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Root cross sections showing (a) buttressed T-beam shape of a single root, (b) buttressed T-beam shape formed by four fused roots, (c) I-beam shape root, and (d) tabular shape root.
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Soil-root plate dimensions and structural root architecture were examined on 46-year-old Sitka spruce (Picea sitchensis (Bong.) Carr.) trees that had been mechanically uprooted. Rooting depth was restricted by a water table, and root system morphology had adapted to resist the wind movement associated with shallow rooting. The spread of the root sy...
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... buttressed part of the root (adjacent to the stem) was frequently made up of several roots fused together, but the overall cross-sectional shape was similar regardless of the number of constituent roots (see Figures 4a and 4b). Analysis of single centered roots ( Figure 5) indicated that T-angles were largest (i.e., having a pronounced T-beam shape as in Fig- ure 4a) at the 0.5 m and 0.75 m radii. ...
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... buttressed part of the root (adjacent to the stem) was frequently made up of several roots fused together, but the overall cross-sectional shape was similar regardless of the number of constituent roots (see Figures 4a and 4b). Analysis of single centered roots ( Figure 5) indicated that T-angles were largest (i.e., having a pronounced T-beam shape as in Fig- ure 4a) at the 0.5 m and 0.75 m radii. The T-angle decreased from the 0.75 m radius to a minimum at the 1.25 m radius (Figure 5a). ...
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... away from the tree at the 0.75 and 1.0 m radii, root I-angles were larger (more I-beam shaped) on windward roots than on lee- ward roots for both shallow and deep rooted trees. An example of a distinctive I-beam root, with a large I-angle, is shown in Figure 4c. Differences between mean I-angles were significant only at a radius of 1.25 m where windward roots of shallowly rooted trees had substantially greater I-angles than roots of other groups (P < 0.05), although differences at 0.5 m also approached significance (P = 0.06). ...
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... of growth rings on the sections revealed that asymmetric growth frequently occurred before the tree was 3 years old (Figure 4). Roots initially became elliptical, but then often developed an I-beam shape (Figure 4c). ...
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... of growth rings on the sections revealed that asymmetric growth frequently occurred before the tree was 3 years old (Figure 4). Roots initially became elliptical, but then often developed an I-beam shape (Figure 4c). As roots thickened further, the narrow central section often filled in, producing a slab shape (Figure 4d), or if the root was close to the stem, a buttress T-beam shape (Figures 4a and 4b). ...
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... initially became elliptical, but then often developed an I-beam shape (Figure 4c). As roots thickened further, the narrow central section often filled in, producing a slab shape (Figure 4d), or if the root was close to the stem, a buttress T-beam shape (Figures 4a and 4b). Com- pression wood was not observed in any of the root sections. ...
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... initially became elliptical, but then often developed an I-beam shape (Figure 4c). As roots thickened further, the narrow central section often filled in, producing a slab shape (Figure 4d), or if the root was close to the stem, a buttress T-beam shape (Figures 4a and 4b). Com- pression wood was not observed in any of the root sections. ...
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Citations
... Wind-exposed terrestrial trees are consistently stronger than more sheltered neighbouring trees (Mitchell, 2012). This increased strength is due to growth responses to force (thigmomorphogenesis), including a change in the extent and shape of roots and trunks (Nicoll et al., 2008;Nicoll and Ray, 1996). These thigmomorphogenic responses have been reported in the roots, stems, and canopies of diverse coastal plants, including mangroves, saltmarshes and pines (Lee et al., 2019;Redelstein et al., 2018;Vovides et al., 2018). ...
... Strong winds impact tree growth, stability, and morphology (Bonnesoeur et al., 2016;Gardiner, 2021). Crowns bear the brunt of the wind force, leading to various growth patterns and structural adaptations (Jaffe, 1973;Telewski, 1995;Nicoll and Ray, 1996;Stokes, 1999;Meng et al., 2006;Telewski, 2012;Badel et al., 2015;Gardiner et al., 2016;Kamimura et al., 2019;Dèfossez et al., 2021). Wind-exposed trees often exhibit different growth patterns compared to sheltered trees (Nicoll and Ray, 1996;Cucchi et al., 2004;Brüchert and Gardiner, 2006;Nicoll et al., 2008;Niez et al., 2019;Tomczak et al., 2020;Dèfossez et al., 2021). ...
... Crowns bear the brunt of the wind force, leading to various growth patterns and structural adaptations (Jaffe, 1973;Telewski, 1995;Nicoll and Ray, 1996;Stokes, 1999;Meng et al., 2006;Telewski, 2012;Badel et al., 2015;Gardiner et al., 2016;Kamimura et al., 2019;Dèfossez et al., 2021). Wind-exposed trees often exhibit different growth patterns compared to sheltered trees (Nicoll and Ray, 1996;Cucchi et al., 2004;Brüchert and Gardiner, 2006;Nicoll et al., 2008;Niez et al., 2019;Tomczak et al., 2020;Dèfossez et al., 2021). Trees, conversely, influence wind patterns (Zhu et al., 2000;Dupont and Brunet, 2008a;Finnigan et al., 2009;Dupont and Patton, 2012;Angelou et al., 2019). ...
The wind-induced response of the branches, the stem, and the roots of an open-grown European beech (Fagus sylvatica L.) was investigated to determine how the airflow's kinetic energy transferred to the tree is dissipated. The instrumentation in the above-ground tree parts consisted of 69 Tree Response Sensors. The response of the primary roots to the wind load was recorded with six Tree Strain Sensors. The measurements were used to record the tree's main vibration modes and quantify the energy dissipation from the measurement signals. The signal energy is reduced linearly by 90% from the crown periphery to the stem base. The base of the stem responds to higher wind loads than the branches and the upper part of the stem. The first-order mode frequency band is the narrowest in the roots. To dissipate the kinetic energy transferred to it as efficiently as possible, all tree parts vibrate in overlapping frequency bands in fundamental mode, resulting in mode coupling from the crown periphery to the roots. Mode coupling enables the elastic energy to be transferred as efficiently as possible via the roots to the ground to withstand wind loads and return to the resting position as quickly as possible.
... The difference between regular street trees and trees in important protected area in Shanghai might result from the relatively standardized management of trees with high historical value, thereby reducing the risk of branch and trunk risk occurrence possibility. The high-risk level of root system is mainly due to the limited area available for tree growth, poor soil fertility, and inadequate growth space for root systems, making it difficult for roots to extend and grow to the surrounding area to enhance their wind resistance (Nicoll and Ray, 1996). Additionally, road adjustments and the frequent belowground pipeline construction resulted in the direct cutting of street tree roots, making it difficult to support the trees in all directions. ...
The traditional visual tree assessment method is subjective in evaluating tree risks and therefore not effective in precisely detecting internal decay in tree trunk and root systems. To improve the accuracy of street tree risk assessment, a new nondestructive testing method was proposed. This new tree risk assessment method combines different non-destructive testing technologies, such as sonic tomography and ground-penetrating radar, which could significantly increase the accuracy of risk assessment in tree trunks and roots. The method was applied to evaluate the risk of 1,001 street trees in Shanghai’s historical feature protection area. The results revealed that despite most street trees having low branch and trunk risk levels, more than one-third had high root risk levels. The risk factors of street trees were mainly in the trunk and root system, with a significant correlation between the street tree risk level and tree cavities, diseases, and insect pests, as well as the depth and range of the root distribution, leaning, and internal decay in trunks. With the help of non-destructive testing and risk assessment analysis, as well as targeted prevention measures, the possibility of street risk damage was largely reduced, including street trees tilting and collapsing during typhoons, etc.
... It helps track the evolution of key ideas and technologies, which ultimately drives advancements in the field. The five most cited articles in the tree stability-related literature are presented in Table 5 and shown visually in Figure 4. Four out of five of the most cited publications belong to a single cluster (i.e., Coutts [28], Gardiner et al. [35], Nicoll and Ray [51], and Coutts [52]) and all align with the red cluster in Figure 4. These studies mainly evaluated the impact of anchorage on tree stability. ...
... PEER REVIEW 9 of 28 (Red [19,21,23,28,35,51,52,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78], Green [10,26,[79][80][81][82][83][84], Blue [27,56,[85][86][87][88][89][90][91][92], and Yellow [58][59][60][93][94][95][96][97][98][99] examined root systems and tree stability, wind damage and forest ecosystem, tree stability assessment and forest management, and tree dynamics and mechanical properties, respectively). Figure 5 highlights the international collaborations among authors. ...
... The low international collaboration could be attributed to low funding, language barriers, and low research outputs. (Red [19,21,23,28,35,51,52,[62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78], Green [10,26,[79][80][81][82][83][84], Blue [27,56,[85][86][87][88][89][90][91][92], and Yellow [58][59][60][93][94][95][96][97][98][99] examined root systems and tree stability, wind damage and forest ecosystem, tree stability assessment and forest management, and tree dynamics and mechanical properties, respectively). Figure 5 highlights the international collaborations among authors. ...
Forest preservation and management are paramount for sustainable mitigation of climate change, timber production, and the economy. However, the potential of trees and forests to provide these benefits to the ecosystem is hampered by natural phenomena such as windthrow and anthropogenic activities. The aim of the current research was to undertake a critical thematic review (from 1983 to 2023) informed by a bibliometric analysis of existing literature on tree stability. The results revealed an increase in tree stability research between 2019 and 2022, with the USA, France, and Italy leading in research output, while Scotland and England notably demonstrated high research influence despite fewer publications. A keyword analysis showed that tree stability can be divided into four themes: tree species, architecture, anchorage, and environmental factors. Prominent studies on tree stability have focused on root anchorage. However, more recently, there has been a growing emphasis on urban forestry and disease-induced tree damage, underscoring a shift towards climate change and diversity research. It was concluded that considerable knowledge gaps still exist; that greater geographic diversification of research is needed and should include tropical and sub-tropical regions; that research relating to a wider range of soil types (and textures) should be conducted; and that a greater emphasis on large-scale physical modelling is required. Data and knowledge produced from these areas will improve our collective understanding of tree stability and therefore help decision makers and practitioners manage forestry resources in a more sustainable way into the future.
... Resistance to uprooting is critical in biological roots to resist grazing [28,60] and more complex loading scenarios, including mass wasting [68] and windstorms [14,[52][53][54]70]. Three main phases and respective contributors have been identified during pullout tests of root systems: initial stiffness depending on material stiffness, surface area and projected area of the zone of rapid taper; ultimate capacity resulting from root cooperation emerging from synchronous mobilization of roots; and softening governed by the failure of individual roots and soil matrix during the propagation of loads throughout the root-soil system affected by root diameter and orientation [9]. ...
Deep foundation and anchorage systems are often comprised of simple linear elements, limited by design, materials and techniques employed to build them. Their stability is attained by transferring structural loads to deeper, more stable soil layers across a larger area, reducing potential for excessive settlement and providing resistance against lateral forces from external factors including wind and earthquakes. In comparison, root systems distribute loads to a large volume of soil through a branched morphology of semiflexible elements. Roots also penetrate soil media, reduce erosion, create habitats, and exchange, store and transport resources, while continuously sensing and adapting to environmental conditions. Insights from their integration of multifunctionality can be transferred to civil engineering through biomimicry. As a first step toward designing root-inspired foundations, the effects of various morphological traits (laterals’ length, number of nodes, number of laterals, branching angle and laterals’ cross section) on foundation performance are evaluated through vertical pullout tests. Out of the model properties, general trends were observed, including the positive correlation between models’ surface area and maximum force reached. Yet, due to complex interactions between the model and granular media, no model property fully explained differences in pullout resistance of all models. The effects of each root trait on pullout resistance were analyzed separately, which can serve to adapt the design of root-inspired foundations and exploit granular physics principles. Potential reasons for surprising and counterintuitive results are also presented. Further studies could evaluate the assumptions given as potential explanations of these results by studying identified counterintuitive scenarios.
... In forests, only canopy trees (dominant, codominant trees) face noticeable wind loads because a greater proportion of the trees in the upper canopy is directly exposed to wind loading (MacFarlane and Kane 2017). A more aggregated crown in the lower crown section could help reduce the wind dynamic loading, since wind movement is limited by neighbor proximity (Nicoll and Ray 1996;Vovides et al. 2018). In our study, we only demonstrated that the mean wind speed had a large effect on the crown displacement. ...
Key message
Korean pine trees expressed significant crown displacement. Nearest neighbor competition had the largest effect on the crown displacement compared to the slope direction and mean direction of wind.
Abstract
The crown displacement of individual trees exhibits an adaptive response driven by neighbors, but it can also be the result of wind force and slope effects. In our research, we focused on the crown displacement of planted Korean pine trees in northeast China. A total of 51 trees aged 8–56 years were destructively harvested to measure branch attributes. The gravity centers of the upper, lower and entire crown were calculated. The Markov chain Monte Carlo (MCMC) algorithm, generalized mixed effects model, and circular statistics were used to determine the response of crown displacement to biotic and abiotic factors. The results showed that the dominant tree had the largest absolute crown displacement, and the suppressed tree expressed the largest relative crown displacement. The lower crown showed more apparent crown displacement than the upper crown. The Korean pine was displaced in a northeastern direction. Nearest neighbor competition had the largest effect on the crown displacement compared to the slope direction. Slope direction had a slightly larger effect than the mean direction of wind. The crown displacement for the lower crown was more affected by the interaction of the wind, slope and neighbor competition than the upper crown. No relationship between crown displacement and stem eccentricity for the planted Korean pine was detected.
... The significantly reduced mortality rate over time is likely to be connected to the acclimation of the retention trees to new conditions, e.g. via morphological modifications that increase wind resistance (Nicoll and Ray, 1996;Valinger, 1992). ...
Deadwood is essential for species diversity in forests. Forest management has led to the shortage of deadwood in managed forests and, consequently, to the decline of biodiversity. Prescribed burning and tree retention during harvests may promote deadwood formation, but the long-term effectiveness of these methods is not known. We examined patterns of tree mortality and deadwood dynamics following tree retention and prescribed burning in Finnish boreal forests in a large-scale replicated field experiment with two factors: retention level (10 or 50 m3/ha) and burning (burned or unburned). We monitored 2744 trees individually for 20 years. Deadwood input was initially high after the treatments, since nearly all retention trees on the burned sites and about one third of the trees on the unburned sites died within four years. For the rest of the monitoring period, deadwood input was much lower since the mortality rate of retention trees decreased to a level similar to the background mortality rate. After 20 years from the treatments, deadwood volume varied from about 40 m3/ha on the burned sites with 50 m3/ha retention to about 5 m3/ha on the unburned sites with 10 m3/ha retention. Prescribed burning altered deadwood composition e.g. via the complete mortality of fire-susceptible tree species. Still, deadwood diversity was mainly affected by retention level. Lastly, prescribed burning generated high numbers of snags, which fell rather quickly, with an estimated maximal longevity of 49 years. We conclude that the combination of a high retention level and prescribed burning produces high volumes of diverse deadwood, and thereby has the potential to support the conservation of deadwood-associated biodiversity in managed forests. However, the stand-scale continuity of deadwood throughout the forestry rotation period is still uncertain. The application of management methods should be adjusted at the landscape level to ensure the continuity of deadwood habitats.
... Tree roots have been extensively investigated in botanical research [8,24,30] and the architecture of many species is well documented and it is also possible to 3D print the complex architecture of some root structures. It was deemed impractical to carry out experimental research on structures that could not realistically be built at scale on site. ...
The field of bio-inspired design has been explored extensively in some engineering disciplines. However, biomimicry remains an area under development for geotechnics. One natural system that has been the focus of recent work is tree roots. Those structures are able to provide compressive and tensile support for substantial loads through an anchorage system that is more efficient than common manmade piles. Roots have been able to adapt and improve according to their environment, resulting in relatively shallow foundation systems if compared to piles, which require the use of more material to extend to greater depths. This study explores different proposed pile designs based on tree roots and their effects on bearing and uplift capacity. The root structure–soil interaction during loading is visualized using a synthetic transparent sand and 3D-printed tree root inspired models. The transparent soil is made of fused quartz and a mixture of mineral oils with matching refractive indices. Spatial displacements within the supporting soils were obtained by tracking the movements of the speckle pattern created by the interaction of the fused quartz and a laser light sheet. Images were captured throughout the experiments and then analyzed using Digital Image Correlation, which also provided strain fields. The results were used to identify potentially more effective configurations for the design of bio-inspired deep foundations.
... In the early stage of lateral root lignification, since the 209 cambium at the root junction is continuous, the secondary xylem in its upper and lower parts is axially 210 connected to its parent root (Klepper, 1983), like the symmetrical structure of HA1 ( Figure 2CF; Figure 3C). 211 As the further development, the lateral root usually undergoes asymmetrical thickening and produces more 212 upward-connected vessels to enhance its water transport efficiency (Klepper, 1983;Nicoll & Ray, 1996), 213 similar to the asymmetrical structure of HA2 ( Figure 2EH; Figure 3D). The different root xylem structures 214 could lead to various hydraulic "safety-efficiency" trade-off strategies (Loepfe et al., 2007;Pratt et al., 2021;215 Bouda et al., 2022). ...
Many tree species have developed extensive root systems that allow them to survive in arid environments by obtaining water from a large soil volume. These root systems can transport and redistribute soil water during drought by hydraulic redistribution (HR). A recent study revealed the phenomenon of evaporation-driven hydraulic redistribution (EDHR), which is driven by evaporative demand (transpiration). In this study, we confirmed the occurrence of EDHR in Chinese white poplar (Populus tomentosa) through root sap flow measurements. We utilized micro-computed tomography technology to reconstruct the xylem network of woody lateral roots and proposed conceptual models to verify EDHR from a physical perspective. Our results indicated that EDHR is driven by the internal water potential gradient within the plant xylem network, which requires three conditions: high evaporative demand, soil water potential gradient, and special xylem structure of the root junction. The simulations demonstrated that during periods of extreme drought, EDHR could replenish water to dry roots and improve root water potential up to 38.9%-41.6%. This highlights the crucial eco-physiological importance of EDHR in drought tolerance. Our proposed models provide insights into the complex structure of root junctions and their impact on water movement, thus enhancing our understanding of the relationship between xylem structure and plant hydraulics.
... Wind speed is higher at higher elevations (Körner, 2007). This may lead to the swaying of trees, breaking off stems, and striding their roots (Thomas et al., 2015), a situation that disturbs root-soil contact, lessening water absorption, and increasing water stress (Nicoll & Ray, 1996). ...
Understanding the change in vegetation composition along elevational gradients is critical for species conservation in a changing world. We studied the species richness, tree height, and floristic composition of woody plants along an elevation gradient of protected habitats on the eastern slope of Mount Meru and analyzed how these vegetation variables are influenced by the interplay of temperature and precipitation. Vegetation data were collected on 44 plots systematically placed along five transects spanning an elevational gradient of 1600 to 3400 m a.s.l. We used ordinary linear models and multivariate analyses to test the effect of mean annual temperature and precipitation on woody plant species richness, tree height, and floristic composition. We found that species richness, mean tree height, and maximum tree height declined monotonically with elevation. Models that included only mean annual temperature as an explanatory variable were generally best supported to predict changes in species richness and tree height along the elevation gradient. We found significant changes in woody plant floristic composition with elevation, which were shaped by an interaction of mean annual temperature and precipitation. While plant communities consistently changed with temperature along the elevation gradient, levels of precipitation were more important for plant communities at lower than for those at higher elevations. Our study suggests that changes in temperature and precipitation regimes in the course of climate change will reshape elevational gradients of diversity, tree height, and correlated carbon storage in ecosystems, and the sequence of tree communities on East African mountains. K E Y W O R D S Arusha National Park, floristic diversity, mean annual precipitation, mean annual temperature, mountain, tree height, woody plant community
