Vegetative Functions Research Articles

AGE DYNAMICS OF VEGETATIVE AND NEURODYNAMIC FUNCTIONS AMONG CHILDREN AT THE AGE OF 5-7 DURING MENTAL LOADS

Purpose. To trace changing dynamics of vegetative and neurodynamic functions among children at the age of 5-7 during mental loads. The study usually starts for the senior pre-school and junior school age. Individual children’s features and work of organ systems ensure adaptive reactions (including those during intensive mental loads). Therefore, we should pay attention to age dynamics of statistical and spectral peculiarities of heart rhythm for pre- and post-load states of kids. Material and methods. 112 children at the age of 5-7 participated in the research. They come from senior pre-school and junior school institutions in Sumy, a Ukrainian city. The research determines functional activities and nervous power of children via the Diahnost-1M methodology. The Fazahraf methodology estimates values of the cardiovascular system and influence of the vegetative nervous system on the heart rhythm. The technique collected and analyzed electrical potentials of spectral peculiarities of regulatory functions and significant statistical values of the heart rhythm. Because of the stage-by-stage research approach and data heterogeneity, we conducted a multi-level mathematical assessment. Most data were not subject to normal distribution since there was a sharp asymmetry of low-stage discretization. Results. Children may have different features during and after mental loads. They can be defined via most spectral and statistical values of the varying heart rhythm. The heart rhythm reactions among children at the age of 5 are shifted to sympathicotonia. During mental loads, the dominance of sympathetic influence and instable control of regulatory systems was typical for the 6-year-old sample. Besides, we established a relation between nervous power and cardiovascular activities (r=0.42; р<0.05). In contrast to other age samples, the 7-year-old group showed a balanced cooperation of the sympathetic and parasympathetic nervous systems. Simultaneously, there was an obvious resistance to external stimuli during mental loads (r=-0.36; р<0.05). Conclusions. Children at the age of 7 are more adapted to solve mental tasks with a certain speed. Therefore, we should pay a great attention to age functioning of physiological systems. In this way, we may apply the person-centered approach within the study process to raise adaptive abilities of the children’s nervous system

Variable resource allocation pattern, biased sex-ratio, and extent of sexual dimorphism in subdioecious Hippophae rhamnoides.

Evolutionary maintenance of dioecy is a complex phenomenon and varies by species and underlying pathways. Also, different sexes may exhibit variable resource allocation (RA) patterns among the vegetative and reproductive functions. Such differences are reflected in the extent of sexual dimorphism. Though rarely pursued, investigation on plant species harbouring intermediate sexual phenotypes may reveal useful information on the strategy pertaining to sex-ratios and evolutionary pathways. We studied H. rhamnoides ssp. turkestanica, a subdioecious species with polygamomonoecious (PGM) plants, in western Himalaya. The species naturally inhabits a wide range of habitats ranging from river deltas to hill slopes. These attributes of the species are conducive to test the influence of abiotic factors on sexual dimorphism, and RA strategy among different sexes. The study demonstrates sexual dimorphism in vegetative and reproductive traits. The sexual dimorphism index, aligned the traits like height, number of branches, flower production, and dry-weight of flowers with males while others including fresh-weight of leaves, number of thorns, fruit production were significantly associated with females. The difference in RA pattern is more pronounced in reproductive traits of the male and female plants, while in the PGM plants the traits overlap. In general, habitat conditions did not influence either the extent of sexual dimorphism or RA pattern. However, it seems to influence secondary sex-ratio as females show their significant association with soil moisture. Our findings on sexual dimorphism and RA pattern supports attributes of wind-pollination in the species. The observed extent of sexual dimorphism in the species reiterates limited genomic differences among the sexes and the ongoing evolution of dioecy via monoecy in the species. The dynamics of RA in the species appears to be independent of resource availability in the habitats as the species grows in a resource-limited and extreme environment.

Shifts in the trends of vegetation greenness and photosynthesis in different parts of Tibetan Plateau over the past two decades

Ecosystems on the Tibetan Plateau (TP) are fragile and sensitive to climate change and thus provide insight into the climate regulations on vegetation structure and function. In this study, we utilized the Normalized Difference Vegetation Index (NDVI) and solar-induced chlorophyll fluorescence (SIF) to explore vegetation dynamics during the growing season from 2000 to 2021, and further investigated how climate change has influenced them. Based on both NDVI and SIF, significant vegetation greening trends were observed in northeastern TP across the study period due to continuous increases in both temperature and water availability. Browning trends were observed in southwestern TP due to decreasing precipitation and enhanced warming stress during 2000–2007, but the trends reversed after 2007. In the southeastern region, we also detected a turning point of a more prominent greening trend in 2016. Moreover, changes in SIF exhibited greater magnitude compared to NDVI, implying vegetation photosynthesis is more sensitive to climate change than greenness, potentially due to variations in light use efficiency. This study strengthens our understanding of climate regulations on vegetation structure and function under different hydrothermal conditions and highlights the need for additional research on the differences between greenness and photosynthesis.

Soil CO2 emissions under different land-use managements in Mato Grosso do Sul, Brazil

Understanding the variability of soil CO2 emission across several land use and cover (LULC) classes and biomes and its relationship with climate variables is important to drive strategies that contribute to meeting local and international demands for sustainable development and low carbon agriculture. The hypothesis of this research is that soil CO2 emission in situ (FCO2) is variable between LULCs across different biomes and that there may be an association between soil CO2 flux and environmental variables such as temperature and soil moisture. This study evaluated FCO2, measured by a portable EGM-5 CO2 gas analyzer, CO2Flux model (obtained by remote sensing approach), soil moisture (SM), soil temperature (ST) and relationship between these variables in different LULC classes. We identified LULCs can contribute to carbon neutralization actions over the Cerrado, Atlantic Forest and Pantanal biomes located in State of Mato Grosso do Sul (MS), Brazil. Four LULC classes were evaluated in each biome: agriculture (soybean cultivation), pasture, eucalyptus plantation, and native vegetation. A principal component analysis (PCA) was performed to verify the relationship between biomes and LULC classes with the variables evaluated, and a Pearson correlation plot was created to assess the relationship between the variables evaluated. The lowest FCO2 values were found in eucalyptus and soybean crops, regardless of biome. Our findings reveal the existence of soil CO2 flux variability between the different LULCs and biomes. Pasture in Pantanal and Atlantic Forest biomes exhibited the highest FCO2 values. Eucalyptus cultivation and native forest showed negative CO2Flux values, regardless of biome. Lower FCO2 values were also observed for soybean cultivation. Such findings reinforce that native vegetation function as carbon sinks and that, therefore, their conservation is vital for the mitigation of CO2 emissions. However, soybean and eucalyptus farming can be strategic for low carbon agriculture in MS and carbon neutralization projects by simultaneously contribute to economic and sustainable development of the regions covered by the biomes evaluated here.

Correlations between vegetative autonomic function and specific left atrial functions in healthy adults: Insights from the three-dimensional speckle-tracking echocardiographic MAGYAR-Healthy Study.

The functioning of the left atrium (LA) is partly controlled by the neural system. It was purposed to evaluate correlations between the result of Ewing's 5 standard cardiovascular reflex tests (SCRTs) characterizing autonomic function and LA volumetric and functional features as assessed by three-dimensional speckle-tracking echocardiography (3DSTE) in healthy individuals. The current study comprised 18 healthy volunteers being in sinus rhythm (mean age: 35 ± 12 years, 10 men). Measurement of blood pressure, ECG, 5 SCRTs, two-dimensional Doppler echocardiography and 3DSTE were performed. These parameters were in normal ranges in all cases. From LA volumetric parameters, only systolic total atrial emptying fraction (r = 0.559, p = 0.037) and early diastolic passive atrial emptying fraction (r = 0.539, p = 0.047) correlated with systolic blood pressure response to standing representing sympathetic autonomic function. From LA strains, peak mean segmental LA radial strain (RS) (r = -0.532, p = 0.050), global and mean segmental LA circumferential strain (CS) (r = 0.662, p = 0.010 and r = 0.635, p = 0.015, respectively) representing systolic LA function correlated with Valsalva ratio representing parasympathetic autonomic function. Global LA-RS (r = -0.713, p = 0.040) and LA-CS (r = 0.657, p = 0.011) and mean segmental LA-CS (r = 0.723, p = 0.003) at atrial contraction representing end-diastolic atrial contraction showed correlations with Valsalva ratio, as well. Peak global and mean segmental LA-CS (r = 0.532, p = 0.050 and r = 0.530, p = 0.050) and the same strains at atrial contraction (r = 0.704, p = 0.005 and r = 0.690, p = 0.006) representing systolic function and end-diastolic atrial contraction correlated with systolic blood pressure response to standing representing both parasympathetic and sympathetic autonomic functions. Significant correlations between features of vegetative autonomic function represented by Ewing's 5 SCRTs and specific LA functions represented by 3DSTE-derived LA volume-based functional properties and strains could be demonstrated in healthy adults.

MEDICAL AND SOCIAL CHARACTERISTICS OF PATIENTS WITH INFERTILITY AND LONG-COVID-19

Purpose. To assess the medical and social characteristics of patients with infertility and longCOVID-19. Materials and methods. The main group consisted of 80 women with infertility who showed signs of “long-COVID”, the comparison group - 40 patients without a history of COVID-19. Socioeconomic status and factors of stressogenic load, fear of coronavirus-19 (FCV-19S scale), autonomic dysfunction (O.M. Wayne questionnaire, 1998). were assessed
 Results. Women with infertility and “long-COVID-19” are characterized by a relatively low level of socio-economic status: a lower level of income, a smaller share of entrepreneurs and housewives, not comfortable enough living conditions. These patients have a higher level of stressogenic load: comorbidity with chronic somatic pathology (58.8%), conflict situations in the family (31.3%), dissatisfaction with their sexual relationships (58.7%). The level of fear of COVID-19 is also significantly higher (29.73±1.31 points according to the FCV-19S questionnaire). Women with infertility and “long-Covid-19” suffer from various manifestations of autonomic disorders - autonomic dysfunction is diagnosed in 82.5% of patients. Symptoms that are typical for “long-Covid-19” are most often noted: reduced work capacity/fatigue (82.5%), attack-like headaches (72.5%), difficulty breathing (47.5%), sleep disturbances (47 .5 %). Conclusion. Women with infertility and “long-COVID-19” need additional examinations to assess vegetative function and psychological state, correction of detected violations.

Comparative Analysis of the Stress Protective Effect of Lithium Salts in an Open Field Test

Systemic response to stress, aimed at eliminating or reducing stress, is accompanied by changes in behavioral, vegetative, motor, sensory, cognitive, and other bodily functions. Stress behavior is an integral part of general behavior. In this work, we set out to study the behavioral activity of rats in an open field test following administration of various lithium salts. The conducted experiments showed that a course application of organic lithium salts improves the motivational characteristics of behavior and the appearance of rats, significantly increases the tentative research behavior of experimental animals, and reduces the level of anxiety, fear, and uncertainty, which can be characterized as an adaptive-stimulating effect. At the same time, the drug demonstrates a cumulative effect. The anabolic effect of lithium orotate is particularly pronounced, which makes it possible to increase body weight gains in the setting of stress of various etiologies.

Ecosystem productivity drives the breeding success of an endangered top avian scavenger in a changing grazing pressure context

Environmental conditions and resource availability shape population dynamics through direct and indirect effects of climate, biological interactions and the human modification of landscape. Even when a species seems dependent on predictable anthropogenic food resources or subsidies, ecosystem-level factors can still determine population dynamics across taxa. However, there is still a knowledge gap about the cascade effects driven by climate, vegetation functioning, resource availability and governmental policies on key aspects of species reproduction for top scavengers. Here we put to good use 22 years (2000−2021) of extensive population monitoring from the endemic Canary Egyptian vulture (Neophron percnopterus majorensis) on the Fuerteventura Island (Canary Islands, Spain) to study the relative importance of demographic factors, ecosystem conditions and availability of anthropogenic food sources on breeding success. Our results suggest that ecosystem-level primary productivity, the number of livestock animals present on the island and Density-dependent processes determine the temporal changes in the breeding success of this species. We firstly accounted for a top-down effect of livestock on island vegetation, where overgrazing directly reduces landscape-level vegetation biomass. We, consequently, found a bottom-up effect between vegetation and the Egyptian vulture's breeding success. In this context, minimal changes in ecological conditions can impact the species inhabiting these ecosystems, with direct consequences on a key population stage, such as breeding season, when energy requirements are higher. These results are especially relevant because cascading and indirect effects of ecosystem processes and governmental policies are often overlooked when pursuing conservation goals of endangered species.

Positive effects of mixed-species plantations on soil water storage across the Chinese Loess Plateau

Soil water storage (SWS) is a key variable influencing hydrological processes and vegetation function in arid and semiarid regions. Although convincing evidence indicated that mixed forests have higher resistance and resilience to climate change and natural disturbance than monocultures, it is unclear how mixed-species plantations affect SWS. By conducting a meta-analysis of 1071 paired observations in mixed-species plantations and monoculture plantations from 45 studies, we showed that, on average, the SWS of mixed-species plantations at 0–500 cm was 10.81% higher than that of monoculture plantations. Importantly, these positive mixture effects increased over time, with greater positive effects in mixed tree and shrub plantations. The effects of mixed-species plantations on SWS shifted from positive to negative with increasing soil depth, and these mixing effects in the topsoil layer (0–100 cm) became more pronounced with increasing stand age. However, the mixture effects on SWS did not vary with the mean annual temperature and precipitation. Moreover, mixed-species plantations were more conducive to enhancing the SWS capacity in areas with a low initial SWS. Structural equation models demonstrated that stand age was the main factor controlling the change in SWS, and soil depth also reduced the effect size of SWS by influencing the initial SWS. Our findings highlight that protecting and promoting functionally diverse forests improves SWS capacity, thereby alleviating soil moisture stress in arid and semiarid regions.

Dynamics of leaf chlorophyll fluorescence parameters can well be tracked by coupling VIS-NIR-SWIR hyperspectral reflectance and light drivers in partial least-squares regression

Chlorophyll α fluorescence (ChlF)-derived parameters provide deep insights into the photosynthetic functions of vegetation, and their rapid tracking is of great interest to plant studies. Unfortunately, traditional approaches such as direct measurements or regressive derivation from leaf traits are impossible to capture their dynamics, owing to their high variability under changing light conditions. Recent advances in reflectance spectroscopy address provide rapid and non-destructive estimates of ChlF parameters but lack thorough investigations. In this study, partial least-squares regression (PLSR), coupled with wavelength point and interval selection methods, was attempted to estimate ChlF parameters quickly and non-destructively using the coupled information from leaf spectroscopy, leaf traits, and light conditions recorded in a synchronous dataset covering ChlF parameters, leaf traits, and leaf hyperspectral reflectance under various light conditions. The results showed that PLSR models using only reflectance spectroscopy information predicted ChlF parameters well and maintained effectively across diverse light conditions, with the one coupled with stepwise regression variable selection performing best. Unexpectedly, the coupling of reflectance spectra and leaf traits achieved only marginal improvements. In comparison, the combination of spectral information with light conditions has further improved the estimation of ChlF parameters (R2: 0.92–0.96, RPIQ: 4.59–7.53) pronouncedly. The results of the present study highlight that the leaf hyperspectral reflectance together with light drivers can efficiently monitor different types of ChlF parameters, strengthening the use of hyperspectral reflectance in plant functions and thus providing valuable information in functional ecology.

Four Decades of Landscape Change on a Granite Dome (Enchanted Rock, Texas): A Photographic Field Work Analysis

This study focuses on photographic analysis of Enchanted Rock, a granite dome in central Texas; fourteen photo pairs compare contrasting views after—thirty-six to forty-six years, and assess changes in geomorphology, sediments, and vegetation on miniature landforms, especially erosional depressions—gnammas and vernal pools. Several distinct landscape changes occurred during the study period, but these affected sites unevenly. Vegetation displayed noticeable differences in plant density and species, particularly a pronounced increase of Opuntia cacti and woody shrubs on several depressions; these changes, however, are not considered permanent, and are interpreted as representing periodic fluctuations due to climatic oscillations such as recurrent drought. Among geomorphic features, a rock pedestal and a tafoni panel—displaying friable, crumbling, material—are seemingly being rapidly obliterated by weathering; their low compressive strength (Schmidt hammer) R values support this idea. In contrast, a large, isolated, boulder near the dome base did not—as anticipated—display any obvious changes. Large stones and gravelly sediments, accumulated on vernal pools, or deposited along rill channels between depressions, showed the most conspicuous alterations. The observed changes are arranged along a presumed developmental sequence portraying subsequent geomorphic stages during pool development, which occur as detached stones gradually weather and eventually disintegrate; both coarse and fine sediments are transported downslope during intense, infrequent rainfall events. Pools, gnammas, rills, sediments, and vegetation function on Enchanted Rock as interconnected geographical units and components of an elaborate drainage network, steadily affecting each other over space and time.

Vegetation Function Analysis in Musamus University Campus Area

The academic community's point of activity, the campus area, requires green open spaces to support its activities. The Musamus University campus area boasts 27 different types of scattered plants. A qualitative methodology was employed to identify the types and functions of vegetation in the Musamus University campus area, including data collection, vegetation mapping, diversity analysis, function identification, and data analysis. The research revealed that the Musamus campus area lacks vegetation, particularly in terms of shading, aesthetic, and guiding functions, although it does serve well as a noise dampener. Therefore, there is a need to increase the quantity of vegetation, especially those that provide shading, aesthetic, and guiding functions.

Use of weed plants as green manure in agriculture

The problem of practical application of weeds in agriculture is considered. Weed flora, just like other vegetation, performs a number of ecological functions and, according to the definition of biogeochemical science, is a phytomass carrying large reserves of biophilic (C, O, N, H, Ca, P, S) and a number of other chemical elements. The function of weed vegetation as a component of ecological stability of agrocenoses remains incompletely studied. In this regard, the article presents data on the results of using weed vegetation in adaptive-biological farming as a green manure fertilizer. Examples of positive effects of weeds on soil fertility and yields of cultivated crops are given.

Future changes in key plant traits across Central Europe vary with biogeographical status, woodiness, and habitat type

Many plant traits covary with environmental gradients, reflecting shifts in adaptive strategies and thus informing about potential consequences of future environmental change for vegetation and ecosystem functioning. Yet, the evidence of trait–environment relationships (TERs) remains too heterogeneous for reliable predictions, partially due to insufficient consideration of trait syndromes specific to certain growth forms and habitats. Moreover, it is still unclear whether non-native and native plants' traits align similarly along environmental gradients, limiting our ability to assess the impacts of future plant invasions. Using a Bayesian multilevel modelling framework, we assess TERs for native and non-native woody and herbaceous plants across six broad habitat types in Central Europe at a resolution of c. 130 km2 and use them to project trait change under future environmental change scenarios until 2081–2100. We model TERs between three key plant traits (maximum height, Hmax; specific leaf area, SLA; seed mass, SM) and individual environmental factors (7 climate variables and % urban land cover) and estimate trait change summed across all environmental effects. We also quantify the change in the average trait difference between native and non-native plants. Our models depict multiple TERs, with important differences attributed to biogeographical status and woodiness within and across habitat types. The overall magnitude of trait change is projected to be greater for non-native than native taxa and to increase under more extreme scenarios. Native woody plant assemblages may generally experience a future increase across all three traits, whereas woody non-natives may decline in Hmax and increase in SLA and SM. Herbaceous Hmax is estimated to increase and SLA to decrease in most habitats. The obtained trait projections highlight conditions of competitive advantage of non-native plants over natives and vice versa and can serve as starting points for projecting future changes in ecosystem functions and services.

Impact of dust load and lead (Pb) stress on leaf functioning of urban vegetation

Impact of dust load and lead (Pb) stress on leaf functioning of urban vegetation

Comparative Verification of Leaf Area Index Products for Different Grassland Types in Inner Mongolia, China

Leaf area index (LAI) is a key indicator of vegetation structure and function, and its products have a wide range of applications in vegetation condition assessment and usually act as important input parameters for ecosystem modeling. Grassland plays an important role in regional climate change and the global carbon cycle and numerous studies have focused on the product-based analysis of grassland vegetation changes. However, the performance of various LAI products and their discrepancies across different grassland types in drylands remain unclear. Therefore, it is critical to assess these products prior to application. We evaluated the accuracy of four commonly used LAI products (GEOV2, GLASS, GLOBMAP, and MODIS) using LAI reference maps based on both bridging and cross-validation approaches. Under different grassland types, the GLASS LAI performed better in meadow steppe (R2 = 0.26, RMSE = 0.41 m2/m2) and typical steppe (R2 = 0.32, RMSE = 0.38 m2/m2); the GEOV2 LAI performed better in desert steppe (R2 = 0.39, RMSE = 0.30 m2/m2). When we assessed their spatial and temporal discrepancies during the period from 2010 to 2019, the four LAI products overall showed a high spatial and temporal consistency across the region. Compared with GLASS LAI, the most consistent to least consistent correlations can be ordered by GEOV2 LAI (R2 = 0.94), MODIS LAI (R2 = 0.92), and GLOBMAP LAI (R2 = 0.87). The largest differences in LAI throughout the year occurred in July for all grassland types. Limited by the location and number of sample plots, we mainly focused on spatial and temporal variations. The spatial heterogeneity of land surface is pervasive, especially in vast grassland areas with rich grassland types, and the results of this study can provide a basis for the application of the product in different grassland types. Furthermore, it is essential to develop highly accurate and reliable satellite-based LAI products focused on grassland from the regional to the global scale according to these popular approaches, which is the next step in our work plan.

The influence of the integration and rehabilitation program on the peculiarities of the formation of the vegetative balance of younger schoolchildren affected by military operations

BACKGROUND: There is little information concerning the health parameters of children who are in the conditions of military hostilities.
 AIM: The aim of the study is to develop and study the impact of a comprehensive integration and rehabilitation program on heart rate variability in primary school children who have experienced the stress of military operations.
 MATERIALS AND METHODS: 128 children of primary school age who found themselves in the zone of active hostilities were under observation. The comparison group consisted of 68 children who lived in territories where military operations were not carried out. The assessment of vegetative functions was carried out according to the indicators of the analysis of temporal and spectral indicators of heart rate variability using the hardware and software complex Poly-Spectrum-12.
 RESULTS: The power of the very low-frequency component (VLF, ms2) of the spectrum in group I of children was also increased by 23.79% in comparison with the comparison group. The respiratory component (HF, ms2) of the general spectrum also had a statistical difference (25.27%) with the indicators of the comparison group at the time of the first study (p 0.05) in the younger schoolchildren evacuated to Rostov-on-Don. Upon repeated examination, it was found that the indicators of mode and variation range increased in all subgroups, except for a subgroup of children who were in the combat zone and were not included in the comprehensive integration and rehabilitation program.
 CONCLUSIONS: According to the results of spectral and temporal analysis of the heart rate, the vagosympathetic balance in younger schoolchildren who experienced the impact of the military operation in the Donbass Region reflects the activation of the sympathetic department of the autonomic nervous system. The developed comprehensive integration and rehabilitation program has shown its greatest effectiveness in children evacuated to Rostov-on-Don.

ПОКАЗАТЕЛИ ВЕГЕТАТИВНОЙ РЕГУЛЯЦИИ СЕРДЦА У МЛАДШИХ ШКОЛЬНИКОВ, ИСПЫТАВШИХ СТРЕСС ВОЕННЫХ ДЕЙСТВИЙ

The autonomic nervous system is particularly susceptible to stress. The results of a study of 
 prospective features of heart rate variability in primary school children who have experienced the stress of 
 military operations are presented. 128 children of primary school age who found themselves in the zone of 
 active hostilities were under observation. The assessment of vegetative functions was carried out by analyzing 
 the components of heart rate variability. The younger students of the Io group had a more pronounced sym pathicotonia already a year after the start of the stress factor exposure. By the end of the third year, the sym pathicotonic orientation of the regulation of the heart rhythm was replaced by vagotonic in children living in 
 the territory of the stressful situation of the war. The peculiarities of vegetative regulation in children who are 
 and have left the combat zone indicate an increase in the costs of the functional reserve to maintain the normal 
 level of functioning of the body

Asymmetric response of Amazon forest water and energy fluxes to wet and dry hydrological extremes reveals onset of a local drought-induced tipping point.

Understanding the effects of intensification of Amazon basin hydrological cycling-manifest as increasingly frequent floods and droughts-on water and energy cycles of tropical forests is essential to meeting the challenge of predicting ecosystem responses to climate change, including forest "tipping points". Here, we investigated the impacts of hydrological extremes on forest function using 12+ years of observations (between 2001-2020) of water and energy fluxes from eddy covariance, along with associated ecological dynamics from biometry, at the Tapajós National Forest. Measurements encompass the strong 2015-2016 El Niño drought and La Niña 2008-2009 wet events. We found that the forest responded strongly to El Niño-Southern Oscillation (ENSO): Drought reduced water availability for evapotranspiration (ET) leading to large increases in sensible heat fluxes (H). Partitioning ET by an approach that assumes transpiration (T) is proportional to photosynthesis, we found that water stress-induced reductions in canopy conductance (Gs ) drove T declines partly compensated by higher evaporation (E). By contrast, the abnormally wet La Niña period gave higher T and lower E, with little change in seasonal ET. Both El Niño-Southern Oscillation (ENSO) events resulted in changes in forest structure, manifested as lower wet-season leaf area index. However, only during El Niño 2015-2016, we observed a breakdown in the strong meteorological control of transpiration fluxes (via energy availability and atmospheric demand) because of slowing vegetation functions (via shutdown of Gs and significant leaf shedding). Drought-reduced T and Gs , higher H and E, amplified by feedbacks with higher temperatures and vapor pressure deficits, signaled that forest function had crossed a threshold, from which it recovered slowly, with delay, post-drought. Identifying such tipping point onsets (beyond which future irreversible processes may occur) at local scale is crucial for predicting basin-scale threshold-crossing changes in forest energy and water cycling, leading to slow-down in forest function, potentially resulting in Amazon forests shifting into alternate degraded states.

Simulating the anchorage behaviour of plant roots of different morphological traits

Slope greening is a nature-based solution that brings multiple environmental and societal benefits to urban built environments. The selection of plant species for this purpose is often based on their landscape values. However, the potential engineering functions of vegetation, such as pull-out resistance to soil sliding, have generally been ignored. Previous studies have attempted to use different root morphological traits to empirically explain the variations in pull-out resistance Pul, but the underlying root–soil load transfer mechanisms have rarely been investigated. This study used a validated three-dimensional (3-D) embedded beam element model in a finite element platform to parametrically investigate the effects of various root morphological traits on the pull-out behaviour of 3-D root systems. Simulation results showed that root systems whose morphology and branching pattern could gain more interfacial shear resistance (oblique second-order laterals in contrast to the horizontal case) and mobilise more root internal stresses (deeper branching point between first- and second-order roots) had higher Pul values. The third-order sinkers were effective in mobilising their tensile strength to resist pull-out only when they were within a certain distance away from the first-order taproot. A new integrated morphological trait was proposed to implicitly capture the different aspects of root–soil interaction mechanisms, and it contributed to approximately 85% of the Pul variability. Our study suggests that among the root systems that have the same volumes, those with either (1) more branch roots (BRs) but shorter lengths or (2) less BR but longer lengths have greater pull-out resistance and are thus more effective to soil stabilisation.