Root Depth Research Articles

Vegetation patterns associated with nutrient availability and supply in high-elevation tropical Andean ecosystems

Abstract. Plants absorb nutrients and water through their roots and modulate soil biogeochemical cycles. The mechanisms of water and nutrient uptake by plants depend on climatic and edaphic conditions, as well as the plant root system. Soil solution is the medium in which abiotic and biotic processes exchange nutrients, and nutrient concentrations vary with the abundance of reactive minerals and fluid residence times. High-altitude ecosystems of the tropical Andes are interesting for the study of the association between vegetation, soil hydrology, and mineral nutrient availability at the landscape scale for different reasons. First of all, because of low rock-derived nutrient stocks in intensely weathered volcanic soils, biocycling of essential nutrients by plants is expected to be important for plant nutrient acquisition. Second, the ecosystem is characterized by strong spatial patterns in vegetation type and density at the landscape scale and hence is optimal to study soil-water–vegetation interactions. Third, the area is characterized by high carbon stocks but low rates of organic decomposition that might vary with soil hydrology, soil development, and geochemistry, all interconnected with vegetation. The páramo landscape forms a vegetation mosaic of bunch grasses, cushion-forming plants, and forests. In the nutrient-depleted nonallophanic Andosols, the plant rooting depth varies with drainage and soil moisture conditions. Rooting depths were shallower in seasonally waterlogged soils under cushion plants and deeper in well-drained soils under forest and tussock grasses (>100 cm). Vegetation composition is a relevant indicator of rock-derived nutrient availability in soil solutions. The soil solute chemistry revealed patterns in plant-available nutrients that were not mimicking the distribution of total rock-derived nutrients nor the exchangeable nutrient pool but clearly resulted from strong biocycling of cations and removal of nutrients from the soil by plant uptake or deep leaching. Soils under cushion plants showed solute concentrations of Ca, Mg, and Na of about 3 times higher than forest and tussock grasses. Differences were even stronger for dissolved Si with solute concentrations that were 16 times higher than forest and 6 times higher than tussock grasses. Amongst the macronutrients derived from lithogenic sources, P was a limiting nutrient with very low solute concentrations (<1 µM) for all three vegetation types. In contrast K showed greater solute concentrations under forest soils with values that were 2 to 3 times higher than under cushion-forming plants or tussock grasses. Our findings have important implications for future management of Andean páramo ecosystems where vegetation type distributions are dynamically changing as a result of warming temperatures and land use change. Such alterations may lead not only to changes in soil hydrology and solute geochemistry but also to complex changes in weathering rates and solute export downstream with effects on nutrient concentrations in Andean rivers and high-mountain lakes.

PATTERNS FOR HANDLING EROSION HAZARDS AND LAND CRITICALITY IN THE BAUMATA WATERSHED IN KUPANG DISTRICT

Baumata watershed is located in Kupang district. The land use conditions are mostly forests, paddy fields, with low root depth and play a major role in the process of causing soil damage, accelerating the rate of erosion and increasing the volume of surface runoff. This research examines the current level of erosion hazard in the existing land use of the Baumata Watershed and its area by considering the Regional Spatial Planning (RTRW) of Kupang Regency and its surroundings in the Baumata Watershed. The method used to calculate the rate of erosion is the MUSLE method where the method uses an approach from the surface runoff factor. The data processing uses a Geographic Information System (GIS). The erosion rate watershed is 3,402,685 tons/ha/year with a watershed area of 2,439.35 ha. Land rehabilitation and soil conservation (ARLKT) directions that are appropriate for the conditions of the Baumata watershed are 87 annual crop cultivation areas. 21 % (2,127.42 ha), Seasonal Plant Cultivation Areas 10.67 % (260.38 ha), and Buffer Areas 2.11 % (51.55 ha). The existence of data and information on the magnitude of erosion rates and land criticality in the Baumata watershed in Kupang district can be used to anticipate early landslide disasters in the area. Keywords: Erosion; Land Criticality; MUSLE; GIS.

Fast, accurate and accessible calculations of leaf temperature and its physiological consequences with NicheMapR

Abstract Mechanistic predictions of ecological niches are fundamentally based on energy and mass exchange processes that, to be realistic, must be linked to microclimate and incorporate behaviour and physiology. Estimates of leaf temperature and associated transpiration and net photosynthesis rates are fundamental in ecology, agriculture and global change biology. Equations for calculating leaf energy budgets have been available for over 60 years and complex models of stomatal behaviour have been developed. However, user‐friendly ways of estimating leaf temperature under realistic microclimatic regimes, including soil moisture effects, remain limited. Here we show that the integrated microclimate and ectotherm functions of the NicheMapR package for the R programming environment can be used to make fast and effective estimates of leaf temperature and associated rates of water loss and photosynthesis for a wide range of leaf functional types, root depths and microhabitats. Stomatal conductance may be constant or simulated to change dynamically (a) as a function of vapour pressure deficit and CO2 concentration, (b) as a function of soil water potential and (c) as a thermoregulatory mechanism to avoid heat stress. We tested the approach against hourly leaf temperature observations in summer from an arid shrubland in Australia, a temperate woodland in Montana USA, along an elevational gradient in Colorado USA, and at a botanical garden in Florida, USA. National or global gridded data sets can provide the required forcing data but local observational data or some combination of local and gridded data can be used. The global ERA5 and NCEP datasets allow historical leaf energy budget calculations to be made anywhere in the world and a Shiny app has been developed to facilitate use of the model with these datasets. Situated leaf energy budget calculations can be used to design informative field programs to collect much needed detailed temporal data on leaf temperature under natural settings, enabling better predictions and interpretations of how plants respond to environmental change.

Chemical constraints are the major limiting factor of root deepening in southern Brazil soils

Large soybean yield gaps are related to irregular rainfall patterns in several rainfed soybean crop regions, such as southern Brazil. More efficient rainwater use can be achieved in these regions through deeper roots. Therefore, assessing the status of soybean rooting and soil-related factors that drive root growth in soybean fields is mandatory for making management decisions that minimize the yield gap. To this end, we conducted a survey in 10 fields in the state of Rio Grande do Sul (RS), Brazil, during the 2021/22 season. Undisturbed soil blocks and cores and disturbed soil samples were collected in trenches up to approximately 80 cm deep when the soybean was at the R5 stage. The roots washed from the soil blocks were scanned to determine the relative root length density (RRLD), whereas the soil cores and disturbed samples were used for physical and chemical analyses. Hierarchical cluster analysis based on the RRLD was performed to group fields according to their similarities in root distribution and soil-related factors. Soybean rooting in RS fields is quite shallow, with >72% of the total RRLD in all fields located within the 0–20 cm layer and <15% deeper than 40 cm in most fields. Chemical constraints, such as high gradient of acidity-related variables along soil profile and low concentration of nutrients below 20 cm depth, limited soybean root deepening in 50% of the fields, while physical constraints were predominant in 30% of the fields. Thus, management strategies for reducing soybean yield gap by increasing rooting depth in fields of RS need to focus on improving subsurface chemical conditions for root growth.

Interannual radial growth response of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to severe droughts: an analysis along a gradient of soil properties and rooting characteristics

Key messageWe analyzed stem growth responses of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to severe drought in 2003/04 and 2018. The results showed high drought tolerance in sandy, loamy, and most silty soils, with limitations on clayey soils. This study indicates the susceptibility of Douglas-firs with shallow root systems to extreme drought and the importance of deep rooting for high drought resilience.ContextAlthough Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is considered a more drought-tolerant substitute for Norway spruce (Picea abies (L.) Karst.) in Europe, there is considerable uncertainty about the drought tolerance of Douglas-fir under climate change, specifically concerning soil properties.AimsThis study aimed to assess the influence of soil texture, plant-available water capacity, and rooting characteristics on the interannual stem growth response of Douglas-fir when exposed to severe drought.MethodsAlong a soil texture gradient from sand to clay, we selected seven closely spaced sites at elevations of approximately 500 m a.s.l. in southern Germany. Mixed-effects models were used to analyze the effects of soil physical and rooting characteristics on growth response indices (resistance, recovery, resilience) related to the severe to extreme droughts in 2003/04 and 2018.ResultsDouglas-fir showed high drought tolerance in sandy, loamy, and most silty soils. However, the results suggest a higher drought stress risk on clayey soils, as well as at specific silty sites with shallow root systems. A higher effective rooting depth increased the resilience of Douglas-fir during the extreme drought in 2018.ConclusionDouglas-fir demonstrated its drought tolerance in most soil textures. In addition, this study supports the need for combined above- and below-ground investigations on factors influencing drought tolerance and the importance of rooting for drought resilience.

Validated simulation of a long-term cropping experiment reveals a pathway for improved productivity

Long-term farming system experiments with comprehensive soil, plant and meteorological data combined with well-validated dynamic farming system models are a powerful combination to evaluate the production and environmental implications of novel innovations in agriculture. A current deficiency is the lack of adequate comprehensive validations for long term crop sequences that capture the dynamics of soil and crop responses without resetting soil conditions, especially for soil mineral nitrogen (Min-N). This reduces confidence in the outcome of scenario analyses for proposed improvements in productivity and sustainability given the central role played by nitrogen (N) dynamics in both processes. We used data from a 30-year long-term experiment (LTE) to validate the APSIM model and achieved excellent predictions for soil and crop responses including the dynamics of Min-N without resetting. A critical step was to ensure that the parameters required for the pools of soil organic matter matched those measured at the site over the full rooting depth (1.6 m) rather than limiting measured values to surface layers and relying on default parameters in deeper layers. In subsequent scenario analyses of agronomic innovations including fallow weed control, earlier sowing and improved N fertiliser strategies, the validated model predicted potential increases in average annual productivity of 1.2 t ha-1 (30%), WUE of 2.0 kg ha-1 mm-1 (30%) and NUE of 13 kg kg-1 (21%) and reductions in average annual N leaching of 8 kg N ha-1 (-33%) and soil organic matter loss of 3.1 t ha-1 (31%) (0–10 cm) could be achieved with specific combinations of synergistic innovations previously investigated separately in shorter-term experiments. Our study represents a rare case of model validation capturing the dynamics of soil water, Min-N, biomass and grain yield in a long-term diverse crop sequence to provide confidence in scenario analyses of production and environmental consequences of agronomic innovations. LTEs provide a valuable resource for such validation, while conclusions drawn from simulation studies that lack comprehensive validation must be considered with caution.

Precrop-treated soil influences wheat (Triticum aestivum L.) root system architecture and its response to drought.

Root system architecture (RSA) plays an important role in the plant's ability to sustain yield under abiotic stresses such as drought. Preceding crops (precrops) can affect the yield of the proceeding crop, partially by affecting the RSA. This experiment aims to explore the interactions between precrop identity, crop genotype and drought at early growth stages. Rhizotrons, sized 60 × 80 × 3.5 cm, were used to assess the early root growth of two winter wheat (Triticum aestivum L.) genotypes, using precrop-treated soil around the seedlings and differing water regimes. The rhizotrons were automatically imaged 3 times a week to track root development. Precrop-treated soil affected the RSA and changes caused by the reduced water treatment (RWT) were different depending on the precrop. Largest of these was the 36% reduction in root depth after wheat, but 44% after OSR. This indicates that effects caused by the precrop can be simulated, at least partially, by transferring precrop-treated soils to controlled environments. The genotypes had differential RSA and reacted differently to the RWT, with Julius maintaining an 8.8-13.1% deeper root system compared to Brons in the RWT. In addition, the combined environmental treatment affected the genotypes differently. Our results could help explain discrepancies found from using precrops to enhance yield as they indicate differences in the preceding crop effect when experiencing drought stress. Further, these differences are affected by genotypic interactions, which can be used to select and adapt crop genotypes for specific crop rotations, depending on the year. Additionally, we have shown a viable method of stimulating a partial precrop effect at the seedling stage in a controlled greenhouse setting using field soil around the germinated seed.

Commercial maize hybrids have smaller root systems after 80 Years of breeding

Roots have gained attention for their role in improving plant function in high-stress environments and providing ecosystem services such as soil organic carbon storage. An important step in breeding for enhanced root phenotypes is understanding how root traits have changed historically due to selection for yield and other aboveground traits. However, among the few era panel studies focused on roots, there are conflicting findings about how breeding has altered traits such as root system length and biomass, while other traits such as root depth distribution, root size class distribution, and tissue quality remain largely unexplored. Our aim was to assess breeding-driven changes in root traits that are relevant to resource acquisition and soil carbon sequestration. We grew twelve maize (Zea mays L.) hybrids from the Corteva/Pioneer ERA panel, spanning from 1936 to 2014, in 1.5 m deep mesocosms. At the eight-leaf stage, intact root systems were imaged and analyzed using a custom root phenotyping platform, and roots and shoots were subjected to carbon and nitrogen analysis and Diffuse Reflectance FTIR to assess variation in tissue composition. We found that the newest hybrids produced 40% less root biomass and 36% less root length than the oldest hybrids, with declines of 0.024 g year−1 (s.e.: 0.005, p < 0.01) and 0.86 m year−1 (s.e.: 0.23, p < 0.01) with no changes in maximum rooting depth, which averaged 113 cm (±5.62). , and no directional shifts in chemical composition. We also found a decline in the root-to-shoot ratio from 0.58 g g−1 to 0.46 g g−1 (s.e.: 0.0006, p < 0.05). Our results suggest that selection for yield has indirectly decreased root system size over 80 years of maize breeding. Smaller root systems of modern hybrids may contribute to the higher optimum plant populations and higher yields of modern maize hybrids.

River Ecomorphodynamic Models Exhibit Features of Nonlinear Dynamics and Chaos

AbstractModeling the nonlinear interactions between flow, sediment, and vegetation is essential for improving our understanding and prediction of river system dynamics. Using simple numerical models, we simulate the key flow‐sediment‐vegetation interaction where the disturbance is intrinsically generated by the presence of vegetation. In this case, biomass growth modifies the flow field, induces bed scour, and thus potentially causes vegetation uprooting when erosion exceeds root depth. Our results show that this nonlinear feedback produces deterministic chaos under a wide range of conditions, with complex aperiodic dynamics generated by a period‐doubling route to chaos. Moreover, our results suggest relatively small values of Lyapunov time, spanning 2–4 growth‐flood cycles, which significantly restrict the predictability of riverbed evolution. Although further spatial and temporal processes may add complexity to the system, these results call for the use of ensemble methods and associated uncertainty estimates in ecomorphodynamic models.

Fine Root Density Dynamics and Carbon Stock of Eucalyptus spp.: Interplay of Age, Genotype, and Edaphoclimatic Conditions.

Roots play a fundamental role in forest ecosystems, but obtaining samples from deep layers remains a challenging process due to the methodological and financial efforts required. In our quest to understand the dynamics of Eucalyptus roots, we raise three fundamental questions. First, we inquire about the average extent of the roots of two contrasting Eucalyptus genotypes. Next, we explore the factors that directly influence the growth and depth of these roots, addressing elements such as soil type, climate, and water availability. Lastly, we investigate how the variation in Eucalyptus species may impact root growth patterns, biomass, and carbon stock. In this study, we observed that the maximum root depth increased by an average of 20% when genotypes were grown on sites with higher water availability (wet site). E. urophylla stands had a higher biomass and carbon stock (5.7 Mg C ha-1) of fine roots when cultivated on dry sites (annual rainfall~727 mm) than the wet sites (annual rainfall~1590 mm). In E. grandis × E. camaldulensis stands, no significant differences were observed in the stock of fine root biomass (3.2 Mg C ha-1) between the studied environments. Our results demonstrated that genotypes with greater drought tolerance (E. grandis × E. camaldulensis) tend to maintain higher stocks of fine root biomass (3.2-6.3 Mg ha-1) compared to those classified as plastic (E. urophylla), regardless of the edaphoclimatic conditions of the cultivation site. Finally, our research helps understand how Eucalyptus trees adapt to their environment, aiding sustainable forest management and climate change mitigation. We also provide a practical tool to estimate underground biomass, assisting forest managers and policymakers in ensuring long-term forest sustainability.

STABILITY ASSESSMENT OF ROOT-REINFORCED SLOPES USING FINITE ELEMENT LIMIT ANALYSIS

Slope instability poses serious threats to infrastructure and environmental sustainability. As a result, numerous reinforcement techniques have been used as disaster mitigation attempts to prevent slope failure. Among various traditional slope reinforcement methods, the use of vegetion root is more cost-effective and environmentally friendly. This paper presents stability assessment of root-reinforced slopes. Firstly, slope models were built for case of bare and root-reinforced slopes. The slope angles were varied in the range of 15º ~ 55 º. The root cohesion and depth of root zone were adjusted within the ranges of 0 ~ 20 kPa and 0 ~1.5 m, respectively. The strength reduction finite element limit analysis method was applied to evaluate the stability of the slopes in this study. The results indicate that factor of safety increases with the increasing of root cohesion and depth of root zone. The best factor of safety was obtained for the case with root cohesion and depth of root zone of 20 kPa and 1.5 m, respectively. Shear dissipation contours of the slope models also show that root reinforcement reduces shear dissipation energy along the failure surface, consequently lowering the possibility of slope failure.

Impacts of Climate Change and Adaptation Strategies for Rainfed Barley Production in the Almería Province, Spain

Mediterranean water-stressed areas face significant challenges from higher temperatures and increasingly severe droughts. We assess the effect of climate change on rainfed barley production in the aridity-prone province of Almería, Spain, using the FAO AquaCrop model. We focus on rainfed barley growth by the mid-century (2041–2070) and end-century (2071–2100) time periods, using three Shared Socio-economic Pathway (SSP)-based scenarios: SSP1-2.6, SSP2-4.5, and SSP5-8.5. Using the paired t-test, Spearman and Pearson correlation coefficient, Root Mean Squared Error, and relative Root Mean Squared Error, we verified AquaCrop’s ability to capture local multi-year trends (9 or more years) using standard barley crop parameters, without local recalibration. Starting with a reference Initial Soil Water Content (ISWC), different soil water contents within barley rooting depth were modelled to account for decreases in soil water availability. We then evaluated the efficiency of different climate adaptation strategies: irrigation, mulching, and changing sowing dates. We show average yield changes of +14% to −44.8% (mid-century) and +12% to −55.1% (end-century), with ISWC being the main factor determining yields. Irrigation increases yields by 21.1%, utilizing just 3% of Almería’s superficial water resources. Mulches improve irrigated yield performances by 6.9% while reducing irrigation needs by 40%. Changing sowing dates does not consistently improve yields. We demonstrate that regardless of the scenario used, climate adaptation of field barley production in Almería should prioritize limiting soil water loss by combining irrigation with mulching. This would enable farmers in Almería’s northern communities to maintain their livelihoods, reducing the province’s reliance on horticulture while continuing to contribute to food security goals.

Using spectral vegetation indices and machine learning models for predicting the yield of sugar beet (Beta vulgaris L.) under different irrigation treatments

Yield prediction is essential for production planning, resource management, and competitive advantages. The use of vegetation indices and machine learning for yield prediction is rapid, practical, and accurate and contributes to the development of digital agriculture. Although many studies have been carried out on yield estimation, the number of studies on sugar beet and irrigation applications is limited. To solve this problem, in this study yield prediction of sugar beet under different irrigation treatments was carried out using spectral reflection-based vegetation indices obtained by proximal measurements and developed machine learning models. The multilayer perceptron (MLP), random forest (RF), k-nearest (kNN), bagging (BAG), support vector regression (SVR), gaussian processes (GP), and CustomNet (CN) predictors were used in yield prediction. The irrigation treatments included I100 (application of irrigation to increase the available moisture to field capacity by around 45–50% of the water holding capacity at the root depth), I75 (75% of the water applied in the control group), I50 (50% of the water applied in the control group), and I125 (25% of the water applied in the control group). The combinations of vegetation indices were determined using Pearson correlation and principal component analysis. OSAVI, SAVI, and NDVI had the most significant influence on the yield prediction of sugar beet. Among the combinations used, the kNN1 model (including all attributes as input) showed high R2 values of 0.99 for training and 0.64 for testing. In addition, the kNN3 model (including Treatment, NDVI, NWI, and OSAVI as inputs) had R2 values of 0.97 for training and 0.65 for testing, indicating successful outcomes. However, the MLP1 and SVR1 models had lower results with test R2 values of 0.53 and 0.56, respectively. The results demonstrate the successful application of machine learning and vegetation indices for yield prediction. The proposed approaches could encourage agricultural experts and researchers in future work for yield mapping and identification.

Repeated clearing as a mechanism for savanna recovery following bush encroachment

Abstract Many savannas are experiencing increased cover of trees and shrubs, resulting in reduced herbaceous productivity, shifts in savanna functional structure and potential reductions in ecotourism. Clearing woody plants has been suggested as an effective management strategy to mitigate these effects and restore these systems to an open state with higher rates of grass production and herbivory. This study investigated the effectiveness of repeated shrub clearing as a tool to mitigate bush encroachment in a semi‐arid savanna in southern Africa. We present data from a 7‐year experiment in the Mthimkhulu Game Reserve bordering Kruger National Park, South Africa. Colophospermum mopane stems and resprouting shoots were basally cut 2–3 times per year (2015–2022) in three pairs of treatment and control plots of 60 × 60 m. We monitored changes in soil moisture, grass biomass and herbivore activity via dung counts. We assessed C. mopane physiological responses to repeated cutting using non‐structural carbohydrates and stable water isotopes to infer changes to energy storage and functional rooting depth, respectively. The cleared treatment had higher soil moisture and grass biomass than the control treatment. Dung counts showed impala and buffalo visited the cleared treatment more frequently than the control treatment. Repeated cutting had limited effects on C. mopane survival in the first 2–3 years after initial clearing, but 80% of individuals were dead after 7 years. Repeatedly cut C. mopane had lower belowground starch concentrations and used water from shallower soil depths than C. mopane in control plots. Synthesis and applications. Repeated cutting increased soil moisture availability and grass biomass, and attracted charismatic grazing herbivores. While more costly than once‐off clearing methods, this practice created more employment opportunities for a neighbouring rural community. Transforming portions of the ecosystem to a grass‐dominated state may increase ecotourism potential through improved game viewing in open systems.

The effect of drought‐induced leaf traits onFicusleaf palatability is species specific

AbstractDrought has a significant impact on plant–insect interactions by altering plant survival, growth, leaf quality, and defense traits. Tropical plants are particularly vulnerable to water depression because of shallow root depth. In the context of climate change, drought events are expected to increase in frequency and intensity; however, their impact on tropical ecosystems remains poorly known. Insect herbivores represent the largest feeding guild of arthropods, and they devour four to five times more plant material than vertebrates do. Understanding how drought affects plant traits and leaf palatability in a keystone and ecologically diverse plant genus, such asFicus(Moraceae), is crucial for predicting how climate change might alter tropical plant–insect interactions. We examined the impact of drought intensity and duration on the leaf nutritional quality, defensive traits, and herbivory damage by caterpillars in three tropical and one MediterraneanFicusspecies in a greenhouse. We also conducted food choice trials with generalist caterpillars to evaluate the impact of drought on herbivores. Drought intensity and duration had no direct effect on leaf palatability across theFicusspecies. However, drought indirectly affected leaf palatability via drought‐induced leaf traits in a species‐specific manner. Drought intensity and duration decreased leaf water content, resulting in decreased leaf palatability inF. benjaminaandF. lyrata. Leaf defensive traits such as flavonoid concentration were affected by drought intensity and decreased leaf palatability inF. carica. Drought influenced the leaf traits ofF. elastica, but none of them affected leaf palatability. Overall, this study establishes the link between drought and insect feeding on plants via leaf traits. The species‐specific responses to drought highlight the significance of climate‐related plant life histories in relation to climate change, underscoring the need for further investigations.

Meibography-Guided Electroepilation for Congenital Distichiasis: A Novel Surgical Technique.

Congenital distichiasis is managed either by ablation, using laser, cryotherapy, or electroepilation, or by surgical excision with mucous membrane grafting. Ablative procedures are usually blind as the exact depth of distichiatic eyelashes is unknown. The described surgical technique utilizes meibography for imaging the root and depth of distichiatic eyelashes that aided in performing electroepilation. Six patients (n = 24 eyelids; mean age 15.5 ± 12.2 years) underwent infrared meibography (Oculus Keratograph 5 M) and noninvasive tear breakup time prospectively. Eyelashes were electroepilated using a premarked needle inserted at a depth based on meibography findings in 4 patients. Surgical success was defined as no distichiatic eyelash regrowth and functional success was defined as the resolution of symptoms at a minimum of 3 months of follow-up. All 6 patients had all 4 eyelids involved to varying degrees, with a total of 230 distichiatic eyelashes. The median number of distichiatic eyelashes was 9 in the upper eyelids and 4.5 in the lower eyelids. Meibography revealed visible distichiatic eyelash roots in 70% of eyelashes in the upper eyelid and 87.8% in the lower eyelid, respectively. The median eyelash root depth was 2.7 mm (mean 2.9 mm, range 1.8-5.4 mm). The mean noninvasive tear breakup time was 12.2 seconds despite absent or rudimentary meibomian gland segments seen on meibography. The anatomical success was 75% (12/16 eyelids), and functional success was 87.5% (7/8 eyes) at a median follow-up of 5.5 months. Preoperative infrared meibography in eyelids with congenital distichiasis helps estimate the eyelash depth and can be used to guide eyelash ablation procedures.

Mixed-Species Stands Improve the Coordination between Leaf and Fine Root Traits in a Common Garden Experiment

The coordination between leaf and root traits is conducive to an integrated understanding of whole-plant ecological strategies and reveals how community composition and diversity contribute to defining the functions and services of ecosystems. However, there is limited understanding regarding the impact of species richness and trait categories on the coordination between leaf and root traits. Based on a 9-year common garden experiment, we investigated the leaf and fine root traits of 56 plots (25.8 m × 25.8 m) encompassing various trait categories (trait categories were defined according to the root depth, leaf habit, and mycorrhizal type) and different levels of species richness (1, 2, 4, 8) in the context of a forest biodiversity and ecosystem functioning experiment conducted in subtropical China (BEF-China). We found the following: (1) Our findings indicate that there was generally a significant difference in leaf traits, occasionally in absorptive root traits, and no difference in transport root traits between different trait categories. (2) Conversely, species richness significantly influenced all transport root traits except root nitrogen and most leaf and absorptive root traits. (3) The results demonstrated that trait categories played a crucial role in the coordination between leaf and fine root traits. Additionally, the coordination between leaf and fine root traits increased with higher species richness, particularly in deep-rooted, evergreen, and ectomycorrhizal fungi species. Furthermore, the coordination between leaf and fine root traits was significantly lower in monocultures compared to four- and eight-species mixtures. These results suggest that a significant mixture effect exists in the coordination between leaf and fine root traits due to the comprehensive and divergent capture of above- and belowground resources and reduced intraspecific competition. Therefore, compared to monocultures, mixed-species stands can enhance the coordination of leaf and fine root traits, and it is advisable to establish forests with mixtures of more than four species, dominated by deep-rooted, evergreen, and ectomycorrhizal fungi species, to maintain ecosystem stability and functional integrity.

Tree water uptake patterns across the globe.

Plant water uptake from the soil is a crucial element of the global hydrological cycle and essential for vegetation drought resilience. Yet, knowledge of how the distribution of water uptake depth (WUD) varies across species, climates, and seasons is scarce relative to our knowledge of aboveground plant functions. With a global literature review, we found that average WUD varied more among biomes than plant functional types (i.e. deciduous/evergreen broadleaves and conifers), illustrating the importance of the hydroclimate, especially precipitation seasonality, on WUD. By combining records of rooting depth with WUD, we observed a consistently deeper maximum rooting depth than WUD with the largest differences in arid regions - indicating that deep taproots act as lifelines while not contributing to the majority of water uptake. The most ubiquitous observation across the literature was that woody plants switch water sources to soil layers with the highest water availability within short timescales. Hence, seasonal shifts to deep soil layers occur across the globe when shallow soils are drying out, allowing continued transpiration and hydraulic safety. While there are still significant gaps in our understanding of WUD, the consistency across global ecosystems allows integration of existing knowledge into the next generation of vegetation process models.

Experimental Study on the Effect of Soil Reinforcement and Slip Resistance on Shallow Slopes by Herbaceous Plant Root System

In this study, Setaria viridis was selected as the research object, the soil reinforcement mode of roots was analyzed, and the general mechanical model of soil reinforcement was proposed. The direct shear tests of root–soil composite and root tensile tests were carried out, and the relationship between the root additional cohesion and root depth was studied. Furthermore, numerical simulations were established to explore the variation law of shallow displacement and slope stability as a function of the root ratio. The results show that the effect of herbaceous plant roots on the soil was composed of material modification and root binding force on the soil. The shear strength improvement of the root–soil composite was mainly reflected by the increase in cohesion. Furthermore, the composite cohesion was positively correlated with the root content but negatively correlated with the water content. With the increase in root diameter, the tensile strength of the Setaria viridis root increased linearly, but its tensile strength decreased and showed a power relation. The greater the total cohesion of the root–soil composite layer, the smaller the total displacement and the higher the slope stability. Thus, the slope’s herbaceous vegetation could effectively control the deformation and slip of the shallow soil, which has good application value for reducing soil erosion in mining areas.

Enhancing precision of root-zone soil moisture content prediction in a kiwifruit orchard using UAV multi-spectral image features and ensemble learning

Accurate and real-time monitoring of soil moisture content (SMC) is of utmost importance for effective field irrigation and maximizing crop water productivity. However, a comprehensive investigation into the inversion study for determining suitable combinations of unmanned aerial vehicle (UAV) image features and enhancing the precision of SMC model prediction has yet to be fully validated within a kiwifruit orchard setting. This study addresses this gap by employing a pre-processing method and an optimal band combination algorithm to assess the impact of various combinations of kiwifruit canopy reflectance and fraction vegetation coverage (FVC) features on the sensitivity of root-zone SMC. Furthermore, an optimal ensemble learning (EL) framework was developed to monitor SMC at various root-zone depths (0–10 cm [SMC10], 0–20 cm [SMC20], 0–30 cm [SMC30], 0–40 cm [SMC40], 0–50 cm [SMC50], 0–60 cm [SMC60]). The key findings of this research highlight the successful derivation of 10 wavebands and FVC features, exhibiting a strong correlation with SMC at different root depths. The gradient boosting (GBDT) model demonstrated the exceptional accuracy in estimating SMC10, with an impressive R2 value of 0.963 ± 0.030 and low RMSE values of 0.238 ± 0.111. Similarly, the eXtreme Gradient Boosting (XGBoost) model outperformed in estimating SMC20 to SMC60, with R2 and RMSE values of 0.963 ± 0.024 and 0.117 ± 0.053, respectively. Additionally, the utilization of the optimal EL model allows for digital mapping of SMC at different depths across fruit growth stages, showcasing superior adaptability for SMC30 to SMC60 (with R2 and RMSE of 0.782 ± 0.090 and 0.037 ± 0.011) compared to SMC10 and SMC20 (with R2 and RMSE of 0.765 ± 0.097 and 0.056 ± 0.024). These results underscore the potential of the EL estimation framework in characterizing the spatial distribution of root-zone SMC at the individual kiwifruit plant level.