scholarly journals Shift from Acquisitive to Conservative Root Resource Acquisition Strategy Associated with Increasing Tree Age: A Case Study of Fraxinus mandshurica

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1797
Author(s):  
Zuwang Li ◽  
Zhi Liu ◽  
Guoqiang Gao ◽  
Xinlei Yang ◽  
Jiacun Gu
Keyword(s):  
Nitrogen Concentration ◽  
Root Exudation ◽  
Specific Root Length ◽  
Root Diameter ◽  
Resource Acquisition ◽  
Tree Age ◽  
Mature Trees ◽  
Tissue Density ◽  
Acquisition Strategy ◽  
Chemical Traits

Tree age has an important effect on the form and function of fine roots. Previous studies have focused on the variations in root morphological and chemical traits among tree ages, while less attention has been given to the physiological traits, impeding a full understanding of the relationship between root resource acquisition strategy and tree age. Here, we measured root morphological (diameter, specific root length, specific root area and tissue density), chemical (nitrogen concentration) and physiological (respiration and exudation rate) traits of young, middle-aged and mature trees of Fraxinus mandshurica in a temperate secondary forest in northeastern China. Our overall aim was to determine how root traits and related resource acquisition strategy change with tree age. The results showed that from young to mature trees, root diameter gradually increased, but specific root length, specific root area, root nitrogen concentration, respiration and exudation rates all decreased, and the significant differences were mainly found between young and mature trees. Pearson’s correlation analysis revealed that the relationships of root respiration and exudation rates to root morphological and chemical traits depended on tree age and the specific traits examined, but these correlations were all significant except for root tissue density when the data were pooled across all tree age classes. Principal component analysis (PCA) showed that the conservative traits represented by root diameter, and the acquisitive traits such as root respiration and exudation rates and related morphological and chemical traits, occupied two ends of the first axis, respectively, while root tissue density occupied one end of the second axis, partially confirming the conceptual framework of “root economics space”. Standardized major axis (SMA) analysis of root exudation and respiration rates showed that young trees allocated more root carbon flux to the formation of root exudation, compared to middle-aged and mature trees. Our findings suggest that root resource acquisition strategy in F. mandshurica appears to shift from an absorptive to conservative strategy associated with increasing tree age, which may have substantial consequences for individual growth and interspecific competition, as well as belowground carbon allocation in ecosystems.

scholarly journals The root economics spectrum: divergence of absorptive root strategies with root diameter

2015 ◽  
Vol 12 (15) ◽  
pp. 13041-13067 ◽  
Author(s):  
D. Kong ◽  
J. Wang ◽  
P. Kardol ◽  
H. Wu ◽  
H. Zeng ◽  
...  
Keyword(s):  
Plant Species ◽  
Root Traits ◽  
Root Diameter ◽  
Resource Acquisition ◽  
Root Tissue ◽  
Plant Roots ◽  
Tissue Density ◽  
Root Tissue Density ◽  
Absorptive Roots ◽  
N Fractions

Abstract. Plant roots usually vary along a dominant ecological axis, the root economics spectrum (RES), depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root strategies as predicted from the RES shift with increasing root diameter. To test this hypothesis, we used seven contrasting plant species for which we separated absorptive roots into two categories: thin roots (< 247 μm diameter) and thick roots. For each category, we analyzed a~range of root traits closely related to resource acquisition and conservation, including root tissue density, carbon (C) and nitrogen (N) fractions as well as root anatomical traits. The results showed that trait relationships for thin absorptive roots followed the expectations from the RES while no clear trait relationships were found in support of the RES for thick absorptive roots. Our results suggest divergence of absorptive root strategies in relation to root diameter, which runs against a single economics spectrum for absorptive roots.

Influence of fine root traits on in situ exudation rates in four conifers from different mycorrhizal associations

2020 ◽  
Vol 40 (8) ◽  
pp. 1071-1079
Author(s):  
Maiko Akatsuki ◽  
Naoki Makita
Keyword(s):  
Root System ◽  
Root Morphology ◽  
Fine Root ◽  
Root Exudation ◽  
Specific Root Length ◽  
Root Traits ◽  
Root Diameter ◽  
Small Scale ◽  
Exudation Rate

Abstract Plant roots can exude organic compounds into the soil that are useful for plant survival because they can degrade microorganisms around the roots and enhance allelopathy against other plant invasions. We developed a method to collect carbon (C) exudation on a small scale from tree fine roots by C-free filter traps. We quantified total C through root exudation in four conifers from different microbial symbiotic groups (ectomycorrhiza (ECM) and arbuscular mycorrhiza (AM)) in a cool-temperate forest in Japan. We determined the relationship of mass-based exudation rate from three diameter classes (&lt;0.5, 0.5–1.0, and 1.0–2.5 mm) of the intact root system with root traits such as morphological traits including root diameter, specific root length (SRL), specific root area (SRA), root tissue density (RTD) and chemical traits including root nitrogen (N) content and C/N. Across species, the mass-based root exudation rate was found to correlate with diameter, SRA, RTD, N and C/N. When comparing mycorrhizal types, there were significant relationships between the exudation and diameter, SRL, SRA, root N and C/N in ECM species; however, these were not significant in AM species. Our results show that relationships between in situ root exudation and every measured trait of morphology and chemistry were strongly driven by ECM roots and not by AM roots. These differences might explain the fact that ECM roots in this study potentially covaried by optimizing the exudation and root morphology in forest trees, while exudation in AM roots did not change with changes in root morphology. In addition, the contrasting results may be attributable to the effect of degree and position of ECM and AM colonization in fine root system. Differences in fine root exudation relationships to root morphology for the two types of mycorrhizae will help us better understand the underlying mechanisms of belowground C allocation in forest ecosystems.

Linking root exudation to belowground economic traits for resource acquisition

2021 ◽  
Author(s):  
Zhihui Wen ◽  
Philip J. White ◽  
Jianbo Shen ◽  
Hans Lambers
Keyword(s):  
Root Exudation ◽  
Resource Acquisition ◽  
Economic Traits

scholarly journals No Ontogenetic Shifts in C-, N- and P-Allocation for Two Distinct Tree Species along Elevational Gradients in the Swiss Alps

Forests ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 394 ◽  
Author(s):  
Jian-Feng Liu ◽  
Ze-Ping Jiang ◽  
Marcus Schaub ◽  
Arthur Gessler ◽  
Yan-Yan Ni ◽  
...  
Keyword(s):  
Tree Species ◽  
Environmental Changes ◽  
Tissue Concentration ◽  
Swiss Alps ◽  
Tree Age ◽  
Nutrient Allocation ◽  
Mature Trees ◽  
Elevational Gradients ◽  
Alpine Treeline ◽  
Adult Trees

Most of our knowledge about forest responses to global environmental changes is based on experiments with seedlings/saplings grown in artificially controlled conditions. We do not know whether this knowledge will allow us to upscale to larger and mature trees growing in situ. In the present study, we used elevation as a proxy of various environmental factors, to examine whether there are ontogenetic differences in carbon and nutrient allocation of two major treeline species (Pinus cembra L. and Larix decidua Mill.) along elevational gradients (i.e., environmental gradient) in the Swiss alpine treeline ecotone (~300 m interval). Young and adult trees grown at the same elevation had similar levels of non-structural carbohydrates (NSCs), total nitrogen (TN), and phosphorus (TP), except for August leaf sugars and August leaf TP in P. cembra at the treeline. We did not detect any interaction between tree age and elevation on tissue concentration of NSCs, TN, and TP across leaf, shoot, and root tissues for both species, indicating that saplings and mature trees did not differ in their carbon and nutrient responses to elevation (i.e., no ontogenetic differences). With respect to carbon and nutrient allocation strategies, our results show that young and adult trees of both deciduous and evergreen tree species respond similarly to environmental changes, suggesting that knowledge gained from controlled experiments with saplings can be upscaled to adult trees, at least if the light is not limited. This finding advances our understanding of plants’ adaptation strategies and has considerable implications for future model-developments.

scholarly journals Root traits are multidimensional: specific root length is independent from root tissue density and the plant economic spectrum

2016 ◽  
Vol 104 (5) ◽  
pp. 1299-1310 ◽  
Author(s):  
Kris R. Kramer-Walter ◽  
Peter J. Bellingham ◽  
Timothy R. Millar ◽  
Rob D. Smissen ◽  
Sarah J. Richardson ◽  
...  
Keyword(s):  
Root Length ◽  
Specific Root Length ◽  
Root Traits ◽  
Root Tissue ◽  
Tissue Density ◽  
Root Tissue Density

scholarly journals Plants in constrained canopy micro-swards compensate for decreased root biomass and soil exploration with increased amounts of rhizosphere carboxylates

2017 ◽  
Vol 44 (5) ◽  
pp. 552 ◽  
Author(s):  
Robert P. Jeffery ◽  
Richard J. Simpson ◽  
Hans Lambers ◽  
Daniel R. Kidd ◽  
Megan H. Ryan
Keyword(s):  
Specific Root Length ◽  
Root Traits ◽  
Trifolium Subterraneum ◽  
Arbuscular Mycorrhizal ◽  
Dry Mass ◽  
Root Diameter ◽  
Soil P ◽  
Fungal Colonisation ◽  
P Concentration ◽  
Foraging Ability

Root traits related to phosphorus (P) acquisition are used to make inferences about a species’ P-foraging ability under glasshouse conditions. However, the effect on such root traits of constrained canopy spread, as occurs in dense pasture swards, is unknown. We grew micro-swards of Trifolium subterraneum L. and Ornithopus compressus L. at 15 and 60 mg kg–1 soil P in a glasshouse. Shoots either spread beyond the pot perimeter or were constrained by a cylindrical sleeve adjusted to canopy height. After 8 weeks, shoot and root dry mass (DM), shoot tissue P concentration, rhizosphere carboxylates, arbuscular mycorrhizal (AM) fungal colonisation, total and specific root length (TRL and SRL respectively), average root diameter (ARD) and average root hair length (ARHL) were measured. In all species and treatments, constrained canopy spread decreased root DM (39–59%), TRL (27–45%) and shoot DM (10–28%), and increased SRL (20–33%), but did not affect ARD, ARHL and AM fungal colonisation. However, shoot P concentration and content increased, and rhizosphere carboxylates increased 3.5 to 12-fold per unit RL and 2.0- to 6.5-fold per micro-sward. Greater amounts of rhizosphere carboxylates when canopy spread was constrained appeared to compensate for reduced root growth enabling shoot P content to be maintained.

scholarly journals Economic strategies of plant absorptive roots vary with root diameter

2016 ◽  
Vol 13 (2) ◽  
pp. 415-424 ◽  
Author(s):  
D. L. Kong ◽  
J. J. Wang ◽  
P. Kardol ◽  
H. F. Wu ◽  
H. Zeng ◽  
...  
Keyword(s):  
Plant Species ◽  
Root Traits ◽  
Root Diameter ◽  
Resource Acquisition ◽  
Root Cortex ◽  
Significant Relationships ◽  
Economic Strategies ◽  
Absorptive Roots ◽  
New Perspective ◽  
N Fractions

Abstract. Plant roots typically vary along a dominant ecological axis, the root economics spectrum, depicting a tradeoff between resource acquisition and conservation. For absorptive roots, which are mainly responsible for resource acquisition, we hypothesized that root economic strategies differ with increasing root diameter. To test this hypothesis, we used seven plant species (a fern, a conifer, and five angiosperms from south China) for which we separated absorptive roots into two categories: thin roots (thickness of root cortex plus epidermis < 247 µm) and thick roots. For each category, we analyzed a range of root traits related to resource acquisition and conservation, including root tissue density, different carbon (C), and nitrogen (N) fractions (i.e., extractive, acid-soluble, and acid-insoluble fractions) as well as root anatomical traits. The results showed significant relationships among root traits indicating an acquisition-conservation tradeoff for thin absorptive roots while no such trait relationships were found for thick absorptive roots. Similar results were found when reanalyzing data of a previous study including 96 plant species. The contrasting economic strategies between thin and thick absorptive roots, as revealed here, may provide a new perspective on our understanding of the root economics spectrum.

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