Adaptation of the Root System to the Environment

A special issue of Forests (ISSN 1999-4907). This special issue belongs to the section "Forest Ecophysiology and Biology".

Deadline for manuscript submissions: closed (20 July 2021) | Viewed by 24214

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Guest Editor
Department of Biotechnology and Life Science, University of Insubria, 21100 Varese, Italy
Interests: root development; plant morpho-physiology; afforestation; fire; biochar
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Special Issue Information

Dear Colleagues,

Plant roots have a fundamental role in water and nutrient uptake while ensuring plant anchorage and stability. Root systems fulfil these functions responding to alterations in environmental conditions through a series of changes at the morphological, physiological, and molecular levels. In response to external disturbances, the finest fraction of the root system modifies traits such as length, the diameter of the root population, specific root length, and life span, whereas the coarse root fraction is spatially displaced to accomplish the highest plant anchorage. Further, wood production in coarse roots is laid down asymmetrically, resulting in an eccentric pattern.

Changes in rooting environment can be ascribed to natural conditions (seasonality of resource availability, sloppy terrain, and prevailing high wind) as well as to the human-induced activities (logging, fire, etc.).

This Special Issue aims to unveil, at all levels of investigation (seedling, singletree, and community level, from morphology to molecular), plant response to environmental clues that may trigger root adaptation mechanisms.

Innovative research is needed to improve our knowledge on forest ecophysiology and biology; new technologies for root investigation will also benevolently considered.

Therefore, we are soliciting full research papers and short communications presenting new findings that will bring advances in forest root research. Due to the high biological variability across tree species and ecosystems, case studies will also be considered for publication.

Dr. Antonio Montagnoli
Guest Editor

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Keywords

  • Fine roots
  • Coarse roots
  • Drought
  • Fire
  • Forest management
  • Disturbance
  • Morphology
  • Physiology
  • Molecular biology

Published Papers (10 papers)

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Editorial

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3 pages, 661 KiB  
Editorial
Adaptation of the Root System to the Environment
by Antonio Montagnoli
Forests 2022, 13(4), 595; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040595 - 10 Apr 2022
Viewed by 1404
Abstract
The plant fine roots system (i [...] Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)

Research

Jump to: Editorial

22 pages, 3691 KiB  
Article
Biochar and/or Compost to Enhance Nursery-Produced Seedling Performance: A Potential Tool for Forest Restoration Programs
by Melissa Simiele, Elena De Zio, Antonio Montagnoli, Mattia Terzaghi, Donato Chiatante, Gabriella Stefania Scippa and Dalila Trupiano
Forests 2022, 13(4), 550; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040550 - 31 Mar 2022
Cited by 9 | Viewed by 2582
Abstract
Today, the use of nursery-produced seedlings is the most widely adopted method in forest restoration processes. To ensure and enhance the performance of transplanting seedlings into a specific area, soil amendments are often used due to their ability to improve soil physicochemical properties [...] Read more.
Today, the use of nursery-produced seedlings is the most widely adopted method in forest restoration processes. To ensure and enhance the performance of transplanting seedlings into a specific area, soil amendments are often used due to their ability to improve soil physicochemical properties and, in turn, plant growth and development. The aim of the present study was to evaluate Populus euramericana growth and development on a growing substrate added with biochar and compost, both alone and in combination. To accomplish this aim, a pot experiment was performed to test biochar and/or compost effects on growing substrate physicochemical characteristics, plant morpho-physiological traits, and plant phenology. The results showed that biochar and/or compost improved growing substrate properties by increasing electrical conductivity, cation exchange capacity, and nutrient concentrations. On the one hand, these ameliorations accelerated poplar growth and development. On the other hand, amendments did not have positive effects on some plant morphological traits, although compost alone increased plant height, and very fine and fine root length. The combined use of biochar and compost did not show any synergistic or cumulative beneficial effects and led to a reduction in plant growth and development. In conclusion, compost alone seems to be the best solution in both ameliorating substrate characteristics and increasing plant growth, highlighting the great potential for its proper and effective application in large-scale forest restoration strategies. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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17 pages, 4604 KiB  
Article
Reconstruction of Conifer Root Systems Mapped with Point Cloud Data Obtained by 3D Laser Scanning Compared with Manual Measurement
by Chikage Todo, Hidetoshi Ikeno, Keitaro Yamase, Toko Tanikawa, Mizue Ohashi, Masako Dannoura, Toshifumi Kimura and Yasuhiro Hirano
Forests 2021, 12(8), 1117; https://0-doi-org.brum.beds.ac.uk/10.3390/f12081117 - 21 Aug 2021
Cited by 6 | Viewed by 2691
Abstract
Three-dimensional (3D) root system architecture (RSA) is a predominant factor in anchorage failure in trees. Only a few studies have used 3D laser scanners to evaluate RSA, but they do not check the accuracy of measurements. 3D laser scanners can quickly obtain RSA [...] Read more.
Three-dimensional (3D) root system architecture (RSA) is a predominant factor in anchorage failure in trees. Only a few studies have used 3D laser scanners to evaluate RSA, but they do not check the accuracy of measurements. 3D laser scanners can quickly obtain RSA data, but the data are collected as a point cloud with a large number of points representing surfaces. The point cloud data must be converted into a set of interconnected axes and segments to compute the root system traits. The purposes of this study were: (i) to propose a new method for easily obtaining root point data as 3D coordinates and root diameters from point cloud data acquired by 3D laser scanner measurement; and (ii) to compare the accuracy of the data from main roots with intensive manual measurement. We scanned the excavated root systems of two Pinus thunbergii Parl. trees using a 3D laser scanner and neuTube software, which was developed for reconstructing the neuronal structure, to convert the point cloud data into root point data for reconstructing RSA. The reconstruction and traits of the RSA calculated from point cloud data were similar in accuracy to intensive manual measurements. Roots larger than 7 mm in diameter were accurately measured by the 3D laser scanner measurement. In the proposed method, the root point data were connected as a frustum of cones, so the reconstructed RSAs were simpler than the 3D root surfaces. However, the frustum of cones still showed the main coarse root segments correctly. We concluded that the proposed method could be applied to reconstruct the RSA and calculate traits using point cloud data of the root system, on the condition that it was possible to model both the stump and ovality of root sections. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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15 pages, 3632 KiB  
Article
Root Foraging Ability for Phosphorus in Different Genotypes Taxodium ‘Zhongshanshan’ and Their Parents under Phosphorus Deficiency
by Rongxiu Xie, Jianfeng Hua, Yunlong Yin and Fuxu Wan
Forests 2021, 12(2), 215; https://0-doi-org.brum.beds.ac.uk/10.3390/f12020215 - 12 Feb 2021
Cited by 2 | Viewed by 1235
Abstract
The phosphorus (P) deficiency is the one of the key constraints for Taxodium ‘Zhongshanshan’ afforestation. A hydroponic experiment was conducted to explore root foraging ability for P in different genotypes of Taxodium ‘Zhongshanshan’ (T.‘Zhongshanshan’) and their parents (T.mucronatum and T.distichum [...] Read more.
The phosphorus (P) deficiency is the one of the key constraints for Taxodium ‘Zhongshanshan’ afforestation. A hydroponic experiment was conducted to explore root foraging ability for P in different genotypes of Taxodium ‘Zhongshanshan’ (T.‘Zhongshanshan’) and their parents (T.mucronatum and T.distichum). Five P levels of CK (31 mg/L), P15 (15 mg/L), P10 (10 mg/L), P5 (5 mg/L), and P0 (0 mg/L) were set up as the P deficiency stress treatment. The plant P contents, root morphological indices, and plant growth traits of different taxodium genotypes were measured. Meanwhile, the root foraging ability for P was evaluated with the membership function method in combination with weight. Results showed that: (1) Except the plant P content, the root morphology, plant net biomass, and height showed significant differences among the different genotypes (p < 0.05); the P deficiency stress had no significant influence on root morphology, but a significant influence on plant net biomass and height and P content; (2) T.mucronatum and T.‘Zhongshanshan’302 had relatively lower values of root length, root surface area, root volume, and plant net biomass, but had no difference of plant P content with the other genotypes; (3) T.mucronatum and T.‘Zhongshanshan’302 had higher root foraging ability for P than the other genotypes; (4) the stepwise regression analysis revealed the root volume as the main factor significantly influencing the root foraging ability. This study concluded that different genotypes of T.’Zhongshanshan’ and their parents had different root foraging ability for P, and breeding and screening the fine varieties is conducive for the afforestation in P-limited areas. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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12 pages, 1587 KiB  
Article
Responses of Swamp Cypress (Taxodium distichum) and Chinese Willow (Salix matsudana) Roots to Periodic Submergence in Mega-Reservoir: Changes in Organic Acid Concentration
by Xinrui He, Ting Wang, Kejun Wu, Peng Wang, Yuancai Qi, Muhammad Arif and Hong Wei
Forests 2021, 12(2), 203; https://0-doi-org.brum.beds.ac.uk/10.3390/f12020203 - 10 Feb 2021
Cited by 21 | Viewed by 2004
Abstract
Organic acids are critical as secondary metabolites for plant adaption in a stressful situation. Oxalic acid, tartaric acid, and malic acid can improve plant tolerance under waterlogged conditions. Two prominent woody species (Taxodium distichum-Swamp cypress and Salix matsudana-Chinese willow) have [...] Read more.
Organic acids are critical as secondary metabolites for plant adaption in a stressful situation. Oxalic acid, tartaric acid, and malic acid can improve plant tolerance under waterlogged conditions. Two prominent woody species (Taxodium distichum-Swamp cypress and Salix matsudana-Chinese willow) have been experiencing long-term winter submergence and summer drought in the Three Gorges Reservoir. The objectives of the present study were to explore the responses of the roots of two woody species during flooding as reflected by root tissue concentrations of organic acids. Potted sample plants were randomly divided into three treatment groups: control, moderate submergence, and deep submergence. The concentrations of oxalic acid, tartaric acid, and malic acid in the main root and lateral roots of the two species were determined at four stages. The results showed that T. distichum and S. matsudana adapted well to the water regimes of the reservoir, with a survival rate of 100% during the experiment period. After experiencing a cycle of submergence and emergence, the height and base diameter of the two species showed increasing trends. Changes in base diameter showed insignificant differences between submergence treatments, and only height was significant under deep submergence. The concentrations of three organic acids in the roots of two species were influenced by winter submergence. After emergence in spring, two species could adjust their organic acid metabolisms to the normal level. Among three organic acids, tartaric acid showed the most sensitive response to water submergence, which deserved more studies in the future. The exotic species, T. distichum, had a more stable metabolism of organic acids to winter flooding. However, the native species, S. matsudana, responded more actively to long-term winter flooding. Both species can be considered in vegetation restoration, but it needs more observations for planting around 165 m above sea level, where winter submergence is more than 200 days. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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14 pages, 1818 KiB  
Article
Gap Size in Hyrcanian Forest Affects the Lignin and N Concentrations of the Oriental Beech (Fagus orientalis Lipsky) Fine Roots but Does Not Change Their Morphological Traits in the Medium Term
by Alireza Amoli Kondori, Kambiz Abrari Vajari, Mohammad Feizian, Antonio Montagnoli and Antonino Di Iorio
Forests 2021, 12(2), 137; https://0-doi-org.brum.beds.ac.uk/10.3390/f12020137 - 26 Jan 2021
Cited by 4 | Viewed by 1848
Abstract
Research Highlights: Fine roots play an important role in plant growth as well as in carbon (C) and nutrient cycling in terrestrial ecosystems. Gaining a wider knowledge of their dynamics under forest gap opening would improve our understanding of soil carbon input and [...] Read more.
Research Highlights: Fine roots play an important role in plant growth as well as in carbon (C) and nutrient cycling in terrestrial ecosystems. Gaining a wider knowledge of their dynamics under forest gap opening would improve our understanding of soil carbon input and below-ground carbon stock accumulation. Single-tree selection is increasingly recognized as an alternative regime of selection cutting sustaining biodiversity and carbon stock, along with timber production, among ecosystem functions. However, the fine root response in terms of morphological and chemical composition to the resulting harvest-created gaps remains unclear. Background and Objectives: This paper investigates the effect in the medium term (i.e., 6 years after logging) of differently sized harvest-created gaps on fine root dynamics and chemical composition. Materials and Methods: A total of 15 differently sized gaps (86.05–350.7 m2) and the adjacent 20 m distant closed canopies (control) were selected in a temperate Fagus orientalis forest (Hyrcanian region, Iran). Eight soil cores were collected at the cardinal points of the gap edge, including four facing the gap area—the same at the adjacent intact forest. Results: For the selected edge trees, the different size of gaps, the core position, and the tree orientation did not affect the investigated morphological traits, except for the slightly higher specific root length (SRL) for the larger fine root fraction (1–2 mm) in the side facing the gap area. Differently, the investigated chemical traits such as N concentration and cellulose:lignin ratio significantly increased with increasing gap size, the opposite for C:N ratio and lignin. Moreover, N concentration and C:N significantly decreased and increased with the fine root diameter, respectively. Conclusions: This work highlighted that, in the medium term and within the adopted size range, artificial gap opening derived from single-tree selection practice affected the chemistry rather than the biomass and morphology of gap-facing fine roots of edge trees. The medium term of six years after gap creation might have been long enough for the recovery of the fine root standing biomass to the pre-harvest condition, particularly near the stem of edge trees. A clear size threshold did not come out; nevertheless, 300 m2 may be considered a possible cut-off determining a marked change in the responses of fine roots. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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15 pages, 2252 KiB  
Article
Evaluating Soil–Root Interaction of Hybrid Larch Seedlings Planted under Soil Compaction and Nitrogen Loading
by Tetsuto Sugai, Satoko Yokoyama, Yutaka Tamai, Hirotaka Mori, Enrico Marchi, Toshihiro Watanabe, Fuyuki Satoh and Takayoshi Koike
Forests 2020, 11(9), 947; https://0-doi-org.brum.beds.ac.uk/10.3390/f11090947 - 29 Aug 2020
Cited by 7 | Viewed by 2618
Abstract
Although compacted soil can be recovered through root development of planted seedlings, the relationship between root morphologies and soil physical properties remain unclear. We investigated the impacts of soil compaction on planted hybrid larch F1 (Larix gmelinii var. japonica×L. [...] Read more.
Although compacted soil can be recovered through root development of planted seedlings, the relationship between root morphologies and soil physical properties remain unclear. We investigated the impacts of soil compaction on planted hybrid larch F1 (Larix gmelinii var. japonica×L. kaempferi, hereafter F1) seedlings with/without N loading. We assumed that N loading might increase the fine root proportion of F1 seedlings under soil compaction, resulting in less effects of root development on soil recovery. We established experimental site with different levels of soil compaction and N loading, where two-year-old F1 seedlings were planted. We used a hardness change index (HCI) to quantify a degree of soil hardness change at each depth. We evaluated root morphological responses to soil compaction and N loading, focusing on ectomycorrhizal symbiosis. High soil hardness reduced the total dry mass of F1 seedlings by more than 30%. Significant positive correlations were found between HCI and root proportion, which indicated that F1 seedling could enhance soil recovery via root development. The reduction of fine root density and its proportion due to soil compaction was observed, while these responses were contrasting under N loading. Nevertheless, the relationships between HCI and root proportion were not changed by N loading. The relative abundance of the larch-specific ectomycorrhizal fungi under soil compaction was increased by N loading. We concluded that the root development of F1 seedling accelerates soil recovery, where N loading could induce root morphological changes under soil compaction, resulting in the persistent relationship between root development and soil recovery. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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19 pages, 2242 KiB  
Article
Plasticity of Root Traits under Competition for a Nutrient-Rich Patch Depends on Tree Species and Possesses a Large Congruency between Intra- and Interspecific Situations
by Zana A. Lak, Hans Sandén, Mathias Mayer, Douglas L. Godbold and Boris Rewald
Forests 2020, 11(5), 528; https://0-doi-org.brum.beds.ac.uk/10.3390/f11050528 - 09 May 2020
Cited by 8 | Viewed by 2734
Abstract
Belowground competition is an important structuring force in terrestrial plant communities. Uncertainties remain about the plasticity of functional root traits under competition, especially comparing interspecific vs. intraspecific situations. This study addresses the plasticity of fine root traits of competing Acer pseudoplatanus L. and [...] Read more.
Belowground competition is an important structuring force in terrestrial plant communities. Uncertainties remain about the plasticity of functional root traits under competition, especially comparing interspecific vs. intraspecific situations. This study addresses the plasticity of fine root traits of competing Acer pseudoplatanus L. and Fagus sylvatica L. seedlings in nutrient-rich soil patches. Seedlings’ roots were grown in a competition chamber experiment in which root growth (biomass), morphological and architectural fine roots traits, and potential activities of four extracellular enzymes were analyzed. Competition chambers with one, two conspecific, or two allospecific roots were established, and fertilized to create a nutrient ‘hotspot’. Interspecific competition significantly reduced fine root growth in Fagus only, while intraspecific competition had no significant effect on the fine root biomass of either species. Competition reduced root nitrogen concentration and specific root respiration of both species. Potential extracellular enzymatic activities of β-glucosidase (BG) and N-acetyl-glucosaminidase (NAG) were lower in ectomycorrhizal Fagus roots competing with Acer. Acer fine roots had greater diameter and tip densities under intraspecific competition. Fagus root traits were generally more plastic than those of Acer, but no differences in trait plasticity were found between competitive situations. Compared to Acer, Fagus roots possessed a greater plasticity of all studied traits but coarse root biomass. However, this high plasticity did not result in directed trait value changes under interspecific competition, but Fagus roots grew less and realized lower N concentrations in comparison to competing Acer roots. The plasticity of root traits of both species was thus found to be highly species- but not competitor-specific. By showing that both con- and allospecific roots had similar effects on target root growth and most trait values, our data sheds light on the paradigm that the intensity of intraspecific competition is greater than those of interspecific competition belowground. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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19 pages, 10799 KiB  
Article
Mechanical Characteristics of the Fine Roots of Two Broadleaved Tree Species from the Temperate Caspian Hyrcanian Ecoregion
by Azade Deljouei, Ehsan Abdi, Massimiliano Schwarz, Baris Majnounian, Hormoz Sohrabi and R. Kasten Dumroese
Forests 2020, 11(3), 345; https://0-doi-org.brum.beds.ac.uk/10.3390/f11030345 - 20 Mar 2020
Cited by 23 | Viewed by 2887
Abstract
In view of the important role played by roots against shallow landslides, root tensile force was evaluated for two widespread temperate tree species within the Caspian Hyrcanian Ecoregion, i.e., Fagus orientalis L. and Carpinus betulus L. Fine roots (0.02 to 7.99 mm) were [...] Read more.
In view of the important role played by roots against shallow landslides, root tensile force was evaluated for two widespread temperate tree species within the Caspian Hyrcanian Ecoregion, i.e., Fagus orientalis L. and Carpinus betulus L. Fine roots (0.02 to 7.99 mm) were collected from five trees of each species at three different elevations (400, 950, and 1350 m a.s.l.), across three diameter at breast height (DBH) classes (small = 7.5–32.5 cm, medium = 32.6–57.5 cm, and large =57.6–82.5 cm), and at two slope positions relative to the tree stem (up- and down-slope). In the laboratory, maximum tensile force (N) required to break the root was determined for 2016 roots (56 roots per each of two species x three sites x three DBH classes x two slope positions). ANCOVA was used to test the effects of slope position, DBH, and study site on root tensile force. To obtain the power-law regression coefficients, a nonlinear least square method was used. We found that: 1) root tensile force strongly depends on root size, 2) F. orientalis roots are stronger than C. betulus ones in the large DBH class, although they are weaker in the medium and small DBH classes, 3) root mechanical resistance is higher upslope than downslope, 4) roots of the trees with larger DBH were the most resistant roots in tension in compare with roots of the medium or small DBH classes, and 5) the root tensile force for both species is notably different from one site to another site. Overall, our findings provide a fundamental contribution to the quantification of the protective effects of forests in the temperate region. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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21 pages, 3664 KiB  
Article
Comprehensive Analysis of the TIFY Gene Family and Its Expression Profiles under Phytohormone Treatment and Abiotic Stresses in Roots of Populus trichocarpa
by Hanzeng Wang, Xue Leng, Xuemei Xu and Chenghao Li
Forests 2020, 11(3), 315; https://0-doi-org.brum.beds.ac.uk/10.3390/f11030315 - 13 Mar 2020
Cited by 13 | Viewed by 2266
Abstract
The TIFY gene family is specific to land plants, exerting immense influence on plant growth and development as well as responses to biotic and abiotic stresses. Here, we identify 25 TIFY genes in the poplar (Populus trichocarpa) genome. Phylogenetic tree analysis [...] Read more.
The TIFY gene family is specific to land plants, exerting immense influence on plant growth and development as well as responses to biotic and abiotic stresses. Here, we identify 25 TIFY genes in the poplar (Populus trichocarpa) genome. Phylogenetic tree analysis revealed these PtrTIFY genes were divided into four subfamilies within two groups. Promoter cis-element analysis indicated most PtrTIFY genes possess stress- and phytohormone-related cis-elements. Quantitative real-time reverse transcription polymerase chain reaction (qRT–PCR) analysis showed that PtrTIFY genes displayed different expression patterns in roots under abscisic acid, methyl jasmonate, and salicylic acid treatments, and drought, heat, and cold stresses. The protein interaction network indicated that members of the PtrTIFY family may interact with COI1, MYC2/3, and NINJA. Our results provide important information and new insights into the evolution and functions of TIFY genes in P. trichocarpa. Full article
(This article belongs to the Special Issue Adaptation of the Root System to the Environment)
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