The raw-material mix ratio and preparation of similar materials are crucial for the success of physical model tests and for accurately reflecting prototype properties. In this study, an optimum similar material for plateau alluvial and lacustrine (PAL) round gravel was developed based on similarity theory. The similar materials were subjected to sensitivity factor analysis and microscopic analysis. Subsequently, the optimum similar material was applied to a three-dimensional (3D) physical model test of an ultradeep foundation pit (FP). The findings show that the similar material prepared with gypsum, LD, bentonite, water, barite powder, and DS at a ratio of 1:1:1.4:3.5:8.8:13.2 was the best for a 3D physical model test of the ultradeep FP in PAL round gravel strata. The sensitivity-factor analysis revealed that barite powder had the greatest impact on gamma, that c and phi were primarily affected by bentonite, and that the LD-gypsum ratio controlled E. A nonuniform particle-size distribution as well as the presence of edge-to-face contacts and small pores between particles constituted the microphysical factors affecting the mechanical properties of the optimum similar material. Using dolomite with a Mohs hardness of 3.5-4 instead of traditional quartz sand with a Mohs hardness of 7 as the raw material can produce a similar material for the target soil with mechanical parameters closer to those of the ideal similar material. The application of the optimum similar material in physical model tests has revealed the stress field response law of ultra deep foundation pit excavation. This study could provide reference and inspiration for the development of similar materials in gravel formations with weaker mechanical properties.

Forests and grasslands often occur side by side in the landscape, forming a complex mosaic system with contrasting environmental conditions, maintained by different fire-vegetation stabilising feedbacks. Woody species that occur along this sharp gradient must adopt viable ecological strategies to deal with the contrasting environments of these ecosystems. For this, plants are challenged to efficiently coordinate the functioning of ecological strategy dimensions above- and below-ground. We tested hypotheses related to structural changes in vegetation and associated shifts in community-level trait patterns and ecological strategies during woody plant encroachment. We surveyed 60 permanent plots in forest-grassland mosaics at two different times (2012-2022) to obtain data on changes in vegetation structure, species composition, abundance and ecological strategies after 10 years without disturbance, capturing a gradient from open and woody plant-encroached grasslands to closed forests. An integrated functional approach was used to assess the different dimensions of plant trait variation, including 10 above- and below-ground traits, representing whole-plant, leaf, stem and root strategies. Woody plant encroachment led to a substantial increase in woody plant density in former grasslands, transforming their structure to resemble that of young forests. Interestingly, we found clear trade-offs between above- and below-ground traits among woody species. On the one hand, the species occurring in grassland had conservative leaves, a strategy for protection against high solar incidence, physical damage and drought, and had roots with a 'do-it-yourself' strategy, which ensures efficiency in the acquisition of nutrients and water in nutrient-limited soils, and had thick bark related to fire resistance. On the other hand, forest species were usually taller and had acquisitive leaves, indicating highly competitive ability in light-limited forests, whereas their roots had an 'outsourcing' strategy of resource uptake to mycorrhizal fungi in the nutrient-rich soils of forests. Synthesis: We advanced the current understanding of woody plant encroachment in grasslands by showing the underlying trait-based trade-offs that enable woody species to occur along the transition between forest and grassland through space and time. Importantly, we have shown how below-ground traits are important in explaining the species strategies, with a negative covariance between above- and below-ground. Our integrative trait-based approach will be helpful in better understanding and managing forest-grassland mosaics in southern Brazil and analogous patchy ecosystems around the world. Florestas e campos frequentemente ocorrem lado a lado na paisagem, formando um sistema mosaico complexo com condiçõ es ambientais contrastantes, mantido por diferentes feedbacks estabilizadores entre fogo e vegetaçã o. Espé cies lenhosas que ocorrem ao longo desse acentuado gradiente devem adotar estraté gias ecoló gicas viá veis para lidar com os ambientes contrastantes desses ecossistemas. Para isso, as plantas precisam coordenar eficientemente o seu funcionamento acima e abaixo do solo. No presente artigo nó s avaliamos mudanç as estruturais na vegetaçã o associadas com mudanç as funcionais na escala de comunidades e nas estraté gias ecoló gicas das espé cies durante o processo de adensamento de espé cies lenhosas. Para isso, realizamos a amostragem de 60 parcelas permanentes localizadas nos mosaicos campo-floresta, em dois perí odos de tempo (2012 e 2022). O objetivo foi de obter dados sobre mudanç as na estrutura da vegetaçã o, composiçã o de espé cies, abundâ ncia e estraté gias ecoló gicas apó s 10 anos sem distú rbios, capturando um gradiente que vai de campos abertos, campo adensado por plantas lenhosas até florestas fechadas. Utilizamos uma abordagem funcional integrada para aavaliar as diferentes dimensõ es funcionais das plantas, incluindo 10 atributos funcionais acima e abaixo do solo (incluindo atributos de folha, caule e raiz). O adensamento de espé cies lenhosas resultou em um aumento substancial na densidade de plantas lenhosas em á reas anteriormente ocupadas por campos, transformando sua estrutura que atualmente se assemelha à de florestas jovens. Curiosamente, identificamos claros trade-offs entre atributos funcionais acima e abaixo do solo em espé cies lenhosas. Por um lado, as espé cies ocorrendo em campos apresentaram folhas conservativas, uma estraté gia para proteçã o contra alta incidê ncia solar, danos fí sicos e seca, alé m de raí zes com uma estraté gia 'faç a você mesmo', garantindo eficiê ncia na aquisiçã o de nutrientes e á gua em solos pobres, e casca espessa relacionada à resistê ncia ao fogo. Por outro lado, espé cies de floresta foram geralmente mais altas e apresentaram folhas aquisitivas, indicando alta competitividade onde existe limitaçã o de luz, enquanto suas raí zes exibiram uma estraté gia de aquisiçã o de recursos mediada por fungos micorrí zicos, no ambiente onde os solos sã o mais ricos. Sí ntese. Avanç amos no entendimento atual sobre o adensamento de espé cies lenhosas sobre os campos ao demonstrar os trade-offs funcionais que permitem a ocorrê ncia de espé cies lenhosas ao longo da transiçã o entre floresta e campo no espaç o e no tempo. Mostramos, especialmente, como atributos funcionais abaixo do solo sã o importantes para explicar as estraté gias das espé cies, com uma covariâ ncia negativa entre atributos funcionais acima e abaixo do solo. Nossa abordagem integrativa baseada em atributos foi ú til para um melhor entendimento e manejo de mosaicos floresta-campo no sul do Brasil e em ecossistemas aná logos ao redor do mundo.

Plant test systems are a sensitive way to detect the genetic effects of various contaminants in environmental compartments: water, soil and sediments. Biotesting of the genotoxicity of soil samples with various activity concentrations of naturally occurring (Ra-226, Th-232, K-40) and artificial (Cs-137) radionuclides in soil, from the territory of the Aragats Massif (Armenia) was carried out with the application of the Tradescantia micronucleus (Trad-M & Scy;N) and stamen hair mutation (Trad-SHM) bioassays of Tradescantia (clone 02) model test-object in the soil - plant system. Undisturbed soil sampling was performed in the southern slopes of the Aragats Massif, from different altitudes (from 1000 to 3200 m above sea level). The soils of the Aragats Massif exhibited a background level of naturally occurring materials (NORM) activity. The highest variability was indicated for K-40. The activity concentration of Cs-137 in soils exhibited a naturally increased as the altitude increased. Tradescantia (clone 02) was grown on the undisturbed soils in the greenhouse. To determine the level of genotoxicity of the studied soil samples, the Tradescantia-based Trad-MCN and Trad-SHM tests were applied. The activity concentrations of NORM and artificial Cs-137 in soil and phytomass were determined using an HPGe detector-based gamma spectrometer (Canberra). Tradescantia (clone 02) accumulated mainly K-40, accumulation of Ra-226 observed in one soil sample. In the areas with elevated activity of NORM, levels of genotoxicity were significantly higher compared to the control soil sample with the low rate of spontaneous mutation frequency. The positive correlation between genetic damages of Tradescantia (MCN and SSH) and contents of K-40 and Ra-226 in soils was revealed. The obtained results indicated the possibility of using Trad-MCN and Trad-SHM tests of Tradescantia (clone 02) for biotesting of background radioactivity in natural areas.

Pine wilt disease (PWD) severely damages the health, stability, and functions of pine forests. However, empirical evidence regarding the impact of PWD on multiple ecosystem services in these forest ecosystems remains limited. This study investigated five ecosystem services, namely carbon sequestration, water conservation, soil nutrient accumulation, biomass nutrient accumulation and understory plant diversity in subtropical Masson pine (Pinus massoniana) forests, and quantified their trade-offs along varying ages of PWD infection (uninfected (0 years), 6, 10, and 16 years). The results showed that PWD infection significantly affected ecosystem services in Masson pine forests, with decreased carbon sequestration, water conservation, and biomass nutrient accumulation in 6 years of PWD infection forests. As the duration of PWD infection increased, the composite score of ecosystem services initially decreased, then increased, and finally decreased again. In contrast, soil conservation and understory plant diversity showed an initial increase, followed by a decline. Moreover, PWD infection increased the trade-offs among ecosystem services, with the highest trade-offs for 10 years of infected forests. PWD infection altered the trade-offs between understory plant diversity and other ecosystem services from low to high levels. Our results suggest that forest management should be strengthened to accelerate the recovery of ecosystem services while controlling PWD infection in these disturbed forests.

Tea gardens are established on acidic soils (pH < 5.5) and undergo extensive fertilization to maximize yield, which inadvertently promotes the proliferation of various weed species. Commelina communis and Tradescantia fluminensis (Commelinaceae) are major threats to tea plantations causing the highest destruction compared to other weed species. This study investigated the mechanisms behind the tolerance exhibited toward elevated aluminum (Al) concentrations in acidic soils and its contribution to these species' invasive behavior and herbicide resistance. Both species displayed only a 17-22% reduction in biomass under 400 M Al, and the Al accumulation remained low, ranging between 100 and 200 mu g g(-1) DW. Interestingly, C. communis responded to low to moderate Al levels (50-150 mu M Al3+) with growth stimulation. Antioxidant enzyme activity and flavonoid and anthocyanin leaf concentrations increased with Al treatment concentrations. Surprisingly, exposure of plants to Al, particularly at the 50 mu M threshold, resulted in a significant reduction in leaf damage inflicted by a spectrum of herbicides (paraquat, glyphosate, clethodim, and 2,4-D), with the effect more pronounced in C. communis. Our results demonstrate that enhancement of antioxidant enzymes and accumulation of detoxifying metabolites, coupled with the accumulation of pivotal intermediates of metabolic pathways under Al treatment collectively contribute to enhanced resistance against an array of herbicides. These findings provide insights into the invasive propensity of C. communis and T. fluminensis, particularly in acidic soil conditions prevalent in tea gardens.

Soil pollution by metals and metalloids as a consequence of anthropogenic industrialisation exerts a seriously damaging impact on ecosystems. However, certain plant species, termed hyperaccumulators, are able to accumulate extraordinarily high concentrations of these metal(loid)s in their aboveground tissues. Such hyperaccumulation of metal(loid)s is known to act as a defence against various antagonists, such as herbivores and pathogens. We investigated the influences of metal(loid)s on potential defence traits, such as foliar elemental, organic and mechanical defences, in the hyperaccumulator plant species Arabidopsis halleri (Brassicaceae) by artificially amending the soil with common metallic pollutants, namely cadmium (Cd) and zinc (Zn). Additionally, unamended and metal-amended soils were supplemented with the metalloid silicon (Si) to study whether Si could alleviate metal excess. Individuals originating from one non-/low- and two moderately to highly metal-contaminated sites with different metal concentrations (hereafter called accessions) were grown for eight weeks in a full-factorial design under standardised conditions. There were significant interactive effects of metal amendment and Si supplementation on foliar concentrations of certain elements (Zn, Si, aluminium (Al), iron (Fe), potassium (K) and sulfur (S), but these were accession-specific. Profiles of glucosinolates, characteristic organic defences of Brassicaceae, were distinct among accessions, and the composition was affected by soil metal amendment. Moreover, plants grown on metal-amended soil contained lower concentrations of total glucosinolates in one of the accessions, which suggests a potential trade-off between inorganic defence acquisition and biosynthesis of organic defence. The density of foliar trichomes, as a proxy for the first layer of mechanical defence, was also influenced by metal amendment and/or Si supplementation in an accession-dependent manner. Our study highlights the importance of examining the effects of co-occurring metal(loid)s in soil on various foliar defence traits in different accessions of a hyperaccumulating species.

Many species have been intentionally introduced to new regions for their benefits. Some of these alien species cause damage, others do not (or at least have not yet). There are several approaches to address this problem: prohibit taxa that will cause damage, try to limit damages while preserving benefits, or promote taxa that are safe. In the present article, we unpack the safe list approach, which we define as a list of taxa alien to the region of interest that are considered of sufficiently low risk of invasion and impact that the taxa can be widely used without concerns of negative impacts. We discuss the potential use of safe lists in the management of biological invasions; disentangle aspects related to the purpose, development, implementation, and impact of safe lists; and provide guidance for those considering to develop and implement such lists.

Black carbon (BC) plays a vital role in Arctic warming.Extensiveinvestigations have been conducted to elucidate the source-receptorrelationships of BC between the Arctic and mid-/high-latitude sources.However, it is unclear to what extent source relocation under globalizationcould disturb Arctic BC contamination and climate forcing from anthropogenicBC emissions. Here, we show that the global supply chain (GSC) relocationfeatured by the southward shift of industries from high-latitude developedcountries to low-latitude developing countries markedly reduces theBC burden in the Arctic using a global chemical transport model (GEOS-Chem)and a multiregional input-output analysis (MRIO). We find thatArctic annual mean BC concentration associated with the GSC relocationdrops by similar to 15% from the case without the GSC relocation. Thetotal net BC level declines 7% over the entire Arctic and 16% in theEuropean Arctic. We also observed markedly declining BC depositionas well as direct and snow albedo radiative forcing in the Arctic.We show that the Arctic BC burden would be further reduced by decreasingBC emissions in China, attributable to its emission reduction andongoing shift of the GSC from China to southern and southeastern Asia. The global supply chain relocation fromhigh-latitude Europeto low mid-latitude Asian countries markedly reduces black carbonburden and snow albedo radiative forcing in the Arctic.

Given abundant energy and mineral resources in northwestern China, the west-east energy and mineral product transmission program play an increasingly important role in China's energy supply and consumption since the 2000s. Rapid growing energy and mineral products under this program might release increasing carbon emissions, causing climate and environmental consequences in northwestern China, which seems to be overlooked before. Here, a multiregional input-output analysis (MRIO) was conducted to investigate the temporal and spatial changes in black carbon (BC) emissions embodied in west-east energy and mineral product transmission from 2007 to 2012. Results were used to estimate BC's climate and environmental impact on China, focusing on northwestern China. The results show that BC emission flow patterns have been altered dramatically in China's domestic trade from 2007 through 2012. By 2012, 48%-77% of the consumption-based BC emissions from welldeveloped Beijing-Tianjin metropolises, East Coast, and South Coast regions were outsourced to other, primarily less-developed regions, of which northwestern China was the largest net BC emission outflow region at 48.8 Gg. The BC radiative forcing over China embodied in the west-east energy transmission was quantified using a compact Earth system model OSCAR. Model estimation shows that more than 30% of BC radiative forcing in northwestern China was related to the consumption from other regions across China. Central and eastern China were two significant contributors to the BC radiative forcing in northwestern China. Severe BC environmental inequality embodied in interprovincial trade was also identified in northwestern and central China provinces among 30 Chinese provinces. Inner Mongolia, Shaanxi, Ningxia, and Xinjiang in northwestern China experienced the most prominent climate and environmental losses via trade with well-developed provinces. These results provide references to alleviate trade-related pollution and climate impacts and to promote BC environmental equality in China.

Warming environmental conditions are often credited with increasing Arctic shrub growth and altering abundance and distribution, yet it is unclear whether tundra shrub expansion will continue into future decades. Water availability may begin to limit Arctic shrub growth if increasing air temperatures create drier soil conditions due to increased evapotranspiration and permafrost-thaw-induced soil drainage. However, few studies have effectively considered how dominant tundra shrub species respond to variations in both temperature and moisture. To better understand the key effects of temperature variation and soil moisture on two dominant circumpolar deciduous shrubs, we studied shrub growth along a natural landscape gradient in West Greenland, which is a region observed to be drying due to ongoing warming. We found that the growth forms of both grey willow (Salix glauca) and dwarf birch (Betula nana) were sensitive to warmer and drier conditions. For both species, increases in air temperature positively correlated with greater shrub volume, with the doubling of canopy volume due to increased woody biomass. Leaf biomass was best predicted by edaphic features including extractable ammonium, which was positively related to soil moisture, and bulk density. Warmer soils tended to be drier, suggesting that ongoing warming in the area could lead to significant water limitation. Our findings suggest that drier soil conditions might be limiting foliar production despite warming temperatures for two circumpolar dominant shrubs,Betula nanaandSalix glauca, which could have wide-ranging, biome-level consequences about ongoing and predicted shrub growth and expansion.