Element Stoichiometry Across Grassland Plant Tissues and Rhizospheres: Role of Plant Traits, Soil and Land‐Use Intensity

A factorial nitrogen and water addition experiment was carried out with one year-old Machilus pauhoi seedlings from Suichuan County, Jiangxi Province, with six treatments being established: two water levels with 80% and 40% of field moisture holding capacity and three nitrogen addition levels of 0, 50, 100 kg N·hm-2. Specific root length, specific root area, average diameter and tissue density of three fine root orders of M. pauhoi were measured to understand the main and interactive effects of short-term nitrogen addition and drought stress on root characters of M. pauhoi seedlings. The results showed that average fine root diameter and specific root length differed significantly among fine root orders. With the increases of root orders, the average root diameter increased, with the maximum being present in the third order (0.97 mm), but specific root length decreased, with the minimum being present in the third order (238.99 cm·g-1). No significant effects of nitrogen addition on specific root surface area, average fine root diameter, specific root length and root tissue density were observed. There were significant effects of water treatments on average fine root diameter, specific root length and root tissue density. Drought stress significantly increased average diameter of the third order fine roots of seedlings and decreased root tissue density of the first and second order fine roots. Specific root length of the third order fine roots in arid environments was significantly lower than that under the normal water supply condition. There was no interactive effects of nitrogen addition and drought stress on fine root morphology of M. pauhoi.

Root traits are multidimensional: specific root length is independent from root tissue density and the plant economic spectrum: Commentary on Kramer‐Walter <i>et al</i>. (2016)

PDF HTML阅读 XML下载 导出引用 引用提醒 武夷山不同海拔毛竹细根功能性状 DOI: 10.5846/stxb202112143536 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（32071555）；福建省科技厅产学合作项目（2019N5009）；福建省教育厅项目（JAT190084） Fine root traits of Phyllostachys edulis at different altitudes in Wuyi Mountain Author: Affiliation: Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:细根作为植物最重要的资源获取功能器官，是影响陆地生态系统的重要组成部分。定量化毛竹的细根功能性状对于理解其生理生态特征响应及生活史策略至关重要。为揭示毛竹细根功能性状随海拔梯度的变化规律以及细根的适应策略，对武夷山不同海拔（840 m、1040 m、1240 m）毛竹细根的碳（C）、氮（N）、磷（P）含量和比根长（SRL）、比根面积（SRA）等性状进行测定，分析细根性状在海拔上的差异及其异速生长关系。结果表明：（1）不同海拔毛竹细根养分性状存在显著差异。毛竹细根C含量在海拔1040 m最大。随海拔升高，细根N、P含量均呈下降趋势，细根C ： N、C ： P随着海拔的升高而增加。（2）细根的结构性状在海拔梯度上差异显著。随海拔升高，细根平均根直径（AvgDiam）、SRL及SRA均呈下降趋势，而根组织密度（RTD）呈升高趋势。（3）细根性状间存在显著的异速生长关系。细根N与P含量存在显著的等速生长关系，二者与C含量存在显著异速生长关系；SRL与SRA存在显著的等速生长关系，二者与RTD存在显著的负等速生长关系，与N含量存在显著的异速生长关系；细根AvgDiam与RTD存在显著的负异速生长关系。毛竹细根功能性状海拔梯度差异显著且细根性状之间呈显著的异速生长关系，表明毛竹细根获取型性状（如SRL）与保守型性状（如RTD）存在权衡，在海拔840 m毛竹倾向于增加根长来获取养分和水分，随海拔升高则采取保守策略，如增加根组织密度。因此，毛竹能够通过自身表型可塑性机制合理权衡细根性状之间的资源配置以适应环境变化。 Abstract:As the most important resource-obtaining functional organ of plants, fine roots are an important part affecting terrestrial ecosystems. Quantifying the fine root functional traits of Phyllostachys edulis is critical to our understanding of the physiological response and ecological characteristics for bamboo's life-history strategies. To investigate the variation of fine root traits of Phyllostachys edulis with altitude gradient and the adaptation strategies of fine roots, the contents of carbon (C), nitrogen (N), phosphorus (P), specific root length (SRL), specific root area (SRA) and other traits of Ph.edulis's fine roots were measured in Wuyi Mountain at different altitudes (840 m, 1040 m, 1240 m), and the differences of fine root traits at different altitudes and the allometric relationship between them were analyzed. The results showed that:(1) there were significant differences in the contents of C, N, P and the ecological stoichiometry among different altitudes. The content of C in fine roots was the highest at the altitude of 1040 m, with the increase in altitude, the content of N and P decreased, leading to the increase of the ratio of C:N and C:P. (2) There were significant differences on the structural traits of fine roots among different altitudes. As the altitude increased, the average root diameter (AvgDiam), SRL, SRA of fine roots all showed a downward trend, while the root tissue density (RTD) showed an upward trend. (3) There was a significant allometric relationship between fine root traits. The significant isometric relationships were found between N and P content in fine roots, but they showed a significant allometric relationship between C content. There was a significant isometric relationship between SRL and SRA, but they showed a significantly negative isometric relationship with RTD, and showed a significant allometric relationship with N content. The significantly negative allometric relationships were found between AvgDiam and RTD. There was a significant difference of fine root functional traits among different altitudes, and a significant allometric relationship between them. Our research showed that there was a trade-off between fine root acquisitive traits (such as SRL) and conservative traits (such as RTD). Ph.edulis tended to increase root length for increasing nutrient absorption at altitude of 840 m, and adopted the conservative strategy (such as increasing root tissue density) with increasing altitude. Therefore, Ph.edulis can rationally balance resource allocation among fine root traits to adapt to environmental changes through phenotypic plasticity mechanism. 参考文献 相似文献 引证文献

Fine roots are sensitive to changes in the soil environment, and play an important role in plant growth and development. To clarify the relationship between fine root traits and rhizosphere soil nutrient characteristics, fine roots of trees belonging to different diameter classes in six-year-old Zenia insignis plantation were sampled. The results showed that root biomass, root length density and root volume density increased with the increases of diameter class. Specific root length and specific root area showed the trend of first rising and then falling and rising again with the increases of diameter class. Root tissue density did not change with diameter class. There were significant diffe-rences in soil pH, water content, total carbon, total phosphorus, ammonium nitrogen, nitrate nitrogen and total available nitrogen contents of rhizosphere soil belonging to different diameter classes. The concentrations of soil total carbon, total nitrogen, nitrate nitrogen and total available nitrogen in the rhizosphere soil of large diameter trees were relatively higher, while the soil water content, total phosphorus and ammonium nitrogen contents of small diameter trees were relatively higher. The concentrations of soil total nitrogen, total carbon, nitrate nitrogen and total available nitrogen were significantly positively correlated with root biomass, root length density and root volume density. The concentrations of soil total phosphorus was significantly positively correlated with root tissue density of fine roots, but negatively correlated with specific root length and specific root area. Soil water content was significantly positively correlated with root biomass and root volume density. Soil pH was significantly positively correlated with the specific root length and specific root area of fine roots, but negatively correlated with root tissue density. Our results provide scientific basis for the selection of excellent germplasm resources of Z. insignis.

Strong effects of plant identity, soil nutrient availability or mycorrhizal fungi on root traits have been well documented, but their interactive influences on root traits are still poorly understood. Here, three crop species (maize, wheat and soybean) were grown under four phosphorus (P) addition levels (0, 20, 40 and 60mg P kg-1 dry soil), and plants were inoculated with or without five combined arbuscular mycorrhizal fungal (AMF) species. Plant biomass, nutrient contents, root traits (including total root length, average root diameter, specific root length and root tissue density) and plants' mycorrhizal responses were measured. Crop species, P level, AMF, and their interactions strongly affected plant biomass and root traits. P fertilization promoted plant growth but reduced mycorrhizal benefits on plant biomass and nutrient uptake. Root traits of maize were sensitive to P addition only under the non-mycorrhizal condition, whilst most root traits of soybean and wheat plants were responsive to mycorrhizal inoculation but not P addition. Mycorrhizal colonization reduced the root plasticity in response to P fertility for maize but not for wheat or soybean. This study highlights the importance of soil nutrient fertility and mycorrhizal symbiosis in influencing root traits.

PDF HTML阅读 XML下载 导出引用 引用提醒 内蒙古高原湖滨湿地优势植物功能性状特征及其适应性 DOI: 10.5846/stxb202110092802 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（32160279，31960249，3211101852）；内蒙古科技重大专项项目（2021ZD0011） Functional traits of dominant plants and their adaptations in lakeshore wetlands of the Inner Mongolia Plateau Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:受人类活动和气候变化的影响，湖泊湖滨带退化速度显著加快。植物功能性状的方法可以量化植物特征，预测植物对外界环境干扰的反应，有助于理解退化湖滨带湿地植物应对环境变化所表现出的适应机制，对湖泊湖滨湿地生态系统植被的恢复与重建具有重要意义。在内蒙古高原典型湖泊湖滨湿地选取芦苇（Phragmites australis）、赖草（Leymus secalinus）、毛茛（Ranunculus japonicus）、鹅绒委陵菜（Potentilla anserina）、碱蓬（Suaeda glauca）、盐角草（Salicornia europaea）和拂子茅（Calamagrostis epigeios）7种优势植物的叶片和根系作为研究对象，对不同湿地植物的11种功能性状变化规律及其与环境因子的关系进行研究。旨在探究环境变化影响下湖滨带湿地植物的物种分布和功能性状的差异，以及湿地植物在不同湖滨带湿地生境下的适应策略。在评估植物功能性状差异基础上，采用环境矩阵连接性状矩阵（RLQ）结合第四角分析（Fourth-Corner）的方法分析环境因子对植物功能性状的影响。结果表明，内蒙古湖滨带湿地中7种优势植物为了适应不同的环境的影响，植物的功能性状均产生不同程度的种间与种内变异，在湖滨带湿地中植物的植株高度、叶片碳含量、叶片氮含量、叶片碳氮比、比根长、根组织密度、根氮含量对环境变化的响应比较敏感，土壤pH与叶片干物质含量呈显著负相关；土壤盐分与植株高度、叶片碳含量和叶碳氮比显著负相关，与叶片氮含量、根组织密度显著正相关；土壤的总氮含量与植株高度显著正相关，与比根长显著负相关；土壤碳氮比与植株高度和叶片碳含量显著负相关，与植物比根长显著正相关；土壤容重与根氮含量显著负相关。研究表明内蒙古高原湖滨带湿地植物的功能性状受环境的作用强烈，植物采取了不同的性状策略来适应环境。 Abstract:The rate of degradation of lakeshore zones has been greatly accelerated by human activities and climate change. The method of plant functional traits can quantify plant characteristics and predict plants responses to externally environmental disturbances, and this method can help us understand the adaptive mechanisms of degraded lakeshore wetland plants in response to environmental changes, which is important for the restoration and reconstruction of lakeshore wetland ecosystem vegetation. In this paper, the leaves and roots of seven dominant plants, Phragmites australis, Leymus secalinus, Ranunculus japonicus, Potentilla anserina, Suaeda glauca, Salicornia europaea and Calamagrostis epigeios, were selected in the lakeside wetlands of typical lakes on the Inner Mongolia Plateau to study the change patterns of 11 functional traits of different wetland plants and their relationships with environmental factors. The aim is to investigate the differences in species distribution and functional traits of wetland plants in the lakeshore zone under the influence of environmental changes, and the adaptation strategies of wetland plants in different lakeshore wetland habitats. Based on the assessment of interspecific and intraspecific variation in plant functional trait, the effect of environmental factors on plant functional traits was analyzed using RLQ combined with Fourth-Corner analysis. The results showed that the functional traits of the seven dominant plant species in the lakeshore zone wetlands of the Inner Mongolia produced different degrees of interspecific and intraspecific variation in order to adapt to different environmental influences, and the plant height, leaf carbon concentration, leaf nitrogen concentration, leaf carbon to nitrogen ratio, specific root length, root tissue density and root nitrogen content of the plants in the lakeshore zone wetlands were sensitive to the environmental changes. In the lakeshore zone wetland environment, soil pH was negatively correlated with leaf dry matter content; soil salinity was negatively correlated with plant height, leaf carbon concentration and leaf carbon to nitrogen ratio, while positively correlated with leaf nitrogen concentration and root tissue density; soil nitrogen concentration was positively correlated with plant height and negatively correlated with root length; soil carbon to nitrogen ratio was negatively correlated with plant height and leaf carbon concentration, but positively correlated with root length; soil bulk density was negatively correlated with root nitrogen concentration. This study shows that the functional traits of wetland plants in the lakeshore zone of the Inner Mongolia Plateau are strongly influenced by the environment, and lakeshore zone plants have adopted different trait strategies to adapt to their environment. 参考文献 相似文献 引证文献

Summary Root, stem and leaf traits are thought to be functionally coordinated to maximize the efficiency of acquiring and using limited resources. However, evidence is mixed for consistent whole‐plant trait coordination among woody plants, and we lack a clear understanding of the adaptive value of root traits along soil resource gradients. If fine roots are the below‐ground analogue to leaves, then low specific root length (SRL) and high tissue density should be common on infertile soil. Here, we test the prediction that root, stem and leaf traits and relative growth rate respond in unison with soil fertility gradients. We measured fine root, stem and leaf traits and relative growth rate on individual seedlings of 66 tree species grown in controlled conditions. Our objectives were (i) to determine whether multiple root traits align with growth rate, leaf and stem traits and with each other and (ii) to quantify the relationships between community‐weighted mean root traits and two strong soil fertility gradients that differed in spatial extent and community composition. At the species level, fast growth rates were associated with low root and stem tissue density and high specific leaf area. SRL and root diameter were not clearly related to growth rate and loaded on a separate principal component from the plant economic spectrum. At the community level, growth rate was positively related to soil fertility, and root tissue density (RTD) and branching were negatively related to soil fertility. SRL was negatively related and root diameter was positively related to soil fertility on the large‐scale gradient that included ectomycorrhizal angiosperms. Synthesis. Root, stem and leaf tissue traits of tree seedlings are coordinated and influence fitness along soil fertility gradients. RTD responds in unison with above‐ground traits to soil fertility gradients; however, root traits are multidimensional because SRL is orthogonal to the plant economic spectrum. In contrast to leaves, trees are not constrained in the way they construct fine roots: plants can construct high or low SRL roots of any tissue density. High RTD is the most consistent below‐ground trait that reflects adaptation to infertile soil.

Assessing the effects of land-use change on plant traits, communities and ecosystem functioning in grasslands: a standardized methodology and lessons from an application to 11 European sites.

The variation of plant traits is closely related to the trade‐offs between resource acquisition and conservation, as well as the accumulation of biomass. However, there has been a lack of comprehensive insights into the variation patterns, phylogenetic conservatism, and covariation with biomass allocation of root system architecture in desert areas. We examined the root systems of 47 annual ephemeral species and evaluated their biomass allocation and six key root system architecture traits. Our results indicated that the variation in root traits mainly originated from interspecific variation (48.78%–99.76%), but intraspecific variation should not be ignored as to why the contribution rate of root tissue density (RTD) reached 51.22%. The six root traits were mainly loaded on the first and second axes of the principal component analysis (PCA), these traits mainly vary along two dimensions. The highest interspecific variation is in RTD (51.63%) and the lowest in topological index (TI; 5.92%). The intraspecific variation value and range of specific root length (SRL), specific root area (SRA), and RTD were significantly higher than TI (p < .05), and they are not limited by phylogenetic relationships (0< K < 1, p > .05). The SRA is positively correlated with SRL (r = .72, p < .001) and negatively correlated with RTD (r = −.57, p < .05). The LMF is positively correlated with SRL, and SRA demonstrated the coordination between water consumption and acquisition. The positive correlation between RMF and MRD indicated the coordination of root carbon investment with exploring soil vertical space. The multi‐dimensional variation of root traits, divergence of RTDs, and convergence of TI are important ecological strategies for annual short‐lived plants to adapt to heterogeneous desert habitats. Meanwhile, these plants achieve optimal access to scarce resources through the high plasticity of resource acquisition (e.g., SRL and SRA) and conservation traits (e.g., RTD), as well as the trade‐offs between them and organ mass fraction.

The role of roots in the resource economics spectrum

1. Below-ground plant functional traits regulate plant–soil interactions and may therefore strongly influence ecosystem responses to global change. Despite this, knowledge of how fine-root functional traits vary among plant species and along environmental gradients has lagged far behind our understanding of above-ground traits. 2. We measured species- and community-level root and leaf trait responses for 50 temperate rain forest species from 28 families of ferns, woody and herbaceous angiosperms and conifers, along a soil chronosequence in New Zealand that exhibits a strong gradient in soil nutrient availability. Relationships among species traits (both above- and below-ground) and their distribution along the chronosequence were tested using phylogenetic generalized least-squares regression to account for plant relatedness. 3. Distinctive root trait syndromes were observed; they were closely linked to species' distribution along the chronosequence. Species growing in the strongly P-limited late stages of the chronosequence had relatively high specific root length (SRL), thin root diameter, high root tissue density, high levels of root branching and low root nutrient concentrations compared to intermediate stages. Species on the youngest site also had high SRL, but had low root tissue density, thick root diameter and high root nutrient concentrations. 4. Species root and leaf nutrient concentrations were positively correlated, reflecting the strong underlying gradient in soil fertility. In contrast, the relationship between SRL and SLA was more complex; there was a weak positive correlation between SRL and SLA, but this conflicted with stronger patterns of increasing SRL and declining SLA with increasing site age. 5. Community-averaged trait values calculated using presence/absence data showed similar trends to the species-level patterns. In contrast, community averages calculated using species abundance-weighted data showed weaker relationships with site age, particularly for morphological traits. This suggests that much of the variation in morphological traits between sites was driven by shifts in the presence of subordinate or 'rare' species rather than by changes in the dominant species. 6. Synthesis. Our study demonstrates co-ordinated species- and community-level changes in root traits along a soil chronosequence. These results highlight the influence of soil nutrition on plant functional traits and contribute to our understanding of the drivers of community assembly in a changing environment.

Above- and below-ground plant traits are not consistent in response to drought and competition treatments.

Characterizing patterns of variation in plant traits across species and environmental gradients is critical for understanding performance of species in ecosystems. One‐dimensional pattern of variation has been demonstrated in leaf traits, which is known as the leaf economic spectrum. However, it is unclear whether such a spectrum exists for root traits. For roots of 15 species from temperate grasslands, we determined respiration rate, relative growth rate, life span and 10 morphological, chemical and anatomical root traits. We further evaluated pairwise and multiple‐trait relationships by Pearson's correlation and principle component analysis including phylogenetic contrasts. We found that root functions were related to three clusters of variation. Root respiration rate and relative growth rate were positively correlated with average root diameter (AD), but they were negatively correlated with specific root length (SRL). In contrast, root life span was not correlated with AD, but it was positively correlated with SRL. These results are inconsistent with the presumption of the root economic spectrum. The principle components analysis revealed a multi‐dimensional pattern of variation in root traits among the 15 coexisting herbaceous species. Moreover, species within the same phylogenetic clades tended to have similar root trait syndromes. Most of the root traits exhibited a significant phylogenetic signal. Synthesis. Our results do not support a one‐dimensional root economic spectrum in the coexisting herbaceous species of temperate grasslands. In contrast, the pattern of variation in root traits was multi‐dimensional. We further demonstrated that species in different phylogenetic clades possess diverse root trait syndromes for efficient resource acquisition. Our findings provide a next step in understanding root functions and plant strategies in temperate grasslands.

Analyzing the effects of nutrient addition on the functional traits of desert plants is important for revealing the responses of desert plant species to environmental changes. In this study, we examined the responses of whole plant, root, stem, leaf and fruit traits of Lycium ruthenicum to the addition of N and P, with an experiment with three (low, medium and high) N and P addition levels and three N/P ratios (5:1, 15:1 and 45:1). The results showed that functional traits of L. ruthenicum had divergent responses to NP addition level and N/P ratio. With the increases of NP addition level, the biomass and specific leaf area were increased, while the root-shoot ratio, leaf dry matter content, root tissue density and specific root length were decreased. Belowground biomass, specific root length and net photosynthetic rate increased with the increases of N/P ratio. The coefficient of variation of 17 functional traits was 7.3%-69.1%. The biomass, root-shoot ratio and speci-fic root length were sensitive traits to NP [plastic index (PI)>0.5], with greater variability (49.4%-69.1%), whereas the leaf length-width ratio, leaf thickness, leaf tissue density, and leaf stem dry matter content were conservative traits (PI<0.20). The results of principal component analysis (PCA) showed that the position of L. ruthenicum in the multivariate feature space exhibited lateral migration with the changes of NP addition levels, with a tendency of higher aboveground and belowground biomass and a lower root-shoot ratio. Leaf tissue density was negatively related to leaf thickness and specific leaf area. Leaf dry matter content was negatively correlated with leaf thickness and specific leaf area but positively associated with leaf tissue density. Biomass had a positive correlation with specific leaf area and a negative relation to specific root length. The results of stepwise regression analysis showed that specific root length, specific leaf area and leaf net photosynthetic rate were major functional traits affecting the biomass of L. ruthenicum. L. ruthenicum adapted to the fluctuations of soil nutrient environment through changing resource utilization strategy, altering root carbon allocation, and also the trade-off and covariance among traits and inconsistent response.

The spatial distribution and characteristics of fine roots (< 2 mm in diameter), and rhizosphere soil properties were studied in a mixed planted forest of black locust (Robinia pseudoacacia L.) and velvet ash (Fraxinus velutina Torr.) 27 years after planting in a coastal saline soil of the Yellow River delta, China. The results of fine root analysis showed that the fine roots of both black locust and velvet ash were mainly distributed in the soil layer at 0–20 cm depth and 50–150 cm from trees. The fine root distribution of both species suggests a strategy of avoiding salinity rather than salt –tolerance. The horizontal spread distance of fine roots of velvet ash was evidently longer than that of black locust. The fine root biomass, specific root length, specific root area, specific root volume and root activity were significantly higher for velvet ash in comparison with black locust. The results of soil analysis showed that rhizosphere soil pH of black locust and velvet ash were significantly lower compared with non-rhizosphere soil. The available N content in rhizosphere soil of black locust was higher than that of velvet ash. However, the contents of soluble salt, organic matter, available P and available K in rhizosphere soil of velvet ash were higher than those of black locust. The above results indicated that the differences between black locust and velvet ash in fine root distribution, characteristics and rhizosphere soil properties were the major reasons for that velvet ash showed stronger acclimation responses than black locust to the coastal saline soil.