Tree architecture is an important component of forest community dynamics - taller trees with larger crowns often outcompete their neighbors, but they are generally at higher risk of wind-induced damage. Yet, we know little about wind impacts on tree architecture in natural forest settings, especially in complex tropical forests. Here, we use airborne light detection and ranging (LiDAR) and 30 yr of forest inventory data in Puerto Rico to ask whether and how chronic winds alter tree architecture. We randomly sampled 124 canopy individuals of four dominant tree species (n = 22-39). For each individual, we measured slenderness (height/stem diameter) and crown area (m2) and evaluated whether exposure to chronic winds impacted architecture after accounting for topography (curvature, elevation, slope, and soil wetness) and neighborhood variables (crowding and previous hurricane damage). We then estimated the mechanical wind vulnerability of trees. Three of four species grew significantly shorter (2-4 m) and had smaller crown areas in sites exposed to chronic winds. A short-lived pioneer species, by contrast, showed no evidence of wind-induced changes. We found that three species' architectural acclimation to chronic winds resulted in reduced vulnerability. Our findings demonstrate that exposure to chronic, nonstorm winds can lead to architectural changes in tropical trees, reducing height and crown areas. La arquitectura de los & aacute;rboles es un componente importante de la din & aacute;mica de la comunidad forestal: los & aacute;rboles m & aacute;s altos con copas m & aacute;s grandes suelen sobrepasar a sus vecinos, pero por lo general corren m & aacute;s riesgo de sufrir da & ntilde;os inducidos por el viento. Sin embargo, es poco lo que se sabe sobre el impacto del viento en la arquitectura de los & aacute;rboles en entornos forestales naturales, sobre todo en bosques tropicales complejos. En este caso, utilizamos LiDAR y 30 a & ntilde;os de datos de campo en Puerto Rico para preguntarnos si los vientos cr & oacute;nicos alteran la arquitectura de los & aacute;rboles. Se tom & oacute; una muestra aleatoria de 124 individuos del dosel de cuatro especies arb & oacute;reas dominantes (n = 22-39). De cada individuo, medimos la esbeltez (altura/di & aacute;metro) y el & aacute;rea de la copa (m2) y evaluamos si la exposici & oacute;n a vientos cr & oacute;nicos influ & iacute;a en la arquitectura teniendo en cuenta la topograf & iacute;a (curvatura, elevaci & oacute;n, pendiente, humedad del suelo) y las variables del vecindario (aglomeraci & oacute;n y da & ntilde;os previos por huracanes). Luego, estimamos la vulnerabilidad mec & aacute;nica de los & aacute;rboles al viento. En los lugares expuestos a vientos cr & oacute;nicos, tres de las cuatro especies crecieron mucho menos (2-4 m) y tuvieron & aacute;reas de copa m & aacute;s peque & ntilde;as. Cecropia schreberiana, en cambio, no mostr & oacute; indicios de cambios inducidos por el viento. La aclimataci & oacute;n arquitect & oacute;nica de tres especies a los vientos cr & oacute;nicos llevaba a una reducci & oacute;n de la vulnerabilidad. Nuestros hallazgos demuestran que la exposici & oacute;n a vientos cr & oacute;nicos puede provocar cambios arquitect & oacute;nicos en los & aacute;rboles tropicales, reduciendo su altura y la superficie de sus copas.

The reduction in the stability of rock slopes due to rainfall is a significant issue in tropical regions. Unsaturated soil, commonly found on hill slopes, provides higher shear strength compared to saturated soil due to matric suction. Soil moisture plays a crucial role in determining slope stability during rainfall events, yet it is often overlooked in geotechnical engineering projects. This study integrates both steady-state and transient analyses to examine how rainfall intensity affects the stability of a rock slope near a tunnel portal. Transient seepage analysis was conducted using SEEP/W to simulate changes in pore water pressure (PWP) resulting from rainfall infiltration under historical and future precipitation conditions. The analysis considers medium (SSP245) and worst-case (SSP585) climate change scenarios as per Coupled Model Intercomparison Project Phase 6 (CMIP6). The findings underscore the significant impact of rainfall-induced infiltration on slope stability and highlight the importance of incorporating soil moisture dynamics in slope stability assessments. The safety factor, initially 1.54 before accounting for rainfall effects, decreases to 1.34 when the effects of rainfall are included.

This study investigates the mechanisms controlling multiphase landslide reactivation at red soil-sandstone interfaces in subtropical climates, focusing on the Eastern Pearl River Estuary. A significant landslide in September 2022, triggered by intense rainfall and human activities, was analyzed through field investigations, UAV photogrammetry, and geotechnical monitoring. Our results demonstrate that landslide evolution is governed by the interplay of geological, hydrological, and anthropogenic factors. Key findings reveal that landslide boundaries are constrained by fractures at the northern trailing edge and granite outcrops in the south, with deformation progressing from trailing to leading edges, indicative of a creep-traction failure mode. Although the landslide is stabilizing, ongoing deformations suggest disrupted stress equilibrium, emphasizing the risks of future reactivation. This work advances the understanding of progressive landslide dynamics at soil-rock interfaces and provides critical insights for risk mitigation in subtropical regions.

This study investigates the cyclic response of unsaturated soils, focusing on the dynamic properties such as damping characteristics and soil stiffness, under varying matric suction and confining stress conditions during cyclic triaxial loading. Despite challenges in evaluating unsaturated soils compared to saturated ones, cyclic triaxial testing emerges as an efficient method for exploring their cyclic behavior. Through a series of experiments with different loading frequencies, stress levels, and suction conditions, the research reveals that as matric suction increases, stiffness rises while the damping ratio decreases. Additionally, comparisons between isotropic and anisotropic stress conditions show that the shear modulus is higher under anisotropic consolidation due to particle reorientation. The study proposes a semi-empirical equation to address the stress and suction dependency of shear modulus, finding a consistent trend between predicted and measured values. Ultimately, the findings underscore the significance of stress state, suction, cyclic shear strain, number of loading cycles and confining pressure in determining soil shear modulus.

Overgrazing is the primary human-induced cause of soil degradation in the Caatinga biome, intensely threatening lands vulnerable to desertification. Grazing exclusion, a simple and cost-effective practice, could restore soils' ecological functions. However, comprehensive insights into the effects of overgrazing and grazing exclusion on Caatinga soils' multifunctionality are lacking. This study examines (i) how overgrazing impacts multiple soil indicators, functions, and overall soil health (SH) and (ii) whether natural early forest growth post-grazing exclusion enhances critical soil functions for ecosystem restoration. We compared preserved dense forests, longterm overgrazed pastures (over 30 years), and young fenced-off open forests (three years old) along a longitudinal transect in the Caatinga biome: 36 degrees W (Sao Bento do Una), 37 degrees W (Sertania), and 40 degrees W (Araripina). Soil samples from the 0-20 cm layer were analyzed for thirteen physical, chemical, and biological indicators for a structured SH assessment, calculating index scores based on soil functions. Forest-to-pasture transition and subsequent overgrazing consistently compacted the soils and decreased nitrogen, carbon (C), microbial biomass C, and glomalin protein, thus degrading the soil's physical, chemical, and biological functions. Regionally, this conversion depleted 14.7 Mg C ha(-1) and reduced overall SH scores by 18%, severely impacting biological functions ( e.g.,-43% for sustaining biological activity). No significant differences in functions or SH were found between grazed pastures and open forests. SH scores and C stocks were highly interrelated (r > 0.5; p < 0.001), suggesting that C losses and SH deterioration were closely aligned. We conclude that overgrazing degrades soil multifunctionality and health across the Caatinga biome, with biological functions most severely damaged and legacies obstructing soil recovery for up to three years of grazing exclusion. Future SH studies should include open forest chronosequences with older ages and active restoration practices ( e.g., planting trees or green manure) to enhance Caatinga's ecological restoration knowledge and efforts.

This paper presents the analysis and results of a 14-year monitoring of slow-moving landslide behavior along a 100 m high slope at Serra do Mar, Brazil. The slope is located near a roadway and an industrial area and was suffering from creep movements triggered by an excavation at its foot. Movements were especially severe during the rainy periods due to water table fluctuation. Inclinometer readings from 2009 to 2011 showed that the sliding involved a soil mass of 15 to 20 m thick and was in the so-called tertiary phase, with relatively high acceleration. Prediction models showed that the slope failure would probably occur in another two to three years, which required immediate implementation of mitigation actions. By the end of 2011, several deep horizontal drains were installed along the slope to reduce the water table level. Since then, the inclinometers showed that acceleration was eliminated and velocity was substantially reduced, bringing the slope back to primary and secondary, stable movements. Monitoring results of deep horizontal drains shows that flow volumes increase substantially during the rainy seasons, showing that the solution efficiently stabilizes the slope. With monitoring results for both secondary and tertiary creep phases, and comparisons to other monitored slopes in the region, benchmark parameters related to slope velocity and acceleration for Serra do Mar slopes are discussed and presented. This constitutes the first organized study on slope movement velocities at Serra do Mar and presents an important contribution to researchers and designers.

AimHigh temperatures during forest fires can cause significant damage to tropical dry forest areas and alter their ecological stability, particularly by affecting seed viability and seedling emergence. This study evaluates the seedling emergence response of 18 dry forest species to fire-simulated temperatures, aiming to assess their potential for restoration in fire-prone Colombian ecosystems.LocationThe seeds used in this study were obtained from three tropical dry forests in Colombia.MethodsA total of 9832 seeds from 18 dry forest species were collected directly from the soil seed bank in three tropical dry forests in Colombia. These seeds were then exposed to simulated forest fire temperatures (100 degrees C, 150 degrees C, and 200 degrees C) for 10 min. Seed viability was analyzed using the 2,3,5-triphenyl tetrazolium chloride reagent (tetrazolium test) and assessed using a generalized linear model. Seedling emergence and mean emergence time were evaluated using one-way analysis of variance (ANOVA) with temperature treatments as factors.ResultsThe study revealed that seedling emergence significantly decreased with higher heat shock temperatures. Notably, Hura crepitans and Parkinsonia aculeata tolerated temperatures up to 100 degrees C, while Caesalpinia pulcherrima and Enterolobium cyclocarpum showed increased emergence at that temperature. Based on their emergence responses, species were classified as stimulated, tolerant, sensitive, or vulnerable. Seed viability declined with rising temperatures, and the mean emergence time increased in species like Cordia alba, Crescentia cujete, and Lonchocarpus violaceus.ConclusionsThis study shows that heat shocks at 150 degrees C and 200 degrees C significantly reduced seed bank viability for most Colombian dry forest species. However, Caesalpinia pulcherrima and Enterolobium cyclocarpum were stimulated by 100 degrees C heat shocks, while Hura crepitans and Parkinsonia aculeata showed no adverse effects. Vulnerable species like Coccoloba acuminata and Pithecellobium dulce exhibited no viable seeds at higher temperatures, suggesting potential local extinctions. These results emphasize the need to focus on heat-tolerant species for restoration efforts in fire-prone ecosystems.

Insect foliar herbivory is ubiquitous in terrestrial ecosystems, yet its impacts on soil nitrogen cycling processes remain not yet well known. To examine the impacts of insect foliar herbivory on soil N2O emission flux and available nitrogen (N), we conducted a pot experiment to measure soil available N content and soil N2O emission flux among three treatments (i.e., leaf herbivory, artificial defoliation, and control,) in two broad-leaved trees (Cinnamomum camphora and Liquidambar formosana) and two conifer trees (Pinus massonianna and Cryptomeria fortunei). Our results showed that insect foliar herbivory significantly increased soil inorganic N (i.e., NH4+-N and NO3--N), dissolved organic nitrogen (DON) and microbial biomass nitrogen (MBN) contents, and urease activity compared to control treatment. However, there were no differences in soil available N contents and urease activity between artificial defoliation and control treatments, implying that insect foliar herbivory had greater impacts on soil available N contents compared to physical damage of leaves. Moreover, soil N2O emission fluxes were increased by insect foliar herbivory in Cinnamomum camphora and Pinus massonianna, but not for the other two tree species, indicating various effect of insect foliar herbivory on soil N2O emission among tree species. Furthermore, our results showed the positive correlations between soil N2O emission flux and soil NO3--N, DON, MBN, and acid protease activity, and soil inorganic N, pH, and MBN mainly explained soil N2O emission. Our results implied that insect foliar herbivory can speed up soil nitrogen availability in subtropical forests, but the impacts on soil N2O emission are related to tree species.

The 2021 Cyclone Seroja was a category 3 storm that made landfall on Lembata Island, causing extensive damage. This study aims to identify key interpretations of sediment transport related to tropical cyclones (TC) Seroja and past floods using a geopedological approach, estimate the return period through frequency analysis, and determine the rainfall threshold for flooding using HEC-RAS software. Extreme rainfall data from global precipitation model (GPM) (2000-2023) in Wei Laing watershed were analysed alongside LiDAR terrain data, physical and chemical properties of soil, and land cover data. Based on geopedological analysis, the result shows that the erosional-transfer zone of Wei Laing Watershed has thin, loamy, and slightly sandy soils due to erosion and limited pedogenesis. The depositional zone contains flood deposits with abrupt vertical texture changes, reflecting transported coarse grains and finer in-situ sediments. The modern flood deposit (TC Seroja flood deposit) was identified by texture, CaCO3 content, organic matter, and coarse organic material. The fine-grained flood deposits (<_ 4 cm) are classified as slackwater deposits, consist of silty clay loam and silt loam textures, reflecting deposition under slow-flowing conditions. TC Seroja corresponds to a 50-year return period. Hydrological modelling indicates a 60 mm/day rainfall threshold for flooding, with 77 flood events recorded between 2000-2023. The model is confirmed by thick past flood deposits enriched with coarse organic materials. These findings provide insight into flood dynamics and sedimentary responses, supporting future flood risk mitigation efforts.

Tropical cyclones (TCs) pose a substantial threat to human life and property, with China being among the most affected countries. In this study, a significant increasing trend is detected for TC destructiveness, primarily measured by precipitation, and for TC-induced damage, measured by direct economic losses (DELs), in the inland areas of East China. In contrast, a similar trend cannot be observed in the coastal regions. The rapid increase of TC-induced damage in the inland areas of East China is directly related to an increase of the annual number of disastrous TCs, which is a result of the increased TC landfall frequency and the increased TC decay timescale after landfall. The increase in specific humidity, soil moisture, and the decrease in vertical wind shear in East China favor the survival of TCs inland. Our results highlight the significance of TC disaster prevention in the inland regions.