Reproductive variability and pollen limitation in three Betula taxa in northern Sweden
Reproductive variability and pollen limitation in three Betula taxa in northern Sweden
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瑞典北部三个桦木类群的繁殖变异性和花粉限制
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
S. Holm
中科院分区：
文献类型：
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作者：
S. Holm
这项为期3年的研究证明，瑞典北部白桦(Betula)的授粉和种子质量在分类群、高海拔和低海拔种群之间存在较大差异，并且不同年份间种子质量与授粉度呈正相关，并通过补充花粉改善山区毛白桦的授粉状况，表明垂穗桦花粉限制表现出相同的趋势，但山区垂穗桦有性生殖能力下降不太明显，更多的可能是由于种子成熟和种子抵御散布前种子捕食的资源有限。相比之下，两种沿海种群的授粉率相对较高，补充授粉对种子质量没有影响。与毛白桦相比，毛白桦的授粉能力和种子质量普遍较低，但与垂穗白桦的山地种群相比则不明显。因此，白桦可能存在花粉受限现象，但不同的分类群、海拔高度和年份对种子质量的影响程度也不同。此外，还存在着根蚊(Semudobia spp，Diptera Cecidomyndae)感染和种子成熟不完全等因素。
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