Differences in the climatic adaptation of silver birch (Betula pendula) and downy birch (B. pubescens) in Finland based on male flowering phenology.

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dc.contributor.author Luomajoki, Alpo
dc.date.accessioned 2011-07-28T14:04:39Z
dc.date.available 2011-07-28T14:04:39Z
dc.date.issued 1999
dc.identifier.citation Acta Forestalia Fennica. 1999. 263: 1-35. fi
dc.identifier.issn 0001-5636
dc.identifier.uri http://hdl.handle.net/10138/27301
dc.description.abstract Male flowering was studied at the canopy level in 10 silver birch (Betula pendula Roth) stands from 8 localities and in 14 downy birch (B. pubescens Ehrh.) stands from 10 localities in Finland from 1963 to 1973. Distributions of cumulative pollen catches were compared to the normal Gaussian distribution. The basis for the timing of flowering was the 50 per cent point of the anthesis-fitted normal distribution. To eliminate effects of background pollen, only the central, normally distributed part of the cumulative distribution was used. Development up to the median point of the distribution was measured and tested in calendar days, in degree days (> 5 °C) and in period units. The count of each parameter began on and included March 19. Male flowering in silver birch occurred from late April to late June depending on latitude, and flowering in downy birch took place from early May to early July. The heat sums needed for male flowering varied in downy birch stands latitudinally but there was practically no latitudinal variation in heat sums needed for silver birch flowering. The amount of male flowering in stands of both birch species were found to have a large annual variation but without any clear periodicity. The between years pollen catch variation in stands of either birch species did not show any significant latitudinal correlation in contrast to Norway spruce stands. The period unit heat sum gave the most accurate forecast of the timing of flowering for 60 per cent of the silver birch stands and for 78.6 per cent of the for downy birch stands. Calendar days, however, gave the best forecast for silver birch in 25 per cent of the cases, while degree days gave the best forecast for downy birch in 21.4 per cent of the cases. Silver birch seems to have a local inclination for a more fixed flowering date compared to downy birch, which could mean a considerable photoperiodic influence on flowering time of silver birch. Silver birch and downy birch had different geographical correlations. Frequent hybridization of birch species occurs more often in northern Finland in than in more southern latitudes. The different timing in flowering caused increasing scatter in flowering times in the north, especially in the case of downy birch. The chance of simultaneous flowering of silver birch and downy birch so increased northwards due to a more variable climate and also higher altitudinal variations. Compared with conifers, the reproduction cycles of both birch species were found to be well protected from damage by frost. fi
dc.language.iso en fi
dc.publisher The Society of Forestry in Finland - The Finnish Forest Research Institute fi
dc.subject rauduskoivu fi
dc.subject hieskoivu fi
dc.subject sopeutuminen fi
dc.subject ilmasto fi
dc.subject fenologia fi
dc.subject fotoperiodismi fi
dc.subject Betula pendula fi
dc.subject Betula pubescens fi
dc.subject males fi
dc.subject flowering fi
dc.subject timing fi
dc.subject pollen fi
dc.subject air temperature fi
dc.subject environmental temperature fi
dc.subject photoperiodicity fi
dc.subject adaptation fi
dc.subject ecology fi
dc.subject physiological requirements fi
dc.subject seasons fi
dc.subject natural hybridization fi
dc.subject male flowering, timing of flowering, pollen catch, heat sum, photoperiodism, adaptation, ecophysiological differences, seasonality, hybridization, Betula fi
dc.title Differences in the climatic adaptation of silver birch (Betula pendula) and downy birch (B. pubescens) in Finland based on male flowering phenology. fi
dc.type Artikkeli fi
dc.identifier.laitoskoodi SMS fi

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