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No.70 (2000/9) >

 
Title :Time-trajectory of Mean Phytomass and Density in Self-thinning Plant Populations
Authors :Hagihara, Akio
Authors alternative :萩原, 秋男
Issue Date :Sep-2000
Abstract :Reconciling the competition-density (C-D) effect observed at a particular moment in time with the 3/2 power law of self-thinning observed over time, a model for describing the time-trajectory of mean phytomass w and density p (briefly, the w-p trajectory) during the course of self-thinning is theoretically derived. The model gives a consistent, full explanation of the w-p trajectories of populations starting with any initial density. The larger value of the relative mortality rate with respect to biological time of a population, which is governed by the 3/2 power law of self-thinning, plays an important role in relieving the C-D effect, so that the w-p trajectories asymptotically approach the self-thinning line on logarithmic coordinates at the earlier stage of growth. The survivorship curve is divided into three types owing to initial density: logistic, exponential and cologistic types of decrease. All populations tend to decrease exponentially in number at the same rate of relative mortality after a sufficient lapse of time, irrespective of their initial density. The populations decreasing exponentially in number follow the 3/2 power law of self-thinning. The carrying capacity of yield is explicitly defined as a function of biological time, so that it is concluded that the carrying capacity increases exponentially with increasing biological time. An approximated expression of the model for the w-p trajectory is proposed and is confirmed to mimic well the time-trajectories of mean stem volume and density during the development of eastern white pine (Pinus strobus L.) plantations.
Type Local :紀要論文
ISSN :0286-9640
Publisher :琉球大学理学部
URI :http://hdl.handle.net/20.500.12000/11818
Citation :琉球大学理学部紀要 = Bulletin of the College of Science. University of the Ryukyus no.70 p.99 -112
Appears in Collections:No.70 (2000/9)

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