The
field study of competition for resources by plants is fundamentally a
question of how constraints on growth, survival, and reproduction change
with different densities of conspecifics and heterospecifics. In a recent
paper in Oikos, Brian Cade and Qingfen Guo demonstrated how survival due
to self-thinning in two Chihuahuan desert annuals could be described more
realistically and rigorously with regression quantile estimates than with
other statistical procedures used previously. Several alternative model
forms were considered, estimates were made across all quantiles [0,1],
but interpretation and model selection focused on estimates for the upper
quantiles (0.90-0.99) where competition constrains the boundary of the
survival distribution. The analysis with regression quantiles supported
a model that allowed for low to high intensity of intraspecific competition
with increasing germination densities, a feature not identified in previous
analyses.
Also at FORT |
U.S. Department of the Interior | U.S. Geological Survey
URL: http://www.fort.usgs.gov/resources/spotlight/blossom/blossom_selfthinning.asp
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