Research

17 pages, 3415 KiB

Open AccessArticle

Root Traits and Biomechanical Properties of Three Tropical Pioneer Tree Species for Forest Restoration in Landslide Areas

by Jung-Tai Lee, Ming-Yang Chu, Yu-Syuan Lin, Kuan-Ning Kung, Wen-Chi Lin and Ming-Jen Lee

Forests 2020, 11(2), 179; https://doi.org/10.3390/f11020179 - 05 Feb 2020

Cited by 24 | Viewed by 2990

Abstract

Frequent earthquakes, monsoon torrential rains and typhoons cause severe landslides and soil erosion in Taiwan. Hibiscus taiwanensis, Macaranga tanarius, and Mallotus paniculatus are major pioneer tree species appearing on landslide-scarred areas. Thus, these species can be used to restore the self-sustaining native vegetation [...] Read more.

Frequent earthquakes, monsoon torrential rains and typhoons cause severe landslides and soil erosion in Taiwan. Hibiscus taiwanensis, Macaranga tanarius, and Mallotus paniculatus are major pioneer tree species appearing on landslide-scarred areas. Thus, these species can be used to restore the self-sustaining native vegetation on forest landslides, to control erosion, and to stabilize slope. However, their growth performance, root traits and biomechanical properties have not been well characterized. In this study, root system and root traits were investigated using the excavation method, and biomechanical tests were performed to determine the uprooting resistance, root tensile strength and Young’s modulus of 1-year-old Hibiscus taiwanensis, Macaranga tanarius, and Mallotus paniculatus seedlings. The results reveal that relative to H. taiwanensis, M. tanarius and M. paniculatus seedlings had significantly larger root collar diameter, longer taproot length, higher root biomass, higher root density, higher root length density, heavier root mass, larger external root surface area, higher root tissue density, larger root volume, longer total root length, and a higher root tip number. Additionally, the height of M. paniculatus seedlings was significantly higher than those of H. taiwanensis and M. tanarius. Furthermore, the uprooting resistance and root tensile strength of M. paniculatus seedlings was significantly higher than those of H. taiwanensis and M. tanarius. Young’s modulus of M. paniculatus and M. tanarius seedlings was also significantly higher than that of H. taiwanensis. These growth characteristics and biomechanical properties demonstrate M. paniculatus and M. tanarius are superior than H. taiwanensis, considering growth performance, root anchorage capability, tensile strength and Young’s modulus. Taken as a whole, the rank order for species selection of these pioneer species for reforestation comes as: M. paniculatus M. tanarius H. taiwanensis. These results, along with knowledge on vegetation dynamics following landslides, allow us to better evaluate the effect of selective removal management of pioneer species on the resilience and sustainability of landslides. Full article

(This article belongs to the Special Issue The Ecology of Fine Roots and Mycorrhizas in Forests)

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18 pages, 2670 KiB

Open AccessArticle

Host Phylogenetic Relatedness and Soil Nutrients Shape Ectomycorrhizal Community Composition in Native and Exotic Pine Plantations

by Chen Ning, Gregory M. Mueller, Louise M. Egerton-Warburton, Wenhua Xiang and Wende Yan

Forests 2019, 10(3), 263; https://doi.org/10.3390/f10030263 - 15 Mar 2019

Cited by 14 | Viewed by 3347

Abstract

Exotic non-native Pinus species have been widely planted or become naturalized in many parts of the world. Pines rely on ectomycorrhizal (ECM) fungi mutualisms to overcome barriers to establishment, yet the degree to which host specificity and edaphic preferences influence ECM community composition [...] Read more.

Exotic non-native Pinus species have been widely planted or become naturalized in many parts of the world. Pines rely on ectomycorrhizal (ECM) fungi mutualisms to overcome barriers to establishment, yet the degree to which host specificity and edaphic preferences influence ECM community composition remains poorly understood. In this study, we used high-throughput sequencing coupled with soil analyses to investigate the effect of host plant identity, spatial distance and edaphic factors on ECM community composition in young (30-year-old) native (Pinus massoniana Lamb.) and exotic (Pinus elliottii Engelm.) pine plantations in China. The ECM fungal communities comprised 43 species with the majority belonging to the Thelephoraceae and Russulaceae. Most species were found associated with both host trees while certain native ECM taxa (Suillus) showed host specificity to the native P. massoniana. ECM fungi that are known to occur exclusively with Pinus (e.g., Rhizopogon) were uncommon. We found no significant effect of host identity on ECM communities, i.e., phylogenetically related pines shared similar ECM fungal communities. Instead, ECM fungal community composition was strongly influenced by site-specific abiotic factors and dispersal. These findings reinforce the idea that taxonomic relatedness might be a factor promoting ECM colonization in exotic pines but that shifts in ECM communities may also be context-dependent. Full article

(This article belongs to the Special Issue The Ecology of Fine Roots and Mycorrhizas in Forests)

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14 pages, 2859 KiB

Open AccessArticle

Soil Fungal Community in Norway Spruce Forests under Bark Beetle Attack

by Petra Veselá, Martina Vašutová, Magda Edwards-Jonášová and Pavel Cudlín

Forests 2019, 10(2), 109; https://doi.org/10.3390/f10020109 - 29 Jan 2019

Cited by 13 | Viewed by 2697

Abstract

Bark beetle infestation is a widespread phenomenon in temperate forests, which are facing significant weather fluctuations accompanying climate change. Fungi play key roles in forest ecosystems as symbionts of ectomycorrhizal trees, decomposers, or parasites, but the effect of severe disturbances on their communities [...] Read more.

Bark beetle infestation is a widespread phenomenon in temperate forests, which are facing significant weather fluctuations accompanying climate change. Fungi play key roles in forest ecosystems as symbionts of ectomycorrhizal trees, decomposers, or parasites, but the effect of severe disturbances on their communities is largely unknown. The responses of soil fungal communities following bark beetle attack were determined using Illumina sequencing of soil samples from 10 microsites in a mature forest not attacked by bark beetle, a forest attacked by bark beetle, a forest destroyed by bark beetle, and a stand where all trees were removed after a windstorm. The proportion of ITS2 sequences assigned to mycorrhizal fungal species decreased with increased intensity of bark beetle attack (from 70 to 15%), whereas the proportion of saprotrophs increased (from 29 to 77%). Differences in the ectomycorrhizal (ECM) fungal community was further characterized by a decrease in the sequence proportion of Elaphomyces sp. and Russula sp. and an increase in Piloderma sp., Wilcoxina sp., and Thelephora terrestris. Interestingly, the species composition of the ECM fungal community in the forest one year after removing the windstorm-damaged trees was similar to that of the mature forest, despite the sequence proportion attributed to ECM fungi decreased. Full article

(This article belongs to the Special Issue The Ecology of Fine Roots and Mycorrhizas in Forests)

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16 pages, 5271 KiB

Open AccessArticle

Responses of Fine Root Functional Traits to Soil Nutrient Limitations in a Karst Ecosystem of Southwest China

by Fujing Pan, Yueming Liang, Kelin Wang and Wei Zhang

Forests 2018, 9(12), 743; https://doi.org/10.3390/f9120743 - 28 Nov 2018

Cited by 26 | Viewed by 3899

Abstract

Soil nitrogen (N) and phosphorus (P) shortages limit the growth of shrubs, and P shortage limit the growth of trees in karst ecosystems. Changes in fine root functional traits are the important strategies for plants to respond to such nutrient shortages. However, such [...] Read more.

Soil nitrogen (N) and phosphorus (P) shortages limit the growth of shrubs, and P shortage limit the growth of trees in karst ecosystems. Changes in fine root functional traits are the important strategies for plants to respond to such nutrient shortages. However, such responses in karst ecosystems are poorly known. To determine the responses of fine root functional traits to soil N and P changes and define their resource-use strategies in the ecosystem, we tested the specific root length (SRL), root tips over the root biomass (RT/RB), and N concentration (N_root) in the fine roots of four plant species (two shrubs (Alchornea trewioides and Ligustrum sinense) and two trees (Celtis biondii and Pteroceltis tatarinowii)) during the dry (January) and the wet (July) season. The results showed that the SRL, RT/RB, and N_root in the fine roots of shrub species were lower than those of tree species, and the three parameters were higher in the wet season than in the dry season. Linear regression models revealed that the SRL, RT/RB, and N_root of overall species increased with increasing soil N and P concentrations and availabilities, and were positively correlated with increasing rhizosphere soil oxalic acid, microbial biomass carbon (C), and the activities of hydrolytic enzymes. In addition, the individual plant species had unique patterns of the three fine root traits that resulted affected by the change of soil nutrients and biochemistry. Thus, the specific root length, root tips over the root biomass, and N concentrations of fine roots were species-specific, affected by seasonal change, and correlated with soil nutrients and biochemistry. Our findings suggests that fine root functional traits increase the ability of plant species to tolerate nutrient shortage in karst ecosystems, and possibly indicated that a P-exploitative strategy in tree species and an N-conservative strategy in shrub species were exhibited. Full article

(This article belongs to the Special Issue The Ecology of Fine Roots and Mycorrhizas in Forests)

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11 pages, 1263 KiB

Open AccessArticle

Maintenance of K⁺/Na⁺ Balance in the Roots of Nitraria sibirica Pall. in Response to NaCl Stress

by Xiaoqian Tang, Xiuyan Yang, Huanyong Li and Huaxin Zhang

Forests 2018, 9(10), 601; https://doi.org/10.3390/f9100601 - 27 Sep 2018

Cited by 13 | Viewed by 3516

Abstract

Using Non-invasive Micro-test Technology (NMT), the Na⁺, K⁺ and H⁺ flux profiles in the root meristem regions were investigated in Nitraria sibirica Pall. seedlings under different NaCl concentrations. NaCl stress increased the K⁺ and Na⁺ contents in [...] Read more.

Using Non-invasive Micro-test Technology (NMT), the Na⁺, K⁺ and H⁺ flux profiles in the root meristem regions were investigated in Nitraria sibirica Pall. seedlings under different NaCl concentrations. NaCl stress increased the K⁺ and Na⁺ contents in the roots of N. sibirica seedlings. NaCl stress significantly increased the steady Na⁺ efflux from the N. sibirica seedling roots. Steady K⁺ effluxes were measured in the control roots (without NaCl) and in the roots treated with 200 mM NaCl, and no significant differences were observed between the two treatments. The steady K⁺ efflux from roots treated with 400 mM NaCl decreased gradually. NaCl treatment significantly increased the H⁺ influx. Pharmacological experiments showed that amiloride and sodium vanadate significantly inhibited the Na⁺ efflux and H⁺ influx, suggesting that the Na⁺ efflux was mediated by a Na⁺/H⁺ antiporter using energy provided by plasma membrane H⁺-ATPase. The NaCl-induced root K⁺ efflux was inhibited by the K⁺ channel inhibitor tetraethylammonium chloride (TEA), and was significantly increased by the H⁺-ATPase inhibitor sodium vanadate. The NaCl-induced K⁺ efflux was mediated by depolarization-activated outward-rectifying K⁺ channels and nonselective cation channels (NSCCs). Under salt stress, N. sibirica seedlings showed increased Na⁺ efflux due to increased plasma membrane H⁺-ATPase and Na⁺/H⁺ antiporter activity. High H⁺ pump activity not only restricts the Na⁺ influx through NSCCs, but also limits K⁺ leakage through outward-rectifying K⁺ channels and NSCCs, leading to maintenance of the K⁺/Na⁺ balance and higher salt tolerance. Full article

(This article belongs to the Special Issue The Ecology of Fine Roots and Mycorrhizas in Forests)

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12 pages, 2702 KiB

Open AccessArticle

Comparison of Root Surface Enzyme Activity of Ericaceous Plants and Picea abies Growing at the Tree Line in the Austrian Alps

by Lixia Wang, Burenjargal Otgonsuren, Wenbiao Duan and Douglas Godbold

Forests 2018, 9(9), 575; https://doi.org/10.3390/f9090575 - 17 Sep 2018

Viewed by 4542

Abstract

Plants with ericoid mycorrhizal and ectomycorrhizal associations coexist at the tree line and in many boreal forests. Both ericoid mycorrhizal and ectomycorrhizal roots are known to produce extracellular enzymes, but ericoid mycorrhizal fungi have been demonstrated in vitro to have higher enzyme activities. [...] Read more.

Plants with ericoid mycorrhizal and ectomycorrhizal associations coexist at the tree line and in many boreal forests. Both ericoid mycorrhizal and ectomycorrhizal roots are known to produce extracellular enzymes, but ericoid mycorrhizal fungi have been demonstrated in vitro to have higher enzyme activities. On hair roots of four ericoid mycorrhizal species (Rhododendron ferrugineum, Vaccinium vitis-idaea, Vaccinium myrtillus, Calluna vulgaris) and on ectomycorrhizal and non-mycorrhizal root tips of Picea abies growing at the tree line (1700 m) in the Austrian Alps, potential activities of eight extracellular root enzymes were estimated. Our results show that the activities of all the different extracellular root enzymes were generally similar among the ericaceous plant species. The mean laccase enzyme activity of ectomycorrhizal root tips of Picea abies was significantly higher than that of both the hair roots and fine roots of the ericaceous species. Leucine-amino-peptidase activity on hair roots was significantly higher than on non-mycorrhizal fine roots for the ericaceous vegetation. However, the mean activity of β-glucuronidase of the ericaceous species was significantly higher in fine roots compared to the hair roots. Generally extracellular root enzyme activity is not higher on ericaceous roots compared to ectomycorrhizas of Picea abies. Full article

(This article belongs to the Special Issue The Ecology of Fine Roots and Mycorrhizas in Forests)

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15 pages, 2881 KiB

Open AccessArticle

Soil Aggregation and Organic Carbon Dynamics in Poplar Plantations

by Zhiwei Ge, Shuiyuan Fang, Han Y.H. Chen, Rongwei Zhu, Sili Peng and Honghua Ruan

Forests 2018, 9(9), 508; https://doi.org/10.3390/f9090508 - 23 Aug 2018

Cited by 25 | Viewed by 3965

Abstract

Soil resident water-stable macroaggregates (diameter (Ø) > 0.25 mm) play a critical role in organic carbon conservation and fertility. However, limited studies have investigated the direct effects of stand development on soil aggregation and its associated mechanisms. Here, we examined the dynamics of [...] Read more.

Soil resident water-stable macroaggregates (diameter (Ø) > 0.25 mm) play a critical role in organic carbon conservation and fertility. However, limited studies have investigated the direct effects of stand development on soil aggregation and its associated mechanisms. Here, we examined the dynamics of soil organic carbon, water-stable macroaggregates, litterfall production, fine-root (Ø < 1 mm) biomass, and soil microbial biomass carbon with stand development in poplar plantations (Populus deltoides L. ‘35’) in Eastern Coastal China, using an age sequence (i.e., five, nine, and 16 years since plantation establishment). We found that the quantity of water-stable macroaggregates and organic carbon content in topsoil (0–10 cm depth) increased significantly with stand age. With increasing stand age, annual aboveground litterfall production did not differ, while fine-root biomass sampled in June, August, and October increased. Further, microbial biomass carbon in the soil increased in June but decreased when sampled in October. Ridge regression analysis revealed that the weighted percentage of small (0.25 mm ≤ Ø < 2 mm) increased with soil microbial biomass carbon, while that of large aggregates (Ø ≥ 2 mm) increased with fine-root biomass as well as microbial biomass carbon. Our results reveal that soil microbial biomass carbon plays a critical role in the formation of both small and large aggregates, while fine roots enhance the formation of large aggregates. Full article

(This article belongs to the Special Issue The Ecology of Fine Roots and Mycorrhizas in Forests)

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16 pages, 2752 KiB

Open AccessArticle

Patterns in Ectomycorrhizal Diversity, Community Composition, and Exploration Types in European Beech, Pine, and Spruce Forests

by Christoph Rosinger, Hans Sandén, Bradley Matthews, Mathias Mayer and Douglas L. Godbold

Forests 2018, 9(8), 445; https://doi.org/10.3390/f9080445 - 25 Jul 2018

Cited by 44 | Viewed by 4309

Abstract

Ectomycorrhizal (EM) fungi are pivotal drivers of ecosystem functioning in temperate and boreal forests. They constitute an important pathway for plant-derived carbon into the soil and facilitate nitrogen and phosphorus acquisition. However, the mechanisms that drive ectomycorrhizal diversity and community composition are still [...] Read more.

Ectomycorrhizal (EM) fungi are pivotal drivers of ecosystem functioning in temperate and boreal forests. They constitute an important pathway for plant-derived carbon into the soil and facilitate nitrogen and phosphorus acquisition. However, the mechanisms that drive ectomycorrhizal diversity and community composition are still subject to discussion. We investigated patterns in ectomycorrhizal diversity, community composition, and exploration types on root tips in Fagus sylvatica,Picea abies, and Pinus sylvestris stands across Europe. Host tree species is the most important factor shaping the ectomycorrhizal community as well as the distribution of exploration types. Moreover, abiotic factors such as soil properties, N deposition, temperature, and precipitation, were found to significantly influence EM diversity and community composition. A clear differentiation into functional traits by means of exploration types was shown for all ectomycorrhizal communities across the three analyzed tree species. Contact and short-distance exploration types were clearly significantly more abundant than cord- or rhizomorph-forming long-distance exploration types of EM fungi. Medium-distance exploration types were significantly lower in abundance than contact and short-distance types, however they were the most frequent EM taxa and constituted nearly half of the EM community. Furthermore, EM taxa exhibit distinct ecological ranges, and the type of soil exploration seemed to determine whether EM taxa have small or rather big environmental ranges. Full article

(This article belongs to the Special Issue The Ecology of Fine Roots and Mycorrhizas in Forests)

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