este redusă (Teodosiu et al 2022).…”