Local seed dispersal in European silver fir (Abies alba Mill.): lessons learned from a seed trap experiment

Abstract

Seed dispersal is an important factor influencing the genetic structure of forest tree populations. Knowledge about the seed shadow is important to assess the ability of tree species to colonize new and disturbed habitats or to respond to environmental change by migrating to more suitable habitats. In a seed trap experiment, we investigated local seed dispersal distances of silver fir seeds (Abies alba Mill.) by explicitly identifying mother trees. For this purpose, we matched microsatellite genotypes of maternal tissues of seeds with the genotypes of adult trees in the studied stand. Furthermore, we analysed the effect of morphological traits on dispersal distance, and we assessed the number of contributing mother trees and compared the seed density of the closed forest-stand with the adjacent blowdown. Based on 674 seeds collected in a grid of 37 seed traps, a significant decline in seed density was observed from within the forest to the forest blowdown area [40 m from the forest edge. A median dispersal distance of 31 m was determined for filled seeds based on direct assignment of seeds to their mother trees. This was higher than that determined in the previous studies using different methods. Dispersal distance was negatively correlated to seed-weight, but this was partially compensated for by the length of seed wings. A very large number of unassigned maternal genotypes (435) suggested that dispersal distance might have been underestimated. Lessons for future studies were: to perform a full genotypic inventory of adult trees in a defined perimeter, to increase the number of microsatellite markers and to study several sites over a period of several years.

Post-fire recovery of Abies cephalonica forest communities: the case of Mt Parnitha National Park, Attica, Greece

“…Nonetheless, we found the same spatial pattern of decreasing seed and regeneration density with distance from the edge of the unburned patch, as expected for wind-dispersed species (Nathan & Casagrandi 2004, Nathan & Neeman 2004, Raftoyannis & Spanos 2015. According to Cremer et al (2012), the median distance of seed dispersal of Abies alba, another fir species which like A. cephalonica produces winged seeds dispersed by wind, was 31 m. In our study, more than 70% of the dispersed seeds and young firs were found within a distance shorter than 50m from the parent trees. This is similar to the results of the dispersal curve of most wind-dispersed tree species, which show a peak at, or very close to, the source, followed by a rapid decline, and a long tail (Nathan & Casagrandi 2004, Nathan & Neeman 2004.…”

The past ecology of Abies alba provides new perspectives on future responses of silver fir forests to global warming

“…Insects, fungi, late frost, frost desiccation, and industrial emissions (especially SO 2 ) may also affect the tree (Lingg 1986, Schu¨tt et al 2004, Ellenberg 2009, Kozakova et al 2011. The seed dispersal of A. alba is efficient and comparable to that of other wind-dispersed trees (e.g., Picea abies; Sagnard et al 2007, Szymura et al 2007, Cremer et al 2012. Taproots allow the species to grow on dry locations, for instance, in the Mediterranean region, because they can reach deep-water reserves that accumulate during the wet winter period (Aussenac 2002).…”

Genetic variation of silver fir progeny from Tisovik Reserve population determined via microsatellite and isozyme markers

“…There are a very few papers (Cremer et al 2006, Pawlaczyk et al 2010, Cremer et al 2012, Gömöry et al 2012, Cvrčková et al 2015 describing the variation of silver fir in nuclear microsatellite DNA markers. It is caused by the difficulties in finding polymorphic loci in this taxa.…”

“…Another Cremer et al's (2012) study was conducted in the Black Forest, a low mountain range in the southwestern part of Germany. He compared mother trees to seeds on five SSR loci (three the same like in our work) and reported that values of expected and observed heterozygosity and the number of detected allelic richness were as follows: SF 1 (Ho = 0.534, He = 0.539, A R = 5), SF 333 (Ho = 0.489, He = 0.720, A R = 6), and SF b5 (Ho = 0.467, He = 0.471, A R = 7) for forest stands and for seeds: SF 1 (Ho = 0.441, He = 0.509, A R = 7), SF 333 (Ho = 0.557, He = 0.693, A R = 7) and SF b5 (Ho = 0.457, He = 0.529, A R = 8).…”