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An elliptical blade is not a true ellipse,but a superellipse–Evidence from two Michelia species

Journal of Forestry Research 2022年第4期33卷 1341-1348页

作者： Yuping Li Karl JNiklas Johan Gielis Ülo Niinemets julian schrader Rong Wang Peijian Shi College of Horticulture Jinling Institute of TechnologyNanjing 210038People’s Republic of China Bamboo Research Institute Nanjing Forestry UniversityNanjing 210037People’s Republic of China Plant Biology Section School of Integrative Plant ScienceCornell UniversityIthacaNY 14853USA Department of Biosciences Engineering University of AntwerpB-2020 AntwerpBelgium Institute of Agricultural and Environmental Sciences Estonian University of Life Sciences51006 TartuEstonia Estonian Academy of Sciences 10130 TallinnEstonia Department of Biological Sciences Macquarie UniversitySydneyNSW 2109Australia Biodiversity Macroecology and BiogeographyUniversity of Göttingen37077 GöttingenGermany

The shape of leaf laminae exhibits considerable diversity and complexity that reflects adaptations to environmental factors such as ambient light and precipitation as well as phyletic legacy.Many leaves appear to be elliptical which may represent a‘default’developmental condition.However,whether their geometry truly conforms to the ellipse equation(EE),i.e.,(x/a)^(2)+(y/b)^(2)=1,remains conjectural.One alternative is described by the superellipse equation(SE),a generalized version of EE,i.e.,|x/a|^(n)+|y/b|^(n)=1.To test the efficacy of EE versus SE to describe leaf geometry,the leaf shapes of two Michelia species(i.e.,M.cavaleriei var.platypetala,and M.maudiae),were investigated using 60 leaves from each species.Analysis shows that the majority of leaves(118 out of 120)had adjusted root-mean-square errors of<0.05 for the nonlinear fitting of SE to leaf geometry,i.e.,the mean absolute deviation from the polar point to leaf marginal points was smaller than 5%of the radius of a hypothesized circle with its area equaling leaf area.The estimates of n for the two species were<2,indicating that all sampled leaves conformed to SE and not to EE.This study confirms the existence of SE in leaves,linking this to its potential functional advantages,particularly the possible influence of leaf shape on hydraulic conductance.

关键词： Bilateral symmetry Leaf ellipticalness index Leaf laminae Leaf roundness index Magnoliaceae

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Quantifyingα-diversity as a continuous function of location——a case study of a temperate forest

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林业研究:英文版 2023年第6期34卷 1683-1691页

作者： Peijian Shi Brady K.Quinn Long Chen Jie Gao julian schrader Bamboo Research Institute College of Ecology and EnvironmentNanjing Forestry University159 Longpan RoadNanjing 210037People’s Republic of China Tropical Silviculture and Forest Ecology University of GottingenBusgenweg 137077 GottingenGermany St.Andrews Biological Station Fisheries and Oceans Canada125 Marine Science DriveSt.AndrewsNB E5B 0E4Canada College of Life Science Xinjiang Normal University102 Xinyi RoadUrumqi 830054People’s Republic of China School of Natural Sciences Macquarie UniversitySydneyNSW 2109Australia Biodiversity Macroecology&BiogeographyUniversity of GottingenBusgenweg 137077 GottingenGermany

α-diversity describes species diversity at local scales.The Simpson’s and Shannon-Wiener indices are widely used to characterizeα-diversity based on species abundances within a fixed study site(e.g.,a quadrat or plot).Although such indices provide overall diversity estimates that can be analyzed,their values are not spatially continuous nor applicable in theory to any point within the study region,and thus they cannot be treated as spatial covariates for analyses of other variables.Herein,we extended the Simpson’s and Shannon-Wiener indices to create point estimates ofα-diversity for any location based on spatially explicit species occurrences within different bandwidths(i.e.,radii,with the location of interest as the center).For an arbitrary point in the study region,species occurrences within the circle plotting the bandwidth were weighted according to their distance from the center using a tri-cube kernel function,with occurrences closer to the center having greater weight than more distant ones.These novel kernel-basedα-diversity indices were tested using a tree dataset from a 400 m×400 m study region comprising a 200 m×200 m core region surrounded by a 100-m width buffer zone.Our newly extendedα-diversity indices did not disagree qualitatively with the traditional indices,and the former were slightly lower than the latter by<2%at medium and large band widths.The present work demonstrates the feasibility of using kernel-basedα-diversity indices to estimate diversity at any location in the study region and allows them to be used as quantifiable spatial covariates or predictors for other dependent variables of interest in future ecological studies.Spatially continuousα-diversity indices are useful to compare and monitor species trends in space and time,which is valuable for conservation practitioners.

关键词： Distance-based weighting Diversity continuum Kernel function Shannon-Wiener index Simpson’s index Tri-cube kernel

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