Narrow genetic base in forest restoration with holm oak (Quercus ilex L.) in Sicily

TL;DR

This study reveals that current seed sampling practices for holm oak in Sicily significantly reduce genetic diversity, highlighting the need for improved strategies to maintain genetic health in forest restoration efforts.

Contribution

It provides empirical evidence of the genetic impact of seed sampling strategies on holm oak restoration, using microsatellite analysis to quantify effective parent numbers.

Findings

Significant reduction in genetic diversity in seedling lots.

Low effective number of seed and pollen donors (Nfe ≈ 2-4, Ne ≈ 35-50).

Inappropriate seed harvest strategy limits genetic variability.

Abstract

In order to empirically assess the effect of actual seed sampling strategy on genetic diversity of holm oak (Quercus ilex) forestations in Sicily, we have analysed the genetic composition of two seedling lots (nursery stock and plantation) and their known natural seed origin stand by means of six nuclear microsatellite loci. Significant reduction in genetic diversity and significant difference in genetic composition of the seedling lots compared to the seed origin stand were detected. The female and the total effective number of parents were quantified by means of maternity assignment of seedlings and temporal changes in allele frequencies. Extremely low effective maternity numbers were estimated (Nfe $\approx$ 2-4) and estimates accounting for both seed and pollen donors gave also low values (Ne $\approx$ 35-50). These values can be explained by an inappropriate forestry seed harvest strategy limited to a small number of spatially close trees.