Competition within stands of Picea sitchensis and Pinus contorta

Competition was analysed in plots of Picea sitchensis and Pinus contorta grown in 50 × 50 hexagonal arrays at 14 cm spacing to ages 7 and 5 years, respectively. Relative growth rates in height (RHGR) became positively related to tree heights during the year before harvest. Frequency distributions of...

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Bibliographic Details
Published in:Annals of botany 1984-03, Vol.53 (3), p.349-362
Main Authors: Cannell, M.G.R, Rothery, P, Ford, E.D
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal, plant and microbial ecology
artificial regeneration
Biological and medical sciences
competition
Dead wood
Demecology
Ecological competition
forestry
Frequency distribution
Fundamental and applied biological sciences. Psychology
growth model
monoculture
Mortality
Picea sitchensis
Pine trees
Pinus contorta
Plant competition
Plants
Plants and fungi
relative growth rate
self-thinning
silviculture
Statistics
Tree felling
Trees
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Summary:Competition was analysed in plots of Picea sitchensis and Pinus contorta grown in 50 × 50 hexagonal arrays at 14 cm spacing to ages 7 and 5 years, respectively. Relative growth rates in height (RHGR) became positively related to tree heights during the year before harvest. Frequency distributions of tree heights became negatively kurtotic with tendencies towards left-skew ness. By the time of harvest, dead trees were evenly dispersed over the plots. Trees with many taller neighbours had lower RHGRs than trees with few taller neighbours, and the RHGRs of intermediate-sized trees were correlated with their ‘competitive status’. Competition was confined mostly to first-order neighbours. Large trees depressed the RHGRs of smaller neighbours and not vice versa; a simple test for this ‘one-sided’ competition is described. Neighbours did not need to greatly overtop a tree to depress its RHGR, they needed only to be at least as tall. Systematic trends in RHGR across the plots, attributed to site heterogeneity, decreased with time, and accounted for only about 10 per cent of the variation in RHGR at harvest. Competitive status accounted for 25 and 38 per cent of the variation in RHGR in the Picea sitchensis and Pinus contorta plots, respectively.
ISSN:0305-7364
1095-8290
DOI:10.1093/oxfordjournals.aob.a086699