Explore the vast range of titles available.

This paper provides an overview of the existing literature on the subject of the assessment and monitoring of tree roots and their interactions with the soil. An overview of tree root system architectures is given, and the main issues in terms of tree health and stability, as well as the impact of trees on the built environment, are discussed. An overview of the main destructive and non-destructive testing methods is presented, and a lack of available research-based outputs in the fields of tree root interconnectivity and soil interaction is highlighted. The effectiveness of non-destructive methods in these areas is demonstrated, in particular that of ground-penetrating radar. The paper references recent developments in estimating tree root mass density and health.

The preservation of natural assets is nowadays an essential commitment. In this regard, root systems are endangered by fungal diseases which can undermine the health and stability of trees. Within this framework, ground penetrating radar (GPR) is emerging as a reliable non-destructive method for root investigation. A coherent GPR-based root-detection framework is presented in this paper. The proposed methodology is a multi-stage data analysis system that is applied to semi-circular measurements collected around the investigated tree. In the first step, the raw data are processed by applying several standard and advanced signal processing techniques in order to reduce noise-related information. In the second stage, the presence of any discontinuity element within the survey area is investigated by analysing the signal reflectivity. Then, a tracking algorithm aimed at identifying patterns compatible with tree roots is implemented. Finally, the mass density of roots is estimated by means of continuous functions in order to achieve a more realistic representation of the root paths and to identify their length in a continuous and more realistic domain. The method was validated in a case study in London (UK), where the root system of a real tree was surveyed using GPR and a soil test pit was excavated for validation purposes. Results support the feasibility of the data processing framework implemented in this study.

BACKGROUND AND OBJECTIVES: Arbuscular mycorrhizal fungi improve plant growth but have not been studied for slope stabilization. Inoculation of these fungi and bamboo intervention can enhance root growth toward the slip plane. The study tests tree roots' responses to seeding in bamboo tubes and the fungi consortium. METHODS: The growth of three fast-growing native Indonesian woody plants: Paraserianthes falcataria, Acacia mangium, and Gmelina arborea, was monitored in a screen house. These plants were seeded in bamboo tubes containing soil from Jati Radio and Citatah. The tubes were placed on an inclined plane resembling a 20o slope. Arbuscular mycorrhizal fungi were added in three doses and controlled by the plots without mycorrhiza and bamboo. FINDINGS: The results showed that bamboo could direct root growth toward the slip plane. The best arbuscular mycorrhizal fungi inoculation results were obtained in Gmelina arborea with a treatment dose of ?3 or 30 grams on Jati Radio and Citatah soils. Both treatments did not show significant differences in both locations. CONCLUSION: Gmelina arborea has the highest phosphorus absorption at 80 percent and the highest biomass weight at 660 grams with ?3 dose in Citatah, and 71 percent with 330 g at the same dose in Jati Radio, which is related to the optimal level of arbuscular mycorrhizal fungi inoculation. Therefore, this species provides the best option for implementing biotechnological strategies to stabilize slopes in areas prone to landslides. Combining bamboo with arbuscular mycorrhizal fungi can direct and accelerate root growth, with the goal of crossing landslide slip planes.

The ongoing climate change is characterized by increased temperatures and altered precipitation patterns. In addition, there has been an increase in both the frequency and intensity of extreme climatic events such as drought. Episodes of drought induce a series of interconnected effects, all of which have the potential to alter the carbon balance of forest ecosystems profoundly at different scales of plant organization and ecosystem functioning. During recent years, considerable progress has been made in the understanding of how aboveground parts of trees respond to drought and how these responses affect carbon assimilation. In contrast, processes of belowground parts are relatively underrepresented in research on climate change. In this review, we describe current knowledge about responses of tree roots to drought. Tree roots are capable of responding to drought through a variety of strategies that enable them to avoid and tolerate stress. Responses include root biomass adjustments, anatomical alterations, and physiological acclimations. The molecular mechanisms underlying these responses are characterized to some extent, and involve stress signaling and the induction of numerous genes, leading to the activation of tolerance pathways. In addition, mycorrhizas seem to play important protective roles. The current knowledge compiled in this review supports the view that tree roots are well equipped to withstand drought situations and maintain morphological and physiological functions as long as possible. Further, the reviewed literature demonstrates the important role of tree roots in the functioning of forest ecosystems and highlights the need for more research in this emerging field.

Background and aims Partitioning the measured net ecosystem carbon dioxide (CO 2 ) exchange into gross primary productivity (GPP) and ecosystem respiration remains a challenge, which scientists try to tackle by using the properties of the trace gas carbonyl sulfide (COS). Its similar pathway into and within the leaf makes it a potential photosynthesis proxy. The application of COS as an effective proxy depends, among other things, on a robust inventory of potential COS sinks and sources within ecosystems. While the soil received some attention during the last couple of years, the role of plant roots is mostly unknown. In our study, we investigated the effects of live roots on the soil COS exchange. Methods An experimental setup was devised to measure the soil and the belowground plant parts of young beech trees observed over the course of 9 months. Results During the growing season, COS emissions were significantly lower when roots were present compared to chambers only containing soil, while prior to the growing season, with photosynthetically inactive trees, the presence of roots increased COS emissions. The difference in the COS flux between root-influenced and uninfluenced soil was fairly constant within each month, with diurnal variations in the COS flux driven primarily by soil temperature changes rather than the presence or absence of roots. Conclusion While the mechanisms by which roots influence the COS exchange are largely unknown, their contribution to the overall ground surface COS exchange should not be neglected when quantifying the soil COS exchange.

Background and Aims. Tree root system structure and development are difficult to assess and poorly understood in natural conditions because of soil heterogeneity and the difficulty in extracting mature tree root systems without damaging them. The purpose of this study was to understand root system development plasticity according to biological and physical parameters: species tree age and size, soil material, water availability, slope angle, and climate. Methods. Two hundred and forty-three mature trees from twelve species were uprooted from homogeneous French dikes fills. Root system structure (root number and size, root system span, depth and volume) was compared between two contrasting soil materials: fine and coarse. Results.Tree species had little influence on root system structure: all root system types and root size could be found for most of the species according to site conditions. Heart root systems were limited to fine material while mixed and tap root systems were found on coarse material. In coarse materials, trees developed few but rather large roots (> 5 cm in diameter and >4 m in length). In fine materials, root systems had three times more roots but they were 40% smaller and shorter. Roots were 20% more numerous and 65% larger on the downslope side due to water availability at dike or riverbank toe. Conclusion. Root system structure was mainly influenced by soil material and water availability and far less by tree species. Tree root systems are opportunistic in developing in the direction where water and nutrients are plentiful: whatever the species, predicting its dimensions and structure requires a thorough investigation of soil and other environmental conditions. This study gives a new insight in root development: it will help predict tree root growth in various environments and particularly on dikes.

Heavy metal pollution is one of the most important environmental problems threatening living organisms and environmental health. Thus, there is much research interest in monitoring and reducing heavy metal pollution. Plants’ potential to accumulate heavy metals in various organs differs greatly. Therefore, it is necessary to determine the most suitable species and organs first and acquire knowledge of the subjects such as the transfer of heavy metals within plants and their particular intake into plants. This study investigated Cr, Co, and V, which are among the most important and dangerous heavy metals, and are listed in the primary pollutant list of the Agency for Toxic Substances and Disease Registry. Their concentrations were studied at different depths of soils where Pinus nigra, Pinus sylvestris, Fagus orientalis, and Abies nordmanniana subsp. bornmüelleriana species are grown, in the leaves, cones, wood, bark, and roots. The results showed that the intake of these elements into plant bodies generally occurs through the soil. Additionally, the highest concentrations in both leaves and roots were generally obtained in Fagus orientalis and Abies nordmanniana subsp. bornmüelleriana species. It can be stated that those species are the most suitable species to monitor and reduce heavy metal pollution.

Walnut trees are cultivated and exploited worldwide for commercial timber and nut production. They are heterografted plants, with the rootstock selected to grow in different soil types and conditions and to provide the best anchorage, vigor, and resistance or tolerance to soil borne pests and diseases. However, no individual rootstock is tolerant of all factors that impact walnut production. In Europe, Juglans regia is mainly used as a rootstock. Like most terrestrial plants, walnut trees form arbuscular mycorrhizal symbioses, improving water and nutrient uptake and providing additional ecosystem services. Effects of arbuscular mycorrhizal symbiosis on root gene regulation, however, has never been assessed. We analyzed the response of one rootstock of J. regia to colonization by the arbuscular mycorrhizal fungus Rhizophagus irregularis DAOM197198. Plant growth as well as the nitrogen and phosphorus concentrations in roots and shoots were significantly increased in mycorrhizal plants versus non-colonized plants. In addition, we have shown that 1,549 genes were differentially expressed, with 832 and 717 genes up- and down-regulated, respectively. The analysis also revealed that some rootstock genes involved in plant nutrition through the mycorrhizal pathway, are regulated similarly as in other mycorrhizal woody species: Vitis vinifera and Populus trichocarpa. In addition, an enrichment analysis performed on GO and KEGG pathways revealed some regulation specific to J. regia (i.e., the juglone pathway). This analysis reinforces the role of arbuscular mycorrhizal symbiosis on root gene regulation and on the need to finely study the effects of diverse arbuscular mycorrhizal fungi on root gene regulation, but also of the scion on the functioning of an arbuscular mycorrhizal fungus in heterografted plants such as walnut tree.

Background: Trees and forests have been used in New Zealand to reduce erosion, particularly from rainfall–triggered landslides, gullying, and earthflows. Most New Zealand tree root research has been conducted during the life of the New Zealand Journal of Forestry Science, with much published in it. Methods: We undertook a retrospective ‘review’ of New Zealand tree root research focusing on soil reinforcement and its application for erosion control, slope stability assessment, and understanding tree stability in forests. The published and grey literature was searched using common search terms and relevant papers assessed. The international literature was not reviewed but helped provide context for the New Zealand studies. Results: Results were aggregated into broad topic areas and key findings summarised. Where multiple studies existed for a particular species, results are presented by species. Selected data are presented to enable inter-species comparisons, and the reader is directed to additional data or the original study. Conclusions: New Zealand tree root research has focused mostly on root description or simple measurements to support applied studies of root structure and function. Nonetheless, such research has made a valuable global contribution in addition to improving the understanding and management of New Zealand’s forests. Studies show that generally, exotic species outperform indigenous species for most empirical root metrics other than root tensile strength. A combination of both lateral and vertical roots provides the best soil reinforcement and contribution to slope stability. Future research should focus on acquiring more field data and improvements in dealing with spatial and temporal variability in model development. Practical tools for land managers to target the right places with the right vegetation (species, amount, density) are a pressing need as changing climate is changing the way we manage natural hazards like landslides, floods and wildfires.