engleski

Morphometric research of samaras of North American ash species from Croatian plantations

Background and Purpose: Fraxinus americana L. and F. pennsylvanica were introduced 100 years ago in forest management in the lowland regions of Croatia to afforestation sites where the native narrow-leaved ash could not survive. These species are not distinguished in the practice in Croatia. Aim of the article was to determinate distinguishing traits between introduced North American ash species based on morphological traits of samaras. Reliable determination is the necessary precondition for successful forest management of plantations of those two species. Materials and Methods: Samaras were collected from 50 trees in Croatian plantations on 5 localities (Karlovac, Dugo Selo, Đurđevac, Batina, Gunja), and from 3 voucher trees of F. americana and from 1 voucher tree of F. pennsylvanica. The following traits were measured: length of samara, length and width of samara wing, length and width of seed cavity and the length of wing along side of seed cavity. The results were evaluated using UPGMA method of cluster analysis with Euclidean distance (DE). Results: The most variable trait was absolute length of wing along seed cavity with coefficient variability (CV) from 8.38% to 23.41%, while the least variable trait was the ratio between length of seed cavity and length of samara (CV = 3.64–7.84%). Samaras from Croatian plantations have shown more similarity with F. pennsylvanica. Cluster analysis separated voucher trees of F. americana from trees from Croatian plantations of North American ash species, while tree of F. pennsylvanica was fitted into the trees from Croatian plantations. Conclusions: Only the presence of F. pennsylvanica in Croatian plantations was confirmed.

Fraxinus americana; Fraxinus pennsylvanica; lowland forest plantations

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