Forked spleenwort, Asplenium septentrionale, is a mainly petrophilous fern species in European mountains and rare on acidic siliceous rocks in lowland areas of the continent, where habitats are fragmented and populations isolated. In Estonia, the single extant population occupies a restricted area and is threatened by human disturbances. An introduction project of the species was prepared to estimate the potential to form new populations in new protected sites using ex-situ propagated young sporophytes as transplantation material, by comparing the recruitment biology of three different donor populations. 

Asplenium septentrionale in nature (photo by Kai Rünk)

First, we carried out a laboratory breeding experiment to evaluate the populations’ ability for intra-gametophytic selfing, and secondly, in a common garden estimated the fitness of offspring. The results showed that the only Estonian donor population showed very high capacity for intra-gametophytic selfing, as well as high rate of sporophytic mortality (83%), and these rates were comparable to one of two reference donor populations in Finland. However, plants of Estonian population were smaller, representing a unique locally adapted genotype. Therefore, it needs more efficient protection in its present location. We suggest that planting material for introduction into nearby new locations should be collected from the local population, as the best locally adapted. Only in the risk of severe environmental change and of extinction, several neighbouring populations could be pooled to maximise genetic diversity.

Citation: Rünk, K., Pihkva, K., Liira, J., & Zobel, K. (2016). Selection of source material for introduction of the locally rare and threatened fern species Asplenium septentrionale.Plant Ecology & Diversity, 9: 167-173 (link to full text)

Asplenium in pot experiment (photo by Kai Rünk)

Abstract:

Background: Forked spleenwort, Asplenium septentrionale, is a mainly petrophilous fern species in European mountains and rare on acidic siliceous rocks in lowland areas of the continent, where habitats are fragmented and populations isolated. In Estonia, the single extant population is very small, occupies a restricted area and is threatened by human disturbances. An introduction project of the species was prepared to form new populations in new protected sites using ex-situ propagated young sporophytes as transplantation material.

Aims: To obtain data on the species recruitment population biology and provide context information for selecting donor plant material.

Methods: We sampled three regional/local donor populations. First, we carried out a laboratory breeding experiment to evaluate the populations’ ability for intra-gametophytic selfing. Second, to estimate differences in fitness of offspring among the populations, we grew young sporophyte plants in a pot experiment under controlled conditions in a common garden.

Results: The Estonian population showed very high capacity (90%) for intra-gametophytic selfing, as well as high rate of sporophytic mortality (83%), but the rates are comparable to one of the reference populations in Finland. However, plants of Estonian population were smaller.

Conclusions: The Estonian population may represent a unique pre-adapted or locally adapted genotype; therefore, it needs more efficient protection in its present location. Planting material for introduction should be collected from the local population, as the best locally adapted. Only in the risk of severe environmental change and of extinction, several neighbouring populations could be pooled to maximise genetic diversity.