| In ecosystem,the characteristic quantities of most plants such as length,diameter and density will gradually increase or decrease over time.Whether it gradually increases or decreases with time,the changes in these characteristic quantities are not same,which reflects the allometric growth relationship between the various characteristic quantities of plants.In recent years,due to the incompleteness of various theories describing the allometric growth of plants,more and more such research is being carried out.From different scales,the allometric scale of plants has different explanations.On the population scale,the allometric scale of plants refers to the allometric scaling relationships between population density and average biomass of the population.The changes of population density during plant growth will affect the individual average biomass in the population,which is the self-thinning process of the population.On the individual scale,it mainly describes the allometric scaling relationships between plant characteristics.During the growing process of individual plants,the growth rates of characteristic quantities such as length and diameter are different.Generally,the fractal dimension is used to describe the growth proportional relationships between each characteristic quantity of the plant.This article focuses on the herbs and shrubs in the forest land of Chongli Mountain area.Combined with allometric equation and statistical methods,the law of power exponential of herbs and shrubs allometric growth are explored.The main conclusions are as follows:(1)At the population scale,the self-thinning power exponent of herbs varies with different richness,but it shows obvious irregularity.The reasons are that the self-thinning power exponent is mainly affected by the population density.The greater the population density at a given resource,the stronger the inhibitory effect on the population.And there is no direct relationship between richness and population density.(2)A variety of plants such as trees and shrubs are distributed in the herb growth area.These plants and herbs compete for resources together,which affects the self-thinning power exponent of herb population.At the same time,inter-species competition between herbs and the resources conditions in the herb growth area will affect the self-thinning power exponent of herb population too.The analysis of variance shows that the woodland type and species richness did not affect the self-thinning power exponent of herb population.(3)On the individual scale,the fractal dimensions of plant individuals corresponding to different shrub species are also different.The length fractal dimensions of the shrub are in the desreasing order:Salix matsudana K.,Corylus heterophylla F.,Malus baccata(L inn.)B.,and Prunus padus L.;The sectional area fractal dimensions are in the desreasing order:Salix matsudana K.,Malus baccata(Linn.)B.,Corylus heterophylla F.and Prunus padus L.;The biomass fractal dimensions in the desreasing order are:Salix matsudana K.,Malus baccata(Linn.)B.,Corylus heterophylla F.and prunus The leaf fractal dimensions in the desreasing order are:Malus baccata(Linn.)B.,Prunus padus L.,Corylus heterophylla F.,Salix matsudana K.(4)The research shows that the length fractal dimension and sectional area fractal dimension of the shrub are greatly affected by the shrub species.Shrubs’ branches of different types show different proportional relationships in length and diameter,which shows the uniquely growing characteristics of the shrub branches.The biomass fractal and leaf fractal of shrubs are less affected by shrub species.The reasons is that the growth time of the shrubs,the resource conditions of the growing environment,and the absorption and utilization of the resources by the shrubs will affect the biomass and leaf number of shrub plants.In this paper,the power exponential law of the allometric scaling relationships of undergrowth vegetation are studied from different scales.The allometric scale between the density of herb population and the average biomass,and the allometric scale relationships between different characteristic quantities of individual shrub plants are analyzed.This study also provides a reference for the rational planning of the vegetation pattern of the forest system. |
