Vulnerable Ecosystems Research Articles

Evidence of Ecosystem Tipping Point on St. Lawrence Island: Widespread Lake Drainage Events After 2018

AbstractInfluenced by climate change, numerous lakes in permafrost regions are draining, showing significant spatial variability. This study focuses on St. Lawrence Island, where over the last two decades, 771 of 3,271 lakes have drained—a rate around 40 times higher than across the entire northern permafrost region. The surge in lake drainage began in 2018, coinciding with record low sea ice extent in the Bering Sea and unprecedented bird mortalities. Using satellite imagery and machine learning methods, we analyzed drainage events to identify the climatic drivers and potential climate thresholds affecting the island's lake ecosystems. Our findings indicate that autumn peak temperatures above 6°C more than triple the drainage probability, and warming‐induced permafrost thawing may be the direct driver of lake drainage. This research highlights the vulnerability of Arctic lake ecosystems to climate change and assists in developing predictive models for permafrost response, crucial for mitigating impacts on Arctic communities.

Potential of Sea Buckthorn (Hippophae rhamnoides L.) Thickets in Preserving Endangered Ecosystems in Kyrgyz Republic

Intensive urbanization from year to year reduces natural ecosystems that play a huge balancing ecological role on the planet. Preservation of natural ecosystems bordering on cultivated ones requires the development of new approaches to mutually beneficial sustainable development. Great potential lies in the preservation of unique ecosystems with wild fruit-bearing plantations. In this article, using the example of the natural ecosystems of the shores of Lake Issyk-Kul, included in the list of Ramsar Convention on the Conservation of Wetlands, the possibility of using natural thickets of sea buckthorn to improve the socio-economic situation of the local population and preserve unique but endangered natural ecosystems is analyzed. Studies have shown that sea buckthorn (Hippophae rhamnoides L.) fruits do not accumulate heavy metals and contain an increased content of ascorbic acid. A survey of the local population showed that local residents do not consider the use of sea buckthorn plantations as a potential source of income, but recognize it as the most environmentally friendly. In order to develop the mutually beneficial development of the local population and natural ecosystems, it is necessary: to use wild-growing fruit-bearing shrubs with the maximum benefit from the annual harvest, among which the sea buckthorn (Hippophae rhamnoides L.) has a potential; to develop recommendations and modern technologies for the production of a wide range of products, using all possible parts of sea buckthorn; educate local people on the importance of preserving natural ecosystems and involve local businessmen in preserving vulnerable ecosystems.

Understanding environmental drivers and trends in chlorophyll-a and related factors across equatorial Indian Ocean regions: implications for marine ecosystem dynamics and vulnerability

ABSTRACT We estimated the concentration of Chlorophyll-a (Chl-a) along with physical and biological factors including sea surface temperature (SST), wind speed and concentration of nitrate and phosphate in the Western, Central and Eastern Equatorial Indian Oceans (WEIO, CEIO and EEIO) using data from the Copernicus Marine Service and ERA-5 for the years 1994 to 2019. Our results show that along with the concentration of Chl-a, nitrate and phosphate have decreased, and sea surface temperature has increased in the EEIO. Due to coastal upwelling off the coast of Somalia and offshore Ekman transport throughout the summer, the southwest monsoon caused a significant increase in concentrations of Chl-a, nitrate, phosphate and wind speed in WEIO during June-July-August-September (JJAS) and October-November-December (OND). SST decreased at this time and deeper water interacted with surface water, increasing biological production. In EEIO, the upwelling zone is primarily maintained by wind-induced divergence throughout the year, whereas stratification in winter prevented surface Chl-a increase. High wind speed and low SST led to increased productivity in WEIO. Comparison of EEIO with WEIO and CEIO demonstrates low levels of Chl-a, phosphate and nitrate. The trends signify that these oceanic zones are highly vulnerable to developing into ecological deserts in the near future.

Mapping tree species of wetlands using multispectral images of UAVs and machine learning: A case study of the Dong Rui Commune

Wetlands provide resources, regulate the environment, and stabilize shorelines; however, they are among the most vulnerable ecosystems in the world. The classification of mangrove species allows the determination of the habitat of each species, thereby serving as a basis for determining protection solutions and planning plans for mangrove conservation and restoration according to each environmental condition. We used Phantom 4 multispectral unmanned aerial vehicles (UAVs) to collect data from wetland areas in the Dong Rui Commune, which is one of the most diverse and valuable wetland ecosystems in northern Vietnam. A tree-species classification map was constructed through a combination of the object-based image analysis method and spectral reflectance values of each plant species, and the characteristic distributions of mangrove plants, including Bruguiera gymnorrhiza, Rhizophora stylosa, and Kandelia obovata, were determined with an overall accuracy of 91.11 % and a kappa coefficient (K) of 0.87. The overall accuracy for Rhizophora stylosa was the highest (94.23 %), followed by Kandelia obovata (93.61 %) and Bruguiera gymnorrhiza (85.50 %). An experiment was conducted to map plant taxonomy in the same area based only on a graph of spectral reflectance values at five single-spectral bands, and normalized difference vegetation index values were constructed, resulting in an overall accuracy of 78.22 % and a K of 0.67. The constructed map is useful for classifying, monitoring, and evaluating the structure of each group of mangroves, thereby serving as a basis for determining the distribution of each mangrove species according to natural conditions and contributing to the formulation of policies for afforestation and mangrove conservation in Dong Rui commune.

Multitemporal monitoring of paramos as critical water sources in Central Colombia

Paramos, unique and biodiverse ecosystems found solely in the high mountain regions of the tropics, are under threat. Despite their crucial role as primary water sources and significant carbon repositories in Colombia, they are deteriorating rapidly and garner less attention than other vulnerable ecosystems like the Amazon rainforest. Their fertile soil and unique climate make them prime locations for agriculture and cattle grazing, often coinciding with economically critical deposits such as coal which has led to a steady decline in paramo area. Anthropic impact was evaluated using multispectral images from Landsat and Sentinel over 37 years, on the Guerrero and Rabanal paramos in central Colombia which have experienced rapid expansion of mining and agriculture. Our analysis revealed that since 1984, the Rabanal and Guerrero paramos have lost 47.96% and 59.96% of their native vegetation respectively, replaced primarily by crops, pastures, and planted forests. We detected alterations in the spectral signatures of native vegetation near coal coking ovens, indicating a deterioration of paramo health and potential impact on ecosystem services. Consequently, human activity is reducing the extent of paramos and their efficiency as water sources and carbon sinks, potentially leading to severe regional and even global consequences.

Diel rhythms of fish frequentation in a temperate mesophotic antipatharian forest and sleeping behaviour of the red swallowtail perch Anthias anthias (Linnaeus, 1758)

A 21-day continuous monitoring of a highly tridimensional forest of the black coral Antipathella subpinnata (Ellis and Solander 1786) was carried out in the NW Mediterranean Sea at 63 m depth using an autonomous lander to investigate the diel short-term dynamics of the vagile fauna associated to the forest. The survey allowed to assess several aspects of the forest attractiveness and its use, especially by the ichthyofauna, including (i) the diversity and shifts of the fish community inhabiting three layers of the environment (seafloor, canopy, water column) between four light phases (dawn, day, dusk, night), (ii) the diel rhythm in forest use of the red swallowtail perch Anthias anthias (Linnaeus 1758) and its sleeping behaviour in terms of fidelity towards resting sites, duration of rests, and awakenings triggers, and, finally, (iii) the influence of biotic and abiotic variables on the fish behaviour. Considering that, so far, only spot censuses have been carried out in these habitats, this study provides a dynamic approach to the study of biodiversity in temperate mesophotic coral forests and offers an insight into the functioning of these complex and vulnerable ecosystems.

Land Use Change Impacts over the Indus Delta: A Case Study of Sindh Province, Pakistan

Land use and land cover changes (LULCCs) are vital indicators for assessing the dynamic relationship between humans and nature, particularly in diverse and evolving landscapes. This study employs remote sensing (RS) data and machine learning algorithms (MLAs) to investigate LULCC dynamics within the Indus River Delta region of Sindh, Pakistan. The focus is on tracking the trajectories of land use changes within mangrove forests and associated ecosystem services over twenty years. Our findings reveal a modest improvement in mangrove forest cover in specific areas, with an increase from 0.28% to 0.4%, alongside a slight expansion of wetland areas from 2.95% to 3.19%. However, significant increases in cropland, increasing from 22.76% to 28.14%, and built-up areas, increasing from 0.71% to 1.66%, pose risks such as altered sedimentation and runoff patterns as well as habitat degradation. Additionally, decreases in barren land from 57.10% to 52.7% and a reduction in rangeland from 16.16% to 13.92% indicate intensified land use conversion and logging activities. This study highlights the vulnerability of mangrove ecosystems in the Indus Delta to agricultural expansion, urbanization, resource exploitation, and land mismanagement. Recommendations include harmonizing developmental ambitions with ecological conservation, prioritizing integrated coastal area management, reinforcing mangrove protection measures, and implementing sustainable land use planning practices. These actions are essential for ensuring the long-term sustainability of the region’s ecosystems and human communities.

Aridity threshold of ecological restoration mitigated atmospheric drought via land‒atmosphere coupling in drylands

Land‒atmosphere coupling intensifies the vulnerability of ecosystems in drylands. However, whether and how ecological restoration would modify the land‒atmosphere coupling across drylands remains unclear. To address these gaps, here we use structural equation model to separate two pathways of land‒atmosphere coupling: vegetation and soil moisture pathways, and investigate the effect of ecological restoration in China’s drylands on land‒atmosphere coupling. Analysis reveals that, land‒atmosphere coupling regulates approximately 30% of atmospheric drought, among which soil moisture pathway contributes twice as much as vegetation pathway. Vegetation greening mitigates atmospheric drought in areas where the aridity index ranges from 0.3 to 0.5, while soil drying exacerbates atmospheric drought in areas where the aridity index ranges from 0.5 to 0.65. The findings identify the optimal regions where ecological restoration helps alleviate the vulnerability of ecosystems under anthropogenic warming. Additionally, the proposed method enhances the understanding of how restored ecosystems contribute to mitigating atmospheric drought.

Travertine deposition rather than tourism activity is the primary contributor to the microplastic risks in alpine karst lakes

Microplastics (MPs) are emerging as anthropogenic vectors to form plastisphere, facilitating microbiome colonization and pathogenic dissemination, thus contributing to environmental and health crises across various ecosystems. However, a knowledge gap persists regarding MPs risks and their driving factors in certain unique and vulnerable ecosystems, such as Karst travertine lakes, some of which are renowned World Natural Heritage Sites under ever-increasing tourism pressure. We hypothesized that tourism activities serve as the most important factor of MPs pollution, whereas intrinsic features, including travertine deposition can exacerbate potential environmental risks. Thus, metagenomic approaches were employed to investigate the geographical distribution of the microbiome, antibiotic resistance genes (ARGs), virulence factor genes (VFGs), and their combined environmental risks in Jiuzhaigou and Huanglong, two famous tourism destinations in Southwest China. The plastisphere risks were higher in Huanglong, contradicting our hypothesis that Jiuzhaigou would face more crucial antibiotic risks due to its higher tourist activities. Specifically, the levels of Lipopolysaccharide Lewis and fosD increased by sevenfold and 20-fold, respectively, from upstream to downstream in Huanglong, whereas in Jiuzhaigou, no significant accrual was observed. Structural equation modeling results showed that travertine deposition was the primary contributor to MPs risks in alpine karstic lakes. Our findings suggest that tourism has low impact on MPs risks, possibly because of proper management, and that travertine deposition might act as an MPs hotspot, emphasizing the importance of considering the unique aspects of travertine lakes in mitigating MPs pollution and promoting the sustainable development of World Natural Heritage Sites.

Dilute concentrations of maritime fuel can modify sediment reworking activity of high-latitude marine invertebrates.

Multiple expressions of climate change, in particular warming-induced reductions in the type, extent and thickness of sea ice, are opening access and providing new viable development opportunities in high-latitude regions. Coastal margins are facing these challenges, but the vulnerability of species and ecosystems to the effects of fuel contamination associated with increased maritime traffic is largely unknown. Here, we show that low concentrations of the water-accommodated fraction of marine fuel oil, representative of a dilute fuel oil spill, can alter functionally important aspects of the behaviour of sediment-dwelling invertebrates. We find that the response to contamination is species specific, but that the range in response among individuals is modified by increasing fuel concentrations. Our study provides evidence that species responses to novel and/or unprecedented levels of anthropogenic activity associated with the opening up of high-latitude regions can have substantive ecological effects, even when human impacts are at, or below, commonly accepted safe thresholds. These secondary responses are often overlooked in broad-scale environmental assessments and marine planning yet, critically, they may act as an early warning signal for impending and more pronounced ecological transitions.

Stream size‐dependent effect of urban land use on occupancy of an apex freshwater carnivore recolonizing past ranges

AbstractAccurate assessment of population trends and factors that limit distributions of threatened species is key to conserving biodiversity. A reduction in impacts of human land use on species habitats may be one of the factors involved in the recolonization of former ranges by native species. The signature of this process could be detected as a temporal reduction of land use effects on species distributions, or as a spatial reduction, with effects persisting only in habitats more sensitive to anthropogenic stressors. We explored these hypotheses in a recolonizing semiaquatic carnivore. Our species of interest was the Eurasian river otter (Lutra lutra) in Italy, a nationally vulnerable species with a restricted but expanding range. Human land use is likely to strongly affect riparian and stream communities through habitat degradation. We used three independent survey datasets collected in 2003, 2009, and 2019 at the southern range periphery, and unpaired‐site occupancy models to account for imperfect detection in otter surveys. To assess how land use affects recolonization by otters, we tested three main model predictions: (1) occupancy increased over years, (2) effects of agricultural and urban land cover on occupancy decreased over years, (3) effects of agricultural and urban land cover were constant across years and changed with stream size and elevation. We found evidence that otter occupancy increased over years, with predicted mean occupancy of 0.27 in 2003 and 0.65 in 2019. An interaction effect of urban land cover with stream size was the strongest predictor of otter occupancy. Interestingly, a higher percentage of urban land cover around streams was predicted to reduce the probability of occupancy at smaller streams, but did not influence occupancy at larger streams. Despite a large increase in occupancy, otters at the southern periphery of the Italian range are still unable to colonize small rivers in urbanized areas. This pattern supports our hypothesis that human land use can affect recolonizing species at sensitive habitats, considering the intrinsic vulnerability of small stream ecosystems to anthropogenic stressors. Restoring small streams impacted by urban areas can be a valuable conservation action to increase habitat connectivity and favor recolonization of otters.

Tropical root responses to global changes: A synthesis.

Tropical ecosystems face escalating global change. These shifts can disrupt tropical forests' carbon (C) balance and impact root dynamics. Since roots perform essential functions such as resource acquisition and tissue protection, root responses can inform about the strategies and vulnerabilities of ecosystems facing present and future global changes. However, root trait dynamics are poorly understood, especially in tropical ecosystems. We analyzed existing research on tropical root responses to key global change drivers: warming, drought, flooding, cyclones, nitrogen (N) deposition, elevated (e) CO2, and fires. Based on tree species- and community-level literature, we obtained 266 root trait observations from 93 studies across 24 tropical countries. We found differences in the proportion of root responsiveness to global change among different global change drivers but not among root categories. In particular, we observed that tropical root systems responded to warming and eCO2 by increasing root biomass in species-scale studies. Drought increased the root: shoot ratio with no change in root biomass, indicating a decline in aboveground biomass. Despite N deposition being the most studied global change driver, it had some of the most variable effects on root characteristics, with few predictable responses. Episodic disturbances such as cyclones, fires, and flooding consistently resulted in a change in root trait expressions, with cyclones and fires increasing root production, potentially due to shifts in plant community and nutrient inputs, while flooding changed plant regulatory metabolisms due to low oxygen conditions. The data available to date clearly show that tropical forest root characteristics and dynamics are responding to global change, although in ways that are not always predictable. This synthesis indicates the need for replicated studies across root characteristics at species and community scales under different global change factors.

Absence of Gigasporales and rarity of spores in a hot desert revealed by a multimethod approach.

Hot deserts impose extreme conditions on plants growing in arid soils. Deserts are expanding due to climate change, thereby increasing the vulnerability of ecosystems and the need to preserve them. Arbuscular mycorrhizal fungi (AMF) improve plant fitness by enhancing plant water/nutrient uptake and stress tolerance. However, few studies have focused on AMF diversity and community composition in deserts, and the soil and land use parameters affecting them. This study aimed to comprehensively describe AMF ecological features in a 5,000 km2 arid hyperalkaline region in AlUla, Saudi Arabia. We used a multimethod approach to analyse over 1,000 soil and 300 plant root samples of various species encompassing agricultural, old agricultural, urban and natural ecosystems. Our method involved metabarcoding using 18S and ITS2 markers, histological techniques for direct AMF colonization observation and soil spore extraction and observation. Our findings revealed a predominance of AMF taxa assigned to Glomeraceae, regardless of the local conditions, and an almost complete absence of Gigasporales taxa. Land use had little effect on the AMF richness, diversity and community composition, while soil texture, pH and substantial unexplained stochastic variance drove these compositions in AlUla soils. Mycorrhization was frequently observed in the studied plant species, even in usually non-mycorrhizal plant taxa (e.g. Amaranthaceae, Urticaceae). Date palms and Citrus trees, representing two major crops in the region, however, displayed a very low mycorrhizal frequency and intensity. AlUla soils had a very low concentration of spores, which were mostly small. This study generated new insight on AMF and specific behavioral features of these fungi in arid environments.

Climate Change and Health: Preparing for the Future

Climate change presents a critical public health crisis, disproportionately affecting vulnerable populations worldwide. Rising temperatures lead to increased heat-related illnesses and worsened air quality, exacerbating respiratory and cardiovascular conditions. Wildfires release pollutants that further compromise health, while changes in weather patterns expand the range of infectious diseases. Low-income and indigenous communities face heightened risks due to limited resources and reliance on vulnerable ecosystems. Effective responses require strengthened healthcare systems, enhanced urban planning for resilience, public health campaigns, and advocacy for robust climate policies integrating health considerations. Keywords: Adaptation, Climate Change, Public Health, Policy Advocacy.

Effects of Human Harvesting, Residences, and Forage Abundance on Deer Spatial Distribution.

It has been known that harvesting by humans strongly influences individual within-home range habitat selection of many deer species; however, little is known about the effect of harvesting on coarse-scale habitat selection (i.e., spatial distribution). We examined the summer spatial distribution of sika deer Cervus nippon in relation to human harvesting and other factors, such as human residences, forage abundance, and cover, using pellet group counts at Mount Fuji, central Japan, in 2018. In the study area, harvesting is conducted at medium elevation areas throughout the year, but not at high or low elevation areas where access is difficult or harvesting is prohibited. Spatial distribution of deer was significantly biased to non-harvesting areas and far from residential areas, suggesting that they avoid riskier spaces by establishing a landscape of fear. High-quality food resources (deciduous broad-leaved trees and forbs) were more abundant in harvesting areas than in non-harvesting areas, suggesting that foraging pressure by deer reduce them. However, there were no differences in abundances of more fibrous dwarf bamboo between harvesting and non-harvesting areas, and spatial distribution of deer was significantly biased to higher dwarf bamboo abundance areas, suggesting that the dwarf bamboo is an alternative food resource in non-harvesting areas where supplies of high-quality food were limited. Our results suggest that human harvesting pressure and residences shifted the spatial distribution of deer from the montane forests to subalpine/alpine zones, which may increase damage to vulnerable ecosystems due to severe foraging pressure.

Hoping the best, expecting the worst: Forecasting forest fire risk in Algeria using fuzzy logic and GIS

Forest fires pose severe threats to ecosystems and communities globally, especially in vulnerable semi-arid regions like North Africa. Understanding the key factors influencing forest fire dynamics is essential for effective management and mitigation. This study aims to comprehensively analyze forest fire risk patterns in Djebel El Ouahch's massif (Algeria), focusing on integrating bioclimatic, fuel, geomorphological, and human factors through advanced fuzzy logic and geographic information system (GIS) techniques. Climatic station data, satellite imagery, and GIS were employed to map bioclimatic parameters, land cover, and geomorphological features. Fuzzy logic systems were applied to integrate these factors, assigning appropriate weights based on their significance. The resulting forest fire prediction model was defuzzified to generate predictive maps indicating varying vulnerability levels within the study area. Predictive maps delineated areas of low to high forest fire risk. Low-risk zones were characterized by sparse vegetation, while high-risk regions featured densely vegetated slopes near human settlements. The study identified critical factors influencing vulnerability, emphasizing the impact of climate, terrain, and human activities. Urgent attention was directed toward high-risk areas, necessitating tailored fire prevention measures and strategic urban planning to minimize human-induced risks. The results underscored the complex interaction of natural and anthropogenic factors in shaping forest fire susceptibility. Understanding these dynamics facilitates evidence-based policymaking, enhancing forest fire preparedness, biodiversity preservation, and community safety. Additionally, the study emphasized the need for continuous research incorporating real-time climate data and socio-economic factors to refine predictive models. This research provided valuable insights into forest fire risk patterns in Djebel El Ouahch, serving as a foundation for targeted fire management strategies. By bridging the gap between theoretical knowledge and practical application, this study contributes significantly to sustainable forest management and disaster mitigation efforts globally, emphasizing the importance of proactive measures in safeguarding vulnerable ecosystems and communities.

Macroplastic and Microparticle Pollution in Beach Sediments from Urias Coastal Lagoon (Northwest Mexico).

This study investigates the occurrence and characteristics of macroplastic and polymer microparticles in the Urias coastal lagoon's beach sediments, in northwest Mexico. Coastal lagoons, productive and vulnerable ecosystems, are impacted significantly by anthropogenic activities, leadings to their pollution by various contaminants, including plastics. Our research involved sampling sediments from four sites within the lagoon that were influenced by different human activities such as fishing, aquaculture, thermoelectric power plant operations, industrial operations, and domestic wastewater discharge. Our methodology included collecting macroplastics and beach sediment samples, followed by laboratory analyses to identify the plastic debris' size, shape, color, and chemical composition. The results indicated a notable presence of macroplastic items (144), predominantly bags, styrofoam, and caps made of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET). The polymer microparticles were mainly fibers, with cotton and polyester as the most common polymers, suggesting a significant contribution from clothing-related waste. The dominant colors of the microparticles were blue and transparent. High densities were observed in areas with slower water exchange. Our findings highlight the urgent need for better waste management practices to mitigate plastic pollution in coastal lagoons, preserving their ecological and economic functions.

Impact of land-use change on ecological vulnerability in the Yellow River Basin based on a complex network model

The Yellow River Basin in China, which is characterized by significant soil erosion and arid to semi-arid conditions, has experienced severe ecological issues due to prolonged excessive development and land-use changes. Studies on ecosystem vulnerability have become a major basis for supporting the sustainable and healthy development of watershed ecosystems. Based on the land-use data of 2000, 2005, 2010, 2015, and 2020, this study used a complex network model to identify the key types of land-use transformation in the Yellow River Basin. The cascade failure model was used to evaluate the impact of land-use transformation on ecological vulnerability in the Yellow River Basin of China. The land-use changes in the Yellow River Basin from 2000 to 2020 exhibit significant heterogeneity in both quantity and direction. Among them, the total area of agricultural land showed a downward trend as a whole, and the area rebounded slightly from 2000 to 2015. The growth trend of construction land area is obvious, with a year-on-year increase of 46.81 % in 20 years. Through network identification, we found that ecological land types such as forest, grassland, and dryland are the primary factors contributing to land area outflow. Conversely, artificial land types including urban land, rural residential land, and other built-up land predominantly serve as factors for land area inflow. The Yellow River Basin experiences frequent land-use transitions, resulting in the poor stability of the land transfer network. However, the study reveals that the ecosystem service value increases as the areas of paddy fields, dryland, urban land, rural residential land, and bare land decrease; this trend contributes to mitigating ecological vulnerability. To ensure the overall stability of the ecosystem and implement healthy and sustainable development, the maximum reduction in the areas of dryland, forest, paddy, and grass should be limited to 40 %, 30 %, 50 %, and 50 %, respectively, in future planning and design processes. In conclusion, the land-use transformation in the Yellow River Basin of China has profound implications for ecological vulnerability. The research findings can provide valuable references for future ecological research on areas facing similar challenges in protecting ecological fragility.

Emplacing Ecological Grief in Last Chance Tourism: Cryospheric Change and Travel in the Arctic

Last Chance Tourism (LCT) is an increasingly popular phenomenon whereby tourists seek encounters with vanishing landscapes, cultures, and endangered species. However, there are concerns that it is not sufficiently ecologically informed, has a large carbon footprint, and may put further pressure on vulnerable ecosystems and communities. This review specifically focuses on the Arctic, which is a major global frontier for LCT and is at the forefront of disruptive and accelerating climate change. It draws on theoretical insights from the Ecological Grief concept to chart a new research focus as well as a pathway to share empathy, concern, and sorrow between scientists, communities, and visitors. Key literature sources on LCT and Ecological Grief were selected from major international scientific journals and monographs. The major findings of the study are (i) the Arctic cryosphere is a life-sustaining entity and disruptive changes in its mechanisms currently threaten the unique ecologies and culture of the region and (ii) LCT must be attentive to the emotive accounts of loss and grief associated with cryospheric change and emplace both human and non-human voices in the narrative. These findings are relevant for LCT researchers, tourism planners, and conscious travelers in the Arctic who prioritize destination sustainability.

Global critical soil moisture thresholds of plant water stress

During extensive periods without rain, known as dry-downs, decreasing soil moisture (SM) induces plant water stress at the point when it limits evapotranspiration, defining a critical SM threshold (θcrit). Better quantification of θcrit is needed for improving future projections of climate and water resources, food production, and ecosystem vulnerability. Here, we combine systematic satellite observations of the diurnal amplitude of land surface temperature (dLST) and SM during dry-downs, corroborated by in-situ data from flux towers, to generate the observation-based global map of θcrit. We find an average global θcrit of 0.19 m3/m3, varying from 0.12 m3/m3 in arid ecosystems to 0.26 m3/m3 in humid ecosystems. θcrit simulated by Earth System Models is overestimated in dry areas and underestimated in wet areas. The global observed pattern of θcrit reflects plant adaptation to soil available water and atmospheric demand. Using explainable machine learning, we show that aridity index, leaf area and soil texture are the most influential drivers. Moreover, we show that the annual fraction of days with water stress, when SM stays below θcrit, has increased in the past four decades. Our results have important implications for understanding the inception of water stress in models and identifying SM tipping points.