Effects of climate,biotic factors,and phylogeny on allometric relationships:testing the metabolic scaling theory in plantations and natural forests across China

Background:Metabolic scaling theory(MST)is still in debate because observed allometric exponents often deviate from MST predictions,and can change significantly depending on environment,phylogeny,and disturbance.We assembled published scaling exponents from literatures for three allometric relationships linked to biomass allocation:leaf biomassdiameter(LD),stem biomassdiameter(SD),and root biomassdiameter(RD).We used data from natural forests and plantations across China to test the following hypotheses:1)the allometric relationships of trees support the predictions of MST on a broad scale;2)the observed deviations from MST predictions are caused by climate,biotic factors,and/or phylogeny;3)abiotic and biotic factors influence allometric relationships in plantations and natural forests differently,and different allometric relationships(i.e.LD,SD,and RD)are affected differently.We related these scaling exponents to geographic climate gradient,successional stage,stand density,leaf form and phenology,and phylogeny.We used mixedeffect models to examine the major factors affecting tree allometries.Results:In natural forests,SD and RD scaling exponents were consistent with MST predictions in primary forests,but were significantly lower in secondary forests.Both SD and RD scaling exponents in plantations had a medium value that fell between those of the secondary and primary forests,despite plantations being similar in species characteristics and age to secondary forests.The SD and RD exponents were significantly affected by factors that are not yet considered in MST,including winter coldness which explained 2.76%–3.24%of variations,successional stage(7.91%–8.20%of variations),density(a surrogate for competition,5.86%–8.54%of variations),and especially phylogeny(45.86%–56.64%of variations explained).However,the LD scaling exponents conformed to MST predictions in primary,secondary,and plantation forests,and was not strongly explained by most factors.Conclusion:MST is only applicable to primary(steadystate)forests,and climate,biotic factors and phylogeny are causes of the observed deviations of allometric relationships from MST predictions.Forest management practices in plantations have a strong influence on tree allometries.LD allometry is more strongly controlled by biophysical constraints than SD and RD allometries,however,the mechanisms behind this difference still need further examinations.

Motoyosi Sugita—A “Widely Unknown” Japanese Thermodynamicist Who Explored the 4th Law of Thermodynamics for Creation of the Theory of Life

The purpose of this paper is to introduce to you, the Western people, nowadays a “widely unknown” Japanese thermodynamicist by the name of Motoyosi Sugita and his study on the thermodynamics of transient phenomena and his theory of life. This is because although he was one of the top theoretical physicists in Japan before, during and after WWII and after WWII he promoted the establishment of the biophysical society of Japan as one of the founding members, he himself and his studies themselves have seemed to be totally forgotten nowadays in spite that his study was absolutely important for the study of life. Therefore, in this paper I would like to present what kind of person he was and what he studied in physics as a review on the physics work of Motoyosi Sugita for the first time. I will follow his past studies to introduce his ideas in theoretical physics as well as in biophysics as follows: He proposed the bright ideas such as the quasi-static change in the broad sense, the virtual heat, and the field of chemical potential etc. in order to establish his own theory of thermodynamics of transient phenomena, as the generalization of the Onsager-Prigogine’s theory of the irreversible processes. By the concept of the field of chemical potential that acquired the nonlinear transport, he was seemingly successful to exceed and go beyond the scope of Onsager and Prigogine. Once he established his thermodynamics, he explored the existence of the 4th law of thermodynamics for the foundation of theory of life. He applied it to broad categories of transient phenomena including life and life being such as the theory of metabolism. He regarded the 4th law of thermodynamics as the maximum principle in transient phenomena. He tried to prove it all life long. Since I have recently found that his maximum principle can be included in more general maximum principle, which was known as the Pontryagin’s maximum principle in the theory of optimal control, I would like to explain such theories produced by Motoyosi Sugita as detailed as possible. And also I have put short history of Motoyosi Sugita’s personal life in order for you to know him well. I hope that this article helps you to know this wonderful man and understand what he did in the past, which was totally forgotten in the world and even in Japan.

Morphological characteristics of blood cells in monitor lizards:is erythrocyte size linked to actual body size?

Blood cell morphology and count are not uniform across species.Recently,between-species comparisons revealed that the size of red blood cells is associated with body size in some lizard taxa,and this finding was interpreted in the context of the metabolic theory.In the present study,we examined the numbers and the size of blood cells in 2 species of monitor lizards,the mangrove-dwelling monitor(Varanus indicus)and the savannah monitor(V.exanthematicus),and we compared these traits in individuals of different body size.The results revealed that during the course of ontogeny,the size of red blood cells increases with body mass.Because the mass-specific metabolic rate decreases with body size and the cell volume-to-surface ratio decreases with the cell size,changes in the erythrocyte size might be the result of oxygen transport adjustment.

Asymmetric competition for light varies across functional groups

Aims Asymmetric competition for light may depress the growth rates(GRs)to different extents for different-sized tree individuals.Various responses of different functional groups to light availability result that tree individuals of different functional groups may experience different competition intensities,e.g.canopy and deciduous species grow faster and demand more light than understory and evergreen species.In this study,we estimated the effects of asymmetric competition for light using individual GRs and explored the effects of asymmetric competition on growth among different functional groups(e.g.canopy vs.understory species and deciduous vs.evergreen species).Methods We measured growth in circumference to determine the radial increments of a total of 2233 stems with diameter at breast height≥5.0 cm in a permanent plot(140×80 m^(2))located in a typical evergreen and deciduous broadleaved mixed forest on Mt Shennongjia,China.All of the measurements were carried out at~6-month intervals every April and October from 2012 to 2014,and biomass of each individual was calculated based on its diameter and species-specific allometry.We then calculated GRs of annual biomass growth(growth between October and the next October).Considering the hypothesis that asymmetric competition for light among trees of different sizes may result in a steeper allometric growth curve with increasing tree size,we further divided the sampled trees into different subsets according to their height,at intervals of 1 m,and then fitted the scaling relationship between the logarithm of the biomass GR(logGR)and the logarithm of diameter(logD)for each height class using standardized major axis regression.Finally,we used simple linear regression to test whether the scaling exponent was related to tree height.The above analyses were conducted for the annual growth of all tree species,canopy species,understory vs.treelets species and deciduous vs.evergreen species.Important findings We observed a concave curve for the relationship between logGR and logD with an increase in the scaling exponent between logGR and logD with increasing tree height.This pattern held for the annual growth of canopy species and deciduous species but not for the annual growth of understory species,treelets or evergreen species.These results suggest that asymmetric competition for light is more important in regulating the GRs of the fast-growing species,such as canopy species and deciduous species,than those of shade-tolerant species,such as understory species,treelets and evergreen species.