Reproductive variability and pollen limitation in three Betula taxa in northern Sweden

• Published in: Ecography
• Main Author: Holm, Stig‐Olov
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1994
• Subjects: Ecology, Evolution, Behavior and Systematics; Northern Sweden
• Online Access: http://dx.doi.org/10.1111/j.1600-0587.1994.tb00078.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1600-0587.1994.tb00078.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0587.1994.tb00078.x

This 3‐yr study documents large variation in pollination and seed quality in birches (Betula) in northern Sweden between taxa, high and low altitude populations, and among years Seed quality was positively correlated with pollination degree and improved by pollen supplementation in B pubescens ssp pubescens in the mountain area, indicating pollen limitation Betula pendula showed the same tendency, but less pronounced Reduced sexual reproduction of B pendula in the mountain area might more often be due to limited resources for seed maturation and defense of the seeds against predispersal seed predation In contrast, coastal populations of both species display relatively high pollination rates and supplemental pollination had no effect on seed quality, suggesting that pollen limitation is rare or absent here The mountain birch Betula pubescens ssp tortuosa showed generally lower pollination and seed quality compared with B pubescens ssp pubescens , but not compared with mountain populations of B pendula It is concluded that pollen limitation may occur in Betula , but to what extent varies with taxon, altitude and year The seed quality is also strongly affected by other factors such as infections of gall midges (Semudobia spp, Diptera Cecidomyndae) and incomplete seed maturation