Wind-driven gap development in Birkley Wood, a long-term retention of planted Sitka spruce in upland Britain

2007 ◽  
Vol 37 (10) ◽  
pp. 1787-1796 ◽  
Author(s):  
C.P. Quine ◽  
D. C. Malcolm
Keyword(s):  
Wind Speed ◽  
Stand Structure ◽  
Sitka Spruce ◽  
Picea Sitchensis ◽  
Stand Development ◽  
Gap Formation ◽  
Planted Forests ◽  
Seed Sources ◽  
Strong Winds

Management of planted forests in Britain is changing to incorporate biodiversity and other nontimber values by lengthening rotations, seeking alternatives to clear-felling, and identifying stands for nonintervention. However, there are particular uncertainties over stand development of exotic species on areas of high windthrow hazard. This study considered the effect of strong winds between 1987 and 2000 on stand development of Sitka spruce ( Picea sitchensis (Bong.) Carrière) planted in 1923. Windthrown gap area increased eightfold through at least 38 separate events. Windthrow of trees assessed as stable occurred during periods of higher wind speed than those with windthrow of trees assessed as vulnerable, and there was a nonlinear relationship between wind speed and increase in gap area. Gap expansion contributed more to the increase in gap area than new gap formation, and the centre of the largest gap migrated downwind. Nevertheless, a substantial proportion of the stand remains undisturbed to an extent not predicted. Therefore, a complex stand structure may develop, including a partial wave of natural regeneration of Sitka spruce in the expanding gaps, but species diversification will be slow due to the absence of local seed sources. The results provide insights for stand dynamics in windy, maritime environments.

Heritability of height growth in 10-year-old Sitka spruce

1985 ◽  
Vol 27 (6) ◽  
pp. 729-734 ◽  
Author(s):  
Francis C. Yeh ◽  
Sven Rasmussen
Keyword(s):  
Sitka Spruce ◽  
Height Growth ◽  
Picea Sitchensis ◽  
Breeding Program ◽  
Progeny Test ◽  
Northwest Coast ◽  
Phenotypic Variance ◽  
Family Selection ◽  
Sources Of Variation

Ten-year height growth for Picea sitchensis (Bong.) Carr. was studied in a progeny test of 42 wind-pollinated families from seven stands on the northwest coast of Vancouver Island. Although stand and family-within-stand effects were significant sources of variation, 79% of the phenotypic variance in 10-year height was associated with differences among trees within family plots. Estimates of heritability ([Formula: see text], [Formula: see text], and [Formula: see text]) indicate that a combination of stand, family-within-stand, and progeny-within-family selection will be effective for a long-term breeding program to increase tree heights in Sitka spruce.Key words: Picea, heritability, quantitative.

Long-Term Wind Speed Trends over Australia

2012 ◽  
Vol 25 (1) ◽  
pp. 170-183 ◽  
Author(s):  
Alberto Troccoli ◽  
Karl Muller ◽  
Peter Coppin ◽  
Robert Davy ◽  
Chris Russell ◽  
...  
Keyword(s):  
Wind Speed ◽  
Atmospheric Circulation ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Long Period ◽  
The Mean ◽  
Strong Winds ◽  
Circulation Changes ◽  
Linear Trends

Abstract Accurate estimates of long-term linear trends of wind speed provide a useful indicator for circulation changes in the atmosphere and are invaluable for the planning and financing of sectors such as wind energy. Here a large number of wind observations over Australia and reanalysis products are analyzed to compute such trends. After a thorough quality control of the observations, it is found that the wind speed trends for 1975–2006 and 1989–2006 over Australia are sensitive to the height of the station: they are largely negative for the 2-m data but are predominantly positive for the 10-m data. The mean relative trend at 2 m is −0.10 ± 0.03% yr−1 (−0.36 ± 0.04% yr−1) for the 1975–2006 (1989–2006) period, whereas at 10 m it is 0.90 ± 0.03% yr−1 (0.69 ± 0.04% yr−1) for the 1975–2006 (1989–2006) period. Also, at 10 m light winds tend to increase more rapidly than the mean winds, whereas strong winds increase less rapidly than the mean winds; at 2 m the trends in both light and strong winds vary in line with the mean winds. It was found that a qualitative link could be established between the observed features in the linear trends and some atmospheric circulation indicators (mean sea level pressure, wind speed at 850 hPa, and geopotential at 850 hPa), particularly for the 10-m observations. Further, the magnitude of the trend is also sensitive to the period selected, being closer to zero when a very long period, 1948–2006, is considered. As a consequence, changes in the atmospheric circulation on climatic time scales appear unlikely.

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