Plant Morphology and Function, Geometric Morphometrics, and Modelling: Decoding the Mathematical Secrets of Plants

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Plant Ecology".

Deadline for manuscript submissions: closed (20 April 2023) | Viewed by 32016

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Special Issue Editors

College of Urban and Environmental Sciences, Peking University, Beijing 100871, China
Interests: plant morphology and function; leaf traits; climate change; plant growth
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Guest Editor
Bamboo Research Institute, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, China
Interests: dendrochronology; wood anatomy; plant physiology; climate change; bamboo; statistical models
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Guest Editor
Department of Biosciences Engineering, University of Antwerp, B-2020 Antwerp, Belgium
Interests: botany; geometry; shape; differentiation

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Guest Editor
Bamboo Research Institute, College of Biology and the Environment, Nanjing Forestry University, Nanjing 210037, China
Interests: botany; scaling; geometry; applied spatial statistics; forest ecology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The morphological characteristics of plants are closely related to their environmental adaptability and reflect their survival strategies. Thus, plant morphology is the embodiment of plant function. The shapes of the leaves, fruits, seeds, roots and trunks of different plants exhibit natural symmetry. However, there is also a certain degree of morphological variation from this perfect symmetry. Even for the same plant species, significant differences in morphological characteristics can be found at different developmental stages. The quantification of the morphological characteristics of plants by establishing mathematical models, especially geometric models and statistical models, is an important research method in the field of plant morphology. The mathematical analysis of the area and shape of the leaves, flowers, seeds, tree rings, and other morphological characteristics of plants by establishing models is of great assistance to understanding the survival strategies of plants. Similarly, it is important to study the functional properties of plants at large spatial scales to help us better understand how elements of plant morphology adapt to environmental changes. Luckily, ten years ago, a universal geometric equation created by Dr. Johan Gielis was proposed. This equation can be used to describe universal natural shapes, especially symmetrical shapes. Moreover, this model provides a strong tool for uncovering the secrets of plant development and evolution.

This Special Issue of Plants is poised to introduce new case studies and novel approaches to determine the morphological characteristics of different plants and their environmental adaptability strategies. In addition, this Special Issue will also focus on quantifying the geometry of the natural shapes of plants to show their survival and evolutionary traits.

Dr. Jie Gao
Dr. Weiwei Huang
Prof. Dr. Johan Gielis
Dr. Peijian Shi
Guest Editors

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Keywords

  • climate change
  • Gielis equation
  • plant morphology
  • plant functional traits
  • population dynamics
  • symmetry
  • spatial distribution pattern
  • theoretical biology

Published Papers (17 papers)

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Editorial

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2 pages, 195 KiB  
Editorial
Plant Morphology and Function, Geometric Morphometrics, and Modelling: Decoding the Mathematical Secrets of Plants
by Jie Gao, Weiwei Huang, Johan Gielis and Peijian Shi
Plants 2023, 12(21), 3724; https://doi.org/10.3390/plants12213724 - 30 Oct 2023
Cited by 1 | Viewed by 953
Abstract
Functional plant traits include a plant’s phenotypic morphology, nutrient element characteristics, and physiological and biochemical features, reflecting the survival strategies of plants in response to environmental changes [...] Full article

Research

Jump to: Editorial

13 pages, 6484 KiB  
Article
Curvature Analysis of Seed Silhouettes in Silene L.
by Emilio Cervantes, José Luis Rodríguez-Lorenzo, José Javier Martín-Gómez and Ángel Tocino
Plants 2023, 12(13), 2439; https://doi.org/10.3390/plants12132439 - 25 Jun 2023
Cited by 4 | Viewed by 970
Abstract
The application of seed morphology to descriptive systematics requires methods for shape analysis and quantification. The complexity of lateral and dorsal views of seeds of Silene species is investigated here by the application of the Elliptic Fourier Transform (EFT) to representative seeds of [...] Read more.
The application of seed morphology to descriptive systematics requires methods for shape analysis and quantification. The complexity of lateral and dorsal views of seeds of Silene species is investigated here by the application of the Elliptic Fourier Transform (EFT) to representative seeds of four morphological types: smooth, rugose, echinate and papillose. The silhouettes of seed images in the lateral and dorsal views are converted to trigonometric functions, whose graphical representations reproduce them with different levels of accuracy depending on the number of harmonics. A general definition of seed shape in Silene species is obtained by equations based on 40 points and 20 harmonics, while the detailed representation of individual tubercles in each seed image requires between 100 and 200 points and 60–80 harmonics depending on their number and complexity. Smooth-type seeds are accurately represented with a low number of harmonics, while rugose, echinate and papillose seeds require a higher number. Fourier equations provide information about tubercle number and distribution and allow the analysis of curvature. Further estimation of curvature values in individual tubercles reveals differences between seeds, with higher values of curvature in S. latifolia, representative of echinate seeds, and lower in S. chlorifolia with rugose seeds. Full article
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10 pages, 717 KiB  
Article
Rapid Adaptation of Chimonobambusa opienensis Leaves to Crown–Thinning in Giant Panda Ecological Corridor, Niba Mountain
by Di Fang, Junren Xian, Guopeng Chen, Yuanbin Zhang, Hantang Qin, Xin Fu, Liyang Lin, Yuxuan Ai, Zhanbiao Yang, Xiaoxun Xu, Yuanxiang Yang and Zhang Cheng
Plants 2023, 12(11), 2109; https://doi.org/10.3390/plants12112109 - 26 May 2023
Cited by 1 | Viewed by 890
Abstract
Leaf traits reflect the ecological strategy in heterogeneous contexts and are widely used to explore the adaption of plant species to environmental change. However, the knowledge of short-term effect of canopy management on understorey plant leaf traits is still limited. Here, we studied [...] Read more.
Leaf traits reflect the ecological strategy in heterogeneous contexts and are widely used to explore the adaption of plant species to environmental change. However, the knowledge of short-term effect of canopy management on understorey plant leaf traits is still limited. Here, we studied the short-term effect of crown–thinning on the leaf morphological traits of bamboo (Chimonobambusa opienensis), an important understorey plant and staple food for the giant panda (Ailuropoda melanoleuca) of Niba Mountain. Our treatments were two crown–thinnings (spruce plantation, CS, and deciduous broad-leaved forest, CB) and two controls (broad-leaved forest canopy, FC, and the bamboo grove of clearcutting, BC). The results showed that: the CS enhanced the annual leaf length, width, area, and thickness, CB decreased almost all annual leaf traits, and perennial leaf traits in CS and CB were the opposite. The log-transformed allometric relationships of length vs. width, biomass vs. area were significantly positive while those of specific leaf area vs. thickness were significantly negative, which varied largely in treatments and age. The leaf traits and allometric relationships suggested that the CS created a more suitable habitat for bamboo growth. This study highlighted that the understorey bamboo leaf traits could adapt the improved light environment induced by crown–thinning rapidly. Full article
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20 pages, 4834 KiB  
Article
Plasticity in the Morphology of Growing Bamboo: A Bayesian Analysis of Exogenous Treatment Effects on Plant Height, Internode Length, and Internode Numbers
by Chongyang Wu, Yucong Bai, Zhihua Cao, Junlei Xu, Yali Xie, Huifang Zheng, Jutang Jiang, Changhong Mu, Wenlong Cheng, Hui Fang and Jian Gao
Plants 2023, 12(8), 1713; https://doi.org/10.3390/plants12081713 - 20 Apr 2023
Cited by 3 | Viewed by 2563
Abstract
Sucrose (Suc) and gibberellin (GA) can promote the elongation of certain internodes in bamboo. However, there is a lack of field studies to support these findings and no evidence concerning how Suc and GA promote the plant height of bamboo by regulating the [...] Read more.
Sucrose (Suc) and gibberellin (GA) can promote the elongation of certain internodes in bamboo. However, there is a lack of field studies to support these findings and no evidence concerning how Suc and GA promote the plant height of bamboo by regulating the internode elongation and number. We investigated the plant height, the length of each internode, and the total number of internodes of Moso bamboo (Phyllostachys edulis) under exogenous Suc, GA, and control group (CTRL) treatments in the field and analyzed how Suc and GA affected the height of Moso bamboo by promoting the internode length and number. The lengths of the 10th–50th internodes were significantly increased under the exogenous Suc and GA treatments, and the number of internodes was significantly increased by the exogenous Suc treatment. The increased effect of Suc and GA exogenous treatment on the proportion of longer internodes showed a weakening trend near the plant height of 15–16 m compared with the CTRL, suggesting that these exogenous treatments may be more effective in regions where bamboo growth is suboptimal. This study demonstrated that both the exogenous Suc and GA treatments could promote internode elongation of Moso bamboo in the field. The exogenous GA treatment had a stronger effect on internode elongation, and the exogenous Suc treatment had a stronger effect on increasing the internode numbers. The increase in plant height by the exogenous Suc and GA treatments was promoted by the co-elongation of most internodes or the increase in the proportion of longer internodes. Full article
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9 pages, 3222 KiB  
Communication
Time Effects of Global Change on Forest Productivity in China from 2001 to 2017
by Jiangfeng Wang, Yanhong Li and Jie Gao
Plants 2023, 12(6), 1404; https://doi.org/10.3390/plants12061404 - 22 Mar 2023
Cited by 5 | Viewed by 1378
Abstract
With global warming, the concentrations of fine particulate matter (PM2.5) and greenhouse gases, such as CO2, are increasing. However, it is still unknown whether these increases will affect vegetation productivity. Exploring the impacts of global warming on net primary [...] Read more.
With global warming, the concentrations of fine particulate matter (PM2.5) and greenhouse gases, such as CO2, are increasing. However, it is still unknown whether these increases will affect vegetation productivity. Exploring the impacts of global warming on net primary productivity (NPP) will help us understand how ecosystem function responds to climate change in China. Using the Carnegie-Ames-Stanford Approach (CASA) ecosystem model based on remote sensing, we investigated the spatiotemporal changes in NPP across 1137 sites in China from 2001 to 2017. Our results revealed that: (1) Mean Annual Temperature (MAT) and Mean Annual Precipitation (MAP) were significantly positively correlated with NPP (p < 0.01), while PM2.5 concentration and CO2 emissions were significantly negatively correlated with NPP (p < 0.01). (2) The positive correlation between temperature, rainfall and NPP gradually weakened over time, while the negative correlation between PM2.5 concentration, CO2 emissions and NPP gradually strengthened over time. (3) High levels of PM2.5 concentration and CO2 emissions had negative effects on NPP, while high levels of MAT and MAP had positive effects on NPP. Full article
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16 pages, 5222 KiB  
Article
Temporal Changes in Litterfall and Nutrient Cycling from 2005–2015 in an Evergreen Broad-Leaved Forest in the Ailao Mountains, China
by Shiyu Dai, Ting Wei, Juan Tang, Zhixiong Xu and Hede Gong
Plants 2023, 12(6), 1277; https://doi.org/10.3390/plants12061277 - 10 Mar 2023
Cited by 2 | Viewed by 1447
Abstract
The study of litter can provide an important reference for understanding patterns of forest nutrient cycling and sustainable management. Here, we measured litterfall (leaves, branches, etc.) from a wet, evergreen, broad-leaved forest in Ailao Mountains of southwestern China on a monthly basis for [...] Read more.
The study of litter can provide an important reference for understanding patterns of forest nutrient cycling and sustainable management. Here, we measured litterfall (leaves, branches, etc.) from a wet, evergreen, broad-leaved forest in Ailao Mountains of southwestern China on a monthly basis for 11 years (2005–2015). We measured the total biomass of litter fall as well as its components, and estimated the amount of C, N, P, K, S, Ca, and Mg in the amount of litterfall. We found that: The total litter of evergreen, broadleaved forest in Ailao Mountains from 2005 to 2015 was 7.70–9.46 t/ha, and the output of litterfall differed between years. This provides a safeguard for the soil fertility and biodiversity of the area. The total amount of litterfall and its components showed obvious seasonal variation, with most showing a bimodal pattern (peak from March to May and October to November). The majority of litterfall came from leaves, and the total amount as well as its components were correlated with meteorological factors (wind speed, temperate and precipitation) as well as extreme weather events. We found that among years, the nutrient concentration was sorted as C > Ca > N > K > Mg > S > P. The nutrient concentration in the fallen litter and the amount of nutrients returned showed a decreasing trend, but the decreasing rate was slowed through time. Nutrient cycling was influenced by meteorological factors, such as temperature, precipitation, and wind speed, but the nutrient utilization efficiency is high, the circulation capacity is strong, and the turnover time is short. Our results showed that although there was nutrient loss in this evergreen, broad-leaved forest, the presence of forest litterfall can effectively curb potential ecological problems in the area. Full article
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9 pages, 2464 KiB  
Article
Effects of Soil Nutrients on Plant Nutrient Traits in Natural Pinus tabuliformis Forests
by Jie Gao, Jiangfeng Wang and Yanhong Li
Plants 2023, 12(4), 735; https://doi.org/10.3390/plants12040735 - 7 Feb 2023
Cited by 2 | Viewed by 1566
Abstract
In light of global warming, the interaction between plant nutrient traits and soil nutrients is still unclear. Plant nutrient traits (e.g., N and P) and their stoichiometric relationships (N/P ratio) are essential for plant growth and reproduction. However, the specific role of soil [...] Read more.
In light of global warming, the interaction between plant nutrient traits and soil nutrients is still unclear. Plant nutrient traits (e.g., N and P) and their stoichiometric relationships (N/P ratio) are essential for plant growth and reproduction. However, the specific role of soil nutrients in driving variation in plant nutrient traits remains poorly understood. Fifty natural Pinus tabuliformis forests were used as the research object to clarify the interaction between plant nutrient traits and soil nutrients. We show that: (1) The Nmass, Pmass and N/P ratios of leaves were significantly higher than those of roots. The N/P ratio of both leaves and roots was less than 14. (2) Leaf nutrient traits showed diverse relationship patterns with root nutrient traits throughout the growing period. Significant changes were found in root nutrient PC2 (the second principal component of root nutrient traits) and leaf nutrient PC1 (the first principal component of leaf traits), and non-significant changes were found in other relationships between leaf and root traits (p > 0.05). Root nutrient traits explained 36.4% of the variance in leaf nutrient traits. (3) With the increase in soil nutrient PC2 (related to N), leaf PC2 (related to N) showed a significant trend of first decreasing and then increasing (p < 0.05). Only the soil Nmass was significantly correlated with the leaf Nmass (p < 0.05), which demonstrated that the growth and survival of Pinus tabuliformis forests were mainly affected by N-limitation. Full article
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13 pages, 4667 KiB  
Article
Linking Leaf Functional Traits with Soil and Climate Factors in Forest Ecosystems in China
by Xingyu Zhou, Jiaxun Xin, Xiaofei Huang, Haowen Li, Fei Li and Wenchen Song
Plants 2022, 11(24), 3545; https://doi.org/10.3390/plants11243545 - 15 Dec 2022
Cited by 4 | Viewed by 1827
Abstract
Plant leaf functional traits can reflect the adaptive strategies of plants to environmental changes. Exploring the patterns and causes of geographic variation in leaf functional traits is pivotal for improving ecological theory at the macroscopic scale. In order to explore the geographical variation [...] Read more.
Plant leaf functional traits can reflect the adaptive strategies of plants to environmental changes. Exploring the patterns and causes of geographic variation in leaf functional traits is pivotal for improving ecological theory at the macroscopic scale. In order to explore the geographical variation and the dominant factors of leaf functional traits in the forest ecosystems of China, we measured 15 environmental factors on 16 leaf functional traits in 33 forest reserves in China. The results showed leaf area (LA), carbon-to-nitrogen ratio (C/N), carbon-to-phosphorus ratio (C/P), nitrogen-to-phosphorus ratio (N/P), phosphorus mass per area (Pa) and nitrogen isotope abundance (δ15N)) were correlated with latitude significantly. LA, Pa and δ15N were also correlated with longitude significantly. The leaf functional traits in southern China were predominantly affected by climatic factors, whereas those in northern China were mainly influenced by soil factors. Mean annual temperature (MAT), mean annual precipitation (MAP) and mean annual humidity (MAH) were shown to be the important climate factors, whereas available calcium (ACa), available potassium (AK), and available magnesium (AMg) were shown to be the important climate factors that affect the leaf functional traits of the forests in China. Our study fills the gap in the study of drivers and large-scale geographical variability of leaf functional traits, and our results elucidate the operational mechanisms of forest–soil–climate systems. We provide reliable support for modeling global forest dynamics. Full article
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11 pages, 3704 KiB  
Article
Comparison of Two Simplified Versions of the Gielis Equation for Describing the Shape of Bamboo Leaves
by Weihao Yao, Ülo Niinemets, Wenjing Yao, Johan Gielis, Julian Schrader, Kexin Yu and Peijian Shi
Plants 2022, 11(22), 3058; https://doi.org/10.3390/plants11223058 - 11 Nov 2022
Cited by 2 | Viewed by 1783
Abstract
Bamboo is an important component in subtropical and tropical forest communities. The plant has characteristic long lanceolate leaves with parallel venation. Prior studies have shown that the leaf shapes of this plant group can be well described by a simplified version (referred to [...] Read more.
Bamboo is an important component in subtropical and tropical forest communities. The plant has characteristic long lanceolate leaves with parallel venation. Prior studies have shown that the leaf shapes of this plant group can be well described by a simplified version (referred to as SGE-1) of the Gielis equation, a polar coordinate equation extended from the superellipse equation. SGE-1 with only two model parameters is less complex than the original Gielis equation with six parameters. Previous studies have seldom tested whether other simplified versions of the Gielis equation are superior to SGE-1 in fitting empirical leaf shape data. In the present study, we compared a three-parameter Gielis equation (referred to as SGE-2) with the two-parameter SGE-1 using the leaf boundary coordinate data of six bamboo species within the same genus that have representative long lanceolate leaves, with >300 leaves for each species. We sampled 2000 data points at approximately equidistant locations on the boundary of each leaf, and estimated the parameters for the two models. The root–mean–square error (RMSE) between the observed and predicted radii from the polar point to data points on the boundary of each leaf was used as a measure of the model goodness of fit, and the mean percent error between the RMSEs from fitting SGE-1 and SGE-2 was used to examine whether the introduction of an additional parameter in SGE-1 remarkably improves the model’s fitting. We found that the RMSE value of SGE-2 was always smaller than that of SGE-1. The mean percent errors among the two models ranged from 7.5% to 20% across the six species. These results indicate that SGE-2 is superior to SGE-1 and should be used in fitting leaf shapes. We argue that the results of the current study can be potentially extended to other lanceolate leaf shapes. Full article
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17 pages, 4908 KiB  
Article
Responses of Forest Net Primary Productivity to Climatic Factors in China during 1982–2015
by Ziqiang Du, Xuejia Liu, Zhitao Wu, Hong Zhang and Jie Zhao
Plants 2022, 11(21), 2932; https://doi.org/10.3390/plants11212932 - 31 Oct 2022
Cited by 13 | Viewed by 1844
Abstract
Forest ecosystems play an important role in the global carbon cycle. Clarifying the large-scale dynamics of net primary productivity (NPP) and its correlation with climatic factors is essential for national forest ecology and management. Hence, this study aimed to explore the effects of [...] Read more.
Forest ecosystems play an important role in the global carbon cycle. Clarifying the large-scale dynamics of net primary productivity (NPP) and its correlation with climatic factors is essential for national forest ecology and management. Hence, this study aimed to explore the effects of major climatic factors on the Carnegie–Ames–Stanford Approach (CASA) model-estimated NPP of the entire forest and all its corresponding vegetation types in China from 1982 to 2015. The spatiotemporal patterns of interannual variability of forest NPP were illustrated using linear regression and geographic information system (GIS) spatial analysis. The correlations between forest NPP and climatic factors were evaluated using partial correlation analysis and sliding correlation analysis. We found that over thirty years, the average annual NPP of the forests was 887 × 1012 g C/a, and the average annual NPP per unit area was 650.73 g C/m2/a. The interannual NPP of the entire forest and all its corresponding vegetation types significantly increased (p < 0.01). The increase in the NPP of evergreen broad-leaved forests was markedly substantial among forest types. From the spatial perspective, the NPP of the entire forest vegetation gradually increased from northwest to southeast. Over the years, the proportions of the entire forest and all its corresponding vegetation types with a considerable increase in NPP were higher than those with a significant decrease, indicating, generally, improvements in forest NPP. We also found climatic factors variably affected the NPP of forests over time considering that the rise in temperature and solar radiation improved the interannual forest NPP, and the decline in precipitation diminished the forest NPP. Such varying strength of the relationship between the interannual forest NPP and climatic factors also varied across many forest types. Understanding the spatiotemporal pattern of forest NPP and its varying responses to climatic change will improve our knowledge to manage forest ecosystems and maintain their sustainability under a changing environment. Full article
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20 pages, 1800 KiB  
Article
Does the Spatial Pattern of Plants and Green Space Affect Air Pollutant Concentrations? Evidence from 37 Garden Cities in China
by Chengkang Wang, Mengyue Guo, Jun Jin, Yifan Yang, Yujie Ren, Yang Wang and Jiajie Cao
Plants 2022, 11(21), 2847; https://doi.org/10.3390/plants11212847 - 26 Oct 2022
Cited by 4 | Viewed by 1769
Abstract
Relevant studies have demonstrated that urban green spaces composed of various types of plants are able to alleviate the morbidity and mortality of respiratory diseases, by reducing air pollution levels. In order to explore the relationship between the spatial pattern of urban green [...] Read more.
Relevant studies have demonstrated that urban green spaces composed of various types of plants are able to alleviate the morbidity and mortality of respiratory diseases, by reducing air pollution levels. In order to explore the relationship between the spatial pattern of urban green spaces and air pollutant concentrations, this study takes 37 garden cities with subtropical monsoon climate in China as the research object and selects the urban air quality monitoring data and land use type data in 2019 to analyze the relationship between the spatial pattern and the air pollutant concentration through the landscape metrics model and spatial regression model. Moreover, the threshold effect of the impact of green space on air pollutant concentrations is estimated, as well. The results showed that the spatial pattern of urban green space was significantly correlated with the concentrations of PM2.5 (PM with aerodynamic diameters of 2.5 mmor less), NO2 (Nitrogen Dioxide), and SO2 (Sulfur dioxide) pollutants in the air, while the concentrations of PM10 (PM with aerodynamic diameters of 10 mmor less) pollutants were not significantly affected by the green space pattern. Among them, the patch shape index (LSI), patch density (PD) and patch proportion in landscape area (PLAND) of forest land can affect the concentration of PM2.5, NO2, and SO2, respectively. The PLAND, PD, and LSI of grassland and farmland can also have an additional impact on the concentration of SO2 pollutants. The study also found that there was a significant threshold effect within the impact mechanism of urban green space landscape pattern indicators (LSI, PD, PLAND) on the concentrations of PM2.5, NO2, and SO2 air pollutants. The results of this study not only clarified the impact mechanism of the spatial pattern of urban green space on air pollutant concentrations but also provided quantitative reference and scientific basis for the optimization and updating of urban green space to promote public health. Full article
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13 pages, 4569 KiB  
Article
Varying Responses of Vegetation Greenness to the Diurnal Warming across the Global
by Jie Zhao, Kunlun Xiang, Zhitao Wu and Ziqiang Du
Plants 2022, 11(19), 2648; https://doi.org/10.3390/plants11192648 - 8 Oct 2022
Cited by 8 | Viewed by 1244
Abstract
The distribution of global warming has been varying both diurnally and seasonally. Little is known about the spatiotemporal variations in the relationships between vegetation greenness and day- and night-time warming during the last decades. We investigated the global inter- and intra-annual responses of [...] Read more.
The distribution of global warming has been varying both diurnally and seasonally. Little is known about the spatiotemporal variations in the relationships between vegetation greenness and day- and night-time warming during the last decades. We investigated the global inter- and intra-annual responses of vegetation greenness to the diurnal asymmetric warming during the period of 1982–2015, using the normalized different vegetation index (NDVI, a robust proxy for vegetation greenness) obtained from the NOAA/AVHRR NDVI GIMMS3g dataset and the monthly average daily maximum (Tmax) and minimum temperature (Tmin) obtained from the gridded Climate Research Unit, University of East Anglia. Several findings were obtained: (1) The strength of the relationship between vegetation greenness and the diurnal temperature varied on inter-annual and seasonal timescales, indicating generally weakening warming effects on the vegetation activity across the global. (2) The decline in vegetation response to Tmax occurred mainly in the mid-latitudes of the world and in the high latitudes of the northern hemisphere, whereas the decline in the vegetation response to Tmin primarily concentrated in low latitudes. The percentage of areas with a significantly negative trend in the partial correlation coefficient between vegetation greenness and diurnal temperature was greater than that of the areas showing the significant positive trend. (3) The trends in the correlation between vegetation greenness and diurnal warming showed a complex spatial pattern: the majority of the study areas had undergone a significant declining strength in the vegetation greenness response to Tmax in all seasons and to Tmin in seasons except autumn. These findings are expected to have important implications for studying the diurnal asymmetry warming and its effect on the terrestrial ecosystem. Full article
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9 pages, 2911 KiB  
Article
Comparison of Leaf Shape between a Photinia Hybrid and One of Its Parents
by Xiao Zheng, Karl J. Niklas, David A. Ratkowsky, Yabing Jiao, Hui Ding and Peijian Shi
Plants 2022, 11(18), 2370; https://doi.org/10.3390/plants11182370 - 11 Sep 2022
Cited by 6 | Viewed by 3737
Abstract
Leaf shape and size can vary between hybrids and their parents. However, this has seldom been quantitatively tested. Photinia × fraseri is an important landscaping plant in East Asia as a hybrid between evergreen shrubs P. glabra and P. serratifolia. Its leaf [...] Read more.
Leaf shape and size can vary between hybrids and their parents. However, this has seldom been quantitatively tested. Photinia × fraseri is an important landscaping plant in East Asia as a hybrid between evergreen shrubs P. glabra and P. serratifolia. Its leaf shape looks like that of P. serratifolia. To investigate leaf shape, we used a general equation for calculating the leaf area (A) of broad-leaved plants, which assumes a proportional relationship between A and product of lamina length (L) and width (W). The proportionality coefficient (which is referred to as the Montgomery parameter) serves as a quantitative indicator of leaf shape, because it reflects the proportion of leaf area A to the area of a rectangle with L and W as its side lengths. The ratio of L to W, and the ellipticalness index were also used to quantify the complexity of leaf shape for elliptical leaves. A total of >4000 leaves from P. × fraseri and P. serratifolia (with >2000 leaves for each taxon) collected on a monthly basis was used to examine: (i) whether there is a significant difference in leaf shape between the two taxa, and (ii) whether there is a monotonic or parabolic trend in leaf shape across leaf ages. There was a significant difference in leaf shape between the two taxa (p < 0.05). Although there were significant differences in leaf shape on a monthly basis, the variation in leaf shape over time was not large, i.e., leaf shape was relatively stable over time for both taxa. However, the leaf shape of the hybrid was significantly different from its parent P. serratifolia, which has wider and more elliptical leaves than the hybrid. This work demonstrates that variations in leaf shape resulting from hybridization can be rigorously quantified and compared among species and their hybrids. In addition, this work shows that leaf shape does not changes as a function of age either before or after the full expansion of the lamina. Full article
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15 pages, 1921 KiB  
Article
Growth and Development Responses of the Rhizome-Root System in Pleioblastus pygmaeus to Light Intensity
by Weiwei Huang, Yongyan Ding, Shucong Wang, Chao Song and Fusheng Wang
Plants 2022, 11(17), 2204; https://doi.org/10.3390/plants11172204 - 25 Aug 2022
Cited by 11 | Viewed by 1733
Abstract
Light, as a primary source of energy, directly or indirectly influences virtually all morphological modifications occurring in both shoots and roots. A pot experiment was conducted to assess the growth patterns of one-year-old Pleioblastus pygmaeus plants’ rhizome-root systems and their responses to different [...] Read more.
Light, as a primary source of energy, directly or indirectly influences virtually all morphological modifications occurring in both shoots and roots. A pot experiment was conducted to assess the growth patterns of one-year-old Pleioblastus pygmaeus plants’ rhizome-root systems and their responses to different light intensities from 11 March to 26 December 2016. The experiment design scheme was 3.87% (L1), 11.25% (L2), 20.25% (L3), 38.76% (L4), 60.70% (L5), and 100% full sunlight (control CK). The results indicated that along the growing period from March to December, eight of the eleven studied parameters of the rhizome-root system showed significant variability and diverse growth patterns. In addition, light intensity is a key factor for determining P. pygmaeus plants’ rhizome and root growth. Specifically, the light intensity had a significant, positive, and linear/or almost linear impact on the number of old and new rhizomes, old rhizome length, new rhizome diameter, as well as the culm root diameter. A nonlinear and positive relationship was found between light intensity and the listed three parameters, i.e., new rhizome length, new rhizome internode length, and rhizome root length. The value of the above-mentioned three parameters significantly increased when affected from 0% to 40–60% of full sunlight and then gradually increased until 100% of full sunlight. The ratio of aboveground dry weight to underground dry weight (A/U ratio) showed a single peak curve with increasing light intensity and presented the highest value under ca. 55% full sunlight. Furthermore, 40% full sunlight (equal to an average light of 2232 lux) might be the threshold for P. pygmaeus rhizome-root system growth. When the light intensity was below 40%, the generalized additive models (GAMs) predicted value of most studied parameters decreased to lower than zero. In conclusion, current study provides a solid basis for understanding the dynamic growth and development of P. pygmaeus rhizome-root system, and its responses to different light conditions, which could be used as inputs to P. pygmaeus plant cultivation. Full article
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16 pages, 6992 KiB  
Article
Climatic Factors Determine the Distribution Patterns of Leaf Nutrient Traits at Large Scales
by Xianxian Wang, Jiangfeng Wang, Liuyang Zhang, Chengyu Lv, Longlong Liu, Huixin Zhao and Jie Gao
Plants 2022, 11(16), 2171; https://doi.org/10.3390/plants11162171 - 21 Aug 2022
Cited by 9 | Viewed by 1681
Abstract
Leaf nutrient content and its stoichiometric relationships (N/P ratio) are essential for photosynthesis and plant growth and development. Previous studies on leaf nutrient-related functional traits have mainly focused on the species level and regional scale, but fewer studies have investigated the distribution patterns [...] Read more.
Leaf nutrient content and its stoichiometric relationships (N/P ratio) are essential for photosynthesis and plant growth and development. Previous studies on leaf nutrient-related functional traits have mainly focused on the species level and regional scale, but fewer studies have investigated the distribution patterns of the leaf N and P contents (LN, LP) and N/P ratios (N/P) in communities and their controlling factors at a large scale; therefore, we used LN, LP, and N/P data at 69 sites from 818 forests in China. The results showed significant differences (p < 0.05) in the LN, LP, and N/P at different life forms (tree, shrub, and herb). Neither LN, LP, nor N/P ratios showed significant patterns of latitudinal variation. With the increase in temperature and rainfall, the LN, LP, and leaf nutrient contents increased significantly (p < 0.001). Across life forms, LN at different life forms varied significantly and was positively correlated with soil P content (p < 0.001). The explanatory degree of climatic factors in shaping the spatial variation patterns of LN and N/P was higher than that of the soil nutrient factors, and the spatial variation patterns of the leaf nutrient traits of different life forms were shaped by the synergistic effects of climatic factors and soil nutrient factors. Full article
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12 pages, 2631 KiB  
Article
Quantifying the Variation in the Geometries of the Outer Rims of Corolla Tubes of Vinca major L.
by Lin Wang, Qinyue Miao, Ülo Niinemets, Johan Gielis and Peijian Shi
Plants 2022, 11(15), 1987; https://doi.org/10.3390/plants11151987 - 30 Jul 2022
Cited by 6 | Viewed by 1922
Abstract
Many geometries of plant organs can be described by the Gielis equation, a polar coordinate equation extended from the superellipse equation, [...] Read more.
Many geometries of plant organs can be described by the Gielis equation, a polar coordinate equation extended from the superellipse equation, r=a|cosm4φ|n2+|1ksinm4φ|n31/n1. Here, r is the polar radius corresponding to the polar angle φ; m is a positive integer that determines the number of angles of the Gielis curve when φ ∈ [0 to 2π); and the rest of the symbols are parameters to be estimated. The pentagonal radial symmetry of calyxes and corolla tubes in top view is a common feature in the flowers of many eudicots. However, prior studies have not tested whether the Gielis equation can depict the shapes of corolla tubes. We sampled randomly 366 flowers of Vinca major L., among which 360 had five petals and pentagonal corolla tubes, and six had four petals and quadrangular corolla tubes. We extracted the planar coordinates of the outer rims of corolla tubes (in top view) (ORCTs), and then fitted the data with two simplified versions of the Gielis equation with k = 1 and m = 5: r=acos54φn2+sin54φn31/n1 (Model 1), and r=acos54φn2+sin54φn21/n1 (Model 2). The adjusted root mean square error (RMSEadj) was used to evaluate the goodness of fit of each model. In addition, to test whether ORCTs are radially symmetrical, we correlated the estimates of n2 and n3 in Model 1 on a log-log scale. The results validated the two simplified Gielis equations. The RMSEadj values for all corolla tubes were smaller than 0.05 for both models. The numerical values of n2 and n3 were demonstrated to be statistically equal based on the regression analysis, which suggested that the ORCTs of V. major are radially symmetrical. It suggests that Model 1 can be replaced by the simpler Model 2 for fitting the ORCT in this species. This work indicates that the pentagonal or quadrangular corolla tubes (in top view) can both be modeled by the Gielis equation and demonstrates that the pentagonal or quadrangular corolla tubes of plants tend to form radial symmetrical geometries during their development and growth. Full article
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10 pages, 5005 KiB  
Article
The Modified Brière Equation and Its Applications
by Jun Jin, Brady K. Quinn and Peijian Shi
Plants 2022, 11(13), 1769; https://doi.org/10.3390/plants11131769 - 3 Jul 2022
Cited by 3 | Viewed by 1466
Abstract
The Brière equation (BE) is widely used to describe the effect of temperature on the development rate of insects, and it can produce both symmetrical and asymmetrical bell-shaped curves. Because of its elasticity in curve fitting, the integrated form of BE has been [...] Read more.
The Brière equation (BE) is widely used to describe the effect of temperature on the development rate of insects, and it can produce both symmetrical and asymmetrical bell-shaped curves. Because of its elasticity in curve fitting, the integrated form of BE has been recommended for use as a sigmoid growth equation to describe the increase in plant biomass with time. However, the start time of growth predicted by the sigmoid growth equation based on the BE is not completely comparable to empirical crop growth data. In the present study, we modified the BE by adding an additional parameter to further increase its elasticity for data fitting. We termed this new equation the modified Brière equation (MBE). Data for the actual height and biomass of 15 species of plants (with two cultivars for one species) were fit with the sigmoid growth equations based on both the BE and MBE assuming that the growth start time was zero for both. The goodness of fit of the BE and MBE sigmoid growth equations were compared based on their root-mean-square errors and the corresponding absolute percentage error between them when fit to these data. For most species, we found that the MBE sigmoid growth equation achieved a better goodness of fit than the BE sigmoid growth equation. This work provides a useful tool for quantifying the ontogenetic or population growth of plants. Full article
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